NATIONAL LIBRARY OF MEDICINE
             Washington
Founded 1836
U. S. Department of Health, Education, and Welfare
Public Health Service 
 
 
         SOLD BY
    JAMES WEBSTER,
  No. 10, South Eighth street,
i      PHILADELPHIA.
e~~^^—</w^---,
\ 
 
SYSTEM OF  ANATOMY
FOR. THE USE OF
STUDENTS OF MEDICINE.
BY CASPAR WISTAR, M. D.

   PROFESSOR OF ANATOMY
          IN THE
   UNIVERSITY OF PENNSYLVANIA.
VOLUME I.            ^
                 ISf?
          PHILADELPHIA:
PUBLISHED BY THOMAS DOBSON AT THE STONE HOUSE,
        No. 41, SOUTH SECOND STREET.
          Fry and Hammerer, Printers.
               1811. 
District of Pennsylvania, to wit:
 .**•**••   BE IT REMEMBERED, That on the thirty-first day of
 ;SEAL.* October, in the thirty-sixth year of the independence of the
 »•••«•»• united States of America, A. D. 1811, Thomas Dobson, of
the said district, hath deposited in this office the title of a book, the
right whereof he claims as proprietor, in the words following, to wit:

  " A System of Anatomy for the use of Students of Medicine. By Cas-
    " par Wistar, M.  D.  Professor of Anatomy in the University of
    " Pennsylvania. Volume I."

  In conformity to the act of the congress of the United States, intitu-
led, " An act for the encouragement of learning, by securing the copies
of maps, charts and books, to the authors and proprietors of such  co-
pies during the times  therein mentioned."—And also to the act, enti-
tled, " An act supplementary to an act, entitled " An act for the en-
couragement of learning, by securing the copies of maps, charts, and
books, to the authors and proprietors of such copies during the times
therein mentioned," and extending the benefits  thereof to the arts of
designing, engraving,  and etching historical and other prints."
                                  D. CALDWELL,
                             Clerk of the district of Pennsylvania 
PREFACE.
 i HE following work is intended for the use of the stu-
dent of Anatomy when the objects which it describes are
before him.
   Convinced that the structure of the human body cannot
be properly understood without studying the real subject,
I have not attempted to communicate an idea of it by de-
scription without demonstration; and as this is the nature
of the work, there are no engraved plates in it.
   Although  a description of this  kind cannot be read in
the first instance without demonstration, it may be very
useful afterwards, by preserving the recollection of that
structure which has  been  previously studied and under-
stood.
   Minute anatomical descriptions increase the labours of
students; and, therefore, while their utility to the surgeon
is unquestioned,  they have received but little attention
from many physicians.
   The propriety of this is certainly doubtful, as anatomy
is the basis upon which  the true doctrines of physiology
must be  erected;  but if it were true  in the utmost extent,
the situation of the practice of medicine and surgery, in
this portion of the United States, requires from students
of medicine ati accurate knowledge of anatomy. 
iv                  PREFACE.
  The scattered situation of our fellow citizens does not
generally admit the practitioners of medicine to live very
near to each other; and every medical gentleman, who has
therefore the exclusive practice of a large circle, must
necessarily attend to those cases of surgery which  do not
admit of delay.  Although the great operations may be
referred to surgeons who  are distinguished  by their dex-
terity and skill, yet a large majority of practitioners must
necessarily take charge of the cases above mentioned; and
therefore ought to have a competent knowledge of anato-
my. How can they proceed without it in obscure luxations;
in wounds of deep  seated  arteries; in  cases of hernia,
which require immediate  operation, &c. &c?
  My object is to present to the students a description of
the human structure, corresponding with the method ob-
served in the demonstrations of the anatomical lectures.
  For this purpose it was not necessary to attempt a work
wholly original, as many parts of such a work would dif-
fer only in phraseology from descriptions already in use.
I have therefore adopted Innes' description of the mus-
cles; but have arranged  them differently. The works of
the first and second Monro on the Bones and the Bursae
Mucosas, have supplied me  with a great deal of matter:
and I have made a liberal use of what suited my purpose
in the valuable publications of Mr.  Fyfe and Mr. John
Bell.  The works of the French  anatomists, Sabatier,
Boyer, Gavard and Bichat, have been very useful to me;
especially those of the  last mentioned very  ingenious
author.
  I have had to regret the want of many valuable works
which  have never reached  us. The General Anatomy of
Soemmering, and the anatomical publications of Scarpa,
have not come to my hands: and although this has been 
PREFACE.
v
in some measure supplied by the numerous detached pub-
lications of Soemmering, and by compilations from Scar-
pa, I have  a strong desire to study these works, and in-
dulge the expectation of gratifying it soon.
  As a general description of the nature and structure of
bones, muscles, tendons, &c. is prefixed to each  of  the
divisions in which these parts are described, I have omit*
ted a general history of the subject, or an introduction; for
if it were not very superficial, it would anticipate these
descriptions.
  With a view to preliminary studies, it may be observed,
that an acquaintance with the chemical nature of the dif-
ferent parts of the body will be very useful to the student;
as without it, he cannot completely understand the account
of these parts.
   Here I wish it were proper to stop; but I am very sen-
sible  that it is necessary, on my own account, to proceed
one step further, and to  state, that this  work has been
composed under the continued pressure of business, which
could not be postponed. The  natural effects of this  cir-
cumstance  are but too visible in it, and require all the
indulgence that my readers can extend to them.

  17* The typographical errors  will be noticed in a  table of
errata at the close of the work. 
 
CONTENTS OF VOL. I
   PART I.

OSTEOLOGY.
                 CHAPTER I.
OF THE STRUCTURE OF BONES—OF CARTILAGES—OF THE
  FORMATION OF BONE—OF THE TERMS USED IN DESCRI-
  BING BONES.
                  SECTION I.
                                             Vag*
\JF the structure of Bones.....1
                  SECTION II.
Of Cartilages and their structure    - '   -    -   •   A
                 SECTION III.
Of the formation of Bone -    -    -       , -   -   s
                 SECTION IV.
Of the terms used in the description of Bones and their
  articulations      ...«...g

                 CHAPTER II.
OF THE SKELETON AND ITS DIFFERENT PARTS, AND THE
  INDIVIDUAL BONES OF WHICH THEY ARE COMPOSED.
                  SECTION I.
                   Of the Head     -     -     10
                 THE CRANIUM.
                    ......11
                                             14
Of the Sutures
      Os Frontis 
 
CONTENTS OF VOL. I.
   PART I.

OSTEOLOGY.
                 CHAPTER  I.
OF THE STRUCTURE OF BONES—OF CARTILAGES—OF THE
  FORMATION OF BONE—OF THE TERMS USED IN DESCRI-
  BING BONES.
                  SECTION I.

\JF the structure of Bones
                  SECTION II.
Of Cartilages and their structure
                 SECTION III.
Of the formation of Bone  -   -    -    -        •    5
                 SECTION IV.
Of the terms used in the description  of Bones and their
  articulations      .......    e

                CHAPTER II.
OF THE SKELETON AND ITS DIFFERENT PARTS, AND THE
  INDIVIDUAL BONES OF WHICH THEY ARE COMPOSED.
                  SECTION I.
                   Of the Head      -     -      10
                  THE CRANIUM.
                    ......11
                                             14
1
Of the Sutures
      Os Frontis 
viii                CONTENTS.
                                                   Page
OftheOssaParietalia     -      -      -      -      17
           Temporum.....18
      Os Occipitis     -     ...--    22
         Ethmoides      -    ....      24
         Sphenoides......28
      Foramina of the Sphenoid Bone     -      -     32
                      the face                     33
Of the Ossa Maxillaria Superiora      -      -     -    34
           Unguis     -      -      ...    38
           Malarum      ...     -       39
           Palati      ...     -               40
           Spongiosa, or Turbinata Inferiora    -     -  43
      Vomer      .......    ib.
      Maxilla inferior or lower Jaw   -    -    -       44
      Teeth.......47
      Os Hyoides     ..-.--       52
      Orbit of the Eye       -       -       -       -    54
      Cavity of the Nose       -      -      -      -  56
      Cavity of the Cranium    -     -     -      -    59
      Internal basis of the Cranium      -      -      60
      External basis of the Cranium      -       -       62
      Side of the Head      -                         64
      Form of the Cranium                            65
      Head of the Foetus     -      -      -      -    67

                    SECTION II.
                     Of the Trunk                    70
Of the Spine, and True Vertebra                       ib.
      False Vertebrae       -     -     -          -  84
      Vertebral Cavity for containing the spinal marrow  88
      Thorax—Ribs    ......     ib.
      Sternum       .......   94
      Movement of the Ribs in respiration    -    -    97
      Pelvis.......98
      Trunk of the Foetus      -      -      -     -    106

                    SECTION III.
              Of the Superior Extremities      -     108
Of the Scapula.......110
      Arm.......115
      Fore Arm       -    -     -    -    -    -    120
      Ulna       .....       ib.
      Radius      .....    122
      Hand    ......  125 
                   CONTENTS.                 ix

                                                Page
Of the Carpus    -    -.....125
      Metacarpus      -      -      -      -      131
      Thumb and Fingers.....134

                   SECTION IV.
              Of the Inferior Extremities.
Of the Os Femoris......138
      Tibia    -    -.....ib.
      Fibula      -...,..   144
      Tarsus      -      -      -      -      -    149
      Metatarsus    -    -    -    -    -    -      156
      Toes      -       -      -       -      -     158
Observations  on the General Structure of the Foot    -   ib.
Of the Sesamoid Bones    -    -    -    -    -     160
      Extremities of the Foetus                      ib.

                    PART II.
                     MYOLOGY.

                  CHAPTER I.
              OF MUSCLES IN GENERAL            162

                  CHAPTER  II.
            OF THE INDIVIDUAL MUSCLES       169 to 264
Alphabetical  arrangement of the Muscles    -    -    265

                    PART III.
 OF THE LIGAMENTS  AND MEMBRANES WHICH CON-
   NECT THE DIFFERENT PARTS OF THE BODY TO EACH
   OTHER, AND OF THE ARTICULATIONS.

                   CHAPTER I.
             OF LIGAMENTS IN GENERAL           269

                  CHAPTER  II.
A GENERAL ACCOUNT OF ARTICULATIONS AND OF  BURS*
                      MUCOSJE.

                    SECTION  I.
Of Articulations......-  273

                          b 
CONTENTS.
p»gt
                    SECTION II.
Of Bursae Mucosas     -     -    -    -  •  -    -    275

                  CHAPTER III.
           OF PARTICULAR ARTICULATIONS.
The connexion of the Head with the Vertebrae     -    276
The Articulations of the Vertebrae with each other   -   277
    Articulation of the Lower Jaw     -    -    -    280
                      Clavicle and Sternum    -     281
                      Clavicle, and Scapula   -    -   282
                      Os Humeri and Scapula   -    282
                      Elbow    -    -    -    -    284
                      Wrist  ....       285
                      Carpal and Metacarpal Bones   287
                      Fingers    ....   288
                      Ribs    ...    -      289
                      Hip Joint                      ib.
                      Knee    ....      291
                      Tibia and Fibula      -     -    293
                      Leg and Foot    ...   294
                      Astragalus and Os Calcis   -   295
                      Os Calcis and Cuboides   -    296

                  CHAPTER IV.
OF PARTICULAR LIGAMENTS, AND THE SITUATION OF THE
             INDlVmUAL BURSJE MUCOSAE.

                     SECTION I.
Enumeration of the most important Ligaments which  have not
                    been described.
Ligaments proper to the Scapula    ....   297
The Interosseous Ligament of the Fore Arm  -     -     ib.
Ligaments retaining the Tendons of the Muscles of the
  Hand and Fingers in their position    -              298
Ligaments on  the anterior part of the Thorax    -      299
          of the Bones of the Pelvis     ...     jD,
          retaining the Tendons of the Muscles of the
            Foot and Toes in their proper positions    302

                    SECTION II.
     Enumeration of the moat important Bursa Mucosa   303
Appendix to the three preceding parts     -    -    -   308
Observations on the motions of the Skeleton   -          ib' 
                  CONTENTS.                xi
                                              Page
                   PART IV.
  OF THE BRAIN AND SPINAL MARROW: OF THE EYE
                  AND THE EAR.
                  CHAPTER  I.
                  OF THE BRAIN.
                   SECTION I.
Of the Membranes of the Brain and Sinuses of the Dura
  Mater........315
                  SECTION II.
Of the Cerebrum    -.....321
                  SECTION HI.
Of the Cerebellum......332
                  SECTION IV.
Of the Basis of the Brain and the Nerves which proceed
  from it........333

                 CHAPTER II.
             OF THE SPINAL MARROW      ,      S.19

                 CHAPTER TIL
                   OF THE EYE.
                  SECTION I.
Of the parts auxiliary to the Eye    ....   343
                  SECTION II.
Of the Ball of the Eye    -    -    -   -    -    -  349
                  SECTION III.
Of the Humors of the Eye.....365
Observations on the Dissection of the Eye    -    -    371

                 CHAPTER IV.
                   OF THE EAR.
                  SECTION I.
Of the External Ear......374 
xii               CONTENTS.
                                               Page
                  SECTION II.
Of the Cavity of the Tympanum    .    -    -    -   379
Observations on the above described structure     -    387
                  SECTION III.
Of the Labyrinth.......588
Observations on the Labyrinth    -    -   -    -   396

                    PART  V.
 OF THE GENERAL INTEGUMENTS: OR THE CELLULAR
            MEMBRANE AND THE SKIN.

                  CHAPTER I.
           OF THE CELLULAR MEMBRANE          398

                  CHAPTER II.
                   OF THE SKIN.
                   SECTION I.
Of the Cutis Vera......40S
                   SECTION II.
Of the Rete Mucosum......408
                  SECTION III.
 Of the Cuticula or Epidermis     -     -    -    -   413 
SYSTEM  OF ANATOMY.
     PART  I.

OSTEOLOGY.
                   CHAPTER I.

OF THE STRUCTURE OF BONES—OF CARTILAGES—OF THE
 FORMATION OF BONE—OF THE TERMS USED IN DESCRI-
 BING BONES.
                    SECTION I.
             Of the Structure of Bones.
 1 HE human bones, in a recent adult subject, are of a dull
white colour; their texture is varied, not only  in different
parts of the skeleton, but in different places of the same
bone. Thus, in long bones, the middle portion is compact
with a cavity in the center, the extremities are cellular or
spongy, and the central cavities are occupied by a network
formed of thin plates and fibres.  In flat bones, the external
surfaces are composed of firm plates, but the internal sub-
stance is cellular.
  A fibrous  structure is very  obvious  in the bones of
young subjects, and in  some  bones  which  have  been
slightly calcined.
  A lamellated structure  may also be  demonstrated in
many bones.
  Vol. I.                  A 
2                 Structure of Bones.

  In the firmness of their texture and their general aspect,
bones resemble inorganic matter, but there are the strong-
est proofs of their organization.
  For example, if a bone be macerated in certain acid
liquors, the earthy matter will be dissolved, and a membra-
nous or cartilaginous substance will remain, resembling
the  bone in form and size.
  If the bones of a  young  subject, after being injected,
be treated  in  the  same way, this membranous substance
will appear to be very vascular—when the injection has
been successful, it  will appear uniformly reddened bv the
great number  of vessels which are filled with the matter
of injection. These vessels discharge blood when the peri-
osteum is removed from the surface of bones, in the living
subject, and they  also form granulations upon bony sur-
faces that have been thus denuded.
  The existence of absorbent vessels, and even of nerves,
in bones, is equally certain with that of the blood vessels,
but they are not easily demonstrated.
  In a sound state bones have no sensibility, but pain  is
often felt in them when  they are diseased.
  Modern chemistry has ascertained that the earthy mat-
ter of bones is principally a phosphate of lime; carbonate
of lime, in  a smaller quantity, is also found in them. These
earthy substances compose near one half of the  weight  of
bones, and a large  proportion of the remainder appears to
be gelatinous and cartilaginous matter.
  Bones are invested with a firm membrane denominated
periosteum, which is  of a  fibrous texture, and in  some-
places  may be  separated into different  lamina. The exter-
nal surface of the periosteum is connected with the contigu-
ous parts by cellular  membrane, the internal surface  is
connected with the bone  by a great number of fibres and of 
                  Structure of Bones.                3

bloodvessels. The orifices of these vessels  appear when
the periosteum  is  separated  from  bones in the living
subject.
   This membrane covers the whole  bony surface, except
those parts which are invested by cartilages, and the cap-
sular ligaments of joints; those which are occupied by the
insertion of tendons and ligaments, and the bodies of the
teeth. It appears most intimately connected with the sur-
faces of spongy bones, and the extremities of the  long
bones. In a sound state it has very little sensibility; but in
some cases  of disease it appears  to be very sensible; of
course it must be supplied with nerves, although  several
expert anatomists have declared they could not trace them.
   It is probable that the  principal use of the periosteum
is to transmit vessels to the bones for their nourishment,
but death, or exfoliation of the surface, does not always
take place when the periosteum is removed from a por-
tion of bone.
   At the extremities of the long bones, the foramina for
the transmission of bloodvessels and  fibres are  much
larger than they are in the middle; but there is an oblique
canal near the middle of these bones, which transmits ves-
sels to the internal membrane.
   The surface of the internal cavities and cells of bones
is lined by a membrane,  more delicate and more vascular
than the periosteum, which contains the medullary matter
that is always  found in their cavities.
   It has been  said that in some circumstances this mem-
brane has had great sensibility, but the reverse is the case
in common.
   The medullary matter in the large cavities of bones has
a strong resemblance to adeps.  That which is in the cells
at the ends of the long bones appears more fluid. In young
animals it is slightly tinged with a red colour. 
4            Cartilages and their Structure.
                     SECTION II.
          Of Cartilages and their Structure.
   CARTILAGES are white  elastic substances, much
 softer than bones, in consequence of a  smaller quantity
 of earth entering into their composition.
   Their structure is not so  evidently  fibrous as that of
 bones; yet by long maceration,  or by tearing  them asun-
 der, a fibrous disposition is perceptible.
   In articular cartilages their  fibres are parallel to each
 other, and directed towards the  cavities  of the respective
joints.
   Their vessels are extremely  small, though they can be
 readily injected in cartilages where bone is beginning to
 form.  The vessels of the cartilages of the joints, however,
 seem entirely  to  exclude  the  red  blood; no anatomist
 having yet been able to inject them.  They have no can-
 celli, nor  internal  membranes,  for lodging  marrow; no
 nerves can be traced into them; nor do  they  possess any
 sensibility  in the sound state.
   Upon their  surface,  there is  a thin membrane termed
 perichondrium, which in cartilages supplying the place of
 bone,  as in those of the ribs or at the ends  of the long
 bones in children, is a continuation of the periosteum, and
 serves the same general purposes to cartilage  as this does
 to bone.
   Upon the surface of articular cartilages, the perichon-
 drium is a reflection of  the inner surface of the  capsular
iigament,  and  is so very thin, and adheres so closely, as
 to appear like part of the cartilage itself.
   One  set of cartilages supply  the place of bone, and by
 their flexibility admit of a certain degree of motion, while
 their elasticity recovers their natural position, as in the
 nose, larynx, cartilages  of the ribs, &c. 
                  Formation of Bone.                 5

  Another set, in children, supply the place of bone, until
bone  can be formed,  and afford  a nidus for the osseous
fibres to shoot in, as in the long bones of children.
  A third set, and that the most extensive, by the smooth-
ness and lubrication of their surface, allow the bones to
move readily, without any abrasion, as in the cartilages
of the joints.
  A fourth set supply the office both of cartilage and liga-
ment, giving the elasticity of the former and flexibility of
the latter, as in the bones of the spine and pelvis.


                    SECTION  III.
             Of the Formation of Bone.
  THE generality of bones, and particularly those which
are long, are originally formed in cartilage; some, as those
of the skull, are formed between membranes, and the teeth
in distinct bags.
  When ossification is about to begin in a particular part
of a cartilage, most frequently in the centre, the arteries,
which were  formerly transparent, become dilated, and
receive the red blood from which the osseous matter  is
secreted.  This matter retains, for some time, the form of
the vessels which give it origin, till more arteries  being
by degrees dilated,  and more osseous matter  deposited,
the bone at length attains its complete form.
  During the  progress of  ossification, the surrounding
cartilage by degrees disappears; not by being changed into
bone, but by an  absorption of its parts, the new-formed
bone occupying its place.
  The ossification  of broad bones, as those of the head,
begins by one  or more points,  from which the osseons
fibres issue in rays. 
6
Terms used in the
   The ossification of long bones, as in those of the extre-
 mities, begins by central rings, from which the fibres ex-
 tend towards the ends of the bones.
   The ossification of spheri-formed bones begins bv one
 nucleus, as in the wrist; and that of irregular shaped bones
 by different nuclei, as in the vertebrae.
   Some bones are completely formed at the time of birth,
 as the small bones of the ear.
   The generality of bones are incomplete until the age of
 puberty, or between the fifteenth and twentieth year, and
 in some few instances until a later period.
   In children, many parts of bones, particularly the  ends
 of long bones, are distinct from the bodies; they are called
 epiphyses, and can be readily separated from the bodies of
 bones by boiling, or by maceration in water.
   The  epiphyses begin to appear after the  body of the
 bone is ossified,  and are themselves  ossified at seven or
 eight years of age, though their external surface  is  still
 somewhat cartilaginous.
   They a-c joined to the body of the bone by cartilages,
 which are thick in children, but gradually become thinner
 as ossification advances; till at last, in the adult, the exter-
 nal marks of division  are not to be seen, though frequently
 some mark of distinction may be observed in the cancelli.


                    SECTION  IV.
   Of the Terms used in the Description of Bones
              and their Articulations.
  THE study of this subject has been rendered more  dif-
ficult by the unnecessary introduction of many hard words;
but some of these words are so  generally used, that they
ought to be understood by the  student of anatomy. 
                 Description of Bones.               7

  The word process signifies any protuberance or emi-
nence arising from a bone.
  Particular processes receive names from their supposed
resemblance to certain objects; and their names are very
often composed of two Greek words;  thus the term cora-
coid^ which is applied to a well known process, is derived
from the  Greek  words *«g*|, a crow,  and «/?«?, resem-
blance.
  If a process has a spherical form it is called a head. If the
head is flattened on the sides, it is denominated a condyle.
  A rough protuberance is  called a tuberosity. A ridge
on the surface of a bone is called a spine.
  The term apophysis is nearly synonymous with pro-
cess. It signifies a protuberance that has grown out of the
bone, and  is used  in  opposition to the term epiphysis,
which signifies a portion of bone  growing  upon another,
but distinct and separable  from it; as is the case in infancy
with the extremities of the long bones.
  The cavities on the  surfaces of bones are named in the
same way, as will appear  by  a reference  to the  Glossary
at the end of this work.
  Words of this kind have  been used most profusely in
the descriptions of articulations, and here also their util-
ity  is doubtful. Therefore, for many terms used on this
occasion,  the  reader is referred to the Glossary; but the
following are necessary to be understood.

  Symphysis does  not merely imply the  concretion of
     bones originally separate, as its derivation imports;
     but it is  understood also to mean the connexion of
     bones by intermediate  substances. Thus there  are
     three species of symphysis, particularly noticed, viz.
  Synchondrosis) when bones are connected to each other
     by cartilage; as the ribs and sternum. 
8                  Terms used, &c.
  Synneurosis, when they are connected by ligaments, as
    in the movable articulations.
  Syssarcosis when they are connected by muscle.

  The different articulations are of two kinds, viz. Synar-
throsis and Diarthrosis.
  Synarthrosis is the name of that kind of articulation
    which  does not admit of motion. There are three
    species of synarthrosis, viz.
  Suture, when the indented  edges of the two bones are
    received into each other, as is the case with the bones
    of the cranium.
  Gomphosis, when one bone  is  fixed in another, like a
    nail  in a board, as the teeth in their sockets.
  Schindylesis, when the thin edge of one bone is received
    into a narrow furrow of another, as the nasal plate of
    the ethmoid in the vomer.

  Diarthrosis is the name of that kind of articulation
    which admits of motion. Of these articulations there
    are three species, viz.
  Enarthrosis,  when  a large head  is received in a deep
    cavity, as the head of the thigh bone in  the aceta-
    bulum.
  Arthrodia, when a head is connected with a superficial
    cavity.
  Ginglimus, when the extremities of bones apply to each
    other so as to form a hinge.

  But most of the important joints have so many pecu-
liarities that  they cannot be understood without studying
them  separately. It may therefore be doubted whether the
classification and arrangement of joints is any way neces-
sary. 
CHAPTER II.
OF THE SKELETON AND ITS DIFFERENT PARTS, AND THK
   INDIVIDUAL BONES OF WHICH THEY ARE COMPOSED.

 A HE  bones of an animal arranged  and connected to
each other in their natural order, separate from the soft
parts, compose a skeleton.
  The  skeleton is said to be natural when the bones are
connected by their own ligaments, which have been allow-
ed to remain for that purpose.
  It is called artificial, when the bones  are connected with
wire, or any foreign substance.
  The artificial skeleton is best calculated for studying the
motions of the different bones, because the dry and hard
ligaments of the natural skeleton do not allow the bones to
move;  but the bones of young animals do not admit of
the preparation necessary for an artificial skeleton, as their
epiphyses would separate, and they are therefore  formed
into natural skeletons.
  The study of the skeleton and its mechanical properties,
as a piece of machinery, is absolutely necessary to a per-
fect understanding of many motions of the  body, and of
the action and cooperation of muscles; but any observa-
tions on this subject will be  better understood after the
individual bones and the muscles have  been described.

  The  skeleton  is divided into  the head, the  trunk, the
superior and the inferior extremities.
  Vol. I.                     B 
10
The Head.
                     SECTION I.
                    Of the Head.
   THE head comprehends the Skull, or Cranium, and
 Face.
   The  cranium consists of eight distinct bones, which,
 when placed in their natural order, form a large  spheroi-
 dal cavity for containing the brain, with  many foramina
 or apertures that communicate with it.
   These bones are of a flattened form. They are composed
 of two lamina or plates called tables, with a cellular struc-
 ture between them, called medituUium, or diploe. The
 external table is supposed to be more firm than the inter-
 nal.
   The periosteum which is on their external surface is
 called pericranium. Internally, the dura  mater or mem-
 brane which covers the brain, supplies the place of perios-
 teum.
  There are eight of these bones, which are thus denomi-
 nated.  Os Frotuis, Ossa Parietalia,  Ossa Temporum, Os
 Occipitis, Os Sphenoides, and Os Ethmoides. The two last
 are called common bones, to denote that they are connect-
 ed with the bones of the face as well as with those of the
cranium.
  The os frontis forms the whole fore part of the vault of
 the cranium;  the two ossa parietalia form the upper and
middle part of it;  the ossa temporum compose the lower
part of the sides; the os occipitis makes the whole hinder
part, and some of the base; the os ethmoides is placed be-
tween the orbits of the eyes, and the sphenoides  extends
across the base of the cranium. 
The Sutures.
U
                     The Sutures.
   THE above bones  are joined to each other by five
sutures; the names of which are the Coronal, Lambdoidal,
Sagittal, and two Squamous.
   The  coronal suture  is extended over the head, from
within about an inch of the external angle of one eye, to
the like distance from the other; which being near the
place where the ancients wore their garlands, this suture
has hence got its name. Though  the indentations of this
suture are conspicuous in its upper part, yet an inch or
more of its end on each side has none, but is squamous
and smooth.
   The  lambdoidal suture  begins  some way below, and
farther back than the vertex or crown of the head, whence
its two legs are  stretched obliquely downwards, and to
each  side, in  form of the Greek letter A and  are now
generally said to extend themselves to the  base of the
skull: but formerly, anatomists reckoned the proper lamb-
doidal suture to terminate at the squamous sutures; and
the portion continued from them on each  side, where the
indentations are less conspicuous  than  in the upper part
of the  suture, they called additamentum sutune  lamb-
doidis.
   This  suture is sometimes very irregular, being  made
up of a great many small sutures, which surround a num-
ber of insulated bones, that are generally  more conspicu-
ous on  the external surface of the skull than internally.
These bones are commonly called triquetra or wormiana;
their formation is owing to a greater than ordinary num-
ber of points of ossification in the skull, or to the ordinary
bones of the cranium not extending their ossification far
enougha or soon  enough;  in  which case, the unossified 
|2                  The Sutures.
interstice between such bones  begins  a  separate ossifica-
tion, in one or more points; from which the ossification is
extended to form  as  many distinct  bones as there were
points, which are indented into the large ordinary bones,
and into each other.
  The sagittal suture is placed longitudinally, in the mid-
dle  of the  upper part of the skull, and commonly termi-
nates at the middle of the coronal and of the lambdoidal
sutures; between which  it  is said to be placed, as an ar-
row  is between  the  string and the bow.  This suture is
sometimes continued through the middle of the os frontis
down to the root of the nose.
  The squamous agglutinations, or false sutures, are  one
on each side, a  little above  the  ear, of  a semicircular
figure, formed by  the  overlapping (like one  scale upon
another)  of the  upper part of the temporal bones on the
lower part of the parietal, where, in both bones, there are
a great many small risings and furrows, which are indent-
ed into each other; though these inequalities do not appear
till  the bones are  separated.  In some skulls, indeed, the
indentations here are as conspicuous externally as in other
sutures; and  what is commonly called the posterior part
of this squamous suture, always has the evident serrated
form; and therefore is reckoned by some a distinct suture,
under the name of additamentum posterius suturse squa-
mosa?.
  The squamous suture is not confined to the conjunction
of the temporal and parietal bones, but is made use of to
join all the edges of the  bones on which  each temporal
muscle is placed:  for  the  two parts of the  sphenoidal
suture which are continued from the  anterior end of the
common squamous  suture just now described, one of
which runs perpendicularly downwards and the other ho- 
The Sutures.
13
rizontally forwards; and also the lower part of the coronal
suture already taken notice of, may  all be justly said to
pertain to the squamous suture.
  This  structure appears to depend upon the pressure of
the temporal muscle externally, and the resistance of  the
brain within, which make the bones so thin, that their
edges opposed to each other are not sufficiently thick to
stop the extension of their fibres in length, and thus to
cause the common serrated appearance of sutures; but the
narrow edge of the one bone slides  over the other. The
squamous form is  also more  convenient  here;  because
such thin edges of bones,  when accurately  applied one to
another, have scarce any rough surface, to obstruct or hurt
the muscle  in  its contraction; which is still further pro-
vided for,-by the manner of laying  these  edges on each
other; for, in  viewing their outside, we see the temporal
bones covering the  sphenoidal and parietal, and  this  last
supporting the sphenoidal, while both mount on the fron-
tal: from which  disposition it is evident, that, while  the
temporal muscle is contracting, which is the only time it
presses strongly in its motion on the bones, its fibres slide
easily over the external edges.  Another advantage of  this
structure is, that the whole part is made stronger by the
bones thus supporting each other.
  The  indentations of the sutures are not so strongly
marked on the inside as on the  outside of the cranium;
and sometimes the bones seem to be joined by a straight
line: in  some skulls, the  internal surface  is found entire,
while the sutures are manifest without. By this mechan-
ism, there is no risk of the sharp points of the bones grow-
ing inwards, since the external serrae of each of the con-
joined bones rest upon the internal smooth edged table of
the other. 
 14                   Os Frontis.
   The advantages of the sutures are these:  1. The cra-
 nium is more easily formed and extended into a spherical
 figure, than if  it had  been one continued bone. 2. The
 bones which are at some distance  from each  other at
 birth, may then yield, and allow to  the head a change of
 shape, accommodated to the  passage it is engaged in.
 Whence, in difficult parturition, the bones of the cranium,
 instead of being only brought into contact, are.sometimes
 made to mount one upon the other.

                      Os Frontis.
  The os frontis, as its name imports, forms the front part
 of the cranium  and the upper portion of the orbits of the
 eyes.
  The external surface of this bone is smooth at its upper
 convex part;  but several processes and cavities  are  ob-
 servable below: for at the angles of  each orbit, the bone
 projects to form four processes, two internal, and as many
external; which are  denominated  angular.  Between the
 internal  and external angular processes on each  side, an
 arched ridge is extended, on which the  eyebrows are
 placed. Very little above the internal end of each  of these
superciliary  ridges a  protuberance  may  be remarked, in
 most skulls, where there are large cavities within the bone,
 called sinuses.  Between the internal angular processes,
 and in front of the vacuity for the ethmoid bone, the edge
 of the os frontis is serrated for articulation with the ossa
 nasi, and the processes of the upper  maxillary bone; and
 from the centre of this surface a small process arises,
 which is  called  the nasal spine. From the under part ot
 the superciliary ridges, the frontal bone runs a great way
 backwards: these parts are called orbitar processes, which,
 contrary  to the  rest of this bone, are concave  externally. 
                      Os Frontis.                   15

for receiving the  globes of the eyes, with their muscles,
fat, &c.
   In each of the  orbitar processes, behind the middle of
the superciliary ridges, a considerable sinuosity is observ-
ed, where the glandula lacrymalis is  lodged.  Near each
internal angular process, a small pit may be remarked,
where the cartilaginous pully of the superior oblique mus-
cle of the  eye is fixed.  Between the two orbitar processes,
there is a  large vacuity which  the  cribriform  part of  the
os ethmoides occupies. The frontal bone has frequently
little caverns formed in it where it is joined to the ethmoid
bone.
   The foramina, or holes, observable on the external sur-
face of the frontal bone, are three in each side.
   On each superciliary ridge,  at the distance of one-third
of its length from the nose,  is a foramen, or a notch,
through which passes  a branch of the ophthalmic artery
and a small nerve.
   In the internal edge of each orbitar process are two other
foramina denominated anterior and posterior orbitar fora-
mina, which lead to the nose;  sometimes  there  are only
notches or grooves, which join  with similar grooves in  the
bones below, and form foramina.
   The internal surface of the os frontis is concave, except
at the orbitar processes, which  are convex, and support  the
anterior lobes of the brain. This surface is not so smooth
as the external;  for  the larger branches of the arteries of
the dura mater make some furrows in its sides and back
parts, and its lower and fore parts are marked with  the
convolutions of the  anterior lobes of the brain.  In  the
middle of the concave  internal surface is a groove, which
is small at its commencement, and gradually increases in
diameter as it proceeds upwards. This is formed by  the 
 \§                   Os Frontis.

 superior longitudinal sinus; at its commencement is a ridge
 to which the beginning of the falciform process of the dura
 mater is attached. At the root of this ridge is a small fo-
 ramen, sometimes formed jointly by this bone and the eth-
 moid: it  is denominated foramen ca-cum; in it a small pro-
 cess of the falx is inserted, and here the longitudinal sinus
 begins.
  The frontal sinuses are  formed by the separationof the
 two tables of this bone at  the part above the nose and the
 internal  extremities of the superciliary ridges.   In the
 formation of these  cavities, the  external table commonly
 recedes most from the general direction of the bone.
  These cavities are divided by a perpendicular bony par-
 tition, which is sometimes perforated and admits a com-
 munication between them.  Their capacities are often very
 different  in different persons, and on  the different sides of
 the same person. In some persons whose foreheads were
 very flat, they are said to have been wanting. They com-
 municate with the nose by  means of a canal in the  cellular
part of the os ethmoides.
  The os frontis is  composed of two tables, and an inter-
mediate  diploe,  as the other bones of the cranium  are:  it
 is of a mean thickness between the os occipitis and the pa-
rietal  bones;  and is nearly equally dense throughout, ex-
 cept at the orbitar processes, where, by the action of the
 eye on one side, and pressure of the lobes of the brain on
the other, it is made extremely thin and diaphanous, and
the diploe is  entirely obliterated.  In  this place there is so
weak  a defence for the brain, that fencers esteem a push
 in the eye mortal.
  In  such skulls as have the frontal bone divided by the
 sagittal suture, the  partition separating these  cavities is
 evidently composed of two plates, which easily separate. 
Ossa Parietalia.
n
  Each of the frontal sinuses opens into one of the upper-
most cells in the anterior part of the ethmoid bone, and
this cell communicates  with  the  middle channel of  the
nose under the anterior end of the os turbinatum superius.
  This  bone is united with the parietal, ethmoidal and
sphenoidal bones of the head; and with the nasal, maxil-
lary, unguiform and malar bones of the face.

                   Ossa Parietalia.
  Each of the two ossa parietalia is an irregular squarej
its upper and front edges being longer than the one behind
or below. The inferior edge is concave, the middle part
receiving the upper round part of the temporal bone. The
angle formed by the under and anterior edges, is so ex-
tended, as to have the appearance of a process.
  The  external surface of each os parietale is  convex.
Upon it, somewhat below the middle height of the bone,
there is a transverse arched ridge, generally of a whiter
colour than any other part of the bone; from which, in
bones that have strong  prints of muscles, we see a great
many converging furrows, like so many radii  drawn from
a circumference towards a center. From this ridge of each
bone  the temporal muscle rises: and, by the pressure of
its fibres, occasions the furrows just now mentioned.  Be-»
low these we observe, near the semicircular edges, a great
many risings  and depressions, which are joined to  like
inequalities on the inside of the temporal bone, and form
the squamous suture. Near the upper edges of these bones,
towards the hind part, is a  small hole in each, through
which a vein  passes from the teguments of the  head to
the longitudinal sinus.
   On the inner concave surface of the parietal bones, we.
see a great many deep furrows, disposed  somewhat like
   Vol. I.                  C 
18                 Ossa Temporum.

the branches of trees:  the furrows are largest and deepest
at tlu- lower e^ge of each os parietale, especially near  its
anterior angle, where a complete canal is sometimes form-
ed.  On the inside of the upper edge of the ossa parietalia
there is a large sinuosity, frequently larger "m the bone of
one side than of the other,  where the  upper  part of the
falx  is fastened, and  the  superior  longitudinal sinus  is
lodged. Part of the lateral  sinuses generally makes a de-
pression near the angle formed by the lower and posterior
edges of these bones; and the pits made by the convolu-
tions of .the brain are in no part of the skull more frequent
or more conspicuous, than in the internal surface of these
bones.
  The ossa parietalia are the most equal and smooth, and
are  among the  thinnest bones of the  cranium; but they
enjoy the general structure  of two tables and diploe most
perfectly.
  These bones are joined at their foreside to  the os fron-
tis;  at their long inferior angles, to the sphenoid bone; at
their lower edge, to the ossa temporum; behind, to the os
occipitis, or ossa triquetra;  and above, to one another.

                    Ossa  Temporum.
  The ossa temporum are situated at the lateral and infe-
rior parts of the cranium;  each  of them is divided into
three portions, a superior or squamous, a posterior  or
mastoid, and a middle or petrous.
  The squamous portion is nearly semicircular in form
and very thin; its  edge is sharp, and the inner table ap-
pears pared  away to form the squamous suture with the
corresponding edge of the parietal bone. Its external sur-
face is covered by the temporal muscle. At the lower and
anterior part of this surface the zygomatic process arises; 
                   Ossa Temporum.                19

it proceeds forward to join the cheek bone and  form an
arch under which the temporal muscle passes.
  A t the base of the process is the cavity for the condyle
of the lower jaw.  Immediately before this cavity is a
tubercle or protuberance, which forms part of the articu-
lating surface on which the condyle rises when the jaw is
opened.  In the  posterior part of the cavity is a fissure, in
which part of the ligament of this articulation is  fixed.  In
this  fissure  is an aperture which communicates with the
cavity of the tympanum  of the ear, and  is  occupied by
a small nerve called chorda tympani, and also by the ante-
rior muscle of the malleus,  one of the small  bones of the
ear.
  The internal  surface of the squamous  portion is con-
cave; it is marked by pits and small eminences, which cor-
respond with the convoluted surface of the brain; and also
by impressions of the arteries of the dura  mater.
   The mastoid or occipital portion is the smallest of the
three parts of the bone;  it consists of an angular portion,
which occupies  a vacuity between the occipital and parie-
tal bon  ; and of the mastoid process.  The mastoid pro-
cess has some resemblance  to the nipple; it  is  composed
internally of cells,  which communicate with the cavity of
the tympanum.  On the internal side of its base is a deep
groove in which the posterior belly of the digastric muscle
is inserted.  Behiiv! this process is the mastoid hole, which
transmits a vein, and sometimes a small artery.
   On he intern 1 su   ace of this portion is a large groove,
which is formed by the  lateral  sinus. The mastoid hole
above mentioned opens into this groove.           ,
   The petrous portion, which is  situated  between  the
 squamous and  mastoid,  resembles  a triangular pyramid
 lying on one of its sides. When in its proper  position it 
2©                Ossa Temporum.
projects inward and forward. The two upper sides form a
portion of the internal surface of the base of the cranium.
The angle formed by these surfaces is very prominent, and
dh ides the fossa for the middle lobes  of the brain, or ce-
rebrum, from those which contain the cerebellum*
   One of these sides of the petrous  portion  looks  for-
ward  and  outward,  the other backward   and inward.
Each of them has eminences and depressions to corre-
spond with the convolutions of the brain. Near the middle
of the anterior side is a small  furrow, and a foramen de-
nominated Innominatum, or Hiatus Fallopii, which trans-
mits the vidian nerve to  the aqueduct of Fallopius.
   About the middle of the posterior side is the large aper-
ture called meatus auditorius  internus.  The  bottom of
this  cavity is perforated by several foramina; the largest
and uppermost of which is tie orifice of a winding canal,
called improperly the aqueduct of  Fallopius, which trans-
mits the portio dura of  the seventh pair of nerves.  The
other foramina transmit  the fibre  of the portio mollis of
the same nerve.  Posterior to the orifice of the meatus in-
ternus  is a depression with a foramen  in it, which is the
orifice of a proper aqueduct, or canal that passes from the
vestibule of the ear.
   The inferior side of the petrous portion forms a part of
the external surface of the basis of the cranium. On the
back part of it is the external orifice of the  canal through
which the portio dura passes.  It  is called foramen stylo
mastoideum. Before this foramen is a long and slender
styloid process, which varies from one to two inches in
length; it projects almost perpendicularly from the basis
of the cranium, and gives origin to a muscle  of the tongue,
of the os hyoides, and of the pharynx,  and also to several
ligaments. 
                    Ossa Temporum.                21

   On the inside of this process, and rather before it, is the
jugular fossa, which,  when  applied to a corresponding
part of the occipital bone, makes  the posterior foramen
lacerum, through which the internal jugular vein, and the
eighth pair of nerves pass out. A small spine often pro-
jects into this foramen from the temporal  bone, and sepa-
rates  the nerve from the vein;  the nerve  being  anterior.
Before this spine, or partition, is the orifice of the second
aqueduct of the ear, the aqueduct of the cochlea. This
jugular fossa is at the termination of the groove, in the
internal  surface of the bone, made by the lateral sinus. At
a small distance before the jugular fossa is the commence-
ment of the carotid canal, which makes  a curve almost
semicircular, and then proceeds in a horizontal course to
the anterior extremity of the bone; through this winding
canal passes the carotid artery,  and the filaments from the
fifth and sixth pair of  nerveB which are the beginning of
the intercostal nerve.
   Between the carotid canal and the cavity for the condyle
of the lower jaw, at the junction of the anterior part of the
squamous  portion with the petrous portion of this bone,
is a very rough aperture, the bony margin of which ap-
pears  broken;  this is  the orifice of the bony part of the
Eustachian tube, or passage from the  throat  to  the  ear.
This canal is divided lengthways by a thin bony plate; the
upper passage contains the internal muscle of the malleus
bone of the ear; the lower and largest canal is the bony
part of the Eustachian tube.
   The external passage to the  ear is situated between the
zygomatic and the mastoid processes.  The orifice is large
and smooth above, but rough below. The direction of the
canal is obliquely inward and forward.
   The temporal is articulated  with the parietal, occipital 
22                  Os Occipitis.
and sphenoidal bones, and by its zygomatic process, with
the malar bone.

                     Os Occipitis.
  The occipital bone is situated at the posterior and infe-
rior part of the cranium; it is of a rhomboidal figure, with
convex and concave surfaces.
  The upper part of the external  surface is smooth;  at a
small distance above the middle of the bone is the external
occipital protuberance, with a curved line on each side of
it. Near the middle of the bone the trapezii muscles are
attached to this line, and externally, on each side, the occi-
pito frontalis, and the sterno mastoideus.  Under this line
is a d pression, on each sidi, into which are inserted the
complexus and the splenius capitis muscles.
  Below this is the inferior curved line, and still lower is
a muscular  depression to which the rectus minor posticus
is attached,  on each side near the middle; and the rectus
major, and obliquus superior, near the end.
   Below the protuberance is a spine which passes down
the middle of the bone, and at the lower extremity of this
spine is the  great occipital foramen, which forms the com-
munication  between the cavities  of  the cranium, and the
vertebral column.  This great  opening transmits the me-
dulla spinalis with its membranes, and the accessory nerves
of Whit*.
   It is rather of an oval form, and the occipital condyles
are situated anteriorly on its edges. These condyles are of
an irregular oval figure; they are not parallel, but incline
towards each other anteriorly.  Their articulating surfaces
are oblique, looking downward  and outward;  they are
received into corresponding cavities of the atlas,  or first
cervical vertebra,  and form with  them the articulation of 
                     Os Occipitis.                   23

the head and tied. From the oblique position of their
articulating surfaces, as well as the length of their liga-
ments and  the inclination of their axes towards each other,
it results, that th*ir motion is confined to flexion and ex-
tension.  On the internal sides of these condyles is a rough
surface to  whichi are attached the  strong ligaments that
come from the processus dentatus of the second vertebra
of the neck.
   Behind each condyle is a depression in which is situated
the posterior condyloid foramen, for transmitting the ver-
tebral veins; and at their anterior extremities are two large
foramina, through which pass the ninth pair of nerves.
   On the internal surface of the os occipitis is the crucial
ridge, to which are attached the falx, or vertical, and the
tentorium,  or horizont-al process of the dura mater.
   The  groove made by  the longitudinal sinus continues
from the sagittal suture along the upper limb of this cross.
Sometimes it is on the  side of the  ridge, and sometimes
the ridge  is depressed, and  it occupies its place; at the*
center of the  cross, the groove for the longitudinal sinus
divides  into two grooves, for the  lateral sinuses; these
form the  horizontal  limbs  of the  cross, and proceed
towards the foramen  lacejum where  the  lateral sinuses
emerge from the cavity of the cranium.  The lower limb
of the cross is formed by a spine which proceeds from the
center to the great occipital, foramen, and supports the
falx of the  cerebellum. The internal  surface of the bone is
divided by the cross into four portions^ each of which is
considerably depressed. The two upper by the posterior
lobes of the cerebrum, and the lower by those of the cere-
bellum.
  This circumstance  occasions  great inequality  in  the
thickness of the bone, as the depressed portions are ex- 
 24                   Os Ethmoides.
 tremely thin, while the ridge adds greatly to the thickness,
 especially at the center of the cross, which is opposite to
 the great external protuberance.
   Before the great occipital foramen is the cuneifor n pro-
 cess, which is thick and substantial; it terminates by a broad
 truncated extremity, which is articulated with the body of
 the sphenoid bone.  The  internal surface of the cuneiform
 process is somewhat excavated, and forms a large superfi-
 cial groove for the medulla oblongata; on each side of this
 groove  is a small furrow for the inferior petrous sinuses.
   The two upper edges of the occipital bone are  serrated,
 to articulate with those of the parietal, and form the lamb-
 doidal suture. The  inferior edges  are divided  into  two
 portions by a small prominence called the jugular eminence;
 the upper and posterior portion  is also serrated for arti-
 culation with the mastoid portion of the temporal; the in-
 ferior portion, which is hot serrated, applies to the petrous
 portion  of the temporal bone, and  a notch in it contributes
 to the formation of the foramen lacerum.
   The upper angle of this bone is acute, the lateral angles
 are obtuse, and the inferior truncated. It is articulated with
 the parietal, the temporal, and the sphenoidal bones.

                    Os Ethmoides.
   The os ethmoides  is truly one of the most curious bones
of the human body.  It appears almost a cube, not of solid
bone, but exceedingly light and spongy, and consisting of
many convoluted plates, which form a network like honey-
comb. It is  firmly inclosed in the os  frontis, betwixt the
orbitary processes of that bone. One horizontal  plate re-
ceives the olfactory nerves, which  perforate that plate with
such a number of small holes, that  it resembles  a sieve j
whence  the bone is named cribriform, or ethmoid. Other
i 
                      Os Ethmoides.                  25

 plates are so arranged that they form a cellular structure,
 on which the olfactory nerves are   panded b  means of a
 particular membrane; while an additional plat  , appropri.
 ated to the nose, descends  into that cavity in a perpendicu-
 lar direction, and forms  a large  proportion of the partition
 which divides  it into two chambers.
   The cribriform plate is situated in the anterior part of
 the basis of the cranium. The cellular part occupies most
 of the space between the orbits  of  the eyes, and thr per-
 pendicular plate is  to be found in the septum of the nose.
   The ethmoid bone, for the purposes of description, may
 be divided into three parts, viz. the cribriform plate, the
 nasal or perpendicular lamella, and the cellular portions.
   The cribriform plate is oblong in shape, and firm in its
 structure; in the  middle  of the  anterior extremity the
 crista galli projects from its upper surface, dividing it into
 two lateral portions, each of which is  rather concave, and
 occupied by  the bulbous extremity of the olfactory nerve:
 it is  perforated by many  foramina, which  transmit the
 fibres of the aforesaid nerve. Near the crista galli, on each
 side, there is a small fissure, through which passes a ner-
 vous fibre derived  from  the opthalmic branch of the fifth
 pair.—The crista galli varies in  size in different subjects:
 the beginning of the falciform process of the dura mater
 is attached to it, and with the opposite part of the os fron-
 tis it forms the foramen  caecum, already mentioned.  It is
 very conspicuous in the basis of the cranium.
   The nasal plate of the ethmoid bone seems to be conti-
 nued downwards from the  crista galli through  the cribri-
form plate. It is thin, but firm; it forms the upper portion of
the septum of the nose, and to  complete the partition, it
unites with the  vomer and with a plate of cartilage before.
It is very often inclined  to one  side, so that the nostrils
are not of equal size.
   Vol. I.                 D 
26                  <9» Ethmoides.
  At a sma1! distance from this perpendicular plate, on
each side of it,  the cellular portions originate from the
lower surface of the  cribriform plate;  they extend from
before backward, and are as long as the ethmoid bone;
their breadth, between the eye and the cavity of th  nose,
varies in different subjects, from half an inch to more; they
extend downwards from the root of the nose,  or from the
cribriform  plate, more than  half way  to the  roof of the
mouth.  Their external surface on each side forms a part
of the surface of the orbit of the eye, and is called os pla-
num; their internal surface forms part of the external late-
ral surface of each nostril. This surface extends the whole
depth of the nostril, from before backward, but in many
skeletons is extremely imperfect, owing to the great brittle-
ness of the  bony plates of which  it is  composed. When
the bone is perfect, the uppermost half part of this inter-
nal surface is uniformly flat, and rather rough; but below
it, about the middle of the  bone, a deep groove begins,
which extends downwards and backwards, to the posterior
extremity: this is the  upper channel or meatus of the nose.
The edge of the surface immediately above it projects in
a small degree over this channel or groove; having been
described  by Morgagni, it  bears his name, and may  be
considered as one of the spongy or turbinated bones; from
its  situation, it  should be called the first.  The groove is
very deep, and  most  of the cells of the posterior part of
 the ethmoid bone communicate with it, through one or more
foramina at its anterior extremity. The part of the surface
 of the ethmoid which is immediately below this groove, is
 convex; that which is  before and below it, is rather flat; the
 convex part is  the upper spongy or turbinated bone, as it
 has commonly  been called;  it projects obliquely into the
 cavity of the nose, and hangs over the middle channel or 
€ts Ethmoides.                 27
 meatus, which is immediately below the ethmoid bone.
 The internal surface of this spongy bone, w  ich is opposite
 the septum of the nose, is convex and rough or spongy;
 the external  surface is concave. The  anterior cells of the
 ethmoid, and particularly those which the frontal sinuses
 on each side communicate with, open  into the middle
 channel or meatus, under the anterior end of this turbi-
 nated bone.
   This middle channel, or meatus,  is much larger  than
 that above; it extends from the anterior to the posterior
 part of the nostrils, and slopes downwards and backwards,
 The cavity of the upper  maxillary bone, or the antrum
 highmorianum, opens on each side into this meatus, and a
 thin plate of bone extends  from the cellular part of the
 ethmoid so as to cover a part of it.
   The  cellular portions  of the ethmoid  are composed of
 plates thinner than the shell of an egg;  they are entirely
 hollow, and  the cells are very various, in number, size
 and shape.  Some  cells of the uppermost row commu-
 nicate with those of the os frontis, formed by the separa-
 tion of the plates of the orbitar processes of that bone.
   From the  posterior, part of the cribriform plate, where
 it is in contact  with  the lesser wings of the sphenoidal
 bone, thin plates of bone pass down upon the anterior sur-
 face of the body of the os sphenoides, one on each side of
 the azygos process, and often diminish  the opening into
 the sphenoidal cells. These plates are sometimes triangu-
 lar in form, their bases uniting with the  cribriform plate.
 They have been described very differently by different
 authors, some considering them as belonging to the os eth-
 moides, and others to the sphenoid  bone. In the collec-
 tion of bones in the university of Pennsylvania, there is an
ethmoid bone,  taken from  the head of  a  subject rather 
 28                 Os Sphenoides.
 more than two years old, which  was remarkable for the
 perfect state in which the bones separated from each other.
 To this ethmoid bone there are  attached two triangular
 pyramids, in  place of the triangular bones; these pyra-
 mids are hollow, the azygos process  of the os sphenoides
 is received between them; one side of each pyramid applies
 to each side of the azygos process, another side applies to
 the anterior surface of the body of the sphenoid bone, in
 place of the ossa triangularia,and the third side is the upper
 part of one of the posterior nares. There are two apertures
 in each of these  pyramids; one at the base opening direct-
 ly into the nose, near the situation of the opening of the
 sphenoidal sinuses, in the bones of adults; and the other
 in each of the sides in contact with the azygos process.
   There is also  in the same collection, a fragment of this
 bone, which,  although much mutilated,  appears to  have
 been of similar structure.

                    Os Sphenoides.
   The os sphenoides, or pterygoides,  resembles a bat with
 its wings extended. It consists,
   1st, Of a body with two processes arising from it, called
 the lesser wings, or apophyses of Ingrassias.
   2dly, Of two large lateral processes, called the greater
 wings, or temporal processes; and,
   3dly, Of two vertical portions,  denominated pterygoid
processes.
   The body is situated near the center of the cranium, in
 contact with the cuneiform process of the occipital bone;
 the greater wings extend laterally between the frontal and
 temporal bones  as  high  as  the parietal;  while the ptery-
goid processes pass downwards on each side of the poste-
 rior opening of the nose, as low as the roof of the mouth. 
                    Os Sphenoides.                 29

It is therefore in contact with all the other bones of the
cranium, and with many bones of the face.
   The body has a cubic figure, its upper surface forms a
portion of the basis of the cranium; its lower and anterior
surfaces form part of the cavity of the nose;  the posterior
surface is articulated with  the cuneiform process of the
occipital bone;  and laterally it is extended  into the  great
wings, or temporal processes.
   On the upper surface of the body, the lesser wings, or
the apophyses of Ingrassias, project from the lateral and
anterior parts; these wings consist of two triangular plates,
each of which is joined to the other by its base, and to the
body of the os sphenoides by its under surface near the base,
and terminates  in a point; their direction is forwards and
outwards, and their flat surfaces are horizontal. Anteriorly
they are connected by suture to the ethmoid and frontal
bones; their posterior edge is rounded, and detached from
any other bone, forming the upper margin of the foramen
lacerum of the  orbit of the eye; this edge is  thick and
prominent at its internal extremity, and these prominences
are called the anterior clinoidprocesses;  immediately be-
fore them  are  the optic foramina,  which pass obliquely
through the wings into the orbit of the eye, and transmit
on each side the optic nerve and a small artery.
   Behind the optic foramen is a notch, and sometimes  a
foramen, made  by the carotid artery. A groove made by
the optic nerves is often seen extending across the body of
the bone, from  one of the optic foramina to the other. Be-
hind it is a depression, which occupies the greatest part of
this  surface of  the bone, in which the pituitary gland is
lodged: the back part of this depression is bounded by  a
transverse eminence, called the posterior clinoid process.
These three processes are  called clinoid, from  their sup- 
 3.0                 Os Sphenoides.
 posed resemblance  to  the  supporters of a bed ; and  the
 depression for the pituitary gland is called sella turcica,
 from its resemblance to the saddle used by the Turks.
   On each side of the posterior clinoid process is a groove
 in the body of the bone, made by the carotid artery as it
 passes from the foramen caroticum of the temporal  bone.
 The posterior surface of the body  of the sphenoides is
 rough, for articulation with the truncated end of the  cu-
 neiform  process of the  os occipitis.
   On the anterior and  inferior surfaces is a spine, called
 the azygos process, which is received into the base of the
 vomer, and extends forward until it  meets the nasal pi tte
 of the ethmoid bone; on each  side of this spine, in  the
 anterior  surface,  are the orifices of the sphenoidal cells.
 These orifices appear very  differently in different bones;
 in some very perfect specimens, they are irregularly oval,
 being closed below, and on their external sides, by  the
 processes of the ossa palati, and above by the triangular
 plates, as  they have been  called, of the ethmoid bone.
 The cells or sinuses, to which these orifices lead, occupy
 the body of the sphenoidal bone;  they are divided by a
 partition, and  each of them has a communication with  the
 cavity of the nose on its respective side, by the orifice
 above described.  These sinuses do not exist during  in-
 fancy; they increase in  the progress of life, and are very
large in old age.
  Laterally, the body of the sphenoides is extended into
the portions called  the great wings or  temporal pro-
cesses. These great  wings compose  the  largest part of
 the bone,  and their  internal surface forms a  portion  of
 the middle fossa  of the  base of the cranium. Exter-
 nally, the  surface of each great wing is divided into
two portions:  one of which is lateral, and unites to the 
                    Qs Sphenoides.                 31

frontal, temporal, and malar bones, forming part of the
smooth surface for the temporal muscle; the other por-
tion forms part of the orbit of the eye, and is very regular
and smooth.  As  the ethmoid bone forms part of the in-
side, this portion of the great wing forms part of the out-
side of the orbit, and is termed the orbitary process of the
sphenoid bone. The horizontal part of each wing termi-
nates in an acute angle, which penetrates between the pe-
trous portion and the  articulating cavity of the temporal
bone.  In this angle is the foramen  for the principal artery
of the dura mater; near the point of the angle is a small
process, which projects from the basis of the cranium, and
is called styloid.
  The pterygoid processes pass downwards in a direction
almost perpendicular to the base  of the skull.  Each of
them has two plates, and a middle fossa facing backwards?
to complete the comparison  they should be likened to the
legs of the bat, but are inaccurately named pterygoid, or
wing-like processes. The external plates are broadest, and
the internal  are longest. From each side of the external
plates the pterygoid muscles take  their rise. At the root
of each internal plate, a small hollow may be remarked,
where the musculus circumflexus palati rises, and part of
the cartilaginous end of the  Eustachian tube rests. At the
lower end of the same plate, is a hook-like process, round
which the tendon of the last named muscle plays, as on a
pulley. The ossa palati, on each side, rest upon these inter-
nal plates; and therefore the pterygoid processes seem to
support the whole face. 
32
Os Sphenoides.
            Foramina of the Sphenoidal Bone.
     Before these foramina  are described, it is necessary to
       state, that the nerves of the brain  are named numeri-
       cally, beginning with the olfactory, which is foremost.
     It should also be observed, that  each nerve, of the fifth
       pair, is divided, before it passes from the cavity of the
       cranium, into three large branches.

   The first foramina are the optic, which have been al-
ready  described; they transmit the optic, or second pair of
nerves, and a small artery, to the ball of the eye.
   The second foramen, on each side, is the foramen lace-
rum. It commences largely at the sella turcica, and extends
laterally a considerable distance, until it is a mere fissure.
The upper margin of this foramen is  formed by the an-
terior clinoid processes, and the edges of the smaller wings
of the sphenoid bone. This  foramen transmits the third,
fourth  and sixth pair of nerves, and the first branch of the
fifth pair, to the  muscles, and the other parts,  subservient
to the  eye.
  The foramen rotundum, or third hole, is round; as its
name imports.  It is situated  immediately under the fora-
men lacerum, on each side, and transmits the second branch
of the  fifth pair of nerves to the upper maxillary bone.
  The foramen ovale is the fourth hole.  It is larger than
the foramen  rotundum,  and  half an inch behind  it. It
transmits the third branch of the  fifth pair of nerves to the
lower jaw.
  The fifth hole is the foramen spinale.  It is small  and
round, and placed in the point of the spinous process, be-
hind the  foramen ovale, to transmit the principal artery of
the dura  mater, which makes its impression upon the pari-
etal bone. 
                        The Face.                    33

   The sixth foramen  is under the basis of each pterygoid
 process, and is therefore called thepterygoid,or the vidian*
foramen. It is almost hidden by the point of the petrous
 portion of the temporal bone, and  must  be examined in
 the separated bone. It  is nearly equal in size to the spinous
 hole.
   This foramen transmits  a nerve that does  not go out
 from the cavity of the skull, but returns into it. The second
 branch of the fifth pair,  after passing out  of the cranium,
 sends back, through this foramen, a branch called the vi-
 dian, which upon its arrival in the cavity of the cranium,
 enters the temporal bone by the  foramen innommatum.

                      Of the Face.
   The face is the irregular  pile  of bones composing the
 front and under part of the head, and is divided into the
 upper and lower maxillae, or jaws.
   The upper jaw consists of six bones on each side, of
 one single bone placed  in the middle, and of sixteen teeth.
   The thirteen bones  are, two ossa maxillaria superiora,
 two  ossa nasi, two ossa unguis,  two ossa malarum, two
ossa palati, two  ossa spongiosa inferiora,  and the vomer.
   The ossa maxillaria superiora form the principal part
of the cavity of the nose, with the whole lower and fore-
part  of the upper jaw, and a large proportion of the roof
of the mouth.
   The ossa nasi are placed at the upper and front part of
the nose.
  The ossa unguis are  at the internal angles of the orbits
of the eyes.

     • From its reputed discoverer, Vidius, a professor at Paris.
  Vol. I.                    E 
 34            Ossa Maxillaria Superiora.
   The ossa palati in the back part of the palate, extending
 upwards to the orbits of the eyes.
   The ossa spongiosa in the lower part of the cavity of
 the nose;  and
   The vomer  in the partition which separates  the  two
 nostrils.

               Ossa Maxillaria Superiora.
   The ossa maxillaria superiora, or upper jawbones, may
 be considered  as the basis or foundation of the face; as
 thev form a large part of the mouth, the nose, and the or-
 bit of the  eye.
   The central part of each bone, which maybe considered
 as its body, is  hollow, and capable of containing,  in the
 adult, near half an ounce of fluid. The plate which covers
 this  cavity is the bottom of the orbit  of the  eye.  The
 sockets of the  large teeth are below it. The roof of the
 mouth projects laterally from the inside of it.  A process
 for supporting the cheek bone is on the outside; and another
 process goes up before it, which forms the side of the nose.
   In each upper maxillary bone the following parts are to
 be examined.
   The nasal process; the orbitar plate; the malar process;
 the alveolar process; the palatine process; the anterior and
posterior surfaces; the great cavity; the internal or nasal
 surface; and the three foramina.
   The nasal process, which extends upwards to form the
 side of the nose, is rather convex  outwards, to give the
 nostril shape.  Its  side  supports the nasal bone; and a
 cartilage of the alae nasi is fixed to  its edge.
   The margin  of the orbit of the eye is marked  by a sharp
 ridge on the external surface of this process; and the part
 posterior  to  this ridge is concave,  to accommodate the
 lachrymal sac. 
               Ossa Maxillaria Superiora.            35

   The  orbitar plate, which covers the great cavity, and
forms the bottom of the orbit, is rather triangular in form,
and concave.  In the posterior  part is a groove, which pe-
netrates the substance of the bone, as it advances forward,
and terminates in  the  infra-orbitary foramen, below the
orbit. At the place where this plate joins the nasal process
above mentioned, viz., at the  inner angle of the orbit, is
the commencement of the bony canal, which transmits the
lachrymal duct into the cavity of the nose.
   The malar process projects from  the external and ante-
rior corner of the orbitar plate; it supports the malar bone,
and is rough for the purpose of articulating with it.
-  The alveolar processes compose the inferior and external
margins of the upper maxillary bones.  When these bones
are applied to each other they form more than a semi-
circle; their  cavities contain the roots of the teeth,  and
correspond with them, in size and form. They do not exist
long before the formation of the  teeth commences;  they
grow with the teeth; and when  these bodies are removed,
the alveoli  disappear.
   The palate process is a plate  of bone, which divides the
nose from the mouth, constituting the roof of the palate,
and the  floor or bottom of the  nostrils. It is thick where
it first comes off from the alveolar process; it is thin in its
middle; and it is again thick where it meets its fellow of
the opposite side. At the place where the two  upper jaw-
bones meet, the palate plate is turned upwards, so that the
two bones are opposed to each  other in the middle of the
palate, by a broad flat surface, which cannot be seen but by
separating the bones.  This surface is  so very rough, that
the middle palate suture almost resembles the sutures of
the skull; and the maxillary bones are neither easily sepa-
rated, nor easily joined  again.  The meeting of the palate 
 36            Ossa Maxillaria Superiora*

 plates, by a broad surface, makes a rising spine, or sharp
 ridge, towards the nostrils; so that the breadth of the
 surface, by which these bones meet, serves a double pur-
 pose; it joins the bones  securely, and it forms a small
 ridge upon which the edge of the  vomer, or partition of
 the nose, is  planted.  Thus we find the palate plates of the
 maxillary bones  conjoined, forming almost the whole of
 the palate; while  what are properly called the palate bones
 form a very small share of the back part only.   As these
 thinner bones of the face have no  medulla, they are nou-
 rished bv their periosteum only, and are of course perfo-
 rated with many  small holes.
  The anterior surface of the upper  maxillary bone is
 concave; the margin formed by the lower edge of the
 orbit, by the malar process, and by the alveolar processes,
 being more  elevated than the central part. At a small dis-
 tance below the  orbit is the  infra-orbitary foramen for
 transmitting a branch of  the  superior maxillary nerve.
 When these two bones are  applied to each other, and the
 ossa nasi are in their places, they form the anterior orifice
of the nasal cavity, which has a small resemblance to the
 im erted figure of the  heart on cards.
  The posterior surface has been called a process. It ex-
pands to a considerable size, and is united internally and
posteriorly to the ossa palati.
  The great cavity extends from the bottom of the orbit
 of the eye to the roof of the mouth, and from the anu rior
to ihe posterior surface of the bone; it opens in  the cavity
of the nose, and  is called  antrum maxillare, or  Highmo-
rianum.* There  is but  a  small portion of bone between
this cavity and the sockets of the teeth, particularly those
of the second molar tooth.
" After an anatomist who described it 
Ossa Nasi.
37
  The internal or nasal surface of this bone forms a large
part of the cavity of the nose, and is concave. At the root
of the nasal process is a ridge, for supporting the anterior
end of the lower turbinated bone. The nasal process seems
continued into the cavity of the nose, and forms a portion
of the orifice of  the canal for the lacrymal duct, which is
on the external side of this cavity, near its anterior open-
ing, and under the  lower turbinated bone. The orifice in
this bone, by which the antrum maxillare communicates
with the nose, is very large; but it is reduced to a small
size by  a plate from the ethmoid bone, by a portion of the
ossa palati and of the lower spongy bone; each of which
covers a part of it.
  The  three foramina are, 1st. The infra-orbitary fora-
men already described.  2d. The foramen incisivum or
amerior palatine hole, which passes through the palatine
process, from the nose to the niouth.  In  the nose there are
generally two foramina, which unite and form but*one in
the  mouth, immediately behind the middle incisor teeth.
This foramen is closed by the soft parts during life, and
the object of it has not been ascertained. 3d. The poste-
rior palatine foramen, which is formed  by this bone, and
by the os palati, on each  side, is situated in the suture
which joins them to each other, and  transmits to the pa-
late, a branch of  the upper maxillary nerve.
  This bone is united to the frontal, nasal, unguiform, eth-
moid and malar bones, above; to the ossa palati behind; to
the  corresponding bone, on the opposite side; and to the
inferior spongy bone, in the cavity of the nose.

                      Ossa Nasi.
  The ossa  nasi are so named from their prominent situ-
ation at the root of the nose. They are each of an irregn- 
 38                  OssaUnguis.
 lar oblong figure, be ing broadest at their lower end, nar-
 rowest near the middle, and larger again at the top, where
 the edge is rough and thick, and their connexion with the
 os frontis is consequently very strong. They are convex ex-
 ternally, jnd concave within. The lower edges of these bones
 are thin and irregular. Their anterior edges are thick, and
 their connexion with  each other, by means of their edges,
 is firm; the suture between them, extending down the mid-
 dle of the nose, forms a  prominent line on the internal
 surface, by which they are united  to the septum narium.
 The uppermost half of their posterior edges is covered by
 the edges of the nasal processes of the  upper maxillary
 bones; the lower half laps over the edges of these bones;
 and by this structure  they are enabled to resist pressure.
 They are joined above to the os frontis; before, to each
 other; behind, to the upper maxillary bones; below, to the
 cartilages;  and internally, to the septum of the nose.

                     Ossa Unguis.
  The ossa unguis are so  named from their resemblance
to a nail of the  finger. They are situated on the internal
side  of the orbit of the eye, between the os planum of the
ethmoid, and the nasal process of the upper  maxillary
bone. Their external surface is  divided into two portions,
by a middle ridge;  the posterior portion forms part of the
orbit; and the anterior, which is very concave, forms  part
of the fossa, and canal, for  containing the lacrymal sac and
duct. This portion is perforated by many small foramina;
and the whole, being extremely thin and brittle, is therefore
often destroyed by the preparation of the subject. The
internal surface of  this bone  is generally in contact with
the  cells of the ethmoid;  a small portion of the anterior
part is in the general cavity of the  nose.  Each  os unguis 
Ossa Malarum.
39
is joined above to the frontal bone; behind to the os pla-
num; before and  below to the maxillary bone. It some-
times is extended into the nose, as  low as the upper edge
of the inferior spongy bone.

                    Ossa Malarum.
  The ossa malarum are the  prominent square bones,
which form the cheek, on each side. Before, their surface
is convex and  smooth;  backward, it is unequal and con-
cave, for lodging  part of the temporal muscles.
  The four angles of each of these bones have been rec-
koned as processes.  The one at the  external canthus of
the orbit, called the superior orbitar process, is the longest
and thickest.  The second terminates near the middle of
the lower edge of the orbit in a sharp point, and is named
the inferior orbitar process. The third, placed near the
lower part of  the cheek, and thence called maxillary, is
the shortest,  and nearest to a right angle. The fourth,
which is called zygomatic,  because it is extended back-
wards to the zygoma of the temporal bone, ends in a point,
and has one side straight and the other sloping. Between
the two  orbitar angles  there  is a concave  arch, which
makes about a third of the external circumference of the
orbit, from which a  fifth process is extended backwards
within  the orbit,  to form near  one sixth  of that cavity;
and hence  it may be called the internal orbitar  process.
From the lower edge of each of the ossa malarum, which
is  between the maxillary and zygomatic processes, the
masseter muscle takes its origin.
  On the  external surface  of each cheek-bone, one or
more small holes are commonly found, for the transmission
of small nerves or bloodvessels from, and sometimes into,
the orbit.  On  the internal surface are  the holes for the 
 49                  Ossa Palati.
 passage of the nutritious vessels of these bones. A notch, <
 on the outside  of the  internal orbitar process of each of
 these bones, assists to form the great slit common to this
 bone and to the sphenoid, maxillary, and palate bones.
   The substance of these bones is, in proportion  to their
 bulk, thick, hard, and solid, with some cancelli.
   Each of the ossa malarum is joined, by its superior and
 internal orbitar processes, to the os frontis, and to the or-
 bitar process of the sphenoid bone; by the edge between
 the internal and inferior orbitar processes, to the maxillary
 bone; by the side between the maxillary and inferior orbi-
 tar process, again to the maxillary bone; and by the zygo-
 matic process to the os  temporum.

                      Ossa Palati.
   The  ossa palati form the back  part of the roof of the
 mouth, and extend from it along the external sides of the
 posterior openings of the nose,  into the orbit of the eye.
 Each bone may therefore be divided into four parts, the
palate square-bone, the pterygoid process, the nasal lamella,
 and orbitar process.
   The  square-bone  is  irregularly concave, for enlarging
 both the mouth and cavity of the nose. The upper part of
 its internal edge rises in a spine, after the same manner as
 the palate-plate  of the  maxillary bone does, to be joined
 with the vomer. Its anterior edge is  unequally ragged, for
 its firmer connexion with  the  palate-process of the os
maxillare.  The internal edge is thicker than the rest, and
of an equal surface,  for its  conjunction with its fellow of
the other side.  Behind, this bone is somewhat in  form of
a crescent, and thick, for the firm connexion of the velum
pendulum palati; the internal point being  extended back-
wards, to afford origin to the palato-staphylinus or  azygos 
Ossa Palati.
41
muscle. This square bone is well distinguished from  the
pterygoid process by a perpendicular fossa, which, applied
to such another in the maxillary bone, forms a passage for
the palatine branch of the fifth pair of nerves; and by ano-
ther small hole behind this, through which a twig of  the
same nerve passes.
   The pterygoid process is somewhat triangular, having a
broad base,  and ending smaller above. The back part of
this process has three fossa  formed  in it; the two lateral
receive the ends of the two pterygoid plates of the sphenoid
bone; the middle fossa, which  is very superficial, makes
up a part of what is commonly called the fossa pterygoidea.
The foreside of this palatine pterygoid process is rough
and irregular where it joins the back part of the great tube-
rosity  of the maxillary bone.  Frequently several small
holes may be observed in this triangular process, particu-
larly one near the middle of its base, which a little above
communicates with the common and proper holes of this
bone already mentioned.
   The nasal lamella  of. this bone is extremely thin and
brittle, and rises upwards from the upper side of  the ex-
ternal edge of the square bone,  and from the narrow  ex-
tremity of the pterygoid process; it is so weak, and at the
same time so firmly fixed to the maxillary bone, as to be
very liable to be broken in separating the bones.  From the
part where the plate rises, it runs  up broad on the inside
of the tuberosity of the maxillary bone, to form a consi-
derable share of the sides of the maxillary sinus, and to
close up the space between  the sphenoid and the great
bulge of the maxillary bone, where there would otherwise
be a large slit opening into the nostrils. On the middle of the
internal side of this thin plate, there  is a transverse ridge,
continued from one which is similar to it  in the maxillary
   Vol.  I.                 F 
 42                  Ossa Palati.
 bone for supporting the  back part of the os spongiosum
 inferius. Along the outside of this plate, the perpendi-
 cular fossa made by the palate-nerve is observable.
    At the upper and posterior edge of this nasal plate is a
 notch, which, when  applied to the sphenoid bone, forms
 the spheno-palatine foramen, through which a nerve, ar-
 tery, and vein pass  to the nostril; this notch forms  two
 processes on the posterior part of the bone, the inferior of
 which is in contact with the internal plate of the pterygoid
 process of the sphenoidal bone, and has therefore been
 called, by some French anatomists,the pterygoid apophysis
 of the os palati. The superior and anterior portion is the
 proper orbitar process of this bone,  which is situated at
 the  posterior part of the lower  surface of the  orbit,  and
 forms a portion of it. This process of the os palati is hol-
 low; and its cavity generally communicates with the con-
 tiguous cell of the os sphenoides. It has several surfaces,
 one of which is to be found in the orbit, and another in the
 zygomatic fossa.
   The palate square part of the palate-bone, and its ptery- ■
 goid process, are firm and strong, with some cancelli;  but
 the nasal plate,  and orbitar  processes, are very thin and
 brittle.
   The palate-bones are joined to  the  maxillary,  by  the
 fore-edges of the palate square bones; by their thin nasal
 plates, and part  of their  orbitar processes,  to  the same
 bones; by their pterygoid processes, and back part of  the
 nasal plates, to the pterygoid  processes of the os  sphe-
 noides;  by the transverse ridges of their nasal lamellae to
the ossa turbinata inferiora; and by the spines of the square
bones to the vomer. 
Ossa Spongiosa.-*-Vomer.
43
      The Ossa Spongiosa,  or  Turbinata Inferiora.
  The ossa spongiosa, or turbinata inferiora, are so na-
med,  to distinguish them from the upper spongy bones,
which belong to the os ethmoides; but these lower spongy
bones  are quite distinct, and connected in a very slight
way, with the upper jaw-bones.  They are rolled or con-
voluted, very spongy, and exceedingly light. Each of them
is attached to the os maxillare superius, near the transverse
ridge,  by a  hooklike process, and covers a part of the
openinjr of the maxillary sinus. One end is turned towards
the anterior opening of the nose, and covers the end of the
lachrymal duct; the other  end of the same bone points
backwards towards the throat. The  curling plate  hangs
down into the cavity of the nostril, with its convex side
towards the septum. This  spongy bone differs  from the
spongy process of  the ethmoid botie, in being less turbi-
nated or complex, and in having no cells connected with it.

                     The  Vomer.
  The vomer is a thin flat bone, which forms the  back part
of the  septum of  the nose. Its posterior edge extends
downwards from  the body of the os sphenoides to  the
palatine processes of the ossa palati, separating the poste-
rior nares from each other.
  The figure of this bone is an irregular rhomboid. Its sides
are smooth; and its posterior edge appears in an oblique
direction at the back part of the nostrils. The upper edge
is firmly united to the base  of  the  sphenoid bone, and to
the nasal plate of the ethmoid.  It is hollow for  receiving
the processus azygos of the sphenoid; and where it is ar-
ticulated to the nasal plate of the ethmoid, it is composed
of two lamina, which receive this plate between them. The 
44                Maxilla Inferior.
anterior edge has a long furrow  in it, where the middle
cartilage of the nose enters.  The  lower edge is firmly
united to the nasal spines of the maxillary and palate bones.
These edges of the bone are much thicker than its middle,
which is as thin as paper; in consequence ot which, and of
the  firm union or connexion this bone has above and be-
low, it can very seldom  be separated entire in adulta: but
in a child it is much  more easily separated entire; and its
structure is more distinctly seen.
  Its situation  is not always perpendicular,  but often in-
clined and bent to one side, as well as the nasal plate of
the  ethmoid bone.
  It is united above to  the os sphenoides  and the nasal
plate of the ethmoid bone; before, to the middle cartilage
of the nose; and below, to the ossa palati and ossa maxilla-
ria superiora.

           Maxilla Inferior, or Lower faw.
  The form and situation of this bone are so generally
known, that they do not require description. To acquire
an accurate idea of the lower jaw, it is, however, necessary
to examine  attentively  its different parts: viz., the chin,
the sides, the angles, and the processes.
  In subjects where the bones are strongly marked, there
is a prominent vertical ridge in the middle and most ante-
rior part of the chin, which becomes broad below, so as
to form a triangle, and on each side of this triangular pro-
minence are transverse  ridges; from these eminences the
muscles of the lower lip originate.
  On each side of the jaw, commonly under the second of
the bicuspides, or small molar teeth, is the anterior maxil-
lary foramen, through which pass out the remains  of the
inferior maxillary nerve and bloodvessels.  This  foramen 
                   Maxilla Inferior.                45

has a direction upward and backward. At a small distance
behind these foramina, on each side, is the commencement
of a ridge which continues backward until it forms the edge
of the anterior,ox coronoid process. The alveolar processes,
which  form the upper edge of the jaw, are on the inside
of  this ridge; the alveoli or sockets  corresponding with
the roots of the teeth, in number and form. The lower
edge of the jaw, which is denominated the base, is round
and firm, except at the angles, where it is thin.
  The angle is formed at the posterior extremity of the base:
in children it is obtuse; but in adults, whose teeth are per-
fect, it is nearly rectangular. The masseter muscle is in-
serted into the lower jaw, at the angle; and there are seve-
ral inequalities on the surface made by this muscle.
   The anterior, or coronoid process, is rather higher, than
the posterior, and forms an obtuse point; into this process
the temporal muscle is inserted. The anterior edge of the
coronoid process is sharp, and continued into the ridge above
mentioned; from this edge the buccinator muscle arises. As
the alveoli are on the inside of this edge and ridge, the jaw is
very thick at this  place.  There is a semicircular notch be-
tween this process and the posterior, or condyloid; and here
the bone is very thin.
   The condyles are oblong, and are placed obliquely; so
that their longest  axes, if extended until they intersected
each other, would form  an angle of more than  one hun-
dred and forty degrees.  The neck of the process, or the
part immediately below the condyle, is concave on the an-
terior, and convex on the posterior surface.
   On  the inside of the jaw, in the middle of the chin, is a
small  protuberance, sometimes divided by a vertical fis-
sure; to this are attached thefraenum linguae, and some mus-
cles of the tongue and os hyoides. Further back is a ridge 
 46                Maxilla Inferior.
 which extends backwards and upwards, until it approaches
 the alveoli of the last molar teeth, where it terminates in
 an oblong protuberance.  To the anterior part of this line
 the mylohyoidei muscles  art attached; and to the posterior
 extremity, the superior constrictor of the pharynx. The
 surface of the bone above this ridge is smooth, and cover-
 ed with  the  gums and lining membrane of the  mouth.
 The surface  below the posterior part of the line is rather
 concave, to accommodate  the submaxillary gland.
   At a small distance behind the alveoli, and nearly on a
 line with them, midway between the roots of the two pro-
 cesses, is a large foramen for transmitting the third, or in-
 ferior maxillary branch of the fifth pair of nerves, and the
 bloodvessels  which accompany it; the canal,  which com-
 mences here, terminates  at the anterior foramen already
 described. The surface of this canal is perforated by many
 foramina, through which bloodvessels  and nerves pass
 to the different teeth, and to the cancelli of the bone.
 On the anterior side  of  the foramen is a sharppointed
process, from which a ligament passes  to the  temporal
 bone. The nerve and vessels, before they enter into this
foramen, make an impression on the bone; and there is
 generally a small superficial groove which proceeds down-
wards from it, being made by a small nerve which supplies
some of the parts under the tongue.
   At the angle of the jaw, on the inside, is a  remarkable
roughness, where the internal pterygoid muscle is inserted.
   The lower jaw moves like a hinge,  upon its  condy-ss in
the glenoid cavity, when the mouth opens and  shuts in the
ordinary  way. When the  mouth is opened very wide, the
condyles  move forward upon the tubercles before the cavi-
ties:  if the effort to  open  the  mouth is continued, the
lower jaw is fixed in that situation, and the whole head is 
The Teeth,
47
thrown  back, which  separates the upper jaw still further
from the lower.
  The lower jaw can be projected forward without open-
ing the mouth, by the movement of both condyles, at the
same time, on the tubercles.
  This bone "can also rotate upon one condyle, as a center,
whih the other moves out of the glenoid cavity, upon the
tubs, re It: but these important motions  can  be better un-
derstood, after the muscles, and the articulation with the
temporal bone,  in its recent slate, have been described.

                     Of the Teeth.
  In the adult, when the teeth are perfect, there are six-
teen in each jaw, and those in corresponding situations, on
the  opposite sides, resemble each other exactly.
  They are of four kinds, viz. incisores, or the fore teeth;
cuspidati, or the  canine; bicuspides, or the small grinders;
and molares, or the large grinders.
  On each side of the jaw, supposing it divided in the mid-
dle, there are two incisores, one cuspidatus, two bicuspides,
and three molares. They occur in the order in which they
have been named, beginning at the middle of the jaw.
  Each tooth is divided into two parts, viz. the body, or
that portion which is bare, and projects beyond the alveoli
and gums;  and the root, which is lodged in the  socket.
The boundary between these parts, which is embraced by
the  gum, is called the neck of the tooth.
  The body and roots consist of bone, which is more firm
and hard than the substance of the other bones;'but all the
surface of the body, which projects beyond the gums, is
covered with enamel, a substance very different from com-
mon bone. 
 48                   The Teeth.
   Every tooth in its natural condition has a cavity in it,
 which commences at the extremity of each root, and ex-
 tends from it to the body of the tooth, where  it enlarges
 considerably. This cavity is lined by a membrane, and
 contains a nerve, with an artery and vein, which originally
 entered the tooth, by a foramen near the point of the root,
 as ii  evident during the growth of the teeth. These  ves-
 sels,  and the nerve, have been traced into the  teeth, al-
 though in many subjects the foramina appear to be closed
 up.
   The alveoli, or sockets of the teeth, are formed upon the
 edge  of each jaw: the bone, of which they consist, is less
 firm than any other part of the jaws; they correspond ex-
 actly  with the roots of the teeth, and are lined with a vas-
 cular membrane which serves as a periosteum to the roots,
 and assists in fixing them firmly.
  The teeth of different  kinds differ  greatly from each
 other, in  form and size.
  The bodies of the incisores are broad, with two flat sur-
 faces, one anterior and the other posterior;  the anterior
 surface is rather convex, and the posterior concave; they
 meet  in a sharp cutting edge. At this edge  the tooth is
 thinnest  and  broadest; it gradually becomes thicker and
 narrower, as it is nearer the neck. The enamel continues
 further down, on the anterior and posterior surfaces, than
 on the sides.
  The incisores of the upper jaw are broader than those of
the lower, especially the two internal incisores.
  The cuspidati are longer than any other teeth, and are
thicker than the incisores. Their edges are not broad as
tho-c  of the incisores, but pointed; this point is much worn
away  in the progress of life. The enamel covers more of
the lateral part of these teeth than of the incisores. 
                       The Teeth.                   49
   The bicuspides are next to the cuspidati, two  on each
side.  They resemble each other strongly; but the first is
smaller than the other, although it generally has  a longer
root.  The bodies are flattened laterally, but incline to a
roundish form.  On the middle of the grinding surface are
depressions which make the edges prominent. On the ex-
ternal edge there is generally one distinct point in each of
the bicuspides.  The internal edge is lower than the  exter-
nal in the first  bicuspis, which gives it a resemblance to
the cuspidatus.,  In the second bicuspis the internal edge is
more elevated,  although the point is not so distinct as it
is on  the external edge.
   The bicuspides  have generally but one root, which is
often indented lengthways, so as to resemble two  roots
united.
   The three molares, or large grinders, are placed behind
the bicuspides, on each side. The first and second  strongly
resemble each other,  but the third has  several peculiari-
ties.  The body of the large grinders is rather square; the
grinding surface has often five  points,  and three  of  these
are on the external side. In the upper jaw these teeth have
three roots, two situated  externally, and one internally,
which is very oblique in its direction; they are all conical
in their form.  It  seems probable that the roots  of these
teeth  are arranged in this way to avoid the antrum maxil-
lare.  The molares of the  lower jaw have Imt two  roots,
which are flat, and a: j placed, one anterior, and the other
posterior; in each of these broad roots there are two canals,
leading to the central cavity; whereas, in the root of the
upper molares there is but one.  The third grinder is  called
dens sapientice, from its late appearance.-It is shorter and
smaller than the others; its body is rather rounder, and its
roots  are  not  so regular and distinct;  for they are  some-
   Vet. I.                  G 
5(j                   The Teeth.
times compressed together, and sometimes there appears
to have been but one root originally, when the whole tooth
has a conical appearance.  In  some cases the dentes sapi-
entiae take an irregular direction and shoot against the ad-
joining teeth.
   Infants have  a set of deciduous teeth, which differ in
several respects from those of adults. They are but tzventy
in number; the five on each side of each jaw, consist of two
incisores, one cuspidatus, and two molares or large grin-
ders. The first of them generally protrudes through the
gums between the fourth and eighth months of age, the
last, about  the end of the second year. They commonly
appear in pairs,* which succeed each other at irregular in-
tervals. Those of the  lower  jaw are, in most cases, the
first.  The order of  their appearance is this:  The central
incisores are first, then the external incisores on each side;
after these the first molaris, then the cuspidatus, and final-
ly  the last molaris, on each side. There are many devia-
tions from this order of succession, but it takes place in a
majority of cases.
   These deciduous teeth  become loose, and are succeed-
ed by those which are more permanent, nearly in the same
order in which they appeared, but with a progress much
more slow. The  incisores generally become loose between
the sixth and seventh year; the first molares about the
ninth; the cuspidati and the second molaris, not until the
tenth or twelfth, or even fourteenth ; ear. The bicuspides
take the places of the infant molares.
   The three  permanent  molares appear  in  the following
order: The first of them protrudes a short time before the
front teeth are shed;  it is the first of the permanent teeth

  * The two teetn  of a pair do not appear at the same precise time,
bat very near to each other. 
                       The Teeth.                   51
 which appears, and is seen between the sixth and seventh
 year.  The second molaris appears soon after the cuspidati
 and the second  bicuspides are seen. There is then a long
 interval; for the last molaris or dens sapientiae is seldom
 seen before the  twentieth year, and sometimes not until
 the twenty-fifth.

   The teeth  are formed upon pulpy substances, which
 are situated in the alveoli, and are contained in capsules.
 A shell of bone is first formed upon the surface of the pulp,
 which gradually  increases and the pulp diminishes within
 it. The body of the tooth is produced first, and the root is
 formed gradually afterwards; during its formation the root
 has a large opening at the extremity, which is gradually di-
 minished to the small orifice before described. The roots,
 as well as the body, are formed upon the pulpy substance,
 which gradually diminishes as they increase. After the ex-
 ternal surface of the body of the tooth is formed, the enamel
 begins to appear  upon it,  and gradually increases, until it
 is completely invested.  It is probable that'the enamel is
 deposited upon the body of the tooth by the membranous
 capsule which contains  it. This substance, which appears
 to be formed of radiated fibres, is harder and less destruc-
 tible than bone.  Like the substance of bone, it is compos-
 ed of phosphate,  with a small proportion of the carbonate
 of lime; but it is destitute of the cartilaginous or mem-
 branous structure which is demonstrable in bone.
   The pulpy substances, or rudiments of teeth, may be
 seen in the foetus, when  about four months  old. At six
 months, ossification can be seen to have commenced on the
pulps of  the incisores. At the  time of birth, tht bodies  of
the infant teeth are distinctly formed. The alveoli, at first,
have the appearance of grooves in the jaw, which after- 
 52                  Os Hyoides.
 wards are divided by transverse partitions;  they enlarge,
 in conformity to the growth of the teeth, and appear to be
 altogether influenced by them.
   The permanent teeth are formed very early; the rudi-
 ments of the first permanent grinder on each side have
 commenced their ossification at birth. At the same time,
 the rudiments of the permanent incisores  are to be per-
 ceived; and  their bodies will be found, nearly ossified, by
 the time the  infant incisores are protruded  completely
 through the gums.  About the age of six years, if none of
 the infant teeth are shed, there will be forty-eight teeth in
 the two jaws, viz.  the twenty infant, and  twenty-eight
 permanent, teeth, more or less completely formed.

                     Os Hyoides.
   The os hyoides is a small insulated bone, supported be-
 tween the lower jaw and the larynx, by muscles and liga-
 ments, which proceed from the neighbouring parts in va-
 rious directions.
   The figure of this bone, as its name imports, resembles
 the Greek letter  v. In its natural situation the central and
 convex part is anterior, and the lateral portions extend
 backwards.
   The central part is called the body, and the lateral por-
tions the cornua.
   The body is broad, and its upper edge bent inwards; so
that the external surface is convex, vertically, as well as
horizontally. On this surface  is a horizontal  ridge: the
muscles which proceed from the lower jaw are generally
inserted above this ridge, and the muscles from the ster-
num and scapula below it.
   The internal or  posterior  surface of the  body is very
concave. 
                     Os Hyoides.                  53
  The cornua, in young subjects, are distinct  from the
body of the bone, and joined to it by cartilages: near the
body of the os hyoides they are flat; but their figure soon
changes, and they terminate on each side in a  small tu-
bercle.
  On the upper edge of the bone, where the cornua unite
to the  body,  is a process, equal in size to a small grain
of wheat, which has a direction upwards and backwards j
this  is  called the appendix,  or lesser cornu of the os
hyoides; from it proceeds a ligament, which is attached to
the styloid process of the temporal bone, and is sometimes
ossified.
  The basis of the tongue is attached to the os hyoides,
and the motions of the bone have a particular reference to
those of  that  organ; but they will be better understood
when the parts with which it is connected have been de-
scribed. 
54
Orbit of the Eye.
     An acquaintance with the individual bones which can-
       pose the head is principally useful, as it leads to a per-
       fect understanding of the  whole structure, ot which
       each bone is but a small part.
     This structure comprises the cavities which contain the
       brain and the  most important organs of sense, as well
       as the foramina subservient to them, which are of so
       much importance in  the  practice of  medicine and
       surgery, and also in physiology, that the following de-
       scriptions are subjoined.

                    Orbit of the Eye.
   Tht? figure of this cavity is that of a quadrangular pyra-
 mid with its angles  rounded; so that it resembles a cone,
 the bottom being the apex and the orifice the base.
   The diameter of  the  cavit>  passes obliquely outward
 from the apex behind. As the figure is irregular, the side
 next the  nose does  not partake of this general obliquity,
 but extends in a straight direction from behind forwards.
   The orbit is somewhat contracted at its orifice, and en-
 larged immediately within.  The form of the orifice is ra-
 ther oval; as the  transverse diameter is longer than the
 verti' al. Seven bones are concerned  in  the  formation of
 this cavity:  The os frontis and a portion of the lesser wing
 ot the sphenoid bone above; the os  planum or ethmoid,
 the os unguis, and the nasal process of the upper maxillary
 bone, on the inside; the orbitar plate of the  upper maxil-
 lary bone, and the os palati, below; the os malae,  and or-
 bitar plate of the sphenoid bone, on the outside.
   On the upper surface is the depression for the lacrymal
 gland; and at the  orifice is the notch or foramen for  the
sujjraorbitary vessels, &c. which have already been men-
tioned. 
                   Orbit of the Eye.                 55
  On the inner surface are two longifodinal sutures, which
connect the os planum and the os unguis, to the os irontis
above, and the os maxillare below. In the upper suture are
the two internal orbitary foramina mentioned in the des-
cription of the os frontis, the anterior of which transmits
a fibre  of the ophthalmic nerve, with  an artery and vein;
the posterior transmits only  an artery  and vein. There are
also two smaller vertical  sutures on each side  of the os
unguis. On the anterior part of this inner  surface is the
ridge of the os unguis,  and  the groove  for accommodat-
ing the lacrymal sac, which passes  into the canal of the
same name  immediately below.
   On the lower surface is the aforesaid  canal, formed by the
nasal and orbitar processes of .the upper maxillary bone, and
that part of the os unguis which is anterior to the ridge. On
the posterior part of this surface is a groove which pro-
ceeds forwards,  and penetrating into  the bone becomes a
canal that terminates in  the infra-orbitar  foramen; this
groove in the bone is made a canal by the periosteum. The
thin plate which forms this surface is the partition between
the antrum maxillare and the orbit of the eye, and is more
or less absorbed in those cases where polypi of the antrum
maxillare occasion a protrusion of the eye.
   The external surface, formed by the malar bone and the
orbitar plate  of the  sphenoid, is almost  flat. In the poste-
rior part of  the orbit it is bounded by two large fissures,
which  are now to be described.
   In  the posterior  part of the orbit are three apertures:
The optic foramen, the sphenoidal fissure, and the sphenoc
maxillary fissure.
   The optic foramen ope us  almost at the  bottom of the
wbit on the inside;  its direction is forwards and outwards. 
 56               Cavities of the Nose.
   The sphenoidal fissure, formed  principally by the les-
 ser and greater wings of the sphenoidal bone, begins at the
 bottom of the  orbit, and extends  forward, upward and
 outward.  It is broad a the commencement, and gradually
 diminishes to a fissure. This fissure opens directly into
 the cavity of the cranium, and admits the third,  fourth,
 sixth, and one branch of the fifth pair of nerves, an artery
 and a vein.
   The spheno-maxillary  fissure commences also at the
 bottom of the orbit,  and extends forward, outward and
 downward,  between the maxillary bone  and the orbitar
 plate of the sphenoid, from the body of the  sphenoid to
 the malar bone. This fissure  opens  from the orbit direct-
 ly into the zygomatic fossa. In the  recent subject it is
 closed, and only  transmits the infraorbitary nerve and
 vessels, and a small branch of the superior maxillary nerve.
                                                    •
                The Cavities of the  Nose.
   These cavities, which are  separated from each other
 by the septum narium, are contained  between the cribri-
form plate of the ethmoid and  the  palatine processes of
the upper maxillary and palate bones, and between  the an-
terior and posterior nares. They are  therefore of  consi-
derable extent in these directions; but the distance from
the septum to the opposite side of  the nose is so  small,
that each cavity is very narrow.
   The upper surface of each cavity consists of that por-
tion of the cribriform plate of the  ethmoid which is be-
tween the septum and the cellular portions. Anterior to
this, each  cavity is bounded by the internal surface of the
os nasi of its respective side; and posterior to it,  by the
interior surface of the body of the sphenoid bone.  These
anterior and posterior surfaces form obtuse  angles with 
                  Cavities cfthe Nose.                57
the upper surface of the nose, and are immediately above
the openings culled antes ior and posterior nares.  The an-
terior surface partakes of the figure of the os nasi; the up-
per surface h:;s the perforations of the cribriform plate;
the posterior surface has an opening, equal in diameter to
a small quill, that leads into the sphenoidal cell, a.id it is
also broader than -he anterior or superior surface.
   The internal surface, formed by the septum of the nose,
which is composed of the vomer, the nasal plate of the eth-
moid, and a cartilaginous plate, is flat, but rather inclined
to one side or the other, so  as to make a difference in the
nasal cavities.
   The external surface is very irregular: it is formed  by
the cellular portions of  the ethmoid;  bv a small portion of
the os unguis; by the upper maxillary bone; the os turbina-
ting, inferius; the os palati; and the internal pterygoid pro-
cess of the os sphenoides.  The upper part of this  surface is
formed by the internal  surface of the cellular portions of
the ethmoid, which have been described at page 26. It ex-
tends from the  sphenoid bone, very  ne.-'.r to the ossa nasi;
and is  uniformly flat and rough.
   About the middle of it  begins a  deep groove, which
penetrates into the cellular structure of the ethmoides,
and passes  obliquely downwards and backwards. At the
upper end of this  groove is the foramen by which the pos-
terior ethmoidal cells communicate with the nasal cavity.
   This is the upper channel or meatus of the nose. At the
posterior end of it is a large foramen formed by the nasal
plate of  the os palati  and the pterygoid process of the os
sphenoides, and therefore called pterygo-palatine foramen.
It opens externally and  transmits  a nerve and an arterv to
the nose.
   Below the meatus is the upper spongy bone, which pre-
   Vol.  I.                II 
 58              Cavities of the Nose.
 sents a convex surface; its lower edge is rolled up and not
 connected  with the parts about it.  This spongy bone co-
 vers a foramen in the ethmoid bone, bv which its anterior
 cells and the frontal sinuses communicate with the nose.
   Below this spongy bone, is the middle channel or meatus
 of the nose. This channel extends from the anterior to the
 posterior part of the cavity. It is verydeep, as it penetrates
 to the maxillary bone. The cells of the ethmoid are above
 it;  the inferior turbinated bone below it;  and the upper
 spongy bone projects  over it. In this channel is the open-
 ing of the  great cavity of the  upper maxillary bone. At
 the anterior extremity of it is a  small portion of the os
 unguis, which intervenes between the nasal process of the
 upper maxillary bone and the  cells of the ethmoid, and
 continues down to tht  lower spongy bone.
  The lower spongy  bone is nearly horizontal, and very
 conspicuous. It extends* almost from one opening of the
 nose to the other.
  Under this bone is  the third and largest channel or mea-
 tus of the nose. It is  made large by an excavation of the
 upper maxillary bone, particularly at the anterior part. It
 affords a direct and  very easy passage to the posterior
 opening of the nose and  the throat.
  Near the anterior extremity of this meatus is the lower
 orifice of the lacrymal duct, which is  so situated  that  a
probe properly curved can be readily passed into it through
the nostril.
  There are then four foramina on each side, which form
communications between the cavities of the nose and the
adjacent cells, viz.
  One in  the upper meatus which  leads to the posterior
ethmoid cells. 
                 Cavity of the Cranium.             59
   A second in the middle meatus which leads to the an-
terior ethmoid cells and the frontal sinuses.
   A third in the same meatus which opens into the max-
illary sinus.
   A fourth in the anterior surface of the body of the sphe-
noidal bone, which opens into the sphenoidal sinus.
   To these must be  added the  opening of the lacrymal
canal.

    It will be useful to the student of anatomy, after placing
       three or four of the uppermost cervical vertebrae in
      their natural situation, to take a view of

   The Cavity between the Spine and the posterior Nares,
which is bounded, above, by the cuneiform process, pass-
ing obliquely upward and forward; laterally, by soft parts
not yet described;  behind, by the bodies of the cervical
vertebrae; and before, by the posterior nares, each of which
is oblong in form, rounded above, flat below, and separat-
ed from the other by a thin partition, the vomer.


             The Cavity of the Cranium.
   The  upper concave surface of  < is cavity  corresponds
with the figure  of the cranium. The ri ige in it for  sup-
porting the falciform process of the dura mater, the groove
made by the longitudinal sinus, the impressions of the ar-
teries, and the pits made by the convolutions of the brain,
are particularly to be noticed. 
60
Basis oj'the Cranium.
                The Basis of the Cranium
 is much more important, it is divided into three fossae on
 each side: the anterior of those are most superficial, and
 the  posterior the deepest. The bottoms of the anterior
fossa are formed by the  orbitar processes of the os frontis,
 and consequently are convex; between them is the cribri-
form plate of the ethmoid, which is commonly sunk below
 the adjoining surface. The crista galli is very conspicuous;
 and the foramen c;ecum  can almost always  be seen. The
 crista  galli is evidently  the  beginning of the prominent
 ridge,  which continues on the os frontis, and supports the
 falx of the dura mater.  The  posterior margins of  these
 fossae are formed by the less r wings of the sphenoid bone.
   The middle foss.e are formed by the great wings of the
 sphenoidal bone*, and by the  squamous and petrous por-
 tions of the temporal bone. They are lower than the  ante-
 rior, and higher than the posterior fossae. The projection
 of the margin  of the anterior fossae into these  cavities,
 corresponds  with the separation  between  the  anterior
 and middle lobes of the  brain. The  suture between the
 sphenoidal and temporal  bones is  evident in these fossae.
 The upper surface of ihe  body of the sphenoid bone, or the
 sella turcica, is between them; and all the peculiarities of
 its surface are very conspicuous. The  first  five  foramina
 of the  sphenoidal bone can be  easily ascertained, and also,
 the anterior foramen lacerum  and  termination of the fora-
 men caroticum, with the impressions made by the carotid
 arteries on the sides of the sella turcica. The petrous por-
 tions of the temporal bones are the posterior boundaries
 dTthe  middle fossa;.  Their oblique direction, inwards and
 forwards, is particularly remarkable;  being formed like 
                 Basis of the Cranium.               6.1
triangular pyramids. Two of their sides are in the cavity of
the cranium; one, which is anterior, forms a portion of the
middle fossa; and the other forms a part of the posterior
fossa.  The edge between them is very prominent, and has
the tentorium or horizontal process of the dura mater at-
tached to it.  On the anterior surface, in the  middle fossa,
mav be traced the groove and the foramen for the vidian
nerve.
   The posterior fossae are larger as well as deeper than the
other two. Their boundaries are well defined by the edges
of the petrous bones above mentioned, and b,y the grooves
for the horizontal parts of the lateral sinuses. These fossae
are nearly separated from the general cavity by  the  ten-
torium, which is attached to the edge of the petrous bone
and also to the edge of the horizontal part of the groove
for the lateral sinuses. On the tentorium lie the posterior
lobes of the cerebrum; and under it, in the^se fossae, is the
cerebellum.
   These fossae  may be  considered as one great cavity,
which is circular behind,  and somewhat angular before.
The angular surfaces are formed by the posterior sides of
the petrous portions. Between them, is the oblique surface
of the cuneiform process of the occipital bone, which de-
scends to the great foramen.  On the surface  of each pe-
trous bone is the meatus auditorius internus, and the ori-
fice of the aqueduct of the vestibule. Behind the petrous
portion, the  groove for the  lateral sinus is very conspicu-
ous : it terminates in the  posterior foramen lacerum, which
is  evidently formed  by the  temporal and the  occipital
bones. At the anterior part of this foramen is most com-
monly a small bony process, which  separates the  eighth
pair of nerves from the  internal jugular vein,  as they pass
out here. 
52              Basis of the Cranium.
  The anterior condyloid foramen for the passage of the
ninth pair of nerves, appears in the  surface of the  great
occipital  hole, immediately  below the  foramen lacerum.
From the back part of this hole the spine, which forms the
lower limb of the cross,  passes up;  and on each side  of
it are the great depressions which accommodate the two
lobes of the cerebellum.

             External Basis of the Cranium.
  When the head is inverted we see the external protu-
berances of the os occipitis, formerly described. The mas-
toid processes of the ossa temporum are on the same  trans-
verse line with the great foramen of the os occipitis; but
the foramen being larger extends farther forward. On the
inside of the mastoid process, the fissure for the digastric
muscle is very conspicuous, and also the suture between
the mastoid process and the occipital bone.
  The oblique direction of  the occipital condyles and the
slanting position of their articulating surfaces are  particu-
larly striking. The posterior and anterior condyloid fora-
mina for the cervical veins,  and the ninth pair of nerves,
are also in view.  The  position of the  cuneiform process
of tiie os occipitis is by no means horizontal, but extends
forwards and upwards. The petrous or pyramidal portion
of the temporal  bone commences between the  mastoid
process, and the glenoid cavity for the condyle of the lower
jaw, and extends obliquely forwards and inwards, having
the occipital bone behind it, and the glenoid cavity and the
os sphenoides before it.  At the commencement,  the sur-
face of the petrous portion  is not horizontal but oblique,
sloping into the glenoid cavity with a sharp edge  down-
wards. This edge in some cases is curved so as to sur-
round the basis of the stiloid process, which arises in con- 
                  Basis of the Cranium.              63
tact with it, and projects downwards, on each side of the
vertebrae.  Between the mastoid and stiloid process, is the
foranu-n stilo-mastoideum.  On the inside of the stiloid
process, and rather anterior to it, is  the foramen  lacerum
posterior, for the internal jugular vein, the eighth pair of
nerves, Sec.  This  foramen  passes  obliquely backwards
and upwards, and is bounded behind by the jugular pro-
cess of the os occipitis, which bone seems to contribute
most to its formation. Very near to this holt, on the inside,
is the anterior condyloid foramen; and rather anterior to
it is the opening of the carotid canal, which forms a curve
in the bone  as it passes upwards, inwards, and forwards.
   From the foramen lacerum posterior, the suture, between
the cuneiform process of the occipital and the petrous por-
tion of the temporal, extends to the foramen lacerum ante-
rior; which  is closed by cartilage in the recent subject, but
is of an irregular and rather triangular form  in the  mace-
rated head:  this hole is formed by the occipital, sphenoid-
al and petrous bones.  The  suture or connexion  between
the petrous bone and the os sphenoides, is continued on
the anterior side of the petrous bone,  from the fissure of
the glenoid  cavity to the anterior  foramen lacerum. The
stiloid process of the os sphenoides, which is seldom more
than four lines in length, appears at the edge of this suture.
On the inside of the glenoid cavity, and on  the inside of
this process, in the suture formed between the petrous and
sphenoid bones, is the bony orifice of the eustachian tube.
   The foramen spinale for the middle artery of  the dura
mater is at a very small distance from the eustachian tube,
immediately anterior to it; and at a  small distance on the
inside  and in front of this foramen,  is the foramen  ovale,
for tlu inferior maxillary nerve, or the third branch of the
fifth pair. 
64
Side of the Head.
                  The Side of the Head.
   Those portions of the side of the head which are form-
 ed bv the frontal, parietal  and occipital bones, and by the
 squamous  part of the temporal, require no explanation
 here; but the region which is behind the  malar and upper
 maxillary bone, and within the zygomatic processes of the
 temporal and  malar bones,  which  comprises  part of the
 temporal and zygomatic fossae of some anatomists, is both
 important and obscure.
   To obtain a view of this,  the lower jaw should be re-
 moved, and the zygoma sawed away, in  one preparation;
 and in another, the upper  maxillary and  palate bones, of
 one side,  should be applied in their natural position, to
 the os sphenoides,  without an\ of the other bones.
   The upper part of this region, formed by the sphenoi-
 dal, frontal and malar bones, is made concave by the form
 of the external angular part of the os frontis  and of the os
 malae; which projects backward so as to cover a large por-
tion of it.                                          '
   The lower  part  is formed principally by the external
surface of the pterygoid process of the sphenoid bone, and
by the posterior surface of the upper maxillary.  Between
the lower end of the pterygoid process and the upper max-
illary bone, a small portion of the os palati intervenes; but
in many adult subjects it  is  not to be distinguished from
the other bones. At this place, the pterygoid process and
these  bones appear to be in close  contact; but as they
pass upwards they recede from each other so as to  form a
considerable aperture, which continues  the  whole length
of th..- pterygoid process.  This Jiswre, which may be call-
ed pterygopalatine orpterygo-maxillary, would open into
the posterior part of  the  cavity  of  the nose, if the nasal 
                 Form of the Cranium.              65
plate of the os palati did not intervene: this plate forms a
partition, which separates the nose from this fissure; and
the spheno-palatine foramen,  formed principally by  it,
transmits a nerve and bloodvessels to the nose.
   The fissure is vertical: at the back of the orbit, it unites
with the spheno-maxillary fissure of the  orbit, which is
almost horizontal;  and at the place of their junction, the
sphenoidal, or upper fissure of the orbit, opens also.
   The foramen rotundum, which transmits the second
branch of the fifth  pair, or the upper maxillary nerve, is
likewise  situated near this place; and when the upper max-
illary, the sphenoidal, and the palate bones are in their na-
tural situation, the distribution of the branches of this im-
portant nerve can be easily understood : for the same view
presents the course of its various branches; viz. to the nose,
by the spheno-palatine foramen; to the cavity of  the cra-
nium, by the pterygoid foramen; to the orbit, and the in-
ferior orbitary canal, by the spheno-maxillary fissure; and
to the roof of the mouth, by the palato-maxillary canal.

                The Form of the Cranium.
   The form  of the cranium  is that of an  irregular oval.
The greatest length of its cavity is between a part of the
os frontis above the crista galli, and of the  os occipitis
above the center of the crucial ridge.
   The greatest breadth is at about two thirds of the dis-
tance from the first to the last of these  positions. This
transverse diameter touches the sides of the cranium near
the posterior part of the basis of the petrous portion of the
temporal bone. The difference between these longitudinal
and transverse diameters varies greatly in different per-
sons,  as  their craniums approach to the oval or round
figures.
   Vol. I.                 I 
 66              Form of the Cranium.
   The greatest depth of the cavity is between the posterior
 part of the cuneiform process of the occipital bone, and a
 part of the cranium which is nearly over it, about the mid-
 dle of the sagittal suture.
   The figure of the cranium is somewhat varied in differ-
 ent races of  men; and it has been much changed by the
 particular management of several savage nations.
   In North America, the Choctaw tribe of Indians were
 formerly accustomed to make their foreheads perfectly flat,
 and sloping obliquely backwards. They have latterly dis-
 used this practice; but one of their nation,  whose head had
 this form, was in Philadelphia about the year 1796.
   At this time, a tribe who inhabit a district of country
 near the sources of the Missouri river, are in the practice
 of flattening  both  the frontal and occipital regions of the
 head; so that a small part only, of the middle of it, remains
 of the natural form, between these flattened sloping sur-
 faces.
   In the case of the Choctaw man above mentioned, it did
 not appear that his health, or his intellectual operations,
 were any way affected by this form  of his head.
   During infancy, the cranium sometimes increases to a
 preternatural size, as disproportionate to the face  as if
 it were affected by hydrocephalus.  In many of these in-
 stances that disease ultimately shows itself; but in other
 cases,  the preternatural  increase of the  cranium finally
 stops without the occurrence of disease; and the dispro-
portion is lessened by the increase of the face in the ordi-
nary progress of growth.
  In many cases where men have deviated from the ordi-
nary stature,  the head has preserved the common size. It
 is therefore said to be small in giants and large in dwarfs. 
Head of the Foetus.
67
                The Head of the Foetus.
  In the foetus, those bones, which form the vault of the
cranium, originally  consist of one plate only; which  is
composed of radiated fibres.
  At birth, the os frontis consists of two pieces, which join
each other in the middle of the forehead.
  The parietal bones are each in a single piece; but they
are incomplete at their edges and their angles.
  The temporal bones have no appearance of mastoid or
stiloid processes.  Instead of a meatus  auditorius exter-
nus, there is a bony ring in which the membrana tympani
is fixed. The squamous and petrous  portions,  and this
ring, are originally formed separate; but at the period of
birth they often adhere to each other.
  The os occipitis is composed of four pieces: the first and
largest, extends from the beginning or angle of the lamb-
doidal suture to the upper edge of the great occipital fora-
men.  Each side of the foramen, and the condyle on it, is
formed by a distinct piece. The front part is formed by
the cuneiform process, which is separate from the  other
parts and forms the fourth  piece.
  The sphenoidal bone  may be separated  by maceration
into hree pieces. The body and the little wings form one
piece.  Each of  the great wings, with  the pterygoid pro-
cesses united to  it, forms also  a  piece.  The body of the
bone is entirely solid.
  A large  part of  the ethmoid is in a cartilaginous  state.
It is divided  into two portions by a partition of cartilage,
which occupies the place of the nasal plate and the crista
galli.
  In consequence of the imperfect formation of the bones
which compose the vault of the  cranium, there are several 
68                Head of the Foetus.
deficiencies in it.  Thus the superior anterior angles of the
parietal bones being incomplete, and also the upper angles
of the pieces which compose the os frontis, a vacuity with
four sides is occasioned, which is termed the
  Anterior fontanel. This opening may be distinguished
by its form, as well as its greater size, from another vacu-
ity which is produced in a.similar  way at the other end of
the sagittal suture, and called  the
 , Posterior fontanel: but as  there are only three bones
concerned in  its formation, viz. the two parietal and the
Occipital, this  vacuity is triangular.
   Besides these, there are two other vacuities or fontanels
on each  side,  at  the two lower corners of each parietal
bone:  these however are much less than those first des-
cribed.
  The smaller fontanels do not continue open long; but
the anterior fontanel is  seldom completely closed before
the end of the third year.
   It is very obvious, upon an examination of the cranium,
that the  center of the base  is better calculated to  resist
pressure than any other part; as the cuneiform process of
the occipital  bone, the petrous portions of the temporal,
and the body of the sphenoidal bone, which compose a
large part of it, are very firm  and  substantial.
   The face of the foetus differs very essentially from that
of the adult.  Although  the orbits of the eyes are very
large when compared with the size of the head, that por-
tion of the face which is below them is very small and has
little depth.
   The upper maxillary bones have no sinuses in them; and
their orbitar plates are not m  .ch ehvated above the cavi-
ties for containing the posterior teeth: in consequence, the 
                  Head of the Foetus.                69
depth of the face is very small; and its whole aspect is af-
fected.
  The nose of the foetus differs greatly from that of the
adult in respect to its sinuses; for not only are the maxil-
lary cavities wanting, but those of the frontal and sphenoi-
dal bones also.
  The lower jaw is formed in two pieces, which unite at
the middle; and hence the term symphysis is used in  des-
cribing the chin.  This bone is not only less broad in  pro-
portion than that of the adult, but the angles are more ob-
tuse, and the processes which arise  from them are more
sloping.
  The head of the foetus is  much larger in proportion  to
the body than that of the adult. 
70
                    SECTION II.

                    Of the Trunk.
   THE Trunk consists of the Spine, Thorax, and Pel-
 vis.

                      The Spine*
   The spine is the long pile of bones extended from the
 con:  Ils of the occiput to the end of the os coccygis. It
 som-what  resembles two  unequal pyramids joined in a
 common base.  It is not, however, straight;  for its upper
 pan 'o. mg drawn backwards by strong muscles, it gradu-
 ally advances forwards, to support the oesophagus, vessels
 of the head, &c.  Then it turns backwards, to make room
 for the heart and lungs.  It is next bent forwards, to sup-
 port the viscera of  the abdomen.  It afterwards turns
 backwards, for the enlargement of the pelvis. And, lastly,
 it  is reflected forwards, for sustaining the lowest great
 intestines.
   The spine is commonly divided into true and false ver-
 tebrae: the  former  constituting  the long upper pyramid,
 which has its base below; while  the false  vertebrae make
 the shorter lower pyramid, whose base is above.

                   True  Vertebrae,
  The true vertebrae are the twenty-four upper bones of
the spine, on which the several motions of the trunk of our
bodies  are  performed.  Their name is derived from the
Larin verb vertere.
  Each  of  these vertebrae  is  composed of its body and
processes.
  The body is the thick spongy forepart, which is convex 
The Vertebra:.
7-1
before, concave backwards, horizontal and flat in  most
of them above and below. Numerous small holes, especi-
ally on the fore and back part of their surface, give passage
to their vessels, and allow the ligaments to enter their sub-
stance. The edges of the body of each vertebra are cover-
ed, especially at the forepart, with a ring of bone firmer
and  more solid than the substance of the body any where
else.  These rings  seem to be joined to the vertebrae in the
form of  epiphyses. They are of great  use  in  preventing
the spongy bodies from  being broken in the  motions of
the trunk.
   Between the bodies of each two adjoining vertebrae, a
substance between the nature of ligament and cartilage is
interposed; which seems to consist of concentrical curved
fibres, when it is cut horizontally; but when it is divided
perpendicularly, the fibres appear oblique and decussating.
The outer part of these intervertebral ligaments is the most
solid and hard; and they gradually become  softer till they
are almost in  the form  of a glairy liquor in the center.
The  external  fibrous part of each is capable of  being
greatly extended,  and of being compressed into a smaller
space, while the middle fluid part is  incompressible,  or
nearly so. The middle  point is therefore a fulcrum  or
pivot, on which the motion of a ball and  socket may be
made, with such a gradual yielding of the substance  of the
ligament, in whatever direction our spines are moved, as
saves the  body from violent shocks, and their dangerous
consequences. This ligamento-cartilaginous  substance is
firmly fixed to the horizontal surfaces of the bodies  of the
vertebrae,  to connect them:  in which  it is assisted by a
strong membranous ligament, which lines all their con-
cave surface, and by a still stronger ligament that covers
all their anterior convex surface. 
 72                 The Vertebra:.
   The elastic substance seems to be  in a state of com-
 pression by the exterior ligaments and the bones; for, if a
 section be made through a portion of the vertebrae and the
 intervertebral  substance, this substance will expand, so
 that its surface will be much higher than that of the ver-
 tebrae.  It is so elastic, and so much confined, in some sub-
jects, that a sharp knife, if plunged into it, will be gradu-
 ally ejected when the hand is withdrawn.
   The  bodies of the  vertebrae are, with some exceptions,
 smaller and more solid above,  but more spongy as they
 descend.  The  cartilages between them are thick, and the
 surrounding ligaments are strong in proportion to the size
 of the vertebrae.  By this disposition, the greatest weight
 is supported on the  broadest best secured base, and the
 middle of the body is allowed a large and secure motion.
   From each side of the body  of each vertebra, a bony
bridge is produced backwards, and to one side;  from the
posterior end of which one slanting process rises and ano-
ther descends.  The smooth, and generally the flattest, side
of each of these four  processes  is covered with a smooth
cartilage;  and the two lower processes of each upper ver-
tebra are fitted  to, and articulated with, the two upper pro-
cesses of  the vertebra below, having their articular liga-
ments fixed into the rough line round their edges. These
processes  are termed the oblique  or articulating.
   From between the oblique processes of each side, an-
other process extends laterally, which is called the trans-
verse.
   From the back part of the roots of the two oblique pro-
cesses, and of the transverse process of each side, a broad
oblique  bony plate  is  extended  backwards: where these
meet, the  seventh  process of the vertebrae takes  its rise,
and stands out backwards. This being generally sharp- 
                      The Vertebra.                  73
 pointed and narrow-edged, it has therefore been  called
 spinal process; from which this whole chain of bones has
 got its name.
   Besides the common ligament which lines all the inter-
 nal surface of the spinal processes, as well as of the bodies,
 particular ligaments connect the bony bridges and pro-
 cesses of the contiguous vertebrae together.
   The substance of the processes is considerably stronger
 and firmer, and has a thicker external plate, than the bodies
 of the vertebrae themselves.
   The seven processes form a concavity at their forepart,
 which,  joined to  the  one at the back  part of the bodies,
 makes  a great hole; and  when  the vertebrae are placed
 upon each other in their  natural order, these holes form
 a long tube for containing the spinal marrow.
   In the upper and lower edge of each lateral bridge, there
 is a notch. These  are so adapted to each other in the con-
 tiguous vertebrae, as to form a round hole in each side, be-
 tween each two vertebrae, through  which the nerves that
 proceed from the spinal marrow and its bloodvessels pass.
   The  articulations of these  true vertebras  are  conse-
 quently double: for their bodies are joined by the interven-
 ing cartilage above described; and their oblique processes,
 being tipped with cartilages, are so connected by their  li-
 gaments as to allow a small degree of motion on every side.
 Hence it is  evident,  that their center of motion is altered
 in different positions of the trunk: for, when we bow for-
 wards, the weight bears entirely on the bodies of the ver-
tebrae; if we bend  back, the oblique processes  support  it;
 if  we recline to  one side, we rest upon the oblique pro-
cesses of that side and part of the bodies; if we stand erect,
all the bodies and oblique processes have their share  in
our support.
  Vol.  I.                 K 
 74                  The Vertebra:.
   The true vertebra: are divided into three classes which
agree with each other  in their general structure, but are
distinguished by several peculiarities.
   These classes are named Cervical, Dorsal, and Lumbar.
   The cervical are the seven uppermost vertebrae; which
are distinguished from the  rest by these marks: Their bo-
dies are  smaller and more  solid than any others; and are
flatted on the front surface. They are also flat behind, where
small processes rise, to which the internal  ligaments are
fixed. The upper surface of the body of each vertebra is
made hollow, by a slanting thin process which is raised on
each side.  The lower surface  is also hollowed, but  in a
different  manner; for here the posterior edge  is raised a
little, and the anterior one is considerably extended. Hence
the cartilages between these vertebrae are firmly connect-
ed, and their articulations are  secure.
   These cartilages are thick,  especially at  their forepart;
which is one reason  why the vertebrae  project forward as
they descend, and have larger  motion.
   Their oblique processes more justly deserve  that name
than those of any other vertebrae. They are situated slant-
ing; the  upper  ones having their smooth and almost flat
surfaces  facing obliquely backwards and upwards; while
the inferior oblique processes  have these surfaces facing
obliquely forwards and downwards.
   The transverse processes of these vertebrae are framed
in a different manner from those of any other bones of the
spine: for, besides the common transverse process rising
from between the oblique processes of each side, there is
a second one that comes out from the side of the body of
each vertebra; and these two processes, after leaving a cir-
cular hole for the passage of the cervical artery and vein, 
                      The Vertebra.                  75
 unite and form a groove on their upper surface to protect
 the nerves that pass in it. They terminate obtusely on
 each side, for the insertion of muscles.
   The spinal processes project backwards almost horizon-
 tally. They are shorter than  those of any other vertebrae,
 and are forked or double at their ends; they therefore allow
 a more convenient insertion to muscles.
   The thick cartilages between the bodies of these cervi-
 cal vertebrae, the obliquity of their oblique processes, and
 the shortness and horizontal situation of their spinal pro-
 cesses, all conspire to allow them large motion.
   The holes between the bony cross bridges, for the pas-
 sage of the  nerves  from the spinal marrow, have  their
 largest share formed in the lowest of the two vertebrae, to
 which they are  common.
   So far  most of the cervical vertebrae  agree;  but they
 have some particular differences, which require a separate
 consideration.
   The first, from its use in supporting the head, has the
 name of atlas. Contrary to all the other  vertebrae of the
 spine, it  has no body;  but instead of it, there is a bony
 arch.  In the convex forepart of this arch a small rising
 appears; and on  each side of  this protuberance,  a  small
 cavity may be observed. The upper and lower parts of the
 arch are rough and unequal, where the ligaments that con-
 nect this vertebra to the os  occipitis, and to the second
 vertebra, are fixed.  The back  part of the  arch is concave,
 smooth, and covered with a cartilage, in a recent subject,
to receive the tooth-like  process of the second vertebra.
On each side of it a small rough sinuosity  may be remark-
ed, where the ligaments going to the sides of the tooth-
like process of the following vertebra are fastened; and on 
f 6                 The Vertebra:.
each side a small rough protuberance and depression is
observable, where the transverse ligament, which secures
the tooth-like process in the sinuosity, is fixed, and hinders
that process from injuring the medulla spinalis in the flex-
ions of the head.
   The atlas  has as little spinal process as body; but, in-
stead of it, there is a large bony arch,  that the muscles
which  pass over this vertebra at  that place might not be
hurt in extending the  head. On the posterior and upper
part of this arch there are two depressions, where the recti
postici minores take their rise ; and at the lower part  are
two other sinuosities, into which the ligaments that connect
this bone to the following one are fixed.
   The superior oblique processes of the atlas are large,
and more horizontal than  those of any other vertebra.
They form an oblong concav% surface which has an inter-
nal aspect, and corresponds exactly with the articulating
surface on the external side of each condyle of the os oc-
cipitis. Under the external edge of the posterior part of each
of these cavities is the fossa, or deep open channel, in which
the vertebral arteries make  the circular turn, as they  are
about to  enter the great foramen of the occipital bone, and
where the tenth pair of nerves go out.  In some subjects
this fossa is covered with bone. The inferior oblique pro-
cesess, extending from within outwards  and downwards,
are large, circular, and slightly concave.  So that this ver-
tebra, contrary to the  other six, receives the bones with
which it is articulated, both above and below.
   The transverse processes of this vertebra are not much
hollowed or forked; but are longer and  larger than those
of any other vertebra of the neck,  for the  origin and  in-
sertion of several  muscles j and therefore those muscles 
The Vertebra.
77
which move this vertebra on the second have a consider-
able le\rer to act with, because of the distance of their in-
sertion from the axis of revolution.
   The hole for the medulla spinalis is larger in the atlas
than in any other vertebra, not only on account of the me-
dulla being largest here, but also to prevent its being hurt
by the motions of this vertebra on the second.  This large
hole, and the long transverse processes, make this  the
broadest vertebra of the neck.
   The condyles of the os occipitis move forwards and
backwards in the superior oblique processes of this verte-
bra; but from the figure of the bones forming these articu-
lations,  it is evident,  that very little motion can here be
allowed to either side; and there must be still less circu-
lar motion.
  The second vertebra of the neck is called dentata. It
is somewhat of a pyramidal figure, being large, and  ex-
tended downwards, especially in front, to  enter  into a
hollow of the  vertebra below;  while the upper part has a
long process,  with its extremity formed  into an obtuse
point. This process from its supposed resemblance to a
tooth, has given name to the vertebra. The side of it, on
which the concave surface of the anterior arch of the first
vertebra plays, is convex, smooth, and  covered  with a car-
tilage; and it is of the same form behind, to accommodate
the ligament,  which  is extended transversely from one
rough protuberance of the first vertebra to the  other, and
is cartilaginous in  the middle.  A ligament likewise goes
out in  an oblique transverse direction, from each side of
the processus  dentatus, to be fixed at  its other end to  the
first vertebra,  and to the occipital bone; and another liga-
ment rises up  from near the point of the process to the os
occipitis. 
 78                  The Vertebra.
   The superior oblique processes of the vertebra dentata
 are large, circular, very nearly in an horizontal  position,
 and slightly convex, to be adapted to the inferior oblique
 processes of the first vertebra. The inferior oblique pro-
 cesses of this vertebra answer exactly to the description
 given of those common to all the cervical vertebrae.
   The transverse  processes of the vertebra dentata are
 short,  very little hollowed  at their upper part,  and not
 forked at their ends; and the canals through which the
 cervical  arteries pass  are reflected outwards about  the
 middle of  each process;  so that the course of these  ves-
 sels  may be directed towards  the transverse  processes
 of the first vertebra.  Had  this curvature of the arte-
 ries been made in a part so movable as the neck  is, while
 they were not defended by a bone,  and placed in a cavity
 of that bone, scarce a motion could have been performed
 without  the  utmost hazard  of  compression.  This is the
 third instance of similar  mechanism in cases of sudden
 curvature of arteries. The first is the passage of the caro-
 tids through the temporal bones; and  the second is  that
 lately described, where the vertebral arteries  turn round
 the oblique processes of the first vertebra, to come at the
 great hole of the occipital bone.
   The spinal process of this vertebra is thick,  strong,
 and  short,  to give sufficient origin to the musculi recti
majores and  obliqui inferiores, and to prevent the con-
tusion  of these  and other muscles in  pulling the head
back.
  The four cervical vertebrae which are next in order,
have nothing particular in their structure, but  agree with
the general description. The seventh vertebra  approaches
the form of those of the back, having the upper and lower 
The Vertebra.
79
surfaces less excavated than the others.  The oblique pro-
cesses are more perpendicular; and the  spinal as  well as
transverse processes are without bifurcation.
  After an examination of the condyles of the os occipitis,
and of the whole structure of the atlas and vertebra den-
tata, it will be evident, that the flexion and extension of the
head, or its motion backwards and forwards, is effected by
the movements of the condyles of the occipital bone on the
atlas; and that  in the rotation of the head, the atlas re-
volves to  a certain  degree round the processus dentatus
of the second vertebra: the head necessarily moving with it.
  The twelve dorsal may  be  distinguished from the
other vertebra of the spine by  the following marks.
  Their bodies are of a middle size, between those of the
neck and loins.  They are more convex before than either
of the other two sorts; and are flatted laterally by the
pressure of the ribs, which are inserted into small cavities
formed in their  sides. This flatness of their sides, which
makes the figure of these vertebrae almost  an half oval,
is of  great use;  as it affords a  firm articulation to the
ribs,  allows the trachea arteria to divide at a small angle,
and the other large vessels to run secure from the action
of the vital organs. Their bodies are more concave be-
hind  than any of the other two classes. Their upper and
lower surfaces are horizontal.
  The cartilages interposed between the bodies of these
vertebrae are thinner  than in any other of the true verte-
brae;  and  contribute to the concavity of the spine  in the
thorax, by being thinnest at their forepart.
  The oblique  processes are placed almost perpendicu-
larly: the upper ones slanting but a  little forwards, and the
lower ones slanting as much backwards. Their convexity 
  80                 The Vertebra.
/ or conc?.vity is not so remarkable as to require particular
  notice.  Between the oblique processes of opposite sides,
  several  sharp processes stand out from the upper and lower
  parts of the plates which join to form the spinal processes:
  into these  sharp processes strong ligaments are fixed for
  connecting the vertebrae.
   The  transverse processes of the  dorsal  vertebrae are
  long, thicker at  their ends than in the middle, and turned
 obliquely backwards; which may be owing to the pressure
  of the ribs; the tubercles of which are inserted into a de-
  pression near the end of these  processes.
   The spinal processes are long, small-pointed, and sloping
 downwards and backwards. From their upper and back
 part a ridge rises, which is received by a small channel in
 the forepart of  the  spinal  process  immediately above,
 which is here connected to it by a ligament.
   The canal for  the spinal marrow is here more circular,
 but, corresponding to the size of that cord, is smaller than
 in any of the other vertebrae; and a larger share of the holes,
 in the bony bridges for the transmission of the nerves, is
 formed  in the vertebra above than in the one below.
   The connexion of the dorsal vertebrae to the ribs, the
 thinness of their cartilages, the erect situation of the
 oblique  processes, the length,  sloping and connexion  of
 the  spinal processes, all contribute to restrain these verte-
 brae from much motion, which might disturb the actions of
 the  heart and lungs;  and in consequence of the little mo-
 tion allowed  here, the  intervertebral cartilages sooner
 shrivel,  by becoming more  solid} and therefore the first
 remarkable curvature of the spine observed, as people ad-
 vance to old age, is in the least stretched vertebrae of the
 back; or old people first become round-shouldered. 
The Vertebra.
81
  The bodies of the four uppermost dorsal vertebrae devi-
ate from the rule, that the vertebrae become larger as they
descend; for the  first of the four is the largest, and the
other three  below gradually become smaller, to allow the
trachea and large vessels to divide at smaller angles.
  The two uppermost vertebrae of the back, instead of be-
ing very prominent forwards, are flattened by the action of
the musculi longi colli and recti majores.
  The proportional size of the two little depressions in
the body  of each vertebra for receiving the heads of the
ribs, seems to vary in the following manner; the depres-
sion  on  the  upper edge of  each vertebra decreases as far
down as the fourth, and after that increases.
  The transverse processes are longer  in each lower ver-
tebra to the seventh or eighth, with their smooth surfaces,
for the tubercles of the ribs, facing gradually more down-
wards;  but  afterwards, as they  descend, they become
shorter, and the smooth surfaces are  directed more up-
wards.
  The spinous processes of the vertebrae  of the back be-
come gradually longer and more slanting from the first, as
far down as the eighth or ninth vertebra; from which they
manifestly turn shorter and more erect.
  The first vertebra, besides an oblong hollow in its lower
edge, that assists in forming the cavity wherein the second
rib is received, has the whole cavity for  the head of the
first  rib formed in it.
  The eleventh often has the whole cavity for the eleventh
rib in its  body, and wants the  smooth surface on each
transverse process.
  The twelfth always receives the whole head of the last
rib, and has no smooth surface on its transverse processes,
which are very short. The smooth surfaces of its inferior
   Vol. I.                E 
 82                  The Vertebra.
 oblique processes face  outwards as the lumbar do.  In
 general, the  upper vertebrae of the back lose gradually
 their resemblance to those of the neck, and the lower ones
 approach gradually to the figure of the lumbar.
   The lumbar vertebra are five bones, that may be dis-
 tinguished from any others by these marks: 1. Their bodies,
 though  of a circular form at their forepart, are somewhat
 oblong from  one side to the other. The epiphyses on their
 edges are larger; and therefore the upper and lower sur-
 faces of their bodies are more concave than in the verte-
 brae of the back. 2. The cartilages between these vertebra
 are very thick, and render the spine convex within the ab-
 domen, by their great thickness anteriorly. 3. The oblique
 processes are strong  and deep: the superior,  which are
 concave, facing inwards,  and the  convex inferior ones
 facing outwards:  and therefore each  of these  vertebra
 receives the  one above it, and is received by the one be-
 low; which is  not so  evident in  the  other two classes
 already described. 4. Their transverse processes are small,
 long, and almost horizontal, for  allowing large  motion  to
 each bone, and sufficient insertion to muscles, and for sup-
 porting  and defending the internal parts. 5. Between the
 roots of the  superior oblique and transverse processes a
 small protuberance may be observed, where  some of the
 muscles that raise the trunk  of the  body are inserted.
 6. Their spinal processes are strong,  straight, and  hori-
 zontal, with broad flat sides, and a narrow edge above and
 below; this last being depressed  on each side by muscles.
 And at the root of these edges, we see rough surfaces for
 fixing the ligaments.  7.  The medullary canal is larger  in
these bones than in the dorsal vertebrae.  8. The holes for
the passage of the nerves are more equally formed out  of
both the contiguous vertebrae than in the other classes; 
                     The Vertebra.                 83
the upper one furnishes, however, the larger share of each
hole.
   The thick cartilages between these  lumbar vertebrae,
their deep oblique processes, and their  erect spinal pro-
cesses, are  all fit for allowing large motion:  though it is
not so great as what is performed in the neck;  which ap-
pears from comparing the arches which the head describes
when moving on the neck or the loins only.
   The lumbar vertebrae, as they descend, have their ob-
lique processes at a greater distance from each other, and
facing more backwards and forwards.
   The transverse and spinal processes of the first and last
lumbar vertebrae are shorter than those in the middle.
   The epiphyses  round the edges  of  the bodies of the
lumbar vertebrae are  most raised in the two lowest; which
consequently make them appear hollower in the middle
than the others are.
   The body of the fifth vertebra is rather thinner than that
of the fourth.  The spinal process of this fifth is smaller,
and the oblique processes face more backwards and for-
wards, than those of any other lumbar vertebra.
   In consequence of this particular construction, the spine
is  capable of flexion, principally  in an anterior and lateral
direction, and  also of extension. It ought to be remarked
that during flexion it forms a curve, and  not an angle; for,
in  this last  case, the spinal marrow would be more or less
compressed.
   The cervical vertebrae have most motion, and the dorsal
the least. This circumstance is fully explained by the form
of the different parts of these vertebrae,  and by  the differ-
ence in the thickness of their  intervertebral substance.
The necessity of fixing the dorsal vertebrae is very evident:
as  their  motion would greatly interfere with the motions
of the ribs in respiration. 
84                   Os Sacrum.
  The lumbar vertebrae have  more motion than is com-
monly supposed; for, in addition  to  a certain degree of
flexion, they perform a species of rotation or twisting,
which is very observable in persons who are diseased in
one of their hip joints; such persons move the whole pel-
vis, by a rotation of the lumbar vertebrae, to  avoid moving
the diseased joint.

                   False Vertebra.
  The lower pyramid, or under part of the spine, consists
of one large triangular bone called the os sacrum, and of
some small bones denominated the os coccygis.
  These bones are called the false vertebrae, because the
sacrum in young subjects  is composed  of five distinct
bones, each of which has some resemblance  to a vertebra;
but they are completely united in the adult, and form but
one bone, which  is supposed to  have  been denominated
sacrum, because it was offered in sacrifice by the ancients.
  The os sacrum is of a triangular form, with its base up-
wards. It is concave anteriorly, and convex posteriorly.
The middle  of the bone, when viewed anteriorly, appears
to be composed  of the bodies of five vertebrae, united to
each other,  and  their union is marked by four transverse
lines. At the two extremities of each  of these lines, are
large round  holes, which communicate  with the vertebral
cavity of the bone.
  On the exterior sides of these holes the surface is free
from any marks of the original separation.
  The middle of the upper surface, or base of the bone,
is formed for articulating with the last lumbar  vertebra,
and has two oblique processes, with a groove on each side,
which forms part of the foramen for transmitting the
twenty-fourth pair of nerves. 
                      Os Sacrum.                   85
   The back part of the os sacrum is rough and convex: in
the middle there are commonly three processes similar to
the spinous processes of the lumbar vertebrae, and a fourth
which is much smaller.  Below this, there is a deficiency of
the bony spine, and  the vertebral cavity is consequently
open  behind; but the sides of the canal continue lower
down.
   On each side of the spinous processes are four smaller
holes, which are opposite to the larger holes on the ante-
rior surface.  Between the spinous processes and the ante-
rior part, which resembles the bodies of vertebrae, is the
continuation of the vertebral cavity which contains the spi-
nal marrow. From the cauda equina,  contained in this
cavity, the great nerves of the lower extremities pass  off,
through the large holes on the anterior surface, and some
small nerves through the posterior holes.
   In  some bones the spinous processes are entirely defi-
cient, and the cavity above mentioned is completely open
behind; but the contained parts are defended by strong
membranes.
   The anterior part of each lateral surface is covered by a
plate  of cartilage, and  articulated to the os ilium. The
posterior part is rough and perforated by the fibres of the
strong ligaments, which are inserted into it.
   On the posterior surface of the sacrum, the sides of the
open part of the vertebral canal terminate, so as to form a
notch, through which passes the twenty-ninth pair of nerves.
   The os sacrum is very spongy, and is  lighter in propor-
tion to its bulk  than any bone  in the body:  it is defended
by the muscles that cover it and the  ligaments which ad-
here to it.
   It is articulated, above, to the last lumbar vertebra; be-
low, to the os coccygis; and on the sides, to the ossa ilia. 
86                  Os Coccygis.
  That triangular chain of bones depending from the os
sacrum, in which each bone becomes smaller as it de-
scends, till the last ends in a small tubercle, is called os
coccygis.  It is convex behind, and concave before; from
which  crooked  pyramidal figure, which was thought to
resemble a cuckow's beak, the name is derived.
  There are four pieces in people of middle age.  In chil-
dren, they are almost wholly cartilaginous. In old subjects,
all the  bones are united, and become frequently one con-
tinued  bone with the os sacrum.
  The highest of the four bones is the largest, with shoul-
ders extended farther to each side than the end of the os
sacrum; which enlargement may serve as a distinguishing
mark to fix the limits of either bone.  The upper surface of
this bone is a little hollow. From the back of that bulbous
part called its shoulders, a process often rises up on  each
side, to join with the os sacrum. Sometimes these shoul-
ders are joined to the sides of the open end of the verte-
bral canal', to form the hole in each side common  to these
two  bones, for the passage of the twenty-ninth pair of spi-
nal nerves.  Immediately below the shoulders  of the  os
coccygis, a notch may be remarked on each side, where the
thirtieth pair of the spinal nerves passes.  The lower end
of this  bone is formed into a small head, which very often
is hollow in the middle.
  The three lower bones gradually become smaller, and
are spongy,  but are  strengthened by a strong  ligament
which  covers and connects them. Their ends, by which
they are articulated, are formed in the same  manner as
those of the first bone.
  Between each of these four bones  of young subjects a
cartilage is interposed;  therefore their articulation is ana-
logous to  that of the bodies of the vertebras of the neck: 
                     Os Coccygis.                  87
for the lower end of the os sacrum, and of each of the
three superior bones of the os coccygis, has a small de-
pression in the middle; and the upper part of all the bones
of the os coccygis is a little concave, and consequently the
interposed cartilages are thickest in the middle, to fill up
both cavities; by which they connect the bones more firmly.
When the cartilages ossify, the upper end of each bone is
formed into a cavity, exactly adapted to  the protuberant
lower end of the bone immediately above. From this sort
of articulation, it is evident, that, unless when these bones
grow together, all of them are capable of motion; of which
the first and second enjoy the largest share.
   The lower end of the fourth bone  terminates in a rough
point, to which a cartilage is appended.
   To the sides of these bones of the os coccygis, the coc-
cygaei muscles, and part of the levatores ani, and of the
glutaei maximi, are fixed.
   The connexions of these bones hinder them from being
moved to either  side; and their motion backwards and
forwards is much confined: yet as their ligaments can be
stretched by a considerable force, it is of great advantage
in the excretion  of the  faeces alvinae, and much more in
childbearing, that these bones should remain movable;
and the right management of them, in delivering women, is
very important. The mobility  of  the os coccygis dimin-
ishing as people advance in age, especially when its liga-
ments and cartilages have not been kept flexible by being
stretched, is probably one reason why  women, who are
advanced in years before they marry, have generally diffi-
cult parturition.
   These bones serve to sustain the intestinum  rectum;
and, therefore, are curved forwards; by which they are
preserved,  as well as the muscles  and teguments, from
any injury when sitting with the body reclined back. 
88
The Ribs.
 The Vertebral Cavity for containing the Spinal Marrow.
   The canal formed by the foramina of the different ver-
tebrae, when these bones are placed in their natural order,
extends from the great occipital foramen to the end of the
sacrum. Its direction varies with the different curvatures
of the spine, and its figure and diameter are also very dif-
ferent in different places.
   In the cervical vertebrae, it is largest, and nearly trian-
gular in form;  in the dorsal, it is much smaller and almost
cylindrical; in the lumbar, it is somewhat enlarged, and ap-
proaches again to the triangular figure;  in the sacrum, it is
broad, but flat, and diminishes gradually, so as to assume
the form of a long triangle.
   It has a ligamentous lining, which will be described
when an account is given of the fresh bones and their liga-
ments.

                     The Thorax.
   The thorax resembles a flattened cone, cut away oblique-
ly at its basis;  and regularly truncated at its apex.
   It is formed by the dorsal vertebrae behind, the ribs on
the sides, and the sternum before.

                      The Ribs,
   Are long crooked bones, placed  in  an oblique direc-
tion downwards as respects the backbone. Their number
is generally twelve on each side; though sometimes eleven
or thirteen have been found.
   They are convex externally and concave internally.
They are  made smooth by  the action of  the contained
parts, which, on this account, are in no danger of being
hurt bv them. 
                       The Ribs,                    89
   The ribs approach towards a round form at their extre-
 mities  near the vertebrae.  Further forwards they are flat
 and broad, and have an upper and lower edge; each of
 which is made rough by the action of the intercostal mus-
 cles inserted into them. These muscles, being all of nearly
 equal force, and equally stretched in the interstices of the
 ribs, prevent the broken ends of these bones, in a fracture,
 from being removed far out of their natural place, to inter-
 rupt the motion of the vital organs. The  upper edge  of
 the ribs is more obtuse and rounder than the lower, which
 is depressed on its internal side by a long fossa, for lodg-
 ing  the intercostal vessels  and nerves:  on each side  of
 which there is a ridge, to  which the intercostal muscles
 are fixed. The fossa is not observable at the ends of the
 ribs; for, at the posterior, or root, the vessels have not yet
 reached the  bones;  and, at the fore  end,  they are split
 away into branches, to serve the parts between the ribs.
   From this situation of the bloodvessels, has originated
 the rule adopted by surgeons, that the incision in cases of
 empyema, &c. should be made midway between the spine
 and sternum, and that the lower  edge of the upper rib
 should  be avoided.
   At the posterior end of each rib, a little head is formed,
 which is divided by a middle ridge into  two flat or hol-
 low surfaces;  the lowest of which is generally the broad-
 est and deepest. The two surfaces are joined to the bodies
 of two different vertebrae, and the ridge forces itself into
 the intervening cartilage. A little way from this head, we
 find, on the external surface, a small cavity, where mucila-
 ginous  glands are lodged;  and round the head,  the bone
 appears spongy, where the capsular ligament of the articu-
 lation is fixed. Immediately beyond this, a flatted tubercle
rises, with a small cavity at its root, which  is surrounded
  Vol. I.                   M 
 90                    The Ribs.
 by a roughness, for the articulation of the rib with the
 transverse process of the lowest of the two vertebrae, with
 which the head of the rib is joined. Advancing further on
 this external surface, another smaller tubercle may be ob-
 served in most cases, into which, ligaments connecting the
 ribs to each other, and to the transverse processes of the
 vertebrae and portions of the longissimus dorsi, are insert"
 ed.  Beyond this, these bones are made flat by the sacro-
 lumbalis muscle, which is inserted into the part of this flat
 surface furthest  from the spine, where each  rib makes a
 considerable curve, called by some its angle. Then the rib
 begins to turn broad, and continues so to its anterior end,
 which is hollow and  spongy, for the reception of, and firm
 coalition with, the cartilage that runs thence to be inserted
 into the sternum, or to be joined with some other carti-
 lage. In adults, the cavity at this end of the ribs is  gene-
 rally smooth.
   The substance of the ribs is spongy, cellular, and only
 covered with a very thin external lamellated surface, which
 increases  in thickness and strength as it approaches the
 vertebrae.
   To  the fore end  of each rib  a long broad and strong
 cartilage  is fixed, which reaches to the sternum, or is
joined to the cartilage of the next fib. This course, how-
 ever, is not in a straight line with the rib: for the cartilages
 generally  make a considerable flexure, the  concave  part
 of which is upwards; therefore, at their insertion into the
 sternum, they make an obtuse angle above, and  an  acute
 one below. These cartilages are of such a length as never
to allow the ribs  to come to a right angle with the spine;
but they  keep them  situated so  obliquely as to  make the
 angle very considerably obtuse above, till a force exceed-
 ing the elasticity of the cartilage is applied. These cartila- 
The Ribs.
91
ges, as all others, are firmer and harder internally than they
are on their external surface; and sometimes, in old peo-
ple, all their middle substance becomes bony, while a thin
cartilaginous lamella appears externally. The ossification,
however, begins frequently at the external surface. The
greatest alternate motions of the cartilages being made at
their great curvature, that part remains frequently cartila-
ginous after all the rest is ossified.
  The ribs then are articulated at each end, and that be-
hind is  doubly joined to the vertebrae;  for the head is
received into  the cavities of two bodies of the vertebrae,
and the larger tubercle is received into the depression in
the transverse  process of the lower vertebra. When we
examine the double articulation, we must immediately see,
that no other motion can here be allowed than upwards
and downwards. Since the transverse  process hinders the
rib to be thrust  back, the resistance  of the sternum on
the other side prevents the ribs coming forward; and each
of the two joints, with the other parts  attached, oppose its
turning round. But then it is likewise  as evident, that even
the motion upwards and downwards can be but small in
any one  rib at the articulation itself. But as the ribs ad-
vance forwards, the distance from  their center of motion
increasing, the motion must  be larger; and it would be
very conspicuous at their anterior ends, were they not re-
sisted there by the cartilages, which yield so little, that the
principal motion is performed by the middle part of the
ribs, which turns outwards and upwards, and occasions
the twist remarkable in the long ribs at the place near their
fore end where they are  most resisted.
   The ribs differ from each other in the following respects:
   The upper rib is the most crooked; and as they descend
they become straight.  Their obliquity, with respect to the 
92                   The Ribs.
spine, increases as they descend; so that though their dis-
tances from each other are nearly equal at their back part,
yet at their fore ends the distances between the lower ribs
must increase. In consequence of this increased obliquity
of the lower ribs, each of their  cartilages makes a greater
curve in its progress from the rib towards the sternum;
and the tubercles, that are  articulated to the  transverse
processes of the vertebrae, have their smooth surfaces gra-
dually facing more upwards. The ribs becoming thus more
oblique, while the sternum  advances forwards in its de-
scent, makes the distance  between  the  sternum and the
anterior end of the lower ribs  greater than between the
sternum and the ribs above; consequently, the cartilages of
those ribs that are joined to the breast bone are longer in
the lower than in the higher ones. These cartilages are
placed nearer to each other as the ribs descend, which oc-
casions their curvature to be greater.
   The length of the ribs increases  from the first and up-
permost rib, as far down as the seventh;  and from that to
the twelfth, it gradually diminishes.  The superior of the
two  surfaces, by which the ribs are articulated to the bo-
dies  of the vertebrae, gradually increases from the first to
the fourth rib, and is diminished after that in  each  lower
rib.  The  distance of their  angles from  the heads always
increases  as they descend to the ninth, because of the
greater breadth of the sacro-lumbalis muscle.
   The ribs are commonly divided into true and false.
   The  true ribs are the seven uppermost of  each side.
Their cartilages are all gradually longer as they descend,
and  are joined to the breast bone: so that, being pressed
constantly between two bones, they are flatted at both ends;
and  are thicker, harder, and more liable to ossify, than the
other cartilages that are not subject to so much pressure. 
                       The Ribs.                    93
These bones include the heart and lungs; and therefore
are called true ribs.
  The five inferior ribs of each side are the false, whose
cartilages do not reach to the sternum; but on this account,
having less pressure, their substance  is softer. To these
five ribs the circular edge of the diaphragm is connected.
  The first rib of each side  is so situated, that the flat
sides are above  and below,  while  one edge is placed
inwards, and the other outwards, or nearly so: therefore
sufficient space is left above it for the subclavian vessels
and muscles; and the broad concave surface is opposed to
the lungs. But in consequence of this situation, the chan-
nel for the intercostal vessels is not to be found. The head
of this rib is not divided into two plane surfaces by a mid-
dle ridge, because it is only articulated with the first ver-
tebra of the thorax. Its cartilage is ossified in adults, and
is united to the sternum at right angles. This first rib fre-
quently has a ridge rising near the middle of its posterior
edge, where one of the heads of the scalenus muscles rises.
Farther forward  it is flatted, or sometimes depressed by
the clavicle.
  The position of the second rib is such that its two broad
surfaces have oblique aspects, inward and downward, out-
wards and upwards, so as to make the surface of the tho-
rax uniform: and it may be observed of all the ribs, that
the aspect of their surfaces is varied upon this principle,
according to their situation in the thorax.
  The sixth, seventh, and eighth ribs, have their cartilages
nearly contiguous. They are  frequently joined  to each
other by cross cartilages; and frequently the  cartilages of
the eighth, ninth, and tenth, are connected to  the former,
and to each other by firm ligaments.
  The eleventh, and sometimes the tenth rib, has no uv 
  94                  The Sternum.
  bercle for its articulation  with the transverse process of
  the vertebra, to which it is only loosely fixed by ligaments.
  The fossa in its lower edge is not so deep as in the upper
  ribs; because the vessels run more towards the interstice
  between the ribs.  Its front end is smaller than its body; and
  its  short  small cartilage is but loosely connected to the
  cartilage of the rib above.
   The twelfth rib is the shortest and straightestu Its head
 is only articulated with the last  vertebra of the thorax;
 therefore is not divided into two surfaces. This rib is not
 joined to the transverse process of the vertebra; and there-
 fore has no tubercle, being often pulled necessarily inwards
 by  the diaphragm, which  an articulation with the trans-
 verse process  would not have allowed. The fossa is not
 found at its under edge,, because the vessels run below it.
 The forepart of this rib is smaller than its middle, and has
-only a very small pointed  cartilage fixed to it.  To its
 whole internal side the diaphragm is connected.

                      The Sternum
 is the broad flat bone, in the front part of the  thorax. In
 adults it is composed of three pieces, which easily separate
 after the cartilages connecting them are destroyed.  The
 two lower pieces  are frequently found intimately united;
 and very often, in old people, the  sternum is a  continued
 bony substance from one end to the other; though we still
 observe two, sometimes three, transverse lines on its sur-
 face; which are marks of the former divisions.
   The sternum, considered  as one bone, is broadest and
 thickest above, and smaller as it  descends. The internal
 surface of this bone is somewhat concave for enlarging the
 <horax: but the convexity on the external surface is not so 
The Sternum.
95
  conspicuous, because the sides are pressed outwards by
  the true ribs; the round heads of whose cartilages are re-
  ceived into seven smooth pits formed in each side of the
  sternum,  and are  kept firm  there  by strong ligaments,
  which on  the external surface have a particular radiated
,  texture. The pits at the upper part of the sternum are at
  the  greatest distance  one  from another, and, as they de-
  scend, are nearer;  so that the two lowest are contiguous.
     The  substance of the breastbone is cellular, with a very
  thin external plate, especially on its internal surface, where
  we may frequently observe a cartilaginous crust spread
  over it. On both surfaces, however, a strong ligamentous
  membrane is closely braced; and the cells of this bone are
  so small, that a considerable quantity of osseous fibres must
  be employed in  the composition of  it.  Whence, with the
  defence which the  muscles give it, and the movable sup-
  port it has from  the  cartilages, it  is sufficiently secured
  from being broken: for it is strong by its quantity of bone;
  its parts  are kept together by ligaments; and it yields
   enough to elude considerably any violence offered.
     The three pieces which  compose this bone are very dif-
  ferent from each other.
     The first piece resembles a triangle with the corners cut
  off.  The  upper edge  of it is thick,  and has a regular de-
  pression in the middle, to accommodate the trachea. On
  each side  of this depression is a superficial cavity, which
  on viewing it transversely  from before backwards, appears
  a little  convex. Into these cavities  the ends of the clavicles
  are  received. Immediately below them the sides of this
  bone become thinner; and  in each  a  superficial cavity, or a
  rough surface, is to be seen, where the first ribs are received
  or joined to  the sternum.  In the side of the under end  ot
  this first bone, the half of the pit for the second rib on each 
 96                  The Sternum.
 side  is formed.  The upper part of the surface behind is
 covered with a strong ligament, which secures the clavi-
 cles; and is afterwards to be more particularly taken no-
 tice of.
   The second, or middle division of this  bone, is much
 longer, narrower, and thinner, than the first; but excepting
 that it is a little narrower above than below, it  is nearly
 uniform in its dimensions of breadth or thickness. In the
 sides of it are complete pits for the third, fourth, fifth, and
 sixth ribs,  and an half  of the pits  for the second and
 seventh; the lines, which are marks of the former division
 of this bone, being extended from the middle of the pits of
 one side to the middle of the corresponding pits of the
 other side.  Near its middle an unossified part of the bone
 has  sometimes been found; which, freed of the ligamen-
 tous membrane or cartilage that fills  it, is  described as a
 hole. When the  cartilage between this and the first bone
 is not ossified, a manifest motion of this upon the first may
 be observed in respiration; or in raising the sternum, by
 pulling the ribs upwards; or distending the  lungs with air,
 in a recent subject.
   The third hone is much less than the other two, and has
 only one half of  the pit for the seventh rib formed in it;
 wherefore it might be reckoned only an appendix of the
 sternum.  In young subjects it is always cartilaginous, and
 is better known by the name of cartilago xiphoides or ensi-
formis, than any  other. This third bone is seldom of the
 same figure, magnitude, or situation,  in any two subjects;
 for sometimes it  is triangular; with one of the  angles be-
 low, and perpendicular to the middle of the upper side, by
 which it is connected to the second bone. In other persons,
 the point is turned to  one side; or obliquely forwards or
 backwards.  Frequently,  it is nearly of  an  equal breadth, 
                Motion of the Ribs, fcfc.              97
 and often, it is bifurcated; sometimes also, it is unossified
 in the middle.  In the greatest number of adults, it is ossi-
 fied, an^ tipped with a cartilage; in some, one half of it is
 cartilaginous; and in others, it is all in a cartilaginous state.
   The sternum is joined by cartilages to the seven upper
 ribs, except when the first coalesce with it. It is also arti-
 culated with the clavicles.
   It contributes to the formation of the cavity of the tho-
 rax, and supports the mediastinum. As a movable fulcrum
 for the  ribs, it  assists in  respiration;  and it affords origin
 and insertion to several muscles.

  The Movement of the Ribs and Sternum in Respiration.
   The ribs and their cartilages are articulated to the spine
 behind, and the sternum before, in a way which admits of
 a compound motion.
   They are drawn from a position which slopes obliquely
 downwards  and forwards, into one which is more horizon
 tal; and the posterior extremity of each rib,  which is  the
 center of this motion, is moved very little, while the ante
 rior extremity moves much more.
   At the same  time, the ribs perform a rotation outwards,
 upon their extremities connected with the spine and ster-
 num; in consequence of which, the middle of each rib is
 moved outwards to a considerable extent.
   It is very obvious, that by these motions, the thorax must
be enlarged from side to  side, and from behind forwards.
   As the ribs are raised from the oblique towards the ho-
rizontal position, the sternum  is necessarily moved for-
ward by them;  and if this bone does not  move upon the
first rib, the rib must move to accommodate it: a small
motion at the articulation of the rib with the spine, being
sufficient to  produce considerable motion at the lower end
  Vol. L                N 
98                   The Pelvis.
of the sternum. The sternum, therefore, vibrates forward
when the ribs are elevated, and backward when they are
depressed.
   In  easy  respiration  these motions  are not very great,
for then the enlargement of the thorax appears to be pro-
duced by the increase  of its vertical  diameter, in conse-
quence of  the descent of the diaphragm;  but  when the
inspirations are very large, and  when  the descent of the
diaphragm  is  impeded, as in pregnancy, and in ascites,
these motions are very  considerable.
   It ought to be observed, that the first rib has very little
motion, except the rotation which favours the  motion of
the sternum; and that the two lower ribs, having no sup-
port at their anterior extremities, have no rotation.

                      The Pelvis.
  The pelvis  is the cavity at the lower part of the trunk,
formed by the os sacrum, os coccygis, and ossa innominata.
  The ossa innominata are the two large bones which are
connected to the sacrum behind, and to each other, by the
intervention of a cartilage, in front.
  Each of  the ossa innominata is composed of three por-
tions, in children; and although these are united in adults,
so as to form but one bone, yet anatomists have generally
considered  the bone as divided into  its  original  parts,
which are denominated os ilium, os ischium, and os pubis.
  The original separation is at the acetabulum, or cavity
for receiving the head  of the os femoris, which is on the
outside of the os innominatum.  The upper  and posterior
part of this cavity, to the amount of two fifths, is formed
by the os ilium, two fifths of the inferior portion by the os
ischium, and the  anterior fifth by the os pubis. 
                        Os Ilium,                    99
   The os ilium is the largest of the  three portions.  Its
 external surface has been called its dorsum, and the inter-
 nal  concave surface its costa. The semicircular edge at
 the  upper part of the bone, is named the spine: the external
 oblique muscle  of the abdomen is inserted into it, and the
 internal oblique, and the tranversalis  arise from it. The
 ends of the spine are prominent, and therefore are called
 processes. At a small distance below the anterior spinous
 process,  is another protuberance, called the inferior an-
 terior spinous process;  and the edge of the bone between
 these two processes is curved.
   Below the posterior spinal process, another protuberance
 is also observable, which is  applied closely to the os sa-
 crum. Under this is a large notch, which, with the liga-
 ments that pass from theos sacrum to the os ischium,forms
 a foramen, through which the great sciatic nerve, the pyri-
 form muscle, and  some bloodvessels pass.
   The external surface, or dorsum, of the os ilium is gently
 undulated by the action of muscles that lie upon it: the
 gluteus maximus on the posterior, and the gluteus medius,
 and  minimus on the anterior parts of  it. The lower part
 of this bone, which contributes to the formation of the ace-
 tabulum, is the thickest.
   The internal surface of the os ilium is concave, and sup-
 ports some of the intestines. From this concave surface a
 slight concavity  is  continued  obliquely forwards, at the
 inside of the anterior inferior spinal process, where part of
 the psoas and iliacus muscles, with the crural vessels and
nerves, pass.  The large concavity is bounded below by a
sharp ridge, which runs from behind forwards; and, being
continued with such another ridge of the os pubis, forms a
line of partition between the cavities of the abdomen and 
 100                 Os Ischium,
 pelvis. Into this ridge the broad tendon of the psoas par-
 vus is inserted.
   All the internal surface of the os ilium, behind the con-
 tinuance of this ridge, is very unequal: for the upper part
 is flat, but spongy, where the sacro-lumbalis and longissi-
 mus dorsi rise.  Lower  down, there is a transverse ridge,
 from which ligaments go out to the os  sacrum. Imme-
 diately below this ridge, the rough unequal cavities and
 prominences are placed, which are exactly adapted to those
 described on the side of the os sacrum. In the same man-
 ner, the upper part of this rough surface is porous, for the
 firmer adhesion  of  the ligamentous cellular substance;
 while the lower part  is more solid, and covered with a ^iin
 cartilaginous skin, for its immovable articulation with the
 os sacrum. From all the circumference of this large une-
 qual surface, ligaments are extended to the os sacrum, to
 secure more firmly the conjunction of these bones.
   The passages of the medullary vessels are very conspi-
 cuous, both in the dorsum and costa of many ossa ilia;
 but in others they are inconsiderable.
   The posterior and  lower parts of these bones are  thick;
but they are generally  exceedingly  thin and compact at
their middle, where they are exposed to the actions of the
 musculi glutaei and iliacus internus, and to the pressure of
the bowels contained in the belly. The substance of the
 ossa ilia is cellular, except a thin external plate.
   Os Ischium, or hip bone, is of a  middle size between
the two other parts of the os innominatum, and of a very
irregular figure.  Its extent might be  marked  by  an  hori-
zontal line drawn a little below the middle of the acetabu-
lum; for the upper bulbous part of this bone  forms rather
less than  the lower half of that great cavity, and the small 
Os Ischium.
101
leg of it rises to much the same height, on the other side
of the great hole, common to this bone and the os pubis.
   From  the  upper thick part of the os ischium, a sharp
process, called by some authors spinous, stands out back-
wards, from  which  chiefly  the musculus coccygaeus and
superior gemellus, and part of the levator ani, rise; and
the anterior, or internal, sacro sciatic ligament is fixed to it.
Between the  upper part of this ligament and the bones, it
was formerly observed that the pyriform muscle, the pos-
terior crural vessels, and the sciatic nerve pass out of the
pelvis. Immediately below this process,  is a depression
for the tendon of the obturator internus muscle. In a re-
cent subject, this part of the bone, which serves as a pulley
on which the  obturator muscle plays, is covered with a
ligamentous cartilage.
   Below the depression for the obturator muscle, is the
great knob or tuberosity, covered with cartilage or tendon.
The upper part of the tuberosity gives rise to  the inferior
 gemellus muscle.  To a ridge at the inside of this, the ex-
 ternal, or posterior, sacro sciatic ligament is so fixed, that
 between it, the internal ligament, and  the sinuosity of the
 os ischium, a passage is left for the internal obturator mus-
 cle.  The upper thick smooth part of the tuber, called by
 some its dorsum, has two  oblique impressions on  it. The
 inner one gives origin to the long head of the biceps flexor
 tibiae, and seminervosus muscles; and the  semimembrano-
 sus rises from the exterior one, which reaches higher and
 nearer the acetabulum than the other.  The lower, thinner,
 more scabrous part  of the knob, which bends  forwards, is
 also marked with two flat surfaces; whereof  the  internal
 is what we lean upon in sitting, and the external gives rise
 to the largest head of the triceps adductor femoris.  Be-
 tween the external margin of the tuberosity, and the great 
102
Os Pubis.
 hole of the os innominatum, there is frequently an obtuse
 ridge extended  down  from the acetabulum, which gives
 origin to the quadratus femoris. As the tuber advances
 forwards, it becomes smaller, and is rough, for the origin
 of the musculus transversalis and erector penis. The small
 leg of it, which  mounts upwards to join the  os pubis, is
 rough and prominent at its  edge,  where the two lower
 heads of the triceps adductor femoris take their rise.
  The upper and back part of the os ischium is broad and
 thick; but its lower and forepart is narrower and thinner.
 Its  substance is of the structure common to broad bones.
  The os ilium and pubis, of the same sides, are the only
 bones which are contiguous to the os ischium.
  The os pubis, the least of the three portions of the os
 innominatum, is  placed at the upper and front part of it.
 The thick largest part of this bone is employed in forming
 the acetabulum; from which, becoming much smaller, it is
 stretched inwards to its fellow of the other side, where it
 again grows larger, and forms a surface  to  be connected
with the cartilage of its symphysis, and then sends a small
branch downwards to join the end of the small leg of the
 os ischium.  The upper surface  of each os pubis is broad,
near its junction with the cartilage of the symphysis; on the
 internal edge of  this surface begins a ridge which is  con-
tinued from it along the os ilium,  and forms the division
between the  cavities of the abdomen and pelvis. On the
anterior and external edge of this surface of the pubis, at a
small distance from the cartilage, is a prominence or pro-
cess. From this process another ridge, which is  much more
obtuse, extends to the acetabulum.  The upper surface of
the  pubis, which  is included between these ridges, is  con-
cave, for the transmission of the crural vessels, and nerve,
and the psoas and iliacus internus muscles. 
                Foramen Thyroideum             103
  Immediately below the lower ridge, and near the ace-
tabulum, a winding notch is made, which is comprehended
in the great contiguous foramen; but is formed into a hole
in the recent subject, by a subtended ligament, for the pas-
sage of the posterior crural nerve, an artery, and a vein.
The internal end of the os pubis is rough and unequal, for
the firmer adhesion of the thick ligamentous cartilage that
connects it to  its  fellow of the other side. The process
which goes down from that to the os ischium is broad and
rough before, where the gracilis and  upper heads of the
triceps adductor femoris have their origin.
   The  substance of the os pubis  is the same as that of
other broad bones.
   Between the os ischium and pubis a very large irregular
hole is left, which has been  called thyroideum. The whole
of this foramen, except the  notch for the posterior crural
nerve, is filled up, in a recent  subject, with a strong liga-
mentous membrane, that adheres very firmly to its circum-
ference. From this membrane chiefly, the two external and
internal obturator muscles take their rise. The great design
of this hole, besides rendering the bone lighter, is to allow a
strong origin to the obturator muscles, and sufficient space
for lodging them; that there may be no danger of disturb-
ing the functions of the contained viscera of the pelvis by
the actions of the internal; nor of the external being bruised
by the thigh bone, especially by its lesser trochanter, in the
motions of the thigh inwards:  both which inconveniences
must have happened, had the ossa innominata been  com-
plete here, and of sufficient thickness and strength to serve
as the fixed point of these muscles.
   The  bowels sometimes make their way through the
notch for the  vessels, at the  upper part  of this  thyroid
 hole; and this causes a hernia in this  place. 
 104                 Acetabulum.
   The acetabulum is situated near the outside of the great
 foramen. The margin of this cavity is very high, and is
 still much  more  enlarged  by the ligamentous cartilage,
 with which it is tipped in a recent subject: round the base
 of this margin the bone is rough and unequal, where the
 capsular ligament of the articulation is fixed.  At the upper
 and back part of the acetabulum the margin is much larger
 and higher than any where  else; which is very necessary
 to prevent  the head of the  femur from slipping out of its
 cavity at this place, where  the whole  weight of the body
bears upon  it, and consequently might otherwise thrust it
out. As the margin is extended downwards and forwards,
it becomes less; and at  the internal lower part is a defi-
ciency in it; from the one side of which to the other, a
ligament is placed in the recent subject; under which a
large hole  is left. Besides this difference in  the height of
the margin, the acetabulum is otherwise unequal; for the
lower internal part of it is depressed below the cartilagi-
nous  surface of the  upper part, and is not covered with
cartilage; into the upper part of this particular depression,
where it is  deepest and of a semilunar form, the ligament
of the thigh bone, commonly, though improperly, called
the round one, is inserted;  while, in its more superficial
lower part, a large gland-like body is lodged. The great-
est part of  this separate depression is formed in  the os
 ischium.

  The ossa innominata are joined, at their back part, to each
 side of the  os sacrum, by a sort of suture, with a very thin
intervening cartilage, which serves to cement these bones
together; and strong ligaments go from the circumference
of this unequal  surface, to connect them more firmly.
They are connected together at their forepart by the liga- 
                 Position of the Pelvis.            105
mentous cartilage interposed between the two ossa pubis,
and therefore have no motion in a natural state,except what
is common to the trunk of the body, or to the os sacrum.
  Considering  the great weight that is supported in our
erect posture, by the articulation of the ossa innominata
with the os sacrum, there is great reason to think, that if
the conglutinated surfaces of these bones were once sepa-
rated, (without which the ossa pubis cannot move on each
other,) the ligaments would be violently stretched, if not
torn.
  Each os innominatum affords a socket (the acetabulum)
for the thigh bones to move in;  and  the trunk of the body
rolls so much on the heads of the thigh bones, as to allow
here the most  conspicuous motions of the trunk, which
are commonly thought to be performed by the bones of the
spine.
  The form of the cavity of the pelvis, at its upper open-
ing, or brim, is somewhat oval; as a line drawn from one
side to the other, is about an inch longer than  a line drawn
from the back to the front part of it.
  This  margin is well defined by the ridge on the surface
of the ossa ilia, and the upper edge  of the os pubis; but
the margin of the lower opening is very irregular; and it
ought to be observed that the dimensions of this opening
are made less by the sacro sciatic ligaments, than they ap-
pear upon an examination of the bare bones.
  In consequence of the oblique position of the sacrum,
sloping  downwards and backwards, the position of the
pelvis is very oblique. A line drawn through the center of
this cavity, perpendicular to the plain of the upper orifice,
or brim, would not coincide with  the vertical diameter of
the cavity  of the abdomen, but would pass out of that
cavity near the umbilicus.
  Vol. I.                O 
 106            Male and Female Pelvis.
   This cavity, and the bones which form it, are different in
 the two sexes.
   In women the brim of the pelvis is wider, and inclines
 more to the oval form.
   In men this opening is more circular.
   The outlet or lower opening of the pelvis is also larger
 in women.
   This greater size of the pelvis and its openings, in wo-
 men, is derived particularly  from the following circum-
 stances.
   The os sacrum is broader, and sometimes straighter than
 in men.
   The ossa ilia are flatter, and consequently the ossa ischia
 are farther apart.
   The ligamentous cartilage at the  symphysis pubis is
 broader and shorter.
   The angle formed by  the crura of  the ossa pubis with
 each other, at the symphysis, is much larger.

                The Trunk of the Fatus.
   At birth each vertebra consists  of three pieces, connected
by cartilages, viz: The body not perfectly ossified; and a
bone on each side of it,  of a form almost rectangular, on
which the oblique processes are very distinguishable, and
the transverse processes may be ascertained. These bones
are so applied to the body, as to include a triangular space
for the vertebral cavity.  The  ends of their longest por-
tions are nearly in contact behind; but the spinous process
is not formed. The atlas is cartilaginous in front, and has
only the two lateral portions ossified. The vertebra dentata
consists of four pieces; for in addition to the three pieces,
common to the other vertebra;, the processus dentatus is a
 distinct portion. 
                  Trunk of the Fatus.              107
  The false  vertebra, of which the sacrum consists, are
each formed of three bones as the true vertebrae.
  The bones of the os coccygis are cartilaginous, except the
first, which is partly ossified.
  The r\bs  are almost perfect at birth: their heads and
tubercles  covered with cartilage. The necessity of their
motion in respiration, immediately after birth, explains
this difference between them, and most of the other bones
of the foetus.
  The sternum consists of several small bones, surrounded
by flat cartilages. Ossification goes on in these cartilages
from various points;  and the distinct bones  finally unite
into the three pieces of which the sternum is finally com-
posed.
  The ossa  innominata on  each side are formed of three
distinct pieces, united at the acetabulum.
  The spine of the os ilium  is cartilaginous; and the lower
part of the bone is not completely  ossified.
  The back part of the os ischium is ossified; but the por-
tion which forms the acetabulum, the tuber, and the leg, is
cartilaginous.
  The upper part of the os pubis, and that portion which
forms the symphysis, are ossified.  The leg, like that of the
ischium, is cartilaginous. 
108            The Shoulder.—Clavicle.
                    SECTION III.

            Of the Superior Extremities.
   EACH superior extremity consists of the Shoulder,
 the Arm, the Fore Arm, and the Hand.
   The shoulder is  composed of the clavicle and scapula.
 It has been supposed by some persons that the two last
 mentioned bones belong properly to the thorax; but upon
 examining the motions of the upper extremity it will ap-
 pear, that they form an essential part of it: and it is equally
 evident that they do not contribute to the perfection of the
 thorax; they are therefore considered as a part of the up-
 per extremity.
   The clavicle is the  long  crooked bone resembling the
 italic f, which is placed almost horizontally between the
 upper lateral part of the  sternum and  the acromion, or
 most prominent process of the scapula,  which it keeps off
 from the trunk of the body.
   The clavicle, as well as other long bones, is larger at its
 two ends than in the middle. The end next to the sternum
 is triangular:  the angle behind is considerably protruded,
 to form a sharp ridge, to which  the transverse ligament,
 extended from one clavicle to the other,  is fixed. The side
 opposite to this is somewhat rounded. The middle  of this
 protuberant end  is irregularly  hollowed, as  well  as the
 cavity in the sternum for receiving it: but, in a recent sub-
ject,  the irregular  concavities  of both  are supplied  by a
 movable cartilage; which  is  not only much more closely-
 connected every where, by ligaments, to the circumference
 of the articulation, than those of the lower jaw are, but it
 i>ro\vs to  the  two bones at both its internal and external 
The Clavicle.
109
end: its substance at the external end being soft, but very
strong, and resembling the intervertebral cartilages.
   From  its internal end, the clavicle, for about two fifths
of its length, is bended obliquely forwards. On the upper
and  front part of this curvature a small  ridge  is seen,
with a plain rough  surface before it; whence the sterno-
hyoideus and sterno-mastoideus muscles have in part their
origin. Near the lower angle, a small plain surface is often
to be remarked, where the first rib and this bone  are con-
tiguous, and are connected by a firm ligament.  From this
a rough plain surface is extended outwards, where  the
pectoral muscle has  part of its origin. Behind, the bone is
made flat and rough  by the insertion of the  larger share of
the subclavian muscle. The clavicle is then curved back-
wards, and at first is round: but it soon  after becomes
broad and thin; which shape it retains to its external end.
Along the external concavity, a rough sinuosity runs; from
which some part  of  the deltoid muscle takes  its rise:  op-
posite to this, on the convex edge, a scabrous ridge gives
insertion to a share of the cucullaris muscle.  The upper
surface of the clavicle is here flat; but the lower is hollow,
for lodging the beginning of the musculus subclavius; and
towards its back  part, a tubercle rises; to which,  and to a
roughness near it, the strong short  thick ligament, con-
necting this bone to the coracoid process of the scapula, is
fixed.
   The external end  of this bone  is oblong horizontally,
smooth, sloping at the posterior side, and tipped  in a  re-
cent subject with a  cartilage, for its articulation  with the
acromion scapulae. Round this the bone is spongy, for the
firmer connexion of the ligaments.
   The surfaces of contact of this bone, and the scapula,
are remarkably  small, and flat also.
   The medullary arteries, having their direction obliquely 
 1 lo                 The Scapula.
 outwards, enter the clavicles by one or more small passa-
 ges in the middle of their back part.
   The substance of this bone is  the same as of the other
 round long bones.
   The ligaments, which surround the articulation of this
 bone with the sternum, are so short and strong, that little
 motion can be allowed any way;  and the  strong ligament
 that is stretched across the upper furcula of the sternum,
 from the posterior prominent angle of the one clavicle to
 the same place of the other clavicle, serves to keep each of
 these bones more  firmly in  its place. By the  assistance,
 however, of the movable intervening cartilage, the clavicle
 can move at this articulation so that the external extremity
 may be  elevated or depressed, and moved  backwards or
 forwards.  The whole bone may be moved so  as to describe
 a cone; of which the end at the sternum is the apex
  The movements of the scapula and arm are the objects
 of these motions of the clavicle; and the general use of
 the bone is to regulate the motions of these parts.
  From the situation, figure, and use of the clavicles, it
 is evident that they are much exposed to fractures; that
 their broken parts must generally pass  each other; and,
 that they will be kept in their places with  difficulty.

                     The Scapula,
  Or shoulderblade, is the triangular bone situated on the
 upper and  back  part of the thorax. The  back part of the
 scapula has nothing but the thin ends of the  serratus ami-
 cus major, and subscapularis muscles between  it and the
 ribs: but as this bone advances forwards, its  distance from
 the ribs increases.  The longest side of this bone is nearest
 the  spine, and has an oblique position as respects it.  The
 upper or shortest side, called the superior costa of the sca-
pula, is nearly horizontal, and parallel with the second rib. 
                     The Scapula.                  Ill
The lower side, which is named the inferior costa, is ex-
tended obliquely from  the  third to the eighth rib. The
situation of this bone, here described, is when people are
sitting or standing in a state of inactivity, and allowing the
members to remain in the most natural easy posture. The
inferior angle of the scapula is very acute; the upper one
is near to a right angle; and  what is called the anterior
does not deserve the name, for the two sides do not meet
to form an angle.   The body of this bone  is concave
towards the ribs, and convex behind, where it has the name
of dorsum.  Three  processes  are generally reckoned  to
proceed from the scapula. The first is the large spine that
rises  from its convex surface behind, and divides it  une-
qually.  The second process stands out from the fore  part
of the upper side; and, from its imaginary resemblance to
a crow's beak, is named coracoides.  The third process is
the whole thick bulbous fore part of the bone.
   Into  the oblique space the musculus patientiae is insert-
ed. At the root of the spine, on the back part of the base,
a triangular flat surface is formed by the pressure of the
lower fibres of the trapezius.  Below this,  the edge of the
scapula is scabrous and rough, for the insertion of the ser-
ratus major anticus and rhomboid muscles.
   The  back part of the inferior angle is made smooth by
the latissimus  dorsi passing  over  it.  This  muscle also
alters the direction of the inferior costa some way forwards
from this angle:  and so far it is flatted behind by the ori-
gin of the teres major. As the inferior costa advances for-
ward, it is of considerable thickness, is slightly hollowed,
and made  smooth behind, by the teres minor; while it has
a fossa formed into it below, by part of the subscapulars;
and between the two, a ridge with a small depression ap-
pears, where the longus extensor cubiti has its origin. 
 112                 The Scapula.
   The  superior costa is very thin: and near its fore part
 there is a semilunar notch, from one end of which to the
 other, a ligament is stretched; and sometimes the bone is
 continued  to form one, or  sometimes two holes, for the
 passage of the scapular bloodvessels and  nerves.  Imme-
 diately  behind this semilunar cavity, the coraco-hyoideus
 muscle  has its rise. From the notch, to the termination of
 the fossa for the teres minor, the scapula is narrower than
 any where  else, and supports the third process. This part
 has the  name ot cervix.
   The  whole dorsum of the scapula is always said to be
 convex; but, by reason of the raised edges that surround
 it,  it  is divided into two cavities by the spine, which is
 stretched from behind forwards, much nearer to the supe-
 rior than to the inferior costa. The cavity above the spine
 is really concave, where the supra-spinatus muscle is lodg-
 ed; while  the surface of this bone below the spine, on
 which the  infra-spinatus muscle is placed, is convex, ex-
 cept a fossa that runs  at the side of the inferior costa.
   The  internal or anterior.surface of this bone is hollow,
 except in the part above the spine, which is convex.  The
 subscapulars muscle is extended over this surface, where
 it forms several ridges and intermediate depressions, com-
 monly mistaken for prints of the ribs:  they point out the
 interstices of the bundles of fibres of which the subscapu-
 laris muscle is composed.
  The spine rises small  at the base of the scapula, and be-
 comes higher and  broader as it advances forwards.  On
 the sides it is unequally hollowed and crooked, by the ac-
 tions  of the adjacent muscles.  Its ridge  is divided into
 two rough flat surfaces:  into the upper one, the trapezius
 muscle is inserted; and the lower one has part of the del-
toid fixed to it.  The end of the spine, called acromion, or 
The Scapula.
113
 top of the shoulder, is broad  and flat, and is sometimes
 only joined to the spine by a cartilage.  The anterior edge
 of the acromion is  flat, smooth, and covered with a car-
 tilage, for its articulation with the external end of the cla-
 vicle;  and it is hollowed below, to allow a passage to the
 infra and supra spinati muscles, and free motion to the os
. humeri.
    The coracoid process is crooked, with its point inclining
  forwards; so that a hollow  is left at the lower side  of its
  root,  for  the  passage of the subscapularis muscle. The
  end of this  process is marked with three plain surfaces.
  Into the internal, the serratus minor amicus  is inserted;
  from the  external,  one head of the biceps  flexor cubiti
  rises;  and from the lower  one, the coraco-brachialis has
  its origin. At  the upper part of the root of  this process,
  immediately before  the semilunar cavity, a smooth tuber-
  cle appears, where a ligament from  the clavicle is fixed.
  From  the whole of the external side of this  coracoid
  apophysis a broad ligament goes out, which becomes nar-
  rower where it is fixed to the acromion.
     From the cervix scapulae the third process is produced.
  The fore part of this is formed into a glenoid cavity, which
  is of the shape of the longitudinal section  of an egg, being
  broad below and narrow above.  Between the margin of
  this cavity  and the fore part of the root of the spine, a
  large  sinuosity is left for the transmission  of the supra and
  infra spinati muscles; and on the upper part of this margin
  we may remark a smooth surface, where the second head
  of the biceps  flexor cubiti has its origin.  The root of the
  margin is rough all round, for the firmer adhesion of the
  capsular ligament of the articulation, and of the cartilage;
  which is thick on the margin, but becomes very thin as it
     Vol.  I.                  P 
114                 The Scapula.
is continued towards the middle of  the cavity, which it
lines all over.
   The  medullary vessels enter the scapula near the base
of the spine.
   The  substance of the scapula, as  in all other broad flat
bones, is cellular, but of an unequal thickness: for the neck
and third process are thick and strong; the inferior costa,
spine, and coracoid process, are of a middle thickness; and
the body is so pressed by the muscles, as to become thin
and transparent.
   The scapula and clavicle are joined by plain surfaces,
tipped with cartilage; by which  neither bone is allowed
any considerable motion, being tightly tied down by the
common capsular ligament,  and by  a very strong one
which  proceeds  from the coracoid process; but divides
into  two before it is fixed  into the clavicle, with such a
direction, as can either allow this bone to have a  small
rotation, in which its posterior edge turns more backwards,
while the anterior one  rises farther  forwards; or it can
yield to the fore part of the scapula moving  downwards,
while the back part of it  is drawn upwards; in both which
cases, the oblong smooth articulated surfaces of the clavi-
cle and scapula are not in the same plain, but stand a little
transversely, or across each  other,  and thereby preserve
this joint from luxations, to which it would be subject if
cither of the bones was to move on  the other perpendicu-
larly up and  down, without  any rotation. Sometimes a
movable ligamentous cartilage is found in this joint; and
sometimes such a cartilage is only interposed at the  ante-
rior half of it; and in some old subjects a  sesamoid bone
has been found here.
   The scapula is connected to the head, os hyoides verte-
brae, ribs, and arm bone, by muscles, that have one end 
                   The Os Humeri.               115
fastened to these parts, and the other to the scapula, which
can move it upwards, downwards, backwards, or forwards;
fey the quick succession of these motions, its whole body
is carried in a circle. But being also often moved as upon
an axis perpendicular to its plain, its circumference turns
in a circle whose center this  axis is. Whichever of these
motions it performs, it always carries the outer end of the
clavicle and the arm along with it.  The glenoid cavity of
this bone receives the os humeri, which  plays in it, as will
be more fully explained hereafter.
   The use of the scapula is, to serve as a fulcrum to the
arm;  and,  by  altering its position on different occasions,
to allow always to the head of the os humeri a socket to
move in properly situated; and thereby, to assist and to
enlarge greatly the motions of the superior extremity, and
to afford the muscles which rise  from  it more advanta-
geous actions, by altering their directions with respect to
the bone which they are to move.  This bone  also serves
to defend the back part of the thorax,  and  is often  em-
ployed to sustain weights, or to resist forces, too great for
the arm to bear.

                       The Arm.
   The  arm has only one bone, best known by the Latin
name of os  humeri; which is long, round,  and nearly
straight.
   The upper  end of this bone consists of a large round
smooth head, which forms the segment  of a sphere, whose
axis is  not in  a straight line with the axis of the bone, but
stands  obliquely backwards from  it. The  extent of the
head is distinguished by  a circular fossa surrounding its
base, where the head is united to the bone, and the capsu-
lar ligament of the joint is fixed.  Below the  fore part of 
116                The Os Humeri.
its base, two tubercles stand out:  the smallest one, which
is situated  most to the inside, has the tendon of the sub-
scapulars muscle inserted into it. The larger more exter-
nal protuberance is divided, at its upper part, into three
smooth plain  surfaces: into the  anterior  of which, the
musculus supra-spinatus; into the middle  or largest, the
infra-spinatus;  and into the  one  behind, the teres minor,
is inserted. Between these  two tubercles, exactly in the
fore part of the bone, a deep long groove is formed, for
lodging the tendinous head of the biceps flexor cubiti;
which, after passing, in a manner peculiar to itself, through
the cavity of the articulation, is tied down, by a tendinous
sheath extended  across the groove; in  which, and in the
neighbouring  tubercles,  are  several remarkable  holes,
which are  penetrated  by the tendinous and ligamentous
fibres, and by vessels. On each side of this groove, as it
descends in the os humeri, a rough ridge, gently flatted in
the middle, runs from the roots of the tubercles. The ten-
don of the pectoral muscle is fixed into the anterior of
these ridges, and the latissimus dorsi and teres major are
inserted into  the  internal one. A little behind the lower
end of this last,  another rough  ridge  may  be observed,
where the  coraco-brachialis  is inserted. From the back
part of the root of the largest tubercle, a ridge also is con-
tinued; from which the brevis extensor cubiti rises. This
bone is flatted on the inside, about its middle, by the belly
of the biceps flexor cubiti.  In the middle of this plain sur-
face, the entry of the medullary artery is seen slanting ob-
liquely downwards. At the fore side of this plain the bone
rises in  a  sort of ridge, which is  rough, and often has a
great many small  holes in it, where the  strong deltoid
muscle is  inserted; on each side  of which the bone is
smooth and flat, where the  brachius  internus  rises. The 
                   The Os Humeri.               117
exterior of these two flat surfaces is the largest:  behind it
a superficial spiral channel, formed by the muscular nerve
and the vessels that accompany it, runs from behind for-
wards and downwards.
  The body of the os humeri  is flatted behind by the ex-
tensors of the fore arm.
  Near the  lower end of this bone, a large sharp ridge is
extended on its outside; from which the musculus spinator
radii longus, and the longest head of the  extensor carpi
radialis, rise. Opposite to this, there is another small ridge
to which the aponeurotic tendon, that gives origin to the
fibres of the internal and external brachial  muscles, is fix-
ed; and from a little depression on the fore side of it, the
pronator radii teres  rises.
  The body of the os humeri becomes gradually broader
towards the lower end, where it has several processes;  at
the roots of which there is a  cavity before, and  another
behind. The anterior is divided by a ridge into two; the
external, which is the least, receives the end of the radius;
and the internal receives the coronoid process of the ulna,
in the flexions of the fore arm; while, the posterior deep
triangular cavity lodges the olecranon in the extensions of
that limb. The bone between these two cavities  is pressed
so thin by the processes of the ulna, as to  appear transpa-
rent in many subjects. The sides  of the posterior cavity
are stretched out into two processes,  one on each side:
These are called condyles; from each of which a strong
ligament goes out to the bones  of the fore arm. The exter-
nal condyle, which has an oblique direction forwards with
respect to the internal, when the arm is in the most natu-
ral posture, is equally broad, and  has  an  obtuse  smooth
head rising from it forwards.  From the rough part of the
condyle, several muscles arise; and #n the  smooth head 
 118               The Os Humeri.
 the upper end of the radius plays.  The internal condyle is
 more pointed and protuberant than the external, to give
 origin to the flexor muscles of the wrist and hand, &c.
 Between the two condyles, is the trochlea or pulley; which
 consists of two lateral protuberances, and a middle cavity,
 that are smooth and covered  with cartilage. When the
 fore arm is extended, the tendon of the internal brachiaeus
 muscle is lodged in the fore part of the cavity of this pul-
 ley. The  external protuberance,  which  is less than the
 other, has a  sharp edge behind; but forwards, this ridge
 is obtuse, and only separated from the little head, already
 described, by a small fossa, in which the  adjoining edges
 of the ulna and radius move. The internal protuberance of
 the pulley is  largest and highest;  and,  therefore, in the
 motions of the ulna upon it, that bone would be inclined
 outwards, were it not supported by the radius on that side.
 Between this internal protuberance and condyle, a sinuo-
 sity may be remarked, where the ulnar nerve passes.
  The substance and the internal structure of the os hu-
 meri are the same, and disposed in the same way,as in other
 long bones.
  The round head, at the upper end of this bone, is articu-
lated with the glenoid cavity of the scapula; which being
superficial, and  having long ligaments, allows the arm a
free and extensive motion. These ligaments are, however,
considerably  strong. For besides  the  common capsular
ligament, the tendons  of the muscles perform the office,
and have been described under the name of ligaments.
Then the acromion  and coracoid process, with the strong
broad ligaments stretched between them, secure the articu-
lation above, where the greatest and most frequent force
is applied to thrust the head of the bone out of its place.
It is true, that there is not near so strong a defence at the 
                    The Os Humeri.               119
lower part of the articulation; but, in the ordinary pos-
 tures of the"arm, that is, so long as it is at an acute angle
 with the trunk of the body, there cannot be any force ap-
 plied at this place to occasion a luxation, since the joint is
 protected so well above.
   The motions which the arm enjoys by this articulation,
 are to every side; and by the succession of these different
 motions, a circle may be  described. Besides which, the
 bohe performs a small rotation round its own  axis; but
 when  the axis of the bone  is the center of  motion, the
 movements are very different from those which take place
 when the axis of its head is the center; for the axis of the
 head forms a very large angle with the axis of the body of
 the bone. Thus,  when the arm swings backwards and for-
 wards, the axis of the head is the center of motion;  but
 when the elbow  is  bent,  and  the fore arm forms a right
 angle with the os humeri, the  motion which applies the
 fore arm to the thorax, or  removes it, is a rotation of this
 bone on its axis.
   Though the motions of the arm seem to be very exten-
 sive, yet the larger share of them depends on the motions
of the scapula; for the surface of the glenoid  cavity is
directed upwards or  downwards, and to a certain degree
backwards  or forwards, to support the head of the os hu-
meri, This is exemplified when we press the hand against
a body which is before, or  above, or to one side of us.
  The lower end of the os humeri is articulated to the
bones  of the fore arm,  and  carries them  with it in all  its
motions j but serves as a base, on which they perform the
motions peculiar to themselves; as will shortly be descri-
bed. 
120
The Fore Arm.—Ulna.
                    The Fore Arm
   Consists of two bones, one of which is called ulna, from
its being used as a measure; and the other radius, from a
supposed resemblance to the spoke of a wheel.
  These bones are concerned in very different operations.
The ulna forms the elbow  joint with the os humeri: the
radius is the movable basis of the hand.

                        Ulna.
  The length of this bone is equal  to the fore arm, of
which it is a part.  It is thickest above, and gradually di-
minishes until near its lower end.  The body of the bone
is nearly triangular in form. At the upper extremity of the
ulna, on its anterior surface, is a semicircular notch. The
end of the bone which  forms the posterior part of this
notch is denominated olecranon. The anterior part of the
notch is formed by a process called coronoid.  This notch
applies  to  the pulley-like surface on  the internal side
of the lower extremity  of the os humeri, to form the ar-
ticulation of the elbow.  In the middle of the concave sur-
face is a ridge, in consequence of which a small rocking
motion is performed by  the ulna.  The external surface of
the olecranon is rough, and strongly marked. The extensor
muscle of the fore arm  is  inserted into the end of it, and
below this is a flat surface on which we lean. On the out-
side of the coronoid process is a semilunated smooth ca-
vity, lined with cartilage; in which, and in a ligament ex-
tended from  the one to the other end of this cavity, the
round head of the radius  plays.  Immediately below it, a
rough hollow gives  lodging to mucilaginous glands. Be-
low the  root of the coronoid process, this bone is scabrous
and unequal, where the brachiaeus internus is inserted. On 
                         Ulna.                    121
 the outside of that, we observe a smooth concavity, where
 the  beginning of the flexor digitorum profundus sprouts
 out.
   The  external angle of the triangular part of the ulna is
 very sharp, where the ligament that connects the two bones
 is fixed:  the sides  which make this angle are flat and
 rough,  by the  action and adhesion of the many muscles
 which are situated here.  At the distance of one third of
 the  length of the ulna from the top, in  its fore part, the
 passage of the medullary  vessels may be seen slanting up-
 wards.  The  internal side of this  bone is smooth, some-
 what convex, and  the angles at each edge of it are blunted
 by the  pressure of  the muscles equally  disposed about
 them.
   As this bone descends, it  becomes gradually smaller;
 so that its lower end terminates in a little head, standing
 on a small neck; towards the inner and back part of which
 last, an oblique ridge runs, that gives rise to the pronator
 radii quadratus.  The  head  is  somewhat  cylindrical,
 smooth, and covered with a cartilage on its external side,
 to be received into the semilunar cavity of the radius;
 while a styloid process rises from its  inside, to  which is
 fixed a strong ligament that is extended to the os cunei-
 forme  and pisiforme of the wrist. At the  root of the pro-
 cess, the end  of the  bone  is smooth,  and covered with a
 cartilage.  Between it and  the bones of the wrist, a doubly
 concave movable cartilage is interposed;  which is a con-
 tinuation of the cartilage that covers the lower end of the
 radius, and is connected loosely to the root of the styloid
 process, and  to the rough cavity there; in which mucila-
 ginous glands are lodged.
   The ulna  is  principally concerned  in  the articulation
with the  os humeri, and forms a hinge-like joint, which
   Vol. I.                Q 
122                   Radius.
allows extension nearly to a straight line, and flexion to an
acute angle. By the sloping of the pulley-like surface, the
lower part of the arm is turned outwards in the extension,
and  inwards in  the flexion; which  greatly facilitates the
motion of the hand towards the head.

                       Radius.
     Before the  radius is described, it is necessary to ob-
       serve, that the lower end of  this bone occasionally
       revolves  half round the lower end of the ulna, and
       the hand with it.  The relative  situation of these
       parts is therefore different in different positions of
       the hand. In the following description, the palm of
       the hand is supposed to present forwards, and the
       thumb outwards; in which case, the two bones of
       the fore  arm will be parallel to each other.
   The radius is situated on the outside of the fore  arm,
and is rather shorter than the ulna.  Its extremities are the
reverse of those  of the ulna in their proportionate size; and
the body is not so triangular, although it approaches towards
that form. Its upper end is formed into a cylindrical head,
which is  hollowed on the top for an articulation with the
tubercle at the side of the pulley of the os humeri; and the
half cylindrical  circumference next to the ulna is smooth,
and covered with  a cartilage, in order to be received into
the semilunated cavity of that bone. Below the head, the
radius is much smaller; and therefore this part is named
its cervix. At the external root of this neck is a flat tuber-
cle, into the outer part of which the biceps flexor cubiti  is
inserted.  From this a ridge runs  downwards and inwards,
where the  supinator radii brevis is inserted; and a little
below,  and behind this ridge, there is a rough scabrous
surface, where the pronator radii teres is fixed. 
                       Radius.                    123
   The body of the radius is not  straight, but curved ex-
ternally, the greater part of its length.  Its external surface
is rounded; the anterior and posterior surfaces are flatten-
ed; and between them is a sharp spine, to which the strong
ligament extended between the two bones of the fore arm
is fixed. On the anterior surface, at a distance  from its
head nearly equal to one third of the  length of  the  bone,
is the orifice of the canal for the medullary vessels, which
has a direction obliquelv  upwards.
   Towards the lower end, the radius  becomes broader
and flatter, especially on  its forepart,  where the pronator
quadratus muscle is situated.  Its back part, at this end,
has  a flat strong ridge in the  middle, and fossae on each
side. In a small groove, immediately  on the  inside of
the  ridge, the  tendon of the extensor  of the  last joint
of the  thumb plays. In  a large one, inside of this, the
tendons of the indicator, and  of the common  extensor
muscles of the fingers pass. On the outside of  the  ridge
there is a broad depression, which seems again subdivided,
where the two tendons of the extensor carpi radialis are
lodged. The external side of this end of the radius is also
hollowed by the extensors of the first  and second joint of
the thumb.  The  ridges  at the sides of the grooves, in
which the tendons play, have an annular ligament fixed to
them, by which the several sheaths for the tendons  are
formed. The fore part of this end of the radius is also de-
pressed, where the flexors of the fingers and flexor carpi
radialis pass. The internal side is formed into a semilu-
nated smooth cavity, lined with a cartilage, for receiving
the lower end of the ulna.  The lowest part of the radius
is formed into an oblong cavity; in the middle of which is
a small transverse rising, gently hollowed, for lodging mu-
cilaginous glands; while the rising itself is insinuated into 
124                   Radius.
the conjunction  of the  two bones of the wrist that  are
received into the cavity. The external side of this articu-
lation is defended by a remarkable process of the radius,
from which a ligament passes to the wrist;  and this struc-
ture resembles that of the styloid process of the ulna with
its ligament.
  The ends of both the bones of the fore arm being thicker
than the middle,  and the radius being curved, there is a
considerable  distance between the bodies of these bones;
in the larger part of which a strong tendinous, but thin
ligament, is  extended,  to give a  sufficient  surface  for
the origin of the numerous fibres of the muscles situated
here, that are so much sunk between the bones as to be
protected from injuries, to which they would otherwise be
exposed. But this ligament is wanting near the upper end
of the fore arm, where the supinator radii brevis, and flexor
digitorum profundus, are immediately connected.
  As the head of the radius receives the  tubercle of the
os humeri, it is not only bended and extended along with
the ulna, but may be moved almost  half round its  axis:
and, that this motion round its axis may be sufficiently
large, the ligament of the articulation is extended," further
down than ordinary, on  the neck of this bone, before it is
connected to it;  and it is very thin at its upper and lower
part, but makes a firm ring in the middle. This bone is also
joined to the ulna by a double articulation:  for above, a
tubercle of the radius plays in a socket of the ulna; whilst
below, the radius gives the socket, and the ulna the tuber-
cle. But then the motion performed at the two ends is very
different:  for, at  the upper end, the radius does little more
than turn round its axis; while, at the lower end, it moves
nearly  half round the cylindrical end of the ulna;  and, as
the hand is articulated and firmly connected here with the 
                      The Haiid.                  125
radius, they must move together. When the palm is turn-
ed uppermost,  the radius is said to perform supination:
when the back of the hand is above, it is said to be prone.
But then the quickness and large extent of these two mo-
tions are assisted by the ulna, which, as was before ob-
served, can move with  a kind of small rotation on the slo-
ping sides of the pulley. This rocking motion, though very
inconsiderable in the elbow joint itself, is conspicuous  at
the lower end of such a long bone; and the strong liga-
ment connecting this lower end to  the carpus, makes the
hand more readily obey these motions.

                      The Hand.
  The hand comprehends  the whole structure, from the
end of the radius to the points of the fingers.  Its back part
is convex, for greater firmness  and strength; and it is con-
cave before, for containing more surely  and conveniently
such bodies as  we take hold of. One half of the hand has
an obscure motion in comparison of what the other has:
it serves  as a  base to the  movable half, which can  be
extended back very little farther than to a straight line with
the fore arm, but can be considerably bent forwards.
  The hand  consists of the carpus or wrist; metacarpus,
or part adjoining the wrist;  and the fingers, among which
the thumb is reckoned.

                       Carpus.
     No part of the skeleton is  more complex than the car-
       pus. The following description will therefore be of
       little use to a young student, unless the bones are
       before him when he is reading it.  Great advantage
       will be derived from  examining two sets of carpal
       bones;  each set belonging to the same side. 
 126                   Carpus.
     In one of these sets the bones should be connected by
       their natural ligaments; but the two rows separated
       from each other. The bones of the other set should
       be accurately cleaned, so that their forms and sur-
       faces may be examined.
   The carpus is composed of eight small bones, arranged
 in two rows; one  of which rows is  attached to the bones
 of the fore arm, and the other to the  body of the hand.
   These bones are named  from their figure, and shall be
 mentioned in the  order  in which they occur, beginning
 with the row next to the fore arm;  and with the external
 bone in each row.
   They are, Os Scaphoides, Lunare, Cuneiforme, Pisiforme.
 Os Trapezium, Trapezoides, Magnum and Unciforme.

                      First Row.
   Os scaphoides is  the largest of the eight, excepting one.
 It is convex above, concave and oblong below; from which
 small resemblance to a boat, it has got its name. Its smooth
 convex surface is divided by a rough middle fossa, which
 runs obliquely across it. The upper largest division is arti-
 culated  with  the radius. The common ligament of the
joint of  the wrist is fixed into the fossa; and the lower
 division is joined to the trapezium and trapezoides. The
 concavity receives  more than  half of the round head  of
 the os magnum. The internal side of this hollow is formed
 into a semilunar plain, to be articulated with the following
 bone.  The external, posterior, and anterior edges are
 rough, for fixing the ligaments that connect it to the sur-
 rounding bones.
  Os lunare has a smooth convex upper surface, by which
 it is articulated with the radius. The external side, which
 gives the name to the bone, is in the  form of a  crescent, 
                       Carpus,                   127
and is joined with the scaphoid: the lower surface is hol-
low, for receiving part of the head of the os magnum. On
the inside  of this cavity is another smooth, but narrow,
oblong sinuosity, for receiving the upper end of the os
unciforme: and  on the inside of this a small convexity is
found, for its connexion with the os cuneiforme. Between
the great convexity above, and the first deep inferior ca-
vity, there is a rough fossa, in which the circular ligament
of the joint of the wrist is fixed.
   Os cuneiforme is broader above,  and towards the back
of the hand, than it is below and forwards; which gives it
the resemblance of a wedge. The superior slightly convex
surface is included in the joint of the wrist, being opposed
to the lower end of the ulna. Below this the cuneiforme
bone has a rough fossa, wherein  the ligament of the articu-
lation  of the  wrist is fixed. On the external side of this
bone, where it is contiguous to the os lunare, it is smooth
and slightly concave. Its lower surface, where it is conti-
guous  to the os unciforme, is  oblong,  somewhat  spiral,
and concave.  Near the middle of its anterior surface a
circular plain appears, where the os pisiforme is sustained.
   Os pisiforme  is almost  spherical, except  one circular
plain,  or slightly hollow surface,  which is covered with
cartilage for its motion on the cuneiforme bone, from which
its whole rough  body is prominent  forwards into the palm;
having the tendon of the flexor carpi ulnaris, and a liga-
ment from the styloid process of the ulna, fixed to its up-
per part; the transverse ligament of the wrist is connected
to its external side;  ligaments extended to the unciforme
bone, and  to the os metacarpi of the little finger, are at-
tached to its lower part; the Abductor minimi digiti has
its origin from its fore part; and, at the external side of it,
a small depression is formed, for the passage of the ulnar
nerve. 
128
Carpus.
                     Second Row.
   Trapezium has four unequal sides and angles in its back
part, from which it has got its name. Above, its surface
is smooth, slightly hollowed, and semicircular, for its con-
junction with the os scaphoides. Its internal  side is an
oblong concave square, for receiving the following bone.
The inferior surface is formed into a pulley; which  faces
obliquely outwards and  downwards when the palm pre-
sents forward.  On this pulley the first bone of the thumb
is moved.
   At the internal side of the  external  protuberance, a
small oblong smooth surface is formed by the os metacarpi
indicis. The fore part of  the trapezium is prominent in
the palm, and near to the internal side has a sinuosity in
it, where the tendon of the flexor carpi radialis is lodged;
on the ligamentous sheath of which the tendon of the flexor
tertii internodii pollicis plays:  and near this the bone is
scabrous, where the transverse ligament of the wrist is
'connected, the abductor and flexor primi internodii pol-
licis have their origin, and ligaments go out  to the first
bone of the  thumb.
   Os trapezoides, so called from the irregular quadrangu-
lar figure of its back part, is the smallest bone of the wrist
except the pisiforme.  The figure of it is an irregular cube.
It has a small hollow surface above, by which it joins the
scaphoides; a long convex one externally, where it is con-
tiguous to the trapezium;  a small internal one, for its con-
junction with the os magnum; and an inferior convex sur-
face, the edges of which are, however, so raised before and
behind, that a sort  of pulley is formed, where it sustains
the os metacarpi indicis.
   Os magnum, so called because it is the largest bone of 
                       Carpus.                   129
the carpus, is oblong, having four quadrangular sides, with
a round upper end, and a triangular plain one below. The
round head is divided by a small rising, opposite to the
connexion of the os scaphoides and lunare, which together
form the cavity for receiving it.  On  the outside a short
plain surface joins the os magnum to the trapezoides. On
the inside  is a long narrow concave surface, where it is
contiguous to the os  unciforme. The lower end, which
sustains the metacarpal bone of the  middle finger, is trian-
gular, slightly hollowed, and farther advanced on the ex-
ternal side than on the internal, having a considerable ob-
long depression made on the advanced outside by the me-
tacarpal bone of the  fore finger; and generally there is a
small mark of the os metacarpi digiti annularis on  its
internal side.
   Os unciforme has got its name from a thin broad process
that stands out from  it forwards into the palm, and is hol-
low for affording passage to the tendons of the  flexors of
the fingers. To this process also the  transverse ligament
is fixed  that binds down and defends these tendons; and
the flexor and abductor muscles of the  little  finger have
part of their  origin  from  it. The upper plain  surface is
small, convex, and joined with the os lunare: the external
side is long, and slightly  convex, adapted to the contigu-
ous os  magnum.  The external surface is oblique, and
irregularly convex, to be articulated with the cuneiforme
bone. The lower end is divided into two concave surfaces;
the internal is joined with  the metacarpal bone of the lit-
tle finger; and the external one is fitted to the metacarpal
bone of the ring finger.
   The nature of the  carpus will be best understood by stu-
dying the bones placed together, in their natural order, in
the two rows.
   Vol. I.                  K 
130                   Carpus.
   When thus placed they compose a structure of an ob-
long form, whose greatest length extends across the wrist
and forms a concavity in front, while it is convex poste-
riorly.
   Two bones of the first  row, viz.  the scaphoides and
lunare, form an oblong convex surface, which has a trans-
verse position with respect to the arm, and applies to the
concave surface at the end of the radius. These  surfaces
are particularly calculated for flexion and extension, and
also for a considerable motion to each side; and by a suc-
cession of these flexures, in different directions, the hand
performs a circular motion, although it cannot perform at
this joint, a rotation, or revolution on the axis of the car-
pus.
   The under surface of these bones has a deep concavity
which is composed by the scaphoides,  lunare and  cunei-
forme, and receives a prominence of the second row. It
also presents a convex surface formed by the scaphoides,
which is received by the second row.
   The upper surface of the second row, which is concern-
ed in this  articulation, is very  irregular; it has a head
formed by the magnum and unciforme, which  penetrates
deeply into the cavity of the first row.  On  the outside of
this head the trapezium and trapezoides form a surface
which receives the projecting part of the scaphoides; so
that the first row  receives, and is received by the second,
and the two surfaces are well calculated for moving to a
certain extent, in  the way of flexion and extension, upon
each other*
   The lower surface of the second row, which is connected
to the metacarpal  bones, appears like the, side of  an arch,
which is partly induced by the wedge-like form of the two
bones in the center, viz. the trapezoides and the  mag- 
                     Metacarpus.                131
num.  When the hand hangs by the side, and the palm is
forward, all of this surface presents downwards, except
that portion of it which is formed by the trapezium.  This
bone is placed obliquely between  the two rows, and  its
surface for supporting the thumb presents obliquely down-
wards and outwards.
  The trapezoides supports the fore finger, the magnum
the middle finger, and the unciforme both of the remain-
ing fingers.
  The scaphoides and the trapezium are very prominent
at the external side of the anterior concave surface of the
carpus; and the unciforme process, and the os pisiforme on
the internal.

                   The Metacarpus
   Consists of four bones which sustain the fingers.  Each
bone  is long and round, with its ends larger than its body.
The  upper end, which some call the base, is flat and ob-
long, inclining somewhat to the wedge-like form, without
any considerable head or cavity; but it is however some-
what hollowed,  for the articulation with the carpus: It is
made flat and smooth on the sides where these bones are
contiguous to each other. Their bodies are flatted on their
back  part, particularly below the middle, by the tendons of
the extensors of the fingers.  The anterior surface of these
bodies is  a little convex, especially in their middle;  along
which a  sharp ridge stands out, separating the musculi
interossei placed on  each side of these bones, which are
there made flat and plain by these muscles.
   Their  lower ends  are raised into large oblong smooth
heads, whose greatest extent is forwards from the axis of
the bone. At the fore part of each side of the root of each
of these heads, one or two tubercles stand out, for fixing 
 132                 Metacarpus.
 the ligaments that go from one metacarpal bone to another,
 to preserve them from being drawn  asunder.  Round the
 heads a rough  ring may be remarked, for the capsular
 ligaments  of the first joints of the fingers to be fixed to;
 and both sides of these heads are flat, by pressing on each
 other.
   The substance of the metacarpal bones is the same with
 that of all long bones.
   The metacarpal bones are joined above to the bones of
 the carpus,  and to each  other, by  surfaces almost flat.
 These connexions do not admit  of much  motion. The
 articulation of  the round heads, at their lower ends, with
 the cavities of  the first bones of the  fingers, will soon be
 described.
   The concavity  on  the  fore part  of these metacarpal
 bones, and  the position of their bases on the arched carpus,
 cause them to  form a hollow in  the palm of the hand,
 which is often useful to us.  The spaces between them
 lodge muscles,  and their small motion makes them fit sup-
 porters for the  fingers to play on.
  Though  the ossa metacarpi  so far agree, yet  they ma\
 be distinguished from each other by the following marks.
  The metacarpal bone of the forefinger is  generally the
 longest. Its base,  which is articulated with the os trape-
 zoides, is hollow in the middle. The small ridge on the
 external side of this oblong cavity is  smaller than the one
 opposite to it,  and is made flat on the side by the trape-
 zium. The internal ridge is also smooth, and  flat  on its
 outside, for its conjunction  with the os magnum; imme-
 diately below which  a semicircular  smooth flat surface
shows the  articulation of this to the second metacarpal
bone.  The  back part of this base is flatted where the long
head of the extensor carpi radialis is inserted, and its fore 
                     Metacarpus.                 133
part is prominent where the tendon of the flexor carpi
radia'.is is fixed. The tubercle at the internal root of its
head is larger than the external.  Its base is so firmly fixed
to the bone it is connected with,  that it has no motion.
  The metacarpal bone of the middle finger is generally the
second in length: but often  it is as long as the former;
sometimes it is longer;  and it frequently appears  only to
equal the first by the os magnum being farther  projected
downwards than any other bone of the wrist. Its base is a
broad  superficial cavity, slanting  inwards;  the external
posterior  angle of which is  so prominent, as to have the
appearance of a process. The external side of this base is
made plain in the same  way as  the external side of the
former bone, while its internal side has two hollow circu-
lar surfaces, for joining the third  metacarpal bone;  and
between these surfaces  there is a rough fossa, for the ad-
hesion of a ligament, and lodging mucilaginous glands.
The extensor carpi radialis  brevior is inserted into the
back part of this  base. The two sides of this  bone are
almost equally flatted;  but the ridge on  the fore  part of
the body inclines inwards. The tubercles at the fore part
of the root of the head are equal. The motion of this bone
is very little more than that  of the former; and  therefore
these two firmly resist bodies pressed against them by the
thumb or fingers, or both.
  The metacarpal bone of the ring finger is shorter than
the second metacarpal bone. Its base is semicircular  and
convex, for its conjunction with  the os unciforme;  On its
external side are two smooth convexities, and a middle
fossa, adapted to the  second  metacarpal bone. The inter-
nal side has a triangular smooth concave surface to join it
with the fourth one.  The anterior ridge of its body is situ-
ated more to the inside than  to the  outside. The tubercles 
 134                   Thumb.
 near the head are equal. The motion of this third meta-
 carpal bone is greater than the motion of the second.
   The metacarpal bone of the little finger is the smallest
 and  sharpest. Its base is  irregularly convex,  and rises
 slanting inwards.  Its external side is exactly adapted to
 the third  metacarpal  bone. The  internal has no smooth
 surface, because  it is  not contiguous to any other bone;
 but it is prominent where the extensor carpi  ulnaris is in-
 serted. As this metacarpal bone is furnished  with a proper
 moving muscle, has the plainest articulation, is most loose-
 ly connected and least confined, it not only enjoys a much
 larger motion than any of the rest, but draws  the third
 bone with it, when the palm of the hand is to be  made
 hollow by its  advancement  forwards,  and by the promi-
 nence of the thumb opposite to it.

                  Thumb and Fingers.
   The thumb and fourfingers are each composed of three
 bones.

   The thumb is  situated obliquely in respect of the  fin-
 gers;  neither  opposite  directly to them, nor in the same
plane with them   All its  bones  are  much  thicker  and
stronger in proportion to their length,  than the  bones of
the- fingers are: which is extremely necessary, as the thumb
conteracts all  the fingers.
   The first bone of the thumb has its base adapted to the
peculiar articulating surface  of the  trapezium: for, in
viewing it from one side to the other, it  appears convex
in the middle; but when viewed  from behind forwards,
it is concave there. The edge at the fore part of this base
is  extended farther than any  other part; and round the
back part  of the base a rough  fossa may  be  seen, for the 
Thumb.
135
connexion of the ligaments of this joint. The body and
head of this bone are of the same shape as the ossa meta*
carpi; only that the body is shorter, the head flatter, and
the tubercles at the fore part of its root larger.
  The articulation of the upper end of  this bone is re-
markable: for, though it  has  protuberances and depres-
sions adapted to the double pulley of the trapezium, yet it
enjoys a circular motion, as the  joints do where a round
head of the one plays in the orbicular socket of another:
it is however more confined, and  less expeditious,  but
stronger and more secure than  such joints generally are.
   The second bone of the thumb has a large base formed
into an oblong cavity, whose greatest length is  from  one
side to  the  other. Round it several tubercles may be re-
marked, for the insertion of ligaments.  Its body is convex,
or  half-round behind;  but flat  before, for lodging  the
tendon of the long flexor of the thumb, which is tied down
by ligamentous sheaths, that are  fixed on  each side to the
angle at the edge of this flat surface. The lower end of
this second bone has two lateral round protuberances, and
a middle cavity, whose  greatest extent of smooth  surface
is forwards and backwards.
   The articulation of the upper end of this second bone
would,seem calculated for motion in all directions;  yet,
on account of the strength of its lateral ligaments, the ob-
long figure of the joint itself, and mobility of the first joint,
it only allows flexion and extension; and these are generally
much confined.
   The third bone of the thumb is the smallest, with a large
base, whose greate'st extent is from one side to the other.
This base is formed into two cavities and a middle protu-
berance, to  be adapted  to the  pulley of the former bone.
This bone becomes gradually  smaller, till near the lower 
 136                   lingers.
 end, where it is a little enlarged, and has an oval scabrous
 edge. Its body is rounded behind, but is flatter than in the
 former bone, for sustaining the  nail. It is  flat and rough
 before, by the insertion of the flexor tertii internodii.
   The motion of this third bone is confined to flexion and
 extension.

   The regular arrangement of  the bones of the fingers
 in three rows, has obtained for them the name of the three
phalanges. All of them have half round convex surfaces,
 covered with an aponeurosis, formed by the tendons of the
 extensors, lumbricales, and interossei, and placed directly
 backwards, for  their greater strength; and their flat con-
 cave part  is forwards, for taking hold more surely, and for
 lodging the tendons of the flexor muscles.  The  ligaments
 for keeping down  these  tendons are fixed to the angles
 that are between the convex and concave sides.
   The bones of the first phalanx of the fingers answer to
 the description of the second bone of the thumb; only that
 the cavity in their  base is not so oblong; nor is their mo-
 tion on the metacarpal bones so much  confined: for they
 can move laterally or circularly, the fore finger in particu-
 lar, but have no rotation, or a  very small degree of  it,
 round their axis.
   The second bone of the fingers has its base formed into
 two lateral cavities, and a middle protuberance; while the
 lower end has two lateral protuberances and a middle ca-
 vity; therefore it is joined at both ends in  the same man-
 ner; which none of the bones of the  thumb are.
   The third  bone differs nothing from the description  of
 the third bone of the thumb, except in the general distin-
 guishing  marks; and therefore the  second and third pha-"
 lanxof the fingers enjoy only flexion and extension. 
                     The Fingers.                 137
   All the difference of the phalanges of the several fingers
consists in their magnitude. The bones of the middle fin-
ger being the longest and largest; those of the forefinger
come next to these in thickness, but not in length, for those
of the ring finger are a little longer. The little finger has
the smallest bones. Which  disposition is the best contri-
vance for holding the largest bodies;  because the longest
fingers are applied to the middle largest periphery of such
substances as are of a spherical figure.
Vol. I.
S 
138
                   SECTION IV.

             The Inferior Extremities.

  THE inferior extremities consist of the Thigh, Leg
;md Foot.

                     The Thigh
  Consists of one bone only;  the  os femoris, which is
very strong, and larger than any other in the skeleton. It
is nearly cylindrical in the  middle,  and slighdy  curved.
The upper extremity is a spherical head, connected to the
body of the bone by a neck. The lower extremity is much
larger than the body, and is formed into two condyles.
  The upper end of this bone is not continued in a straight
line with the body of it, but the  axis of it inclines obliquely
inwards and upwards, whereby the distance between these
two bones at their upper part  is considerably  increased.
The head is the greater portion of a sphere.  Towards its
lower internal part a round rough spongy pit is observable,
where the strong ligament, commonly, but  inaccurately,
called the round one, is fixed, to be  extended from thence
to the lower internal part of the receiving cavity, where it
is considerably broader than near to the head of the thigh
bone. The neck of the os femoris, has a great many large
holes, into which the fibres of  the strong ligament, conti-
nued from the capsular, enter,  and are thereby firmly uni-
ted to it; and round the root of the neck, where it rises
from the  bone, a rough ridge is found, where the capsular
ligament  of the articulation itself is connected.  Below this
 root, a large unequal protuberance, called trochanter major, 
                     Os Femoris.                 139
stands out;  the external convex part of which is distin-
guished into three different surfaces: whereof the one on
the upper and front part is scabrous and rough, for the in-
sertion of the glutaeus minimus; the superior one is smooth,
and has the glutaeus medius inserted into it; and the one
behind is made flat and smooth, by the tendon of the glu-
taeus maximus passing over it. The upper edge of this pro-
cess is sharp and pointed at its back part, where the glu-
taeus medius is fixed; but  forwards it is more obtuse, and
under it is a depression, into which some of the muscles
which rotate the thigh outwards, are fixed.  From the pos-
terior prominent  part  of  this  great  trochanter,  a rough
ridge  runs backwards  and  downwards, into which the
quadratus is inserted. In the deep hollow, at the internal
upper side of this ridge, the obturator externus is implant-
ed. More internally, a conical process, called trochanter
minor, rises, for the insertion of the musculus  psoas and
iliacus internus;  and the  pectineus is implanted into a
rough hollow below its  internal  root.  The muscles insert-
ed into these two  processes being the principal instruments
of the rotatory motion of the thigh, have  occasioned the
name  of trochanters to  be  given to these processes.
  The body of the os femoris is convex on the fore part,
and concave behind;  which enables us to sit without lean-
ing too much on the posterior muscles.
  On  the posterior concave surface is a broad rough ridge
called linea  aspera, which commences near the great tro-
chanter, and continues downwards, more than two-thirds
of the length of the bone, when  it divides into two ridges
which descend towards each condyle. The internal of these
ridges is the most smooth; and  the space between them is
nearly flat.  Near the end  of each of these  ridges, a small 
140
Os Femoris.
smooth protuberance may often be remarked, where the
two heads of the external gastrocnemius muscle take their
rise; and  from the fore part of the internal tubercle a
strong ligament is extended to the inside of the tibia.
  The lower end of the os femoris is larger than any other
part of it, and is formed into two great protuberances, one
on each side, which are called its condyles:  between them
a considerable cavity is found, especially at the back part,
in which the crural vessels and  nerves  lie. The internal
condyle is longer than the external, which must happen
from the oblique position of this bone, to give less obliquity
to the leg. These processes are of an oblong form, and are
placed obliquely with respect  to each other; being in con-
tact before, and separated to a considerable distance be-
hind.
  They form in front a smooth pulley-like surface, the
external side of which is highest,  on which the patella
moves.
  Below, they are flat; and posteriorly, they are regularly
convex.
  Between these convex portions is a rough  cavity, from
which  the crucial ligament arises,  to  be attached to the
tibia.  Round the lower end of the thigh bone, large holes
are found, into which the ligaments for the security of the
joint are fixed, and bloodvessels pass to the internal sub-
stance  of the bone.
  The thigh bone being articulated  above with the aceta-
bulum of the ossa innominata, which affords its round head
a secure and extensive play, can be moved to every side;
but it  is restrained in its motion outwards, by the high
brims of the cavity, and by the round ligament; for other-
wise the  head of the  bone would have been frequently 
                      Os Femoris.                 141
thrust out at the breach of the brims on the inside, which
allows the thigh to move considerably inwards.  The body
of this bone enjoys little or no rotatory motion, though the
head most commonly moves round its own axis; because
the oblique direction of the neck and head, from the bone,
is such, that the rotatory motion of the head can only bring
the body of the bone forwards and backwards. Nor is the
head, as in the arm, ever capable  of being brought  to  a
straight direction  with its body; so far, however, as the
head can move within the cavity backwards and forwards,
the rest of the bone may have a partial rotation.
  From the oblique position of these bones it results, that
there is a considerable distance between them above, while
the knees are almost contiguous. Sufficient space is there-
by left for the external parts of generation, for the two
great outlets of urine and faeces, and for the large thick
muscles that  move the thigh inwards. At the same  time
this situation of the thigh bones renders our progression
quicker, surer, straighter, and in less room: for, had the
knees been at a greater distance from each other, we  must
have been obliged to describe some part of a  circle  with
the trunk of our body in making a long step; and when
one leg was raised from the ground, our center of gravity-
would have been too far from the base of the other, and
we  should consequently have been in danger of falling; so
that our steps would neither have been straight nor  firm,
nor would it  have been possible to walk in a narrow  path,
had our thigh  bones been otherwise placed.  In conse-
quence, however,  of the  weight of the body bearing so
obliquely  on  the joint of the knee by this situation of the
thighbones, weak rickety children become knock-kneed. 
142
The Leg.—Tibia.
                       The Leg
   Is composed of two bones, the tibia and fibula.
   The patella, being evidently  appropriated to the knee
joint, may be  regarded as common, both to the thigh and
leg.

         ,             77i<? Tibia
   Is the long thick triangular bone, situated at the inter-
nal part of the leg, and continued in almost a straight line
from the thigh bone. The name is derived from its resem-
blance to the ancient musical instrument.
   The upper end of the tibia is large, bulbous, and spon-
gy.  It has a horizontal surface, divided into two cavities,
by a rough  irregular  protuberance, which is hollow at its
most prominent part, as well as before and behind. The
anterior of the two ligaments that compose  the great cru-
cial is inserted into the middle cavity; and the depression
behind receives the posterior ligament. The  two broad
cavities at the sides of this protuberance are not equal: for
the internal  is oblong and deep,  to receive the internal con-
dyle of the thigh bone; while the external is more superfi-
cial and round, for the external condyle. In each of these
two  cavities of a  recent subject, a semilunar cartilage is
placed, which is  thick at its convex edge, and becomes
gradually thinner towards the concave or  interior edge.
The thick convex  edge of each cartilage is connected to
the capsular and other ligaments of the articulation; but so
near to their rise from the tibia, that the cartilages are not
allowed to change their places;  while their narrow ends
are fixed at the insertion of the  strong cross ligament into
the tibia, and seem to have their substance united with it;
therefore a circular hole is left between each cartilage and 
Tibia.
143
the ligament, in which the most prominent convex part of
each condyle of the thigh bone moves. The circumference
of these cavities is rough and unequal, for the firm con-
nexion of the ligaments of the joint.  Immediately below
the edge, at its back part, two rough flatted protuberances
stand out;  into the internal, the tendon of the semimem-
branosus muscle is inserted;  and a part of the cross liga-
ment is  fixed to the external. On the outside of this last
tubercle, a smooth slightly-hollowed surface is formed by
the action of the politaeus muscle.
   Below the fore part of the upper end of the tibia, a large
rough protuberance rises, to which the strong tendinous
ligament of the patella is fixed. On the internal side of this,
there is a broad  scabrous slightly-hollowed  surface,  to
which the internal long ligament of the joint, the aponeu-
rosis of the vastus internus, and the tendons of the semi-
tendinosus, gracilis,  and sartorius, are fixed. Below the
external edge of the upper end of the tibia, there is a flat
circular surface, covered in a  recent subject with cartilage,
for the articulation of the fibula. The body of the  tibia is
triangular.  The anterior angle is very sharp, and is com-
monly called the spine or shin. This ridge is not straight;
but turns first inwards, then outwards, and lastly inwards
again. The plain internal side is smooth and equal, being
little subjected to  the actions of muscles; but the external
side is hollowed above by the tibialis anticus, and below by
the extensor digitorum longus and extensor pollicis longus.
The two angles behind  these sides are rounded by  the ac-
tion of the muscles; the posterior side comprehended be-
tween them is not  so  broad as those already mentioned,
but is more oblique and flatted by the action of the  tibialis
posticus and flexor digitorum longus.  A little above the
middle of the bone, the internal angle terminates, and the 
 144                   Fibula.
 bone is made round by the pressure of the  musculus so-
 laeus. Near to this, the passage of the medullary vessels is
 seen slanting obliquely downwards.
   The lower end of  the tibia is hollowed, with a small
 protuberance in the middle.  The internal side of this ca-
 vity, which is smooth, and in a recent subject is covered
 with cartilage, is  extended into a considerable process,
 commonly named malleolus internus; the point of which is
 divided by a notch, and from it  ligaments are sent out to
 the foot. The external side of this end of the tibia has a
 rough irregular cavity formed in  it for receiving the lower
 end of the fibula. The  posterior  side has two lateral
 grooves, and a small middle protuberance.  In the internal
 depression, the tendons of the musculus tibialis posticus
 and flexor digitorum longus are lodged; and in the exter-
 nal, the tendon of the  flexor longus pollicis plays.  From
 the middle protuberance, ligamentous sheaths go out, for
 tying down these tendons.

                      The Fibula
   Is the small long bone, placed  on the outside of the leg,
opposite to the external angle of the tibia; the shape of  it
 is  irregular.
   The head of the fibula has a circular surface formed on
 its inside, which, in a recent subject, is covered with a
 cartilage; and it is so closely connected to the tibia by liga-
 ments, as to allow only a very small motion backwards and
 forwards.  This head is protuberant and rough on its out-
 side, where a strong-round ligament and  the  musculus
 biceps are inserted; and, below the back part of its internal
 side, a tubercle may be remarked;  that gives rise to the
 strong tendinous part of the solaeus muscle.
   The body of this bone is a little crooked inwards and 
                        Fibula.                   145
backwards: which figure is owing to the actions of the mus-
cles. The sharpest angle of the fibula is forwards; on each
side of which the bone is considerably, but unequally, de-
pressed by the bellies of the several muscles that rise from
or act upon it. The external surface  of the fibula  is de-
pressed obliquely from above downwards and backwards,
by the two peronaei.  Its internal surface is unequally di-
vided into two narrow longitudinal planes, by an oblique
ridge extended from the upper part of the anterior angle.
To this ridge  the ligament stretched between the  two
bones of the leg is connected.  The  anterior  of the  two
planes is very  narrow above, where the extensor longus
digitorum and extensor longus pollicis arise from it; but
is broader below, where it has the print of the nonus vesa-
lii. The posterior plane is broad and hollow, giving origin
to the larger share of  the tibialis posticus. The internal
angle of this bone has a tendinous membrane fixed to it,
from  which some fibres of the flexor digitorum longus
take their rise. The posterior surface of the  fibula is the
plainest and smoothest; but is made flat above by the so-
laeus, and is hollowed below by the flexor pollicis longus.
In the middle of this surface, the canal for the medullary
vessels may be seen slanting downwards.
   The  lower end of the fibula is extended into a spongy
oblong head; on the inside  of which is a convex, irregu-
lar, and frequently a scabrous  surface, that  is received
by the external hollow of the tibia, and so firmly joined to
it, by a very thin intermediate cartilage and strong liga-
ments, that it scarce can move.  Below this the fibula is
stretched out  into a smooth coronoid process, covered
with cartilage on its internal side, and is there contiguous
to the outside of the first bone of  the foot, the astragalus,
to secure the articulation. This process, named malleolus
   Vol. I.                  T 
146
Fibula.
 externus, being situated farther back than the internal mal-
 leolus, and in an oblique direction, obliges us naturally to
 turn the fore part of the foot outwards.  At the lower in-
 ternal part of this process, a spongy cavity for mucilaginous
 glands may be remarked; from its point ligaments are ex-
 tended to the bones of the foot, viz. the astragalus, os cal-
 cis, and os naviculare; and from its inside short strong ones
 go out to the astragalus. On the back part of it a sinuosity
 is made by the tendons of the peronaei muscles.  When the
 ligament extended over these tendons from the one side of
 the depression to the other is broken, stretched too much,
 or made weak by a sprain, the tendons frequently start for-
 wards to the outside of the fibula.
   The conjunction of the upper end of the fibula with the
 tibia is by plain surfaces tipped with cartilage; and  at its
 lower end the cartilage seems to glue the two bones toge-
 ther; not, however, so firmly in young people, but that the
 motion at the other end is very observable.  In old sub-
jects, the two bones of the leg are sometimes  united by
 anchylosis at their lower ends.
   The principal use of this bone is to afford origin and in-
 sertion to muscles; and to give a particular direction to
 their tendons. It likewise assists to make the articulation
 of the foot  more secure and firm, and to complete  the
 hinge-like joint  at  the ancle.  The ends of  the tibia and
 fibula being larger than their middle, a space is  here left,
which is  filled up with a ligament similar to that which is
extended between the bones of the fore arm; and which is
also discontinued at its upper part, where the tibialis ami-
cus immediately adheres to the solaeus and tibialis posti-
cus; but every where else it gives origin to muscular fibres. 
Patella.
147
                  The Patella or Rotula
   Is the small flat bone situated at the fore part of the joint.
 of the  knee. Its  shape  resembles the common figure of
 the heart with its point downwards.  The anterior convex
 surface of the rotula is pierced by a great number of holes,
 into which are inserted the fibres of  the strong ligament,
 that is spread over it.  Its posterior surface is smooth, co-
 vered with  cartilage, and divided  by a  middle convex
 ridge into two cavities, of which the external is largest;
 and both are exactly adapted to the pulley of the os femo-
 ris, on which they are placed in the most ordinary unstrain-
 ing postures of the leg: but when the leg is much bent, the
 patella descends far down on the condyles; and  when  the
 leg is fully  extended, the patella rises higher in its upper
 part than the pulley of the thigh-bone. The plain smooth
 surface is surrounded by a rough prominent edge, to which
 the capsular ligament adheres.  Below, the point  of the
 bone is scabrous, where  the  strong tendinous ligament
 from the tubercle of the tibia is fixed. The upper horizon-
 tal part of this bone is flatted and unequal, where the ten-
 dons of the  extensors of the leg are inserted.
   The substance of the patella is cellular, with  very thin
 firm external plates; but then these cells are so small, and
 such a quantity of bone is employed in their formation,
 that scarce any bone of its bulk is so strong. But notwith-
 standing this strength it is sometimes broken by the vio-
lent straining effort of the muscles.
   The principal motions of the knee joint are flexion and
 extension. In the former of these, the leg may be brought
to a very acute angle with the  thigh, by the condyles of
the thigh bones being round and made smooth  far back-
wards. In performing this, the patella is pulled  down by 
148
Patella.
the tibia. When the leg is to be extended, the patella  is
drawn  upwards, consequently the tibia forwards, by the
extensor muscles;  which, by means of the protuberant
joint, and of this thick bone with its ligament, have the
chord, with which they act, fixed to the tibia at a conside-
rable angle, and act, on that account, with advantage; but
they are restrained from pulling the leg farther than to a
straight line with the thigh, by the posterior part of the
cross ligament, that the body might be supported by a firm
perpendicular column: for at this time the  thigh and leg
are  as  little movable in a rotatory way, or to either side,
as if they were one continued bone.  But when the joint is
a little bent, the rotula is not tightly braced, and the po-
sterior ligament is relaxed; therefore this bone may be mo-
ved a little to either side, or with a small rotation in the
superficial cavities of the  tibia; which is done by the mo-
tion of  the external cavity backwards and forwards, the
internal  serving as a sort of axis. Seeing, then, one part
of the cross ligament is situated perpendicularly, and the
posterior part is stretched obliquely from the internal con-
dyle of the thigh outwards, that posterior part of the cross
ligament prevents the leg from being turned much inwards;
but  it could not hinder  it from turning outwards almost
round,  was  not that motion confined by the lateral liga-
ments of this joint, which can yield little.  This rotation
of the leg outwards is of great advantage to us in crossing
our legs, and turning our  feet outwards, on several ne-
cessary  occasions; though it is necessary that this motion
should not be  very large, to prevent frequent luxations
here. While  all these motions are performing, the part of
the tibia that moves immediately on the condyles is that
which is within the cartilaginous rings, which by the thick-
ness on their outsides make  the cavities  of the tibia more 
The Foot.—Tarsus.
149
 horizontal, by raising their external side where the sur-
 face of the tibia slants downwards.  By these means the mo-
 tions of this joint are more equal and steady than other-
 wise they would have been. The cartilages being capable
 of changing a little their situation, contribute to the differ-
 ent  motions and postures of the limb, and likewise make
 the motions larger and quicker.

                       The Foot.
   The foot is divided  into the tarsus,  metatarsus, and
 toes.
   The sole of the foot is necessarily described as the in-
 ferior part, and the side of the great toe as the internal.

                        Tarsus.
   The tarsus consists of seven spongy bones; to wit, the
 astragalus, os calcis, naviculare, cuboides, cuneiforme ex-
 ternum, cuneiforme medium, and cuneiforme internum.
   The astragalus is the uppermost of these bones. The
 os calcis is below the astragalus, and forms the heel. The
 os naviculare is in the middle of  the internal side of the
 tarsus. The os cuboides is the most external of the row of
 four bones, at its fore part. The os cuneiforme externum
 is placed at the inside of the cuboid. The cuneiforme me-
 dium is between the external and internal cuneiform bones;
 and  the internal cuneiforme is at the internal side of the
 foot.
  The upper part of the astragalus is formed into a large
 smooth head, which is  slightly hollowed in the  middle;
 and therefore resembles a superficial pulley, by which it is
 fitted to the lower end of the tibia. The internal  side of
this head is flat and smooth, to play on the internal mal-
 leolus.  The external side has also such a surface, but 
 150                 Astragalus.
 larger, for its articulation with the external  malleolus.
 Round the base of this head there is a rough  fossa;  and
 immediately before  the head,  as also below its internal
 smooth surface, we find a considerable rough cavity.
   The lower surface of the astragalus is divided by an ir-
 regular deep rough fossa, which at  its internal end is nar-
 row, but  gradually widens as  it stretches obliquely out-
 wards and forwards.  The  smooth  surface, covered with
 cartilage, behind this fossa, is  large, oblong, extended in
 the same oblique situation with the  fossa, and concave for
 its conjunction with the  os calcis.  The posterior edge of
 this  cavity  is formed by two  sharp-pointed rough pro-
 cesses, between which is a depression made by the tendon
 of the flexor pollicis longus. The lower surface before the
 fossa is convex,  and composed of three distinct smooth
 plains. The long one behind, and the exterior or shortest,
 are articulated with  the heel bone; while the internal,
 which is the most convex of the three, rests and moves
 upon a cartilaginous ligament, that  is continued from the
 os calcis to the os naviculare; without which ligament the
 astragalus  could  not be sustained,  but would be pressed
 out of its place by the great weight it supports;  and the
 other bones of the tarsus would be separated. Nor would
 a bone be fit here, because it must have been thicker than
 could conveniently be allowed;  otherwise it would break,
 and would not prove such an easy bending  base, to lessen
 the shock  which is  given  to the body in leaping, run-
 ning, &c.
   The fore part of this bene is  formed into a convex ob-
long smooth head, which is received by the os naviculare,
and is placed obliquely; its longest  axis inclining down-
wards and  inwards.  Round the root of this head, especi-
 ally on the upper surface, a rough fossa may be remarked. 
                        Os Calcis.                  151

    The astragalus is articulated above to the tibia and fibu-
  la, which together form  one cavity. In this articulation,
  flexion and extension are the most considerable motions;
  the other motions being restrained by the malleoli, and
  by the strong ligaments which go out from the points of
  these processes, to the astragalus and os calcis. When the
  foot is bent, as it commonly is when we stand, no lateral
  or rotatory  motion is allowed in this joint; for then the
  head of the astragalus is sunk deep between the malleoli,
  and the  ligaments  are tense:  but when the foot is extend-
  ed, the astragalus can move a little to either side, and with
  a small rotation.  By this contrivance the foot is firm, when
  the weight of the body is to be supported on it; and when
  a foot is raised, we are at liberty to direct it more exactly
  to the place we intend next to step upon.
    The astragalus is joined below to the os calcis; and be-
  fore to  the  os naviculare, in the manner to be explained
  when these bones are described.
    The os calcis is the largest bone of the seven. Behind,
  it is formed into a large knob, commonly called the heel,
  the posterior surface of which is  rough below for the in-
  sertion of what  is called  the tendo achillis, and oblique
  above to allow the heel to be depressed without pressing
  against the tendon. On the upper  surface  of the os calcis,
  there is an irregular oblong smooth convexity, adapted to
  the concavity at the back part of the astragalus ;  and
  beyond  this a narrow fossa is seen, which divides it
'  from two small concave smooth surfaces, that are joined
  to the fore part of the astragalus. The posterior of these
  smooth surfaces, which is the largest, is the upper surface
  of a process which projects inwards: and under it is a small
  sinuosity for the tendon of the flexor digitorum longus. 
152
Os Calcis.
  The external side of this bone is flat, with a superficial
fossa running horizontally, in which the tendon of the
musculus peronaeus longus is lodged. The internal side of
the heel bone is hollowed, for lodging the origin of the
massa carnea, and for the safe passage of tendons, nerves,
and arteries. Under the side of the internal smooth con-
cavity, a particular groove is made by  the tendon of the
flexor pollicis  longus; and  from the thin protuberance of
this internal side the cartilaginous ligament  that supports
the astragalus, goes out to the os naviculare; on which
ligament, and on the edge of this bone to which it is fixed,
the groove is formed for the tendon of the flexor digitorum
profundus.
  The lower surface of this bone is flat at the back part;
and immediately before this plain, there are two tubercles,
from  the internal of which the musculus abductor pollicis,
flexor digitorum sublimis, as also part of the aponeurosis
plantaris, and of the abductor minimi digiti, have their
origin;  and the other part of the abductor minimi digiti
and aponeurosis plantaris rises from the external. Before
these protuberances, this bone is concave,  for lodging the
flexor muscles; and at its fore part, we may observe a rough
depression, from which, and a tubercle behind it, the liga-
ment goes out that prevents this bone from being separated
from  the os cuboides.
  The fore part of the os calcis is formed into an oblong
pulley-like  smooth surface, which is circular at its upper
external end, but is pointed below. The smooth surface is
fitted to the os cuboides.
  Though the surfaces by which the astragalus and os cal-
cis are articulated, seem fit enough  for motion;  yet  the
very strong ligaments, by which these bones are connected,
prevent much motion, and give firmness to this principal
part of our base, which rests on tHe ground. 
             Os Naviculare.—Os Cuboides.          153
  Os naviculare is somewhat oval.  It is formed into an
oblong concavity behind, for receiving the anterior head
of the astragalus. The upper surface is convex. Below, the
surface is very unequal and rough; but hollow for the safety
of the muscles.  Its internal extremity is very prominent.
The  abductor pollicis takes in part its origin from it, the
tendon of the tibialis posticus is  inserted into it, and to it
two remarkable ligaments are fixed; the first is the strong
one, formerly mentioned, which supports the astragalus;
the second is stretched from this bone obliquely across the
foot, to the metatarsal bones of the middle toe, and of the
toe next to the little one. On the outside of the os navicu-
lare there is a semicircular smooth surface, where  it  is
joined to the os  cuboides.  The fore part of this bone is
covered  with cartilage,  and divided into three smooth
plains, fitted to the three ossa cuneiformia.
  The os naviculare and astragalus are joined as a ball and
socket;  and the  naviculare moves in several directions in
turning the toes inwards, or in raising or depressing either
side of the foot, though the motions are greatly restrained
by the ligaments which connect this to the other bones of
the tarsus.
  Os cuboides is an irregular cube.  Behind, it is formed
into an oblong unequal cavity, adapted to the fore part of
the os calcis. On its internal side, there is a small semi-
circular smooth  cavity, to join the os naviculare. Imme-
diately before which, an oblong smooth  plain is made by
the os cuneiforme externum; below this the bone is hol-
low and  rough.  On the internal side of the lower surface,
a round protuberance and fossa are found, where the mus-
culus abductor pollicis has its origin. On the external side
of this surface, there is a broad ridge running forwards and
inwards, covered with cartilage; immediately before which
  Vol.  I.                 U 
154                Os Cuneiforme.
a smooth fossa may be observed, in which the tendon of the
peronaeus primus runs obliquely across the foot.  Before,
the surface of the os cuboides is flat, smooth, and slightly
divided into two plains, for  sustaining the os metatarsi of
the little toe, and of the toe  next to it.
   The form of the back part of the os cuboides, and the
ligaments connecting the joint with the os calcis, both con-
cur in allowing little motion in this part.
   Os cuneiforme externum is shaped like a wedge, being
broad and flat above, with long sides running obliquely
downwards, and terminating in an edge. The upper sur-
face of this bone is  an oblong square. The one behind is
nearly a triangle, but not  complete at the inferior angle,
and is joined to the os naviculare. The external side  is an
oblong square divided as it were by a diagonal; the upper
half of it is smooth, for its conjunction with the os cubo-
ides : the other is a scabrous hollow, with a small smooth
impression made by the os metatarsi of the toe next to the
little one. The internal side of this bone is flattened before
by the metatarsal bone of the toe next to the great one, and
the back part is also flat and smooth where the os cunei-
forme medium is contiguous to it.  The fore part of this
bone is triangular, for  sustaining the os metatarsi of the
middle toe.
   Os cuneiforme, ox minimum, is still more exactly the shape
of a wedge than the former.  Its upper part is square; its
internal side has a flat smooth  surface, for its connexion
with the adjoining bone; the external side is smooth and
a little hollowed, where it is contiguous to the last describ-
ed bone. Behind, this bone is triangular, where it is articu-
lated with the os naviculare; and it is also triangular at its
fore part, where it is contiguous to the os metatarsi of the
toe next to the great one. 
                      Os Cuneiforme.                155
    The broad thick part of the os cuneiforme maximum, or
  internum,  is placed below, and the small thinner edge is
  above. The surface of this os cuneiforme behind, where it
  is joined to the os naviculare, is hollow, smooth, and of a
  circular figure below, but pointed above. The external side
  consists of two smooth and flat surfaces.  With the poste-
  rior, that runs obliquely forwards and outwards, the os
  cuneiforme minimum is joined; and  with the anterior,
  whose direction is longitudinal, the os metatarsi of the toe
  next to the great  one is connected.  The fore part of this
  bone is flat and smooth, for sustaining the os metatarsi of
 the great toe.  The internal side is  scabrous, with two re-
 markable tubercles below, from which the musculus ab-
 ductor pollicis rises, and the tibialis anticus is inserted into
 its upper part.
   The three cuneiform bones are all so secured by liga-
 ments, that very little motion is allowed in any of them.
   These seven bones of the tarsus, when joined, are con-
 vex above, and leave a concavity below, for lodging safely
 the several muscles, tendons, vessels, and nerves, that lie
 in the sole of the foot.  In the recent subject, their upper
 and lower  surfaces are covered with strong ligaments,
 which adhere firmly to them;  and all  the  bones are  so
 tightly connected by these and the other ligaments, which
 are fixed to the rough ridges and fossae, that notwithstand-
 ing the many surfaces  covered with cartilage, some  of
 which are of the form of the very movable  articulations,
 no more motion is here allowed, than is necessary to pre-
 vent too great a shock of the fabric of the body in walking,
leaping, &c. by falling on too solid a base.  If the tarsus was
one continued bone, it would likewise be  much more liable
to be broken; and, the foot could not accommodate itself
to the surfaces we tread  on, by becoming  more or less
hollow, or by raising or depressing either of its sides. 
156
Metatarsus.
                     Metatarsus.
  The Metatarsus is composed of five bones, which agree
in their general characters, with the matacarpal bones;
but may be distinguished from  them by the following
marks: 1. They are longer, thicker, and stronger.  2. Their
anterior round ends are not so broad,  and are less in pro-
portion to their bases.  3. Their bodies are sharper above
and flatter on their sides, with their inferior ridge inclined
more to the outside.  4. The tubercles at the lower part of
the round head are larger.
  The first or internal metatarsal bone is easily distin-
guished from the rest by its thickness. The one next to it
is the longest, and with its sharp edge almost perpendicu-
lar.  The  others are shorter  and more  oblique, as their
situation is more external. Which general remarks, with
the description now to be  given of each, may  teach us to
distinguish them from each other.
  Os metatarsi pollicis is by far the thickest and strongest,
as having much the greatest weight to sustain. Its base is
oblong, irregularly concave, and of a  semilunar figure, to
be adapted to the os cuneiforme maximum. The inferior
edge of this base is a little prominent and rough,  where
the tendon of  the  peronaeus primus  muscle is  inserted.
On its outside an oblique circular depression  is made by
the second metatarsal bone. Its round head has generally
on its fore part a middle ridge, and two oblong cavities,
for the ossa sesamoidea;  and on the external side a de-
pression is made by the following bone.
  Os metatarsi of the second toe is the longest  of the five,
with a triangular base supported by the os cuneiforme me-
dium, and the external side produced into a process;  the
end of which is an oblique smooth plain, joined to the os 
Metatarsus,
157
cuneiforme externum. Near the internal edge of the base,
this bone has two small depressions, made by the os cu-
neiforme  maximum,  between which is a rough cavity.
Farther forwards we may observe a smooth protuberance,
which is joined to the foregoing bone.  On the outside of
the base are two oblong smooth surfaces, for its articulation
with the following bone; the superior smooth surface being
extended longitudinally, and the inferior perpendicularly,
between which there is  a rough fossa.
   Os metatarsi of the middle toe is the second in length.
 Its base, supported by the os cuneiforme externum, is tri-
 angular, but slanting outwards,  where it ends in a sharp-
 pointed  little process;  and the angle  below is not com-
 pleted.
   The internal side of this base is adapted to the preceding
 bone; and the external side has also two smooth surfaces
 covered with cartilage, but of  a different figure; for the
 upper one is  concave, and being round  behind, turns
 smaller as it advances forwards; and the lower surface is
 little, smooth, convex, and very near the edge of the base*
    Os metatarsi oithe fourth toe is nearly as long as the for-
 mer, with a triangular slanting base joined to the os cu-
 boides,  and made round at its external angle; having one
 hollow smooth surface on the outside, where it is pressed
 upon by the following bone; and two on the internal side,
 corresponding to the former bone;  behind which is a long
 narrow surface impressed by the os cuneiforme externum.
    Os metatarsi  of the little  toe is the shortest, situated
 with its two flat sides above and below, and  with the ridges
 laterally. The base of it, part of which rests on the os cu-
 boides, is very large, tuberous, and produced into a long-
 pointed process externally, where part of the  abductor
 minimi digiti is fixed; and into its upper part the peronaeus 
 158       The Toes.—Structure of the Foot,
 secundus is inserted. Its inside has a flat conoidal surface,
 where it is contiguous to the preceding bone.
   When we stand, the fore ends of these metatarsal bones,
 and the  os calcis,  are our only supporters; and therefore it
 is necessary that they should be strong, and should have a
 confined motion.

                       The Toes,
   The bones of the toes are nearly similar to those of the
 thumb and fingers; particularly the two of the great toe,
 which are precisely formed as the two last of the thumb; but
 their position,  as  respects the other toes,  is not oblique;
 and they are proportionally much stronger, because they
 are subjected to a greater force; for they sustain the force
 with which our bodies are pushed forwards by the foot be-
 hind at every step we make; and on them principally the
 weight of the body is supported, when we are raised on
 our tiptoes.
   The three bones in each of the other four toes, compar-
 ed with those of the fingers, differ from them in these par-
 ticulars.  They are less, and smaller in proportion to their
 lengths.  Their bases are much larger than their anterior
 ends. The first phalanx is proportionally much longer than
 the bones of the second and third, which are very short.
   The toe next to the great one has the largest bones in all
 dimensions, and the bones  of the other toes diminish ac-
 cording to the order of their position; those of the exterior
 being least.

           The general Structure of the Foot,
  The foot may be considered as an arch, of which  the
back part of the heel, and the anterior extremities of  the
metatarsal bones and the toes, are the abutments. The heel, 
                 Structure of the Foot,             159
or posterior abutment, is not so broad as the anterior, and
is placed on the outside and not  in the middle of the ex-
tremity of the arch.  The process on the  inside of the os
calcis, which supports the astragalus, increases the breadth
of the arch; and the os naviculare completes it. The arch
thus constructed, does not appear very firm, and this appa-
rent want of strength seems increased by the position of the
anterior portion of the astragalus, a part of which is be-
tween the os calcis and os naviculare, and not supported
by either. These bones however  are firmly connected  by
ligaments, and one which passes from the os calcis to the
os naviculare, under the fore part of the astragalus, gives
effectual support to that bone.
  The outside of the foot, formed by the os calcis, os cu-
boides, and the lesser metatarsal  bone,  does not partake
much of the nature of an arch; for it is almost flat. As the
internal side forms a considerable arch,  the foot is to  be
considered as possessing a double convexity, viz. trans-
versely, as well as longitudinally.
   The  great toe, from its internal situation, is the princi-
pal anterior abutment of the arch on the internal side of the
foot; hence its great  importance.
   The  astragalus which is  the basis of the tibia, and of
eourse pressed by half of the weight of the body when we
stand, appears to be in a situation which is very oblique,
and imperfectly supported;  and  accordingly it has  been
completely forced from its position, by accidents  in which
the leg has been twisted or turned inward, and the foot
prevented from turning with it.  It is probable  that this
misfortune would often take place if the fibula did not
previously yield, as in some of the cases of fracture of that
bone near the external ancle.
  One great object of this peculiar structure is, that the foot 
 160           Extremities of the Fatus.
 may yield in cases of violent and sudden pressure, s  when
 we jump or fall upon the feet. The safety of the foot, and
 the facility of its ordinary movements, are  not the only
 objects of its peculiar  structure, but concussion of the
 whole body, and particularly  of the brain,  is  thereby
 avoided to a certain degree.
   This may be inferred from the fact that many  persons
 suffer violent concussions in consequence of falling  upon
 other parts of the body, who are free from these effects
 when they fall upon the feet.

                 The Sesamoid Bones
   Are seldom larger than half a pea. They are most com-
 monly found at the second joint of the thumb, and of the
 great toe; and are often placed in pairs, especially at the
great toe,  between the tendons of the flexor muscles and
the bones. In these situations they are convex externally,
and on their internal surfaces  they are concave and cover-
 ed with cartilage.
   They are also  sometimes found between  the heads of
the gasteroc nemius  muscle  and  the condyles of the os
femoris.
   In the joints of the thumb and toe they appear to be very
analogous to the patella.

             The Extremities of the  Fatus.
   In the upper extremity  the  clavicle is almost perfect
at birth; but the acromion and coronoid processes of the
scapula, as well as the head, are in a cartilaginous state.
   Both ends of the  os humeri are  cartilaginous. They
afterwards ossify in the  form  of epiphyses, and are united
to the body of the bone.
  The two bones of the fore arm are in the same situation. 
               Extremities of the Fatus.            161
  There are no bones of the carpus; but in their situation
is an equal number of cartilages, which resemble them ex-
actly. These cartilages  are separated from each other by
synovial membranes, as the bones afterwards are. Each of
them ossifies from a single point, except the unciforme.
  The metacarpal bones, and the first bone of the thumb,
have cartilages  at each extremity, which afterwards be-
come epiphyses.
  The bones of the phalanges are likewise cartilaginous at
each extremity.  The extremities next to the hand are
epiphyses; but it is probable that the other extremities os-
sify gradually from their centers. *
  In the lower extremity, the head and neck and two tro-
chanters of the os femoris are cartilaginous,  and form
three epiphyses.
  The  other  end of this bone is also cartilaginous, and
constitutes but one epiphysis, notwithstanding its size; the
ossification commencing in the center.
  At birth, the body of the os femoris is less  curved than
it becomes afterwards;  and the angle formed by the neck
of the bone is less obtuse than in the adult.
  The patella is entirely cartilaginous at birth.
  The two extremities of the tibia and fibula are also car-
tilaginous, and become epiphyses.
  The astragalus and os calcis are somewhat ossified with-
jn, and have a large portion of cartilage exteriorly.
  In place of the other bones of the tarsus, there are car-
tilages of their precise shape, which are as distinct from
each other as the future bones are.
  The state of the metatarsal bones, and the phalanges of
the toes, resembles that  of the bones of the hand.
             * See Nesbit's Osteogeny, page 126,
  Vol. I.                  X 
       SYSTEM OF  ANATOMY.


                  PART  II.



                     MYOLOGY.

                   CHAPTER I.
             OF MUSCLES IN GENERAL.
 I HAT soft, fibrous, red coloured substance, which con-
stitutes so large a proportion  of the volume of the more
perfect animals, is called Flesh or Muscle. '
  By the contraction of this substance, the spontaneous
motions of animals are produced; and on this account the
fibres which compose it have long been  regarded with
particular attention.
  Muscular fibres are not only arranged in those regular
masses on the trunk and limbs of the  body, which are so
familiar to us by the name of muscles, but they also exist
in some of the most important viscera, and  produce the
internal, as well as the external, motions of animals.
  Muscular fibres are connected to each other by cellular
membrane. This membrane surrounds each  muscle:  and
its various laminae, gradually diminishing in thickness,
pass between the different bundles of fibres, and  the  dif-
ferent fibres of which each  muscle is composed. 
             Structure of Muscular Fibres,          163
  The fibres of muscles, when examined with magnifying
glasses, appear to be composed of fibrillae still smaller;
and it  has been supposed that th'.s disision of them ex-
tended beyond our powers of vision, even  when assisted
by microscopes: but so many errors have occurred in mi-
croscopical observations of very minute objects, and so
much difference exists between the reports of different ob-
servers, that the subject at this time does not interest ma-
ny persons; and very little attention is paid, by the anato-
mists and physiologists of the present day, to the opinions
of those observers who supposed they had ascertained the
structure of the ultimate fibrillae.
  These fibrillae have  been represented as simple hollow
tubes, as a  series of globular vesicles, as continuations of
arteries, as terminations of nerves, as structures of rhora-
boidal bodies, and finally, as cellular.*
   It is supposed by one of the latest observers, who ap-
pears to be intitled to great attention,! that the muscular
fibres  are not  thus minutely divided: that a single  fibre,
when separated from the adhering extraneous substances,
and viewed in a powerful microscope, is a solid cylinder,
formed of a pulpy substance, irregularly granulated, and
covered by a portion of the reticular membrane.
   The connexion of these fibres,  with the  bloodvessels
and nerveSy is an important circumstance in the structure
of muscles.
   The arteries of muscles are  very numerous; and they
ramify minutely. They  are accompanied by veins; and it
appears by the successful labours of Ruysch, that  when

  * A statement of these descriptions, with references to the publica-
tions in which they are contained, may be seen in the Elementa Physio-
logist of Haller, vol. IV.
  f Cariysle, in the Croonian Lecture. London Philosophical Transac-
 tions, 1805, Part I. 
164      Bloodvessels and Colour of Muscles.
these arteries  are  fully  injected, they not only communi-
cate with the veins, but also pour out some of their con-
tents in a dew-like effusion in the muscle.*
  These vessels must terminate,  not in cavities of the
muscular fibres, but, exterior to these fibres; otherwise the
dew-like effusion would not be apparent: and it is proba-
ble that the red colour, which is so general in muscles, de-
pends upon a portion of blood effused from these vessels,
and not contained in them; for it has been observed by
Bichat, that in drowned or strangled animals, black disoxy-
genated  hlood occupied all the vessels, while the florid
colour of the muscles continued unchanged; which could
not have been the case if the colour of muscles was owing
to blood in the vessels.
  That the colour of the red muscles is owing to blood, is
rendered certain by the fact that this colour may be com-
pletely washed away while the  fibrous structure  of the
muscle remains unchanged. From this also it may be in-
ferred, that the blood  is  exterior to the muscular fibre,
and to the vessels likewise.
  It is said by Sabbatier that the colour  will likewise be
completely removed by injecting a large quantity of water
through the arteries; this does not invalidate  the inferen-
ces drawn from the other facts; for the water effused from
the  extreme branches of  the  arteries  must necessarily
wash away the blood which was previously effused from
the same branches.
  The water  with which  muscles have  been washed ap-
pears as if some blood hajd been mixed with it; it contains
albumen and  gelatine, with some fibrine, and a peculiar
extractive substance, as well as the red colouring matter.
  The substance of the muscle, when thus separated from
  * See Ruysch's description of the 96th preparation in his Thesaurus
Quartus; and of the 35th  preparation in the Thesaurus Decimns. 
            •      Nerves of Muscles.              165

 the above mentioned matter by washing, appears to be of
 the same nature with the fibrina  of the  blood;  and after
 boiling some time in water, it seems, like that substance,
 to consist of brown insoluble fibres, which are brittle when
 dry.
   When the great function of muscles is under considera-
 tion, nerves appear of more importance than bloodvessels.
   The nerves appropriated to muscles  of voluntary mo-
 tion are more numerous than those appropriated to any
 other parts, except the organs of sense. They  subdivide
 into very fine fibrillae; and it is the opinion of one of the
 latest observers that these fibrillae become soft and trans-
 parent, and  finally blended  with the reticular membrane
 which surrounds the muscular fibres.
   It ought to be noted that muscles are indued with great
 sensibility, and that the smallest puncture cannot be made
 in them without exciting pain. .
   Thus  arranged,  the  fibres of muscles  are most  gene-
 rally attached to tendons, which are inserted into  the bones
 these muscles are intended to move. They are also,  in
 some cases, inserted into tendinous membranes, and other
 parts necessary to  be moved; but  in all such  instances
 these parts are perfectly passive; and the motion in which
 they are concerned  is altogether produced by the contrac-
 tion of the muscular fibres.
   Notwithstanding the gfeat attention that has been paid
 to this important operation of muscular fibres, the imme-
 diate cause is as yet unknown.
   Muscular motion takes place under the following differ-
 ent circumstances.
   1st.  When irritation  or stimulus is applied directly to
the muscular fibre.
  2d. When irritation  is  applied to a nerve connected
with the  muscle.
  3d. When it is induced by volition. 
166        Phenomena of Muscular Motion.
   There are several causes of muscular action which can-
not be arranged under either of these heads, although it is
probable they are not essentially different;  such as the
motions of coughing and sneezing, of yawning, &c.
   The immediate irritation of a muscle is effected by every
mechanical process, which punctures, divides, lacerates or
extends its fibres;  by acrid, and  perhaps other chemical
and peculiar qualities of the substance applied to the mus-
cle; by a sudden change of temperature; and by electricity
and galvanism.
   No satisfactory explanation has yet  been made of the
manner in which muscular contraction is excited, either by
the above  mentioned agents, by irritation applied to a
nerve, or by volition.
   When a muscular fibre begins to contract, there is often
the appearance of a slight tremor in it.  It becomes hard
and rigid:  its length diminishes, and its diameter increa-
ses. If a muscle makes an effort to contract when the parts
to which its extremities are attached are prevented from
moving towards each other  so  that contraction cannot
take place, the  muscle will become  hard and rigid not-
withstanding.
   It has often been inquired whether the whole bulk of a
muscle is diminished or increased by  its contraction. It
now seems generally agreed that the bulk is not increased;
and if there is any real diminution of the fibre itself, it is
very small indeed.
   The irritability of the  muscular  fibre, or its power of
contracting upon the application  of stimulus, exists in a
greater degree in some muscular parts than  others. It is
suspended by the application of narcotic substances; and
it remains, in many cases, a short time after the vital func-
tions have ceased.
   In  a majority of cases  a general contraction seems to 
    Rapidity and Extent of Muscular Contraction.   167
take place in the last moments of life; and after death the
body is stiff in consequence of it; all  the  moveable parts
being fixed in  the  precise situation,  in which they were
when the vital motions ceased. The limbs being generally
in a bended position at that time, if* an attempt be  made
to extend them it will be very evident that the contracted
state of the muscles impedes this  extension. When this
contraction is once overcome, the limbs continue perfectly
flexible, and the muscles are ever  after relaxed;  but the
force of contraction is sometimes so  great that it will re-
quire a considerable exertion of strength to overcpme it.
This  condition of the muscles, after death, although very
common, is not universal: and some dead subjects are per-
fectly relaxed and flexible from  the first cessation of the
vital functions.
   The force with which muscles contract exceeds gready
their inanimate power of cohesion. Thus a muscle, depri-
ved of life, would be completely  lacerated by a weight
suspended from it, which  it could readily  raise by its con-
traction during life. This force of contraction is so great,
that the  tendo  Achillis  and the patella have been repeat-
edly broken by the  mere power of the muscles  inserted
into them.
   The rapidity with which the successive contractions of
the same parts take place is extreme;  and  as a  striking
proof of it, the motions of the tongue, in rapid speaking
or reading, are referred to by physiologists.
   The extent or  degree of muscular contraction is, in some
cases, very great. In proof of this it was stated by the
second Monro, that crude mercury, which passes so rea-
dily through the intestines, could not  be carried along any
parts of  them  whose position happened to be perpendicu-
lar, (as the colon on the right side when we  stand,) unless
the circular fibres of the intestine could contract behind it 
 168      ^tiestion respecting Animal Motion.
 to such a degree as to close completely the cavity of that
 tube.
   An interesting question may be proposed here,—Whe-
 ther the power of motion, as above described, is  exclu-
 sively enjoyed  by muscular  fibres; whether these fibres
 must be supposed to exist in all those parts of the body
 which occasionally perform contraction?
   It has often  been inferred that parts were  muscular
 because  they were capable of contraction; but the ques-
 tion above ought to be decided affirmatively before such
 inferences can be properly made.
  The sac of the taenia hydatigenia appears to be a mem-
 brane of a peculiar structure, very different from muscle;
 yet it is  as capable of contracting as if it were  perfectly
 muscular.*
  The membrane of the  urethra does  not appear to be
 muscular in its structure;  and  yet it has been seen to pro-
 trude a  bougie, which had  passed near to the neck of
 the  bladder, in  a way that indicated regular successive
 contraction, throughout its whole  extent.
  The question above stated may therefore  be considered
 as not yet decided affirmatively.
  Muscular fibres are situated very differently in different
 parts. They compose almost the whole  substance of the
 heart, which is therefore called a hollow muscle.  They.
 also form one of the coats of  the stomach and intestines,
 and  of the  urinary bladder.
  In the muscles on the  trunk and limbs, their arrange-
 ment is very various, being rectilinear, penniform,  radia-
ted, &c.
  There are  a great  many  short fibres, with  an oblique
direction, in  some muscles of small volume; which have
therefore great power and little motion.

  * See the Croonian Lecture by Mr. Home; London Philosophical
Transactions  for 1795, Part I. page 204. 
CHAPTER  II.
             OF THE INDIVIDUAL MUSCLES


      Muscles of the Teguments of the Cranium.

 I HE skin that covers the cranium is moved by a single
 broad digastric muscle, and one small pair.

                 1. Occipito- Frontalis,
   Arises  fleshy from  the transverse protuberant ridge
near the middle of the os occipitis laterally, where it joins
 with the temporal bone;  and tendinous  from the rest of
 that ridge backwards, opposite to the lateral sinus; it arises
 after the same manner on the other side. From thence it
 comes straight forwards, by a broad thin tendon, which
covers the upper part of the cranium at each side, as low
 down as the attollens aurem, to which it is connected, as
also to the zygoma, and covers a part of the aponeurosis
of the temporal muscle; at the upper part of the forehead
it becomes fleshy, and descends with straight fibres.
   Inserted into the orbicularis palpebrarum of each side,
and into the skin of the eyebrows, sending down a fleshy
slip between them, as far as the compressor naris and le-
vator labii superioris alaeque nasi.
   Use. Pulls the skin of  the head backwards; raises the
eyebrows  upwards; and,  at the same time,  it draws up
and wrinkles the skin of the forehead.
  Vol. I.                   Y 
 170              3fuscles of the Ear.
                2. Corrugator Supercilii,
   Arises fleshy from the internal angular process of the
 os frontis, above the joining of the os nasi, and nasal pro-
 cess of the superior maxillary bone; from thence it runs
 outwards, and a little upwards.
   Inserted into the inner and inferior fleshy part of the
 occipito-frontalis muscle, where it joins with the orbicu-
 laris  palpebrarum, and  extends- outwards as far as  the
 middle of the superciliary ridge.
   Use. To draw the  eyebrow of that side  towards the
 other, and make it project over the  inner canthus of the
 eye.  When both act, they pull down the skin of the fore-
 head, and make it wrinkle, particularly between the eye-
 brows.


                Muscles of the Ear.

                  1. Attollens Aurem,
   Arises thin, broad,  and tendinous, from the tendon of
 the occipito-frontalis, from which it is almost inseparable,
 where it covers the aponeurosis of the temporal muscle.
   Inserted into  the upper part of the ear, opposite to the
 antihelix.
   Use. To draw the  ear upwards, and make the parts into
 which it is inserted tense.

                  2. Anterior Auris,
   Arises thin  and membranous near the posterior part of
the zygoma.
   Inserted into a small eminence on the back of the helix,
opposite to the concha.
   Use. To draw this eminence a little  forwards and up-
wards. 
                 Muscles of the Eyelids.             171
                 3. Retrahentes Auris,
  Arise, sometimes by three, but always by two, distinct
small muscles, from the external and posterior part of the
root of the mastoid process, immediately above the inser-
tion of the sterno-cleido-mastoid muscle.
  Inserted into that part of the back of the ear which  is
opposite to the septum that divides the scapha and concha.
  Use. To draw the ear back, and stretch the concha.


               Muscles of the Eyelids.
  The palpebrae  or eyelids, have one muscle common  to
both,  and the upper eyelid one proper to itself.

              1. Orbicularis Palpebrarum,
  Arises, by a number of fleshy fibres, from the outer edge
of the orbitar process  of the superior maxillary bone, and
from  a tendon near the inner angle of the eye: these run
a little downwards, then outwards, over the upper part  of
the cheek, below  the orbit, covering the under eyelid, and
surround the external angle, being loosely connected only
to the skin and fat; run over the superciliary ridge of the
os frontis, towards the inner canthus, where they intermix
with those of the occipito  frontalis and corrugator super-
cilii;  then covering the upper eyelid, they descend to the
inner  angle opposite to the inferior origin of this muscle,
firmly adhering to the internal angular process of  the os
frontis, and to the short round tendon which serves to fix
the  palpebrae and muscular fibres arising from it.
  Inserted, by the short round tendon, into the nasal pro-
cess of the superior maxillary bone, covering the anterior
and upper part of the  lachrymal sac; which tendon can be
"asily felt at the inner canthus of the eye. 
172             Muscles of the Eye.
  Use. To shut the eye, by drawing both lids close toge-
ther, the fibres contracting from the outer angle towards
the inner, press the eyeball, squeeze the lachrymal gland,
and convey the tears towards the puncta lachrymalia.
  The ciliaris of some authors is only a part of this mus-
cle  covering the  cartilages  of the eyelids, called cilia or
tarsi.
  There is often a small fleshy slip which runs down from
the outer and inferior part of this muscle above the zygo-
matics minor, and joins with the levator labii superioris
alaeque nasi.

            2. Levator Palpebra Superioris,
  Arises from the upper part of the foramen opticum of
the sphenoid bone, through which the optic nerve passes,
above the levator oculi, near the trochlearis muscle.
  Inserted, by a broad thin tendon, into the cartilage that
supports the upper eyelid, named tarsus.
  Use,  To open the eye, by drawing the eyelid upwards;
which it does completely, by being fixed to the tarsus,
pulling it below the eyebrow, and within the orbit.


               Muscles of the Eyeball.
  The muscles which move the globe of the eye are six,
viz. Four straight and two oblique.
  The four straight muscles  very much  resemble each
other; all
  Arising by a narrow beginning,  a little  tendinous and
fleshy, from the bottom of the orbit around the  foramen
opticum of the sphenoid bone, where the optic nerve en-
ters, so that they may be taken out  adhering to this nerve;
and all having strong fleshy  bellies. 
                 Muscles of the Eye.             173
  Inserted at the fore part of the globe of the eye into the
anterior part of the tunica sclerotica, and under the tunica
adnata, at opposite sides, which indicates both their names
and Use; so that they scarcely require any further descrip-
tion, but to name them singly.

                   1. Levator Oculi,
  Arises from the upper  part of the foramen opticum of
the sphenoid bone, below the levator palpebrae superioris;
and runs forwards to be
  Inserted into the superior  and fore part of the tunica
sclerotica, by a broad thin tendon.
  Use. To raise up the  globe of the eye.

                  2. Depressor Oculi,
  Arises from the inferior part of the foramen opticum.
  Inserted opposite to the former.
  Use, To pull the  globe of the eye down.

                   3. Adductor Oculi,
  Arises, as the former,  between the obliquus superior
and depressor, being, from its situation, the shortest.
  Inserted opposite to the inner angle.
  Use. To turn the eye towards the nose.

                   4. Abductor Oculi,
  Arises from the bony  partition between the foramen
opticum and lacerum,  being  the longest from its situa-
tion;  and is
  Inserted into the globe opposite to the outer canthus.
   Use.  To move the globe outwards. 
174             Muscles of the Eye.
   The oblique muscles are two:

         1. Obliquus Superior, seu Trochlear is,
   Arises, like the straight muscles^ from the edge of the
foramen opticum at the bottom of the orbit, between the
levator and adductor oculi;  from thence, runs straight
along the pars plana of the ethmoid bone to the upper part
of the orbit, where  a cartilaginous trochlea is fixed to the
inside of the internal angular process  of the  os frontis,
through whicji its tendon passes, and runs a little down-
wards and outwards, inclosed in a loose  membranous
sheath.
   Inserted, by a broad thin tendon, into the tunica sclero-
tica, about half way between the insertion of the attollens
oculi and optic nerve.
   Use. To  roll the  globe of the eye, and turn the pupil
downwards and outwards, so that  the  upper side of the
globe is turned inwards, and the inferior part to the out-
side of the orbit, and the whole globe drawn forwards to-
wards the inner canthus.

                 2. Obliquus Inferior,
  Arises, by a narrow beginning, from  the outer edge of
the orbitar  process of the superior maxillary bone, near
its juncture with the os unguis; and running obliquely
outwards, is
  Inserted  into the sclerotica, in the space between the
abductor and optic nerve, by a broad thin tendon.
   Use. To  draw  the globe of  the eye forwards, inwards,
and  downwards; and, contrary to the superior, to turn
the pupil upwards, towards the inner extremity of the eye-
brow; at the same time, the external part of the globe is 
                 Muscles of the Face.             175
turned towards the inferior side, and the internal rolls to-
wards the upper part.


              The Muscle of the Nose.
  There is only one muscle on each side that can be cal-
led proper to the nose, though it is affected by several
muscles of the face.

                   Compressor Naris,
  Arises, by a narrow beginning, from the root of the ala
nasi externally, where  part of the levator labii superioris
alaeque nasi is connected to it; it spreads into a number of
thin separate fibres, which run up along the cartilage in an
oblique manner towards the dorsum of the nose, where it
joins with its fellow, and is
  Inserted slightly  into the  anterior extremity of the os
nasi and nasal process of the superior  maxillary  bone,
where it meets with some of the fibres descending from
the occipito-frontalis muscle.
   Use. To compress the ala towards the septum nasi, par-
ticularly when we want to smell acutely;  but, if the fibres
of the frontal muscle,  which adhere to it, act, the upper
part of this thin  muscle assists  to pull the ala outwards.
It also corrugates the skin of the nose, and assists in ex
pressing certain passions.

           Muscles of the Mouth and Lips.
  The mouth has nine pair of muscles, which are insert
ed into the lips, and a common  one formed by the termi-
nation of these, viz. three above,  three below, three out-
wards, and the common muscle  surrounds the mouth. 
 176              Muscles of the Face.
   The three above are,

                 1. Levator Anguli Oris,
   Arises, thin and fleshy, from the hollow of the superior
 maxillary bone, between the root of the socket of the first
 dens molaris and the foramen infra-orbitarium.
   Inserted into  the angle of the mouth and under lip,
 where it joins with its antagonist.
   Use. To  draw the corner of the mouth upwards, and
 make that part of the cheek opposite to the chin  promi-
 nent, as in smiling.

        2.  Levator Labii Superioris Alaque Nasi,
   Arises by two distinct origins: the first broad and fleshy,
 from the external part of the orbitar process of the supe-
 rior maxillary bone which forms the lower part of the or-
 bit, immediately above the foramen infra-orbitarium; the
 second portion arises from the nasal process of the supe-
 rior maxillary bone, where it joins the os frontis at the in-
 ner canthus, descending along the edge of the groove for
 the lachrymal sac.  The first and shortest portion is
   Inserted into the upper lip and orbicularis labiorum; the
 second  and longest, into the upper lip and outer part of
 the ala nasi.
   Use. To raise  the upper lip towards the orbit, and a
 little outwards; the second portion serves to draw the skin
 of the nose upwards and outwards, by which the nostril is
 dilated.

      3. Depressor Labii Superioris Alaque Nasi,
  Arises, thin and fleshy, from the os maxillare superius,
immediately above the joining of the gums with the two
dentes incisores and the dens caninus; from thence it runs
up under part of the levator labii superioris alaeque nasi. 
                  Muscles of the Face.              177
   Inserted into the upper lip and root of the ala nasi.
   Use. To draw the upper  lip and ala nasi downwards
and backwards.
   The three below are,

               1. Depressor Anguli Oris,
   Arises, broad and fleshy, from the lower edge of the
maxilla inferior, at the side of the chin, being firmly con-
nected to that part of the platysma myoides, which runs
over the maxilla to the angle of the mouth, to the depres-
sor labii inferioris within, and to the skin and fat  without,
gradually turning narrower; and is
   Inserted into the angle of the mouth, joining  with the
zygomaticus major and levator anguli oris.
   Use. To pull down the corner of the mouth.

             2. Depressor Labii Inferioris,
   Arises, broad and fleshy, intermixed with  fat, from the
inferior part of the lower jaw  next  to the chin; runs
obliquely upwards; and is
   Inserted into the edge  of  the under lip,  extends along
one half of the lip, and is lost in its red part.
   Use. To pull the under lip and the skin  of the side of
the chin downwards, and a little outwards.

              3. Levator Labii Inferioris,
   Arises, from  the lower jaw, at the roots of the alveoli of
two dentes incisores and of the caninus; is
   Inserted into  the under lip and skin of the chin.
   Use. To pull the parts into which it is inserted upwards.
   Vol. I.                   Z 
178              Muscles of the Face.
  The three outward are,

                    1. Buccinator,
  Arises, tendinous and fleshy, from the lower jaw, as far
back as the last dens molaris and  fore part of the root of
the coronoid process; fleshy from the upper jaw, between
the last dens  molaris and  pterygoid process of the sphe-
noid bone;  from the extremity of which it arises tendi-
nous, being continued between both jaws to the constric-
tor pharyngis superior, with which it joins; from thence
proceeding with straight fibres, and adhering close to the
membrane that lines the mouth, it is
  Inserted into the angle of the mouth within the  orbicu-
laris oris.
   Use. To draw the angle of the  mouth  backwards and
outwards, and to contract its cavity, by pressing the cheek
inwards, by which the food is thrust between tb e teeth.

                2. Zygomaticus Major,
   Arises, fleshy, from the os malae, near the zygomatic
suture.
   Inserted into the angle  of the mouth, appearing to be
lost in the depressor anguli oris and orbicularis oris.
   Use. To draw the. corner of the mouth and under lip
towards the origin of the muscle, and make the cheek pro-
minent, as in  laughing.

   i             3. Zygomaticus Minor,
  Arises from the  upper prominent part of  the os malae,
above the origin of the former muscle; and, descending
obliquely downwards and  forwards, is
  Inserted into  the upper lip, near  the  corner of the
mouth, along with the levator anguli oris.
   Use. To draw the corner of the mouth  obliquely out 
              Musoles of the Lower Jaw.          179
 wards, and upwards, towards the external canthus of the
 eye.
   The common muscle is the

                   Orbicularis Oris.
   This muscle is, in a great measure, formed by the mus-
 cles that move the lips; the  fibres of the superior descend-
 ing, those of the inferior ascending, and, decussating each
 other about the corner of the mouth, run along the lip to
join those of the opposite  side, so that the fleshy fibres
 appear to surround the mouth like a sphincter.
   Use. To shut the mouth, by  contracting and drawing
 both lips together, and to counteract  all the muscles that
 assist in forming it.
   There is another small muscle  described by Albinus,
 which he calls Nasalis labii  superioris; but it seems to be
 only some fibres of the  former connected to the septum
 nasi.

             Muscles of the Lower Jaw.
   The lower jaw has four pair of muscles for its elevation
 or lateral motions,  viz. two, which are seen on the side of
 the face,  and two concealed by the angle of the jaw.

                    1. Temporalis,
   Arises, fleshy, from  a semicircular  ridge of the lower
and lateral part of the  parietal bone, from all the  pars
squamosa of the temporal bone, from the  external angu-
lar process of the os frontis, from  the temporal process of
the sphenoid bone, and from an aponeurosis which covers
it; from these different origins the fibres descend like ra-
dii towards the jugum, under  which they pass; and are
  Inserted, by a strong tendon, into the upper part of the
coronoid process of the lower jaw; in the duplicature of 
 180          Muscles of the Lower Jaw.
 which tendon this process is inclosed as in a sheath, being
 continued down all its fore part to near the last dens mo-
 laris.
   Use. To pull the lower jaw upwards, and press it against
 the upper, at the same time drawing it a little backwards.
   N. B. This muscle is covered by a tendinous membrane,
 called its aponeurosis, which  arises from the bones  that
 give origin to the upper and semicircular part of the mus-
 cle;  and, descending over it, is inserted into all the jugum,
 and the adjoining part of the os frontis.
   The use of this membrane is to give room for the ori-
 gin of a greater number of fleshy fibres, to fortify the mus-
 cle in its action, and to serve as a defence to it.

                     2. Masseter,
   Arises, by strong, tendinous, and fleshy fibres,  which
 run in different  directions, from  the  superior maxillary
 bone, where it joins the os malae, and from the inferior and
 anterior part of the zygoma, its whole length, the external
 fibres slanting backwards, and the internal forwards.
   Inserted into the angle of the lower jaw, and from that
 upwards to near the top of its coronoid process.
   Use. To pull the lower to the upper jaw, and by  means
 of its oblique decussation, a little forwards and backwards.

               3. Pterygoideus Internus,
   Arises, tendinous and fleshy, from the  inner and upper
 part of the internal plate  of the pterygoid process, filling
 all the space between the  two plates; and from the  ptery-
 goid process of the os palati between these plates.
   Inserted into the angle  of the lower jaw internally.
   Use. To draw the jaw  upwards, and obliquely towards
the opposite side. 
                 Muscles of the Neck.             181
               4. Pterygoideus Externus,
   Arises from the outer side of the external plate of the
pterygoid process of the sphenoid bone, from part of the
tuberosity of the os maxillare adjoining to it, and from the
root of the temporal process of the sphenoid bone.
   Inserted into a cavity in the neck of the condyloid pro-
cess of the lower jaw; some of its fibres are inserted into
the ligament that connects the movable cartilage and that
process to each other.
   Use. To pull the lower jaw forwards,  and to the oppo-
site side; and to pull the ligament from the joint, that it
may not be pinched during these motions: when both ex-
ternal pterygoid muscles act, the fore teeth of the under
jaw are pushed forwards beyond those of the upper jaw.


The Muscles  which appear about the anterior part
                    of the Neck.
   On the side of the neck are two muscles or layers.

     1. Musculus Cutaneus, vulgo Platysma Myoides,
   Arises, by a  number of slender separate fleshy fibres,
from the cellular substance that covers the upper parts of
the deltoid and pectoral muscles; in their ascent they all
unite to form a thin muscle, which runs obliquely upwards
along the side of the neck, adhering to the skin.
   Inserted into the lower jaw, between its angle and  the
origin of the depressor  anguli oris, to which it is firmly
connected,  and but slightly to the skin that covers the in-
ferior part of the masseter muscle and parotid glands.
   Use. To assist the depressor anguli oris in drawing the
skin of the cheek downwards; and when the mouth is shut,
it draws all that part of the skin, to which it is connected,
below the lower jaw, upwards. 
 182        Muscles between the Lower Jaw
              2. Sterno-Cleido-Mastoideus,
   Arises by two distinct origins:  the  anterior, tendinous
 and a little fleshy, from the top of the sternum near its
junction with the clavicle; the posterior,  fleshy, from the
 upper and anterior part of the clavicle; both unite a little
 above the anterior articulation of the clavicle, to form one
 muscle, which runs  obliquely upwards and outwards, to
 be
   Inserted, by a thick strong tendon, into  the mastoid pro-
 cess, which it surrounds; and, gradually turning thinner,
 is inserted as far back as the lambdoid suture.
   Use. To turn the head to one side, and bend it forwards.


  Muscles situated between the Lower Jaw and Os
                       Hyoides.
  There are four layers before, and  two muscles at the
 side.
  The four layers are,

                    1. Digastricus,
  Arises, by a fleshy belly, intermixed with tendinous
 fibres, from the fossa at the root of the  mastoid process
of the temporal bone, and soon becomes  tendinous; runs
downwards and forwards: the tendon  passes  generally
through the stylo-hyoideus  muscle;  then it is fixed  by a
ligament to the os hyoides; and, having received from that
bone an addition of  tendinous and muscular fibres, runs
obliquely forwards, turns fleshy again, and is
  Inserted, by its anterior belly, into a rough sinuosity at
the inferior and anterior edge of that part of the lower jaw
called the chin. 
                 and the Os Hyoides.              183
  Use. To open the mouth, by pulling the lower jaw down-
wards, and backwards; and when the jaws are shut, to
raise the os hyoides, and consequently the  pharynx, up-
wards, as in deglutition.

                  2. Mylo-Hyoideus,
  Arises, fleshy, from all the inside of the lower jaw, be-
tween  the last dens molaris and the middle of the chin,
where  it joins with its  fellow.
  Inserted into  the lower  edge of the basis  of the os
hyoides, and joins with its fellow.
  Use. To pull the os hyoides forwards, upwards, and to
a side.

                  3. Genio-Hyoideus,
  Arises,  tendinous, from  a rough protuberance in the
middle of the lower jaw internally, or on the inside of the
chin.
  Inserted into the basis of the os hyoides.
   Use. To draw this bone forwards to the chin.

                 4. Genio-Hyo-Glossus,
  Arises, tendinous, from a rough protuberance in the in-
side of the middle of the lower jaw:  its fibres  run, like a
fan, forwards, upwards, and backwards; and are
  Inserted into  the whole length of the tongue, and base
of the os hyoides, near its cornu.
  Use. According to the direction of its fibres, to draw the
tip  of  the tongue  backwards into the mouth, the middle
downwards, and to render its dorsum concave; to  draw
its  root and os hyoides forwards, and to thrust  the tongue
out of the mouth, 
 184    Muscles between Os Hyoides and Trunk.
   Tht two muscles at the side are,

                    1. Hyo-Glossus,
   Arises, broad and fleshy, from the base, cornu, and ap-
 pendix of the os hyoides; the fibres run upwards and out-
 wards, to be
   Inserted into the side of the tongue, near the stylo-glos-
 sus.
   Use. To pull the tongue inwards and downwards.

                     2. Lingualis,
   Arises from the root of the tongue laterally; runs for-
 wards between the hyo-glossus and genio-glossus, to be
   Inserted into the tip of the  tongue, along with part of
 the stylo-glossus.
   Use. To contract the substance of the tongue, and bring
 it backwards, and to elevate the point of the tongue.


 Muscles situated between the Os Hyoides and Trunk.
   These may be  divided into two layers.     ,
   The first layer consists of two muscles.

                  1. Sterno-Hyoideus,
  Arises, thin and fleshy, from the cartilaginous extremity
of the first  rib, the upper and  inner part of the sternum,
and from the clavicle where it joins with the sternum.
  Inserted into the base of the os hyoides.
  Use. To  pull the os hyoides downwards.

                  2. Omo-Hyoideus,
  Arises, broad, thin, and fleshy, from the superior costa
of the scapula, near the semilunar nitch, and from the liga-
ment  that runs across  it; thence ascending obliquely, it 
        Muscles* between Os Hyoides and Trunk.    185
becomes tendinous below the sterno-cleido-mastoid mus-
cle; and, growing fleshy again, is
  Inserted into  the base of the os  hyoides, between  its
cornu and the insertion of the sterho-hyoideus.
  Use. To pull the os hyoides obliquely downwards.
  The second layer consists of three muscles:

                1. Sterno-Thyroideus,
  Arises, fleshy, from the whole edge of the uppermost
bone of the sternum internally, opposite to the cartilage of
the first rib, from which it receives a small part of its ori-
gin.
  Inserted into the surface of the rough line at the exter-
nal part of the inferior edge of the thyroid cartilage.
  Use. To draw the larynx downwards.

                 2. Thyro-Hyoideus,
  Arises from the rough line, opposite to the former.
  Inserted into part of the basis, and almost all the cornu
of the os hyoides.
   Use. To pull the os hyoides downwards, or the thyroid
cartilage upwards.

                 3. Crico-Thyroideus,
  Arises from the side and fore part of  the cricoid carti-
lage, running obliquely upwards.
  Inserted by two portions: the first, into the lower part
of the thyroid cartilage; the second, into its inferior cornu.
  JJse. To pull  forwards  and depress the thyroid, or to
elevate and draw backwards the cricoid cartilage.
  Vol. I.                2 A 
186
Muscles of the Styloid Process.
  Muscles situated between the Lower Jaw and Os
                  Hyoides laterally.
  They are five in number. Three proceed from the sty-
loid process of the temporal bone, from which they have
half of their names; and two from the pterygoid process
of the sphenoid bone.
  The three from the styloid process are,

                   1. Stylo-Glossus,
  Arises, tendinous and fleshy, from the styloid process,
and from a ligament that connects that process to the an-
gle of the lower jaw.
  Inserted into the root of the tongue, runs along its side,
and is insensibly lost near its apex.
  Use. To  draw the tongue laterally and backwards.

                   2. Stylo-Hyoideus,
  Arises by a round tendon, from the middle and inferior
part of the styloid process.
  Inserted into the os hyoides at the junction of the base
and cornu.
  Use. To pull the os hyoides to one side, and a little up-
wards.
  N. B.  Its fleshy belly is generally perforated by the ten-
don of the digastric muscle, on one or both sides. There is
often another accompanying it, called stylo-hyoideus alter;
and has the same origin, insertion, and use.

                 3. Stylo-Pharyngeus,
  Arises, fleshy, from the root of the styloid process.
  Inserted into the side of the pharynx and back part of
the thyroid cartilage. 
                 Muscles of the Palati.             187
   Use. To dilate and raise the pharynx and thyroid carti-
lage upwards.
   The two from the pterygoid process are,

           1. Circumfiexiis, or Tensor Palati,
   Arises from the spinous  process of the sphenoid bone,
behind  the foramen  ovale, which transmits the third
branch of the fifth pair of nerves; from the eustachian
tube, not far from  its osseous part:  it  then runs down
along the pterygoideus internus, passes  over the hook of
the internal plate of the pterygoid  process by  a round ten-
don, Which soon spreads into a broad membrane.
   Inserted into the velum pendulum palati, and the semi-
lunar edge of the os palati, and extends as far as the su-
ture which joins the two bones. Generally some of its pos-
terior fibres join with  the constrictor pharyngis superior,
and palato-pharyngeus.
   Use. To stretch  the velum, to draw it downwards, and
to a side towards the  hook. It has litde effect upon the
tube, being chiefly connected to its osseous part.

                   2. Levator  Palati,
   Arises, tendinous and fleshy, from the  extremity of the
pars petrosa of the temporal bone, where it is perforated
by the eustachian tube, and also  from the membranous
part of the  same tube.
   Inserted into the whole length of the velum pendulum
palati, as far as the root of  the uvula,  and unites with its
fellow.
   Use. To  draw the velum upwards and backwards, so as
to shut the passage from the fauces into  the mouth and
nose. 
188             Muscles of the Fauces.
 Muscles situated about the passage to the Fauces.
  There are  two on each side, and a single one in the
middle.
  The two on each side are,

             1. Constrictor Isthmi Faucium,
  Arises,  by  a  slender beginning, from the side of the
tongue, near its root; from thence running upwards with-
in the anterior arch, before the amygdala; it is
  Inserted into  the middle of the velum pendulum palati,
at the root of the uvula anteriorly, being connected with
its fellow, and with the beginning of the palato-pharyn-
geus.
  Use. Draws the velum toward the root of the  tongue,
which it raises at the same time, and, with its fellow, con-
tracts the passage between the two arches, by which it shuts
the opening into the fauces.

                2. Palato-Pharyngeus,
  Arises,  by a broad beginning, from the middle of the
velum pendulum palati, at the root of the uvula posteriorly,
and from  the tendinous expansion of the  circumflexus pa-
lati.  The  fibres are collected within the posterior arch be-
hind the amygdalae, and run backwards to the top and late-
ral part of the pharynx, where the fibres are scattered, and
mix with those  of the stylo-pharyngeus.
  Inserted into  the edge of the upper and back part of the
thyroid cartilage;  some of its fibres being lost between the
membrane of the pharynx,  and the two inferior constric-
tors.
  Use,  Draws the uvula and velum downwards and back-
wards ; and at  the same  time pulls the thyroid cartilage 
               Muscles of the Pharynx.           189
and pharynx upwards, and shortens it; with the constrictor
superior and tongue, it assists in shutting the passage into
the nostrils; and, in swallowing, it thrusts the food from
the fauces into the pharynx.

                 Salpingo- Pharyngeus
Of Albinus is composed of a few fibres of this muscle, which
   Arise from the anterior and lower part of the cartilagi-
nous extremity of the eustachian tube; and are
   Inserted into the inner part of the last mentioned mus-
cle.
   Use. To assist  the former, and to dilate the mouth of
the tube.
   The one in the middle is the

                    Azygos Uvula,
   Arises, fleshy, from the extremity of the suture which
joins the palate-bones, runs down the whole length of  the
velum and uvula, resembling a small earth-worm, and  ad-
hering to the tendons of the circumflexi.
   Inserted into the apex of the uvula.
   Use. Raises the uvula upwards and forwards, and short-
ens it.


Muscles situated on the posterior part of the Pharynx.
   Of these there  are  three pair.

           1. Constrictor Pharyngis Inferior,
   Arises from the side of the thyroid cartilage, near  the
attachment of the sterno-hyoideus  and thyreo-hyoideus
muscles; and from the cricoid cartilage,  near the crico-
thyroideus.  This muscle is the largest of the three; and is 
190           Muscles of the Pharynx.
   Inserted into the white line, where it joins with its fel-
low ; the superior fibres running obliquely upwards, co-
vering nearly one half of the middle constrictor, and ter-
minating in a point;  the  inferior  fibres run more  trans-
versely, and cover the beginning of the oesophagus.
   Use. To compress that part of the pharynx which it co-
vers, and to raise it with the larynx a little upwards.

           2. Constrictor Pharyngis Medius,
   Arises from the appendix of the os hyoides, from the
cornu of that bone, and from the ligament which connects
it to the thyroid cartilage; the fibres of the superior part
running obliquely upwards, and,  covering a considerable
part of the superior constrictor, terminate in a point.
   Inserted into the middle of the cuneiforme process of the
os occipitis, before the foramen magnum, and joined to its
fellow  at a white line in the middle back part of the pha-
rynx.  The fibres at the middle part run more transverse-
ly than those above or below.
   Use. To compress that part of the pharynx which it
covers, and to draw it and the os hyoides upwards.

           3. Constrictor Pharyngis Superior,
   Arises,  above, from the cuneiforme process  of the os
occipitis,  before the foramen magnum,  near the holes
where  the  ninth pair of nerves passes out; lower  down,
from the pterygoid process of the sphenoid bone; from the
upper and under jaw, near the roots of the last dentes mo-
lares;  and between the jaws, it is  continued with the buc-
cinator muscle; and with some fibres from the root of the
tongue, and from the palate.
   Inserted into  a white line in the middle of the pharynx,
where  it joins with its fellow, and is covered by the con-
strictor medius. 
                Muscles of the Glottis.             191
  Use.  To compress the upper part  of the pharynx, and
draw it  forwards and upwards.


         Muscles situated about the Glottis.
  They consist generally of four pair of small muscles,
and a single one.

            1. Crico-Arytanoideus Posticus,
  Arises, fleshy, from the back part of the cricoid carti-
lage, and is
  Inserted into the pqsterior part of the base of the aryte-
noid cartilage.
  Use. To open the rima glottidis a little, and, by pulling
back the arytenoid cartilage, to stretch the ligament so as
to make it tense.

            2. Crico-Arytanoideus Lateralis,
  Arises,  fleshy,  from  the cricoid cartilage,  laterally,
where it is covered by part of the thyroid, and is
  Inserted into the side of the base of the arytenoid carti-
lage near the former.
  Use,  To open the  rima glottidis, by pulling the liga-
ments from each other.

                3. Thyreo-Arytanoideus,
  Arises from the under and back part  of the middle of
the thyroid cartilage; and, running backwards and a little
upwards, along the side of the glottis, is
  Inserted into the arytenoid cartilage, higher up and far-
ther forwards than the crico-arytaenoideus lateralis.
  Use.  To pull the arytenoid cartilage forwards nearer to
the middle of the thyroid, and consequently to shorten and
relax the ligament of the larynx or glottis vera. 
 192             Muscles of the Glottis.
                4. Arytanoideus Obliquus,
   Arises from the base of one arytenoid cartilage;  and,
 crossing its fellow, is
   Inserted near the tip of the other arytenoid cartilage.
   Use. When both act, they pull the arytenoid cartilages
 towards each other.
   N. B. One of these  is very often wanting.
   The single muscle is the

              Arytanoideus Transversus,
   Arises  from the side of one arytenoid cartilage, from
 near  its articulation with the cricoid to near its tip.  The
 fibres run straight across, and are
   Inserted, in the same manner, into the other arytenoid
 cartilage.
   Use. To shut the rima glottidis,  by bringing these two
 cartilages, with the ligaments, nearer one another.
   Besides these, there are a few  separate muscular fibres
 on each side; which, from  their general  direction, are
 named,

                1. Thyreo-Epiglottideus,
   Arises, by a few pale separated fibres, from the thyroid
 cartilage; and is
   Inserted into the epiglottis laterally.
   Use. To draw the epiglottis obliquely downwards, or,
when both act, directly downwards; and, at the same time,
it expands that soft cartilage.

               2. Arytano-Epiglottideus,
   Arises, by a number of small fibres, from the lateral and
upper part of the arytenoid cartilage; and, running along
the outer side of the external rima, is 
                   Muscles of the Neck.              193
   Inserted into the epiglottis along with the former.
   Use. To pull that side of the epiglottis towards the ex-
 ternal rima; or, when  both act, to pull it close upon the
 glottis. It is counteracted by the elasticity of the epiglottis.


  Muscles situated on  the Anterior Part of the Neck
                 close  to the Vertebra.
   These consist of one layer formed by four muscles.

                    1.  Longus Colli,
   Arises, tendinous  and fleshy, from  the  bodies  of the
 three  vertebrae of  the back laterally; and from the  trans-
 verse processes of the third, fourth,  fifth, and sixth vertebrae
 of the neck, near their roots.
   Inserted into the fore part of the bodies of all the verte-
 brae of the neck, by as many small  tendons, which are co-
 vered with flesh.
   Use. To bend the neck gradually forwards, and to one
 side.

            2.  Rectus Capitis Internus Major,
  Arises, from the  anterior points  of the transverse pro-
 cesses of the third, fourth, fifth, and sixth vertebrae of the
 neck, by four distinct beginnings.
  Inserted into the cuneiform process of the os occipitis,
 a little before the condyloid process.
  Use. To bend the head forwards.

            3. Rectus Capitis Internus Minor,
  Arises, fleshy, from the fore part of the body of the first
vertebra of the neck, opposite to the superior oblique pro-
cess.
  Vol. I.                  2 B 
194             Muscles of the 'Thorax.
  Inserted near the root of the condyloid process of the os
occipitis, under, and a little farther  outwards than the
former muscle.
  Use. To bend the head  forwards.

              4. Rectus Capitis Lateralis,
  Arises, fleshy, from the anterior part of the point of the
transverse process of the first vertebra of the neck.
  Inserted into the os occipitis, opposite to the  foramen
stylo-mastoideum of the temporal bone.
  Use. To bend the head  a little to one side.


    Muscles situated on the Anterior Part of the
                       Thorax.
  These may be divided into two layers. The first layer
consists of one muscle, named

                   Pectoralis Major,
  Arises from the cartilaginous extremities of the fifth and
sixth ribs, where it always intermixes with the external ob-
lique muscle  of the abdomen;  from almost the whole
length of the sternum, and from  near half of the anterior
part of the clavicle: the fibres run towards the axilla in a
folding manner.
  Inserted, by two broad tendons, which cross each other
at the upper and inner part of the os humeri, above the
insertion  of the deltoid muscle, and outer  side of the
groove for lodging the tendon of the long head of the
biceps.
  Use. To move the arm forwards, and obliquely upwards,
towards the sternum.
  The second layer  consists of three muscles. 
Muscles of the Thorax.
195
                     1. Subclavius,
   Arises, tendinous from the cartilage that joins the first
rib to the sternum.
   Inserted, after becoming fleshy, into the inferior part of
the clavicle, which it occupies  from  within an  inch  of
the sternum, as  far  outwards as to  its  connexion, by
ligament, with the coracoid process of the scapula.
   Use. To pull the clavicle downwards and forwards.

                  2. Pectoralis Minor,
   Arises, tendinous and fleshy, from the upper edge of the
third, fourth, and fifth ribs, near where they join with their
cartilages.
   Inserted,  tendinous, into the  coracoid  process of the
scapula; but soon grows fleshy and broad.
   Use, To bring the scapula forwards and  downwards,  or
to raise the ribs upwards.

                  3. Serratus Magnus,
   Arises from the nine superior ribs, by an equal number
of fleshy digitations, resembling the teeth of a saw.
   Inserted, fleshy, into the whole base of  the scapula in-
ternally, between the insertion of  the rhomboid and the
origin of the subscapularis muscles, being folded about the
two angles of the scapula.
   Use. To move the scapula forwards; and, when the sca-
pula is forcibly raised, to draw upwards the ribs.


 Muscles situated between the Ribs, and within the
                      Thorax.
  Between the ribs, on each side, there are eleven double
rows of muscles, which are therefore named  intercostals.
These decussate each other like the  strokes of the letter X. 
196             Muscles of the Th o rax.
                1. Intercostales Externi,
  Arise from the inferior acute edge  of each superior rib,
and run  obliquely forwards,  the  whole length from the
spine  to near the joining of the ribs with their  cartilages;
from which, to the sternum, there is only a thin  membrane
covering the internal intercostals.
  Inserted into the upper obtuse edge of each inferior rib,
as far back as the spine, into which the posterior portion
is fixed.

                2. Intercostales Interni,
  Arise in the same manner as the external: but they begin
at the sternum, and run obliquely backwards, as far as the
angle of the rib;  and from that to the  spine they arc
wanting.
  Inserted in the same manner as the  external.
  Use. By means of these muscles, the ribs are equally
raised upwards during inspiration. Their fibres being ob-
lique, give them a greater power of bringing the ribs near
each  other, than  could  be performed by straight  ones.
But, by the obliquity of the fibres,athey are almost brought
contiguous: and as the fixed points of the ribs are before
and behind, if the external had been continued forwards to
the sternum, and  the internal  backwards to the spine, it
would have hindered their motion, which is  greatest in
the middle, though the obliquity of the ribs renders it less
perceptible; and, instead of raising the fibres fixed to the
sternum and spine, would have depressed the ribs.
   N. B. The  portions of the external intercostals, which
arise from the transverse  processes of the vertebrae where
the ribs  are fixed to  them, and other portions that pass
over  one rib and terminate in  the next below  it, Albinus
calls  Levatores costarwn longiores et breviores. 
Abdominal Muscles.
197
  The portions of the internal that pass over one rib, and
are inserted into the next below it, are by Douglas called,
Costarum depressores proprii Cowperii.
  These portions of both rows assist in raising the ribs in
the same manner as the rest of the intercostals.
  The, muscles within the thorax are one pair, viz.

            Triangularis, or Sterno-costalis,
  Arises, fleshy, and a little tendinous, from all the length
of the cartilago ensiformis  laterally, and from  the edge of
the lower half of the middle bone of the sternum, from
whence its  fibres ascend obliquely upwards and outwards.
  Inserted, generally by three triangular terminations, into
the lower edge of the cartilages of the third,  fourth, and
fifth ribs, near where these join with the ribs.
  Use. To  depress these cartilages, and the extremities of
the ribs; and consequently to assist in contracting the  ca-
vity of the  thorax.
  This muscle often varies; and is sometimes inserted into
the cartilage of the second rib, sometimes into the carti-
lage of the  sixth rib.
     Muscles situated on the anterior part of the
                      Abdomen.
  They consist of three broad layers on each side of the
belly; and of one layer in front.
  The three layers are,

           1. Obliquus Descendens Externus,
  Arises, by eight heads, from the lower edges of an equal
number of inferior ribs, at a little distance from their car-
tilages: it always intermixes, in a  serrated manner, with 
198              Abdominal Muscles.
portions of the serratus major anticus;  and generally co-
heres to the pectoralis major,  intercostals, and latissimus
dorsi; which last covers the edge of a portion of it extend-
ed from the last rib to the spine of the ilium.
  From these origins the fibres run obliquely downwards
and forwards, and terminate  in the  anterior half of the
spine of the  ilium, and in a tendinous membrane, whose
fibres are continued in the same direction until they  meet
the fibres of the  corresponding tendon of the other side,
in a line which extends from the ensiform cartilage to the
os pubis.
  This line is called linea alba, from its white appearance,
which is owing to the connexion  of three  tendons with
each other, without the intervention of muscle, viz. those
of the external and internal oblique, and the transversalis.
  On each side of this line, two long narrow muscles are
situated between these tendons, and do away the white
appearance; but exterior to these muscles, the tendons are
again united, and form a white line on each side, which is
called linea semilunaris, from its curved shape.
  At the lower part of the tendon, near the os pubis, the
fibres are so arranged, that  they  for"m two bands more
firm and dense than the rest of the tendon, which are cal-
led columns: these columns are separated from each other;
and the  vacuity between them is the abdominal  ring, or
aperture, for the passage of the spermatic chord in males,
and  the round ligament of the uterus in females.  This
vacuity or aperture has an oval form, which is occasioned
by some additional  tendinous fibres at the upper part of
it, that have a transverse direction.
  The uppermost of the two columns is continued ob-
liquely downwards,  and  is inserted into the os pubis of
the opposite side, near the  symphysis, decussating the
fibres of the corresponding column  of that side. 
Abdominal Muscles.
199
   The lower edge of the tendon of the external oblique is
attached to the superior anterior spinous process of the
ilium, and is there blended with the  tendinous fascia,
which extends down the thigh.
   From this  process, the edge of the tendon is extended,
like the chord of a bow,  across the concavity formed by
the os ilium and os pubis, and is inserted into the pubis
near its symphysis. As it proceeds from the spine of the
ilium towards  the pubis, the edge  is folded  inwards, so
that the membrane is doubled. The portion which is turn-
ed inwards is very small at its 'commencement, and con-
tinues so for  a great part of  its extent; but becomes much
broader within an inch of its termination. This broad ex-
tremity is inserted into the small process of the pubis near
the symphysis, and into a ridge which continues backward
from the process to the brim of the pelvis, so that the ten-
dinous membrane at this part is doubled; the part which
is turned back being about an inch broad at the  place of
its insertion into the pubis.
   This doubling forms a partial sheath near the pubis for
containing the spermatic chord, and supports it for a short
distance on the inside of the abdominal ring.
   The edge formed by the fold of the membrane is called
Poupart's ligament; and is very firm and  strong; owing to
the membrane being thicker  at that place. The real edge,
or termination of the portion which is folded  inwards, is
arranged in the following manner: The part which is near-
est to the spine of the ilium is continued into the cellular
membrane, or their fascia, which is  between the  internal
oblique and transversalis muscles, and the iliacus internus.
But the edge of that part which is inserted  into the ridge
of the pubis seems to form a portion of a circular opening,
which is occupied in part, but not completely, by the crural
vessels. 
200
Abdominal Muscles.
      A portion of the fascia of the thigh, which covers these
    vessels, passes under this  portion of the  tendon,  and  is
    also inserted into the ridge of the pubis; so that when the
    intestines protrude at this aperture, and are strangulated,
    this portion of the fascia of the thigh must also compress
    them.
      The fascia of the thigh is connected  with the external
    edge, or Poupart's ligament, its whole  extent: and there
    is also a fascia which covers the whole  tendon of  the ex-
    ternal oblique  muscle, and passes from it down upon the
    fascia of the thigh; which also connects the tendon of the
    external oblique  to  the fascia of the  thigh, and  serves
    to bind  it down. From these connexions it  is probable
    that the  tendon is in a very different situation before dis-
    section, from what it is  afterwards; as the division of these
,   connexions, necessarily  made by  the dissection, renders
    it much more loose than it could have been while the parts
    were undivided.  This  structure  has latterly been called
    the crural arch.*

     * The fascia which covers the tendon of the external oblique  muscle,
    and descends upon the thigh, can be  examined very easily in anasarcous
    subjects; as in them, the cellular membrane, which is situated between
   this fascia and the tendon, is somewhat distended by the effused fluid.
     To prepare Poupart's ligament, or the crural arch, for examination,
   remove carefully the cellular membrane from the tendon of the exter-
   nal  oblique, and also from the fascia of the thigh; taking care not to
   remove any part of the fascia which  passes under the tendon to be in-
   serted into the os pubis. Then make an incision in the tendon of the
   external oblique, about three inches above  Poupart's ligament, parallel
   to it and nearly of the same length;  make a second incision from die
   upper end of this, to the junction of the aforesaid  ligament with the
   superior anterior spine of the ilium; and a third incision from the lower
   end to the abdominal ring. Dissect this flap carefully from the internal
   oblique, until the spermatic chord, the cremaster muscle, and the lower
   origin of the internal oblique, are perfectly uncovered. After examining 
Abdominal Muscles.
201
             2. Obliquus Ascendens Internus,
   Arises  from the spine of the ilium, the whole length be-
tween the posterior and superior anterior spinous process;
from the  os sacrum and the three undermost lumbar ver-
tebrae, by a tendon common to it and to the serratus pos-
ticus inferior muscle; from Poupart's ligament, at the mid-
dle of which it sends off the beginning of the cremaster
muscle; and the spermatic cord in the male, or  round  li-
gament of the womb in the female, passes under its thin
edge, except a few detached fibres.
   Inserted into the cartilago ensiformis, into the cartilages
of the seventh, and those of all the false ribs;  but, at the
upper part, it is extremely thin, resembling a cellular mem-
brane, and only becomes fleshy at the cartilage of the tenth
rib.  Here its tendon divides  into two layers:  the ante-
rior layer, with a great  portion of the inferior  part of the
posterior  layer, joins the tendon of the external oblique,
and runs  over the rectus to be inserted into the whole
length of  the linea alba. The posterior layer joins the ten-
don of the transversalis muscle as low as half way between
the umbilicus and os pubis;  but, below this place, only a
few fibres of the posterior layer are seen, and the rest of it
passes before  the  rectus muscle, and is inserted into the
linea alba; so that  the whole tendon of the external oblique
muscle, with the anterior  layer of the internal oblique,
passes before the rectus muscle; and the  whole  posterior
layer of the internal oblique, together with the whole ten-
don of the transversalis muscle, excepting at the inferior
part, passes behind the rectus, and is inserted into the linea

the internal surface of the tendon, and its  insertion at the pubis, the
fascia of the thigh may be  dissected, so that its connexion with the
folded edge of the tendon, und its insertion into the pubis, may also be
examined.
   Vol. I.                2  C 
202              Abdominal Muscles.
alba.  At its undermost part, it is inserted into the fore part
of the os pubis.
  Use. To assist the former; but it bends the trunk in the
reverse direction.

                   3.  Transversalis,
  Arises, tendinous, but soon becoming fleshy, from the
inner or back part of the cartilages of the seven lower ribs,
where some of its fibres are continued with those of the
diaphragm and the intercostal muscles;  by a broad thin
tendon, connected to the transverse processes of the last
vertebra of the back and the four superior vertebrae of the
loins: fleshy, from the  whole  spine of the os ilium inter-
nally, and from the tendon of the external oblique muscle
where it  intermixes with some  fibres of  the internal ob-
lique.
  Insertedinto the cartilago ensiformis, and into the whole
length of the linea alba, excepting its lowermost part.
  Use. To support and compress the abdominal bowels;
and it is so particularly well adapted for the latter pur-
pose, that it might be called the proper constrictor of the
abdomen.
  The long muscle in the middle is named,

                  Rectus  Abdominis.
  Arises, by two heads, from the ligament of the cartilage
which joins the two  ossa pubis  to  each  other;  runs up-
wards the whole length of, and parallel to, the linea alba,
growing broader and thinner as it ascends.
  Inserted into the cartilages of the three inferior true ribs,
and often intermixes with some fibres of the pectoral mus-
cle.
  It is generally divided by three tendinous intersections: 
Abdominal Muscles.
203
 the first is at the umbilicus; the second, where it runs over
 the cartilage of the seventh rib; and the third in the middle
 between these; and there is commonly a half intersection
 below the umbilicus. These  intersections  seldom  pene-
 trate through the whole thickness of the muscle: they ad-
 here firmly to  the  anterior part of the sheath, but very
 slightly to the posterior layer.*
   Use. To compress  the fore part, but more particularly
 the lower part of the belly; to bend the trunk  forwards,
 or to raise the pelvis.  By its tendinous intersections, it is
 enabled to contract at any of the intermediate spaces; and,
 by its connexion  with the  tendons of the other muscles,
 it is prevented from changing  place, and from rising into
 a prominent form when  in action.
   The short muscle in the middle  is named

                       Pyramidalis.
   Arises  along  with  the rectus;  and, running upwards
 within the same sheath, is
   Inserted, by an acute termination, near half way between
 the os pubis and umbilicus, into the linea alba andjnner
 edge of the rectus muscle.
   As it is frequently wanting in both  sides, without any
 inconveniency, its
   Use seems to be, to assist the inferior part of the rectus.
  * T6 obtain an accurate idea of the arrangement of the tendons of the
three large pair of abdominal muscles, it will be necessary to raise or
separate the  external oblique muscle and tendon from the internal ob-
lique and its tendon, as far as the linea semilunaris, and to separate the
internal oblique in the same manner from the transversalis; and then to
make an incision in the tendon of the external oblique parallel to the
linea alba, and about an inch and a half from it, so as to bring the whole
of the rectus muscle into view. The structure of the sheath which con-
tains the rectus can then be examined. 
204
Muscles of the Testes.
   Muscles about the Male Organs of Generation.
   The testicles are said to have a thin muscle common to
 both, and one proper to each.
   The common muscle is called the

                        Dartos.
   This consists of muscular fibres blended with the cellu-
 lar membrane lining the scrotum;  and therefore this por-
 tion of skin is capable of being corrugated and relaxed in
 a greater degree than in other places.
   The muscle proper to each testicle is the

                      Cremaster,
   Arises from the internal oblique, where a few fibres of
 that muscle intermix with the transversalis, near the junc-
 tion of the os ilium and pubis, over which part it  passes,
 after having pierced the ring of the externus obliquus; and
 then it descends upon the spermatic cord.
   Inserted into  the tunica vaginalis of the testicle, upon
 which  it spreads, and is insensibly lost.
   Use. To suspend and draw up the testicle, and to com-
 press it in the act of coition.
   The penis has three pair of muscles:

                   1. Erector Penis,
  Arises, tendinous and fleshy, from the tuberosity of the
os ischium, and runs upwards, embracing the  whole crus
of the penis.
  Inserted into the strong tendinous membrane that covers
the corpora cavernosa penis, near as far up as the union of
these bodies. 
Accelerator Urina.
205
  Use. To compress the crura penis, by which the blood
is pushed from it into the fore part of the  corpora caver-
nosa; and the penis is by that means more completely dis-
tended. The erectores seem likewise to keep the penis in
its proper direction.

     2* Accelerator Urina, seu Ejaculator Seminis,
  Arises, fleshy, from the sphincter  ani and membranous
part of the urethra; and tendinous, from the crus, nearly as
far forwards as the beginning  of the corpus cavernosum
penis:  the inferior fibres  run more  transversely;  and the
superior descend, in an oblique direction.
  Inserted into a line in the middle of the bulb where it
joins with its fellow, by which the bulb is completely in-
closed.
  Use. To drive the urine or semen forwards;  and, by
grasping the bulb of the urethra, to push the blood towards
its corpus cavernosum and the glans, by which they are
distended.

                3. Transversus Perinei,
  Arises from the tough fatty membrane  that covers the
tuberosity of the os  ischium;  from thence it runs trans-
versely inwards, and is
  Inserted into the accelerator urinae, and into that part of
the sphincter ani which covers the bulb.
  Use. To dilate the bulb, and draw the perineum and
verge of the anus a litde outwards and backwards.
  There is often a fourth muscle, named

               Transversus Perinei Alter.
  Arises behind the former, runs more obliquely forwards,,
and is 
 206               Muscles of the Anus.

   Inserted into that  part of the accelerator urinae which
 covers the anterior part of the bulb of the urethra.
   Use. To assist the former.

   Since this work went to press the Medico-Chirurgical Transac-
 tions have been received here. They contain a description  of two
 small muscles of the membranous part of the urethra, by James Wil.
 son, Esq. F. R. S Each muscle has a tendon which at first is round, but
 soon becomes flattened as it descends. It is affixed to the back part
 of the  symphysis pubes, about one eighth of an inch above the lower
 edge of the cartilaginous arch of the  pubes, and nearly at the same
 distance, below the attachment of the tendon of the bladder: to which,
 and to  the tendon of the corresponding muscle, it is connected by very
 loose cellular membrane.  The  tendon descends at first  in contact
 with, and parallel to its fellow: it soon becomes broader and sends off
 fleshy fibres, which also increase in breadth, and, when near the upper
 surface of the membranous part of the urethra, separate from those of
 the opposite side; spread themselves on the side of the  membranous
 part of the urethra through its whole extent; then fold themselves
 under it, and meet in a middle tendinous line with similar fibres of the
 opposite side.
  Its action seems to be to draw up the membranous part of the ure-
 thra, and compress it against the  inside of the  cartilaginous arch  of
 the pubes:  and also to contract the circle round the membranous por-
 tion;  so as to diminish and even close up the passage for the urine.



                  Muscles of the Anus.

   The anus has a single muscle, and one pair.
   The single muscle  is


                       Sphincter  Ani.
   Arises from the skin and fat that surround the verge of
 the anus on both sides, nearly as  far out as the tuber of the
os ischium:  the fibres are gradually collected into an  oval
form,  and surround the extremity of the rectum. 
                 Muscles of the Anus,             207
  Inserted, before, by a narrow point, into the perineum,
acceleratores urinae, and transversi perinei; behind, by an
acute termination, into the extremity of the os coccygis.
  Use. Shuts the passage through the anus into the rectum;
pulls down the bulb of the urethra, by which it assists in
ejecting the urine and semen.
  N.  B. The sphincter internus of Albinus and Douglas
is only that part of the circular fibres of the muscular coat
of the rectum, which surrounds its extremity.

                     Levator Ani,
  Arises from the os pubis within the pelvis, as far up as
the upper edge of the foramen thyroideum, and joining of
the os pubis with the os ischium; from the thin tendinous
membrane that  covers the obturator internus and  coccy-
geus muscles; from the spinous process of the os ischium;
and its fibres run down like rays from a circumference Jo
a center.
  Inserted into the sphincter ani, acceleratores urinae, and
anterior part of  the two last bones of the  coccygis; sur-
rounds the extremity of the rectum, neck of the bladder,
prostate gland, and part of the vesiculae seminales;  so that
its  fibres behind and below the os coccygis joining  it with
its  fellow, they together very much resemble the shape of
a funnel.
  Use. To draw the  rectum upwards after the evacuation
of  the faeces, and to assist in shutting it;  to  sustain  the
contents of the pelvis, and to help in ejecting  the semen,
urine, and contents of the rectum; and, perhaps, by pres-
sing upon the veins, to contribute greatly to the erection
of the penis. 
208
Muscles of the Female
    Muscles of the Female Organs of Generation.
   The clitoris has one pair,

                   Erector Clitoridis.
   Arises from  the crus of the os ischium internally, and
in its ascent covers  the crus of the clitoris as far up as the
os pubis.
   Inserted into the upper part of the crus and body of the
clitoris.
   Use. Draws the clitoris downwards and backwards; and
may serve to make the body of the clitoris more tense, by
squeezing the blood into it from its crus.
   The vagina has one pair,

                  Sphincter Vagina.
   Arises from the sphincter ani, and  from the posterior
side of the  vagina, near the perineum: from thence it runs
up the side of the vagina, near its external orifice, oppo-
site to  the  nymphae, and covers  the corpus cavernosum
vaginae.
   Inserted into the  crus and body or  union of the crura
clitoridis.
   Use. Contracts the mouth of the vagina, and compresses,
its corpus cavernosum.
   The perineum has one pair,

                 Transversus Perinei.
   Arises, as in the male, from the fatty cellular membrane
which covers the tuberosity of the os ischium.
   Inserted  into the upper part of the sphincter  ani, and
into a white hardish tough substance in the perineum, be*
tween the lower part of the pudendum and anus. 
               Organs of Generation, &c.          209
   Use. To sustain and keep the perineum  in its proper
 place.
   The anus, as in the male, has a single muscle, and  one
 pair.

                    Sphincter Ani,
   Arises, as in the male, from the skin  and  fat surround-
 ing the extremity of the rectum.
   Inserted, above, into the  white tough substance of the
 perineum; and below, into the point of the os coccygis.
   Use. To shut the passage into the rectum; and, by pul-
 ling down the  perineum, to assist in contracting the mouth
 of the vagina.

                     Levator Ani,
   Arises, as in the male, within the pelvis, and  descends
 along the inferior part of the vagina and rectum.
   Inserted into the  perineum, sphincter ani, extremity of
 the vagina, and rectum.
   Use. To raise the extremity of the reotum upwards, to
 contract  the inferior part of the  rectum, and to assist in
 contracting and supporting the vagina; and, perhaps, by
 pressing  on the veins, to contribute to the distention of the
 cells of the clitoris and corpus cavernosum of the vagina,


 Muscles situated within the Cavity of the Abdomen.
  These  consist of a single muscle, and four pair.

                    Diaphragma.
  This broad thin muscle, which makes a complete septum
between the  thorax and abdomen, is  concave  below and
convex above; the middle of it on each side reaching as
  Vol. I.               2D 
210            .     Diaphragm.
high within the thorax of the skeleton as the fourth rib: it
is commonly divided into two portions.
  1. The superior, or

           Greater 3Iuscle of the Diaphragm,
  Arises, by distinct fleshy fibres, from the cartilago ensi-
formis, from the cartilages of the seventh, and of all the
inferior ribs on both sides. The fibres from the cartilago
ensiformis, and from the seventh and eighth ribs, run ob-
liquely upwards and backwards; from the ninth and tenth,
transversely inwards and upwards; and from the eleventh
and twelfth, obliquely upwards.  From these different ori-
gins the fibres run, like radii from  the circumference to
the center of a circle; and are
  Inserted into a cordiform tendon, of  a considerable
breadth,  which is situated in the middle of the diaphragm,
and in which, therefore, the fibres from opposite sides are
interlaced.  Towards the right side the tendon is perfora-
ted, by a triangular hole, for the passage of the vena cava
inferior;  and to the upper convex part of it the pericardi-
um and mediastinum are connected.
  2. The inferior, lesser muscle, or

             Appendix of the Diaphragm,
  Arises from the second, third, and fourth lumbar verte-
brae, by  eight heads; of which, two in the middle, com-
monly called its crura, are the  longest, and begin tendi-
nous. Between the  crura, the aorta and thoracic duct pass;
and, on the outside of these, the great sympathetic nerves
and branches of  the  vena azygos perforate  the  shorter
heads. The muscular fibres run obliquely upwards and
forwards, and form in  the  middle  two  fleshy columns,
which decussate and leave an oval space between them for
the  passage of the oesophagus and eighth pair of nerves. 
                      Diaphragm.                  211
   Inserted, by strong fleshy fibres, into the  posterior part
of the middle tendon.
   Use. The diaphragm is the  principal  agent in respira-
tion, particularly in inspiration: for  when it is in action,
the fibres, from their different attachments,  endeavour to
bring themselves into a plain towards the middle tendon,
by which the cavity of the thorax is  enlarged, particularly
at the sides, where the lungs are chiefly situated; and as
the lungs must always be contiguous to the  inside of the
thorax and upper side of the diaphragm, the air rushes into
them, in order to fill up the increased space. This muscle
is assisted  by the two rows of intercostals, which elevate
the ribs, and the cavity of the thorax is more enlarged. In
time of violent exercise, or whatever cause drives the blood
with unusual celerity towards the lungs, the pectoral mus-
cles, the serrati antici  majores, the serrati  postici supe-
riores, and scaleni muscles, are brought into action.  And
in laborious inspiration, the muscles which arise from the
upper part  of the thorax, when the parts into which they
are inserted are fixed, likewise  assist.  In expiration, the
diaphragm is relaxed and pushed up by the pressure of the
abdominal  muscles upon the viscera  of the abdomen; and
at the same time that they press it upwards^ they also, to-
gether with the  sterno-costales  and serrati postici inferi-
ores,  pull down the ribs,  and  are  assisted  in a 'powerful
manner by  the elasticity of the cartilages that join the  ribs
to the sternum; by which the cavity of the thorax is dimi-
nished, and the air suddenly pushed out of the lungs: and,
in laborious  expiration, the quadrati  lumborum, sacrb-
lumbales, and longissimi  dorsi, concur in pulling down
the ribs.
  The four pair are, 
212              Psoas Muscles, &?c.
               1. ^tiadratus Lumborum.
  Arises, somewhat broad, tendinous and fleshy, from the
posterior part of the spine of the os ilium.
  Inserted into the transverse processes of all the vertebras
of the loins, into the last rib near the spine, and by a small
tendon into the side of the last vertebra of the back.
  Use. To move  the loins to one side, pull down the last
rib, and, when both act, to bend the loins forwards.

                   2. Psoas Parvus,
  Arises, fleshy, from the sides of the two upper vertebrae
of the loins, and sends off a small long tendon, which ends
thin and flat, and is
  Inserted into the brim of the pelvis, at the junction of
the os ilium and pubis.
  Use. To assist the  psoas magnus in bending the  loins
forwards; and, in certain positions, to assist in raising the
pelvis.
  N. B, This muscle is very  often wanting.

                   3. Psoas Magnus,
  Arises, fleshy, from the side of the body, and transverse
process of the last vertebra of the back;  and, in the same
manner, from all those of the loins, by as many distinct
slips.
  Inserted, tendinous, into the trochanter minor of the os
femoris; and fleshy into that bone, a little  below the  same
trochanter.
  Use. To bend the thigh forwards; or, when the inferior
extremity is fixed, to assist in bending the body.

                   4. Hiacus Internus,
  Arises, fleshy,  from the  transverse process of the last
vertebra of the loins, from all the inner lip of the spine of 
Muscles within the Pelvis,
213
the os ilium, from the edge of that bone between its ante-
rior superior spinous process and the acetabulum, and from
most of the hollow part of the ilium.  It joins with the
psoas magnus, where it begins to become tendinous; and is
  Inserted along with it.
  Use. To assist the psoas  in bending the thigh, and to
bring it directly forwards.
  N. B. The insertion of the two last muscles should not
be prosecuted till the muscles of the thigh are dissected.


         Muscles situated within the Pelvis.
  Of these there are two pair.

                1. Obturator Internus,
  Arises from more than one half of the internal circum-
ference of the foramen thyroideum, formed by the os pubis
and ischium.  Its inside is covered by a portion of the leva-
tor ani; and appears to be divided into a number of fasci-
culi, which unite and form a roundish tendon, that passes
out of the pelvis, between the posterior sacro ischiatic li-
gament and tuberosity of the os ischium; where it passes
over the capsular ligament of the thigh bone, it is  inclosed
as in a sheath, by the gemini muscles.
  Inserted, by a round tendon, into the large pit  at the
root of the trochanter major.
  Use. To roll the os femoris obliquely outwards.
  N. B. The insertion of this muscle should not be prose-
cuted, until the muscles of the thigh, to which it  belongs,
are dissected.

                    2. Coccygeus,
  Arises,  tendinous and fleshy, from the spinous process
of the os ischium, and covers the inside of the posterior 
214              Muscles of the Back.
sacro ischiatic ligament: from this narrow  beginning, it
gradually increases, to form a thin  fleshy belly,  inter-
spersed with tendinous fibres.
   Inserted into the extremity of the os sacrum, and near
the whole length of the os coccygis laterally.
   Use. To support and move the os coccygis forwards,
and to tie it more  firmly to the sacrum.


Muscles situated on the Posterior Part of the  Trunk.
   These may be  divided into four layers, and a single
pair.
   The first layer  consists of two muscles, which  cover
almost the whole posterior part of the trunk.

               Trapezius seu Cucularis,
   Arises, by a strong round tendon, from the  lower part
of the protuberance in the middle of the os occipitis behind;
and, by a thin membranous tendon, which covers part of
the splenius and complexus muscles, from the rough curved
line that extends from  the protuberance towards the mas-
toid process of the temporal  bone; runs down  along the
nape of the neck, where it seems to arise from its fellow,
and covers the spinous  processes of the superior vertebrae
of the neck; hut rises from the spinous processes of the two
inferior, and from the spinous processes of all the vertebrae
of the back; adhering, tendinous, to its fellow,  the whole
leigth of its origin.
  Inserted, fleshy,  into the posterior half of the clavicle;
tendinous and fleshy, into the acromion, and into almost
all the spine of the scapula.
   Use. Moves the  scapula according to the three different
directions of its fibres: for  the  upper descending  fibres
''.raw it obliquely upwards; the middle transverse straight 
                  Muscles of the Back.             215

fibres draw it directly backwards; and the inferior ascend-
ing fibres draw it obliquely downwards and backwards.
  N. B. Where it  is inseparably united to its fellow in the
nape of the neck, it is named Ligamentum Nucha or Colli.

                  2. Latissimus Dorsi,
  Arises, by a broad thin tendon, from the  posterior part
of the spine of the  os ilium, from all the spinous processes
of the os sacrum and vertebrae of the loins, and  from the
seven inferior ones of the vertebrae of the back; also, ten-
dinous and fleshy, from the extremities of the three or four
inferior ribs,  a  little beyond their  cartilages, by as many
distinct slips. The inferior  fibres  ascend obliquely, and
the superior run transversely, over the inferior  angle  of
the scapula, towards the axilla, where they  are all collect-
ed, twisted, and folded.
  Inserted, by a strong thin tendon, into the inner edge of
the groove for lodging the tendon of the long head of the
biceps.
   Use.  To pull the arm  backwards and downwards, and
to roll the os  humeri.
  N. B. The insertion of this  muscle should not be pro-
secuted till the muscles of the os humeri, to which it be-
longs, are  dissected.
  The second layer consists of three pair, two on the back,
and one on the  neck.
  On the back:

             1. Serratus Posticus Inferior,
  Arises, by  a broad thin  tendon, in common with that of
the latissimus dorsi, from the spinal processes of the two
inferior vertebrae of the back, and from the three superior
vertebrae of the loins. 
 216              Muscles of the Back.
   Inserted into the lower edges of the four inferior ribs,
 at a little distance  from their cartilages, by as many dis-
 tinct fleshy slips.
   Use. To depress the ribs into which it is inserted.

                    2.  Rhomboideus.
   This muscle is divided into two portions.
   1.  Rhomboideus  major, arises, tendinous, from  the spi-
 nous processes of the five superior vertebrae of the back.
   Inserted into all the basis of the scapula below its spine.
   Use. To draw the scapula obliquely upwards,  and di-
 rectly inwards.
   2. Rhomboideus  minor,  arises, tendinous, from  the spi-
 nous processes of the three inferior vertebrae of the neck,
 and from the ligamentum nuchae.
   Inserted into the base of the scapula,  opposite to its
 spine.
   Use. To assist the former.
   On the neck:

                      3. Splenitis,
   Arises, tendinous, from  the four superior spinous  pro-
 cesses of the vertebrae of the back; tendinous and fleshy,
 from the five inferior of the neck, and adheres firmly to
 the ligamentum nuchae.  At the third vertebra of the neck,
the splenii  recede from each other, so that part of the corn-
 plexus muscle is seen.
   Inserted, by as  many tendons, into the five superior
transverse processes of the vertebrae of the neck; and  ten-
 dinous and fleshy, into the posterior part of the mastoid
process, and into the os occipitis, where  it joins with the
root of that process.
   Use. To bring the head  and upper vertebrae of the neck 
                  Muscles of the Back.              217
 backwards laterally:  and, when both act, to pull the head
 directly backwards.
   N. B. Albinus divides this muscle into two, viz.  That
 portion which arises from  the  five inferior spinous pro-
 cesses of the neck, and is inserted into the mastoid process
 and os occipitis, he calls splenius capitis;  and that portion
 which arises from the third and fourth of the back, and is
 inserted into the five superior transverse processes of the
 neck, is called by him splenius colli.
   The single pair,

               Serratus Superior Posticus,
   Arises, by a broad thin tendon, from the spinous  pro-
 cesses of the three  last vertebrae of the neck, and the two
 uppermost of the back.
   Inserted into the second, third, fourth, and fifth ribs, by
 as many fleshy slips.
   Use, To elevate the ribs, and dilate the thorax.
   The third layer consists of three pair on the back, and
 three on the neck.
   Those on the back are,

                   1. Spinalis Dorsi,
   Arises from the spinous processes of the two uppermost
vertebrae of the loins, and the three inferior of the back by
as many tendons.
   Inserted into the spinous  processes of the nine  upper-
most  vertebrae of the  back, except  the first, by as many
tendons.
   Use.  To erect and fix the vertebra?, and to assist in
raising the spine.
Vol. I.                 2 F 
218              Muscles of the Back
                2. Longissimus Dorsi,
  Arises, tendinous without,  and fleshy within, from the
side, and all the spinous processes of the os sacrum; from
the posterior spine of the os  ilium; from all the spinous
processes; and from the roots of the transverse processes
of the vertebrae of the loins.
  Inserted into all the transverse processes of the verte-
brae of the back, chiefly by small double tendons; also, by
a tendinous and fleshy slip, into the lower edge of all the
ribs, except the two inferior, at a little distance  from their
tubercles.
  Use.  To extend the vertebrae, and to raise and keep the
trunk of the body erect.
  N. B. From the upper part  of this muscle there runs up
a round fleshy  portion which joins with the cervicalis de-
scendens.

                   3. Sacro-Lumbalis,
  Arises, in common with the longissimus dorsi.
  Inserted into all the ribs, where  they begin to be curved
forwards, by as many long and thin tendons; and,
  From the upper part of the six or eight lower ribs, arise
as many bundles of thin fleshy fibres, which soon terminate
in the inner side of this muscle, and are named  musculi ad
sacro-lumbalem accessorii.
  Use.  To pull the ribs down, and assist to erect the trunk
of the body.
  N. B. There is a fleshy slip which runs from the upper
part of this muscle into the fourth, fifth, and sixth trans-
verse processes of the vertebrae of the  neck, by three dis-
tinct tendons:  it is named cervicalis descendens;  and its
use is to turn the neck obliquely  backwards, and  to  one
side. 
and Neck.
219
  On the neck arc,

                     1. Complexus,
  Arises from the transverse processes of the seven supe-
rior vertebrae of the back, and four inferior of the neck, by
as many distinct tendinous origins: in its ascent it receives
a fleshy slip from the  spinous process of the first vertebra
of the back. From these different origins it runs upwards,
and is every where intermixed with tendinous fibres.
  Inserted, tendinous and fleshy, into the inferior edge of
the protuberance  in the middle of theos occipitis,and into
a part of the curved line that runs forwards from that pro-
tuberance.
  Use.  To draw the  head backwards, and to one side;
and, when  both act, to draw the head directly backwards.
  N. B.  The long portion of this muscle that is situated
next the spinous  processes,  lies more loose, and has  a
roundish tendon in the middle of it;  for which reason Al-
binus calls  it biventer cervicis.

               2. Trachelo-Mastoideus,
  Arises from the transverse processes of the three upper-
most vertebrae of the back, and from the five lowermost of
the neck, where it is connected to the transversalis cervi-
cis, by as many thin tendons, which unite into a belly, and
run up under the  splenius.
  Inserted  into the  middle  of the  posterior side of the
mastoid process,  by a thin tendon.
  Use.  To assist the  complexus; but it pulls the head
more to one side. 
220              Muscles of the Back
                  3. Levator Scapula,
   Arises, tendinous and  fleshy, from the transverse pro-
cesses of the five superior vertebrae of the neck, by as many
distinct slips, which soon  unite to form a muscle that runs
downwards and outwards.
   Inserted, fleshy, into the superior  angle of the scapula.
   Use. To pull the scapula upwards, and a little forwards.
   The fourth layer consists of two  pair on the back, two
on the posterior part of the neck,  four small pair situated
immediately below the posterior part of the occiput, and
three on the side of the neck.
   On the back are,

                1.  Semi-spinalis Dorsi,
   Arises, from the  transverse processes of the seventh,
eighth, ninth, and tenth vertebrae of the back, by as many
distinct tendons, which soon grow fleshy, and then become
tendinous again; and are
   Inserted into the  spinous processes of  all the  vertebra
of the back  above the eighth, and into the two lowermost
of the neck, by as many tendons.
   Use. To extend the spine obliquely backwards.

                 2. Multifidus Spina,
   Arises from the  side and  spinous processes of the os
sacrum, and from the posterior part of the os ilium, where
it  joins with the sacrum;  from all the oblique and trans-
verse processes of the  vertebrae of the loins;  from all the
transverse processes of the vertebrae of the back, and from
those of the neck, except  the three first, by as many dis-
tinct tendons, which soon  grow fleshy, run in an oblique
direction; and are 
and Neck.
221
   Inserted,  by distinct tendons, into all the spinous pro-
cesses of the vertebrae of the loins, of the back, and of the
neck, except the first.
   Use.  When the different portions of this muscle act on
one side, they extend the back obliquely, or move it late-
rally; but if they act together on both sides, they extend
the vertebrae backwards.
   On the posterior part of the neck are,

                 1.  Semi-Spinalis Colli,
   Arises, from the transverse processes of the uppermost
sta vertebrae of the  back, by as many distinct tendons,
ascending obliquely  under the complexus.
   Inserted into  the  spinous processes of all the vertebrae
of the neck, except the first and the last.
   Use.  To extend the neck obliquely backwards.

                 2.  Transversalis Colli,
   Arises from the transverse processes of the five upper-
most vertebrae of the back, by as  many  tendinous and
fleshy origins; runs between the trachelo-mastoideus, and
splenius colli and cervicalis descendens.
   Inserted into the transverse processes of all the cervical
vertebrae, except the first and the last.
   Use.  To turn the  neck obliquely backward, and a little
to one side.
   Below the posterior part of the occiput are,

            1. Rectus Capitis Posticus Major,
   Arises, fleshy, from the external part of the spinous pro-
cess  of the second vertebra of the neck; and grows broader
in its ascent, which is not straight, but obliquely outwards.
   Inserted, tendinous and fleshy, into the os occipitis, near 
222            Muscles on the back and
the rectus capitis  lateralis, and the insertion of the obli-
quus capitis superior.
   Use.  To pull the head  backwards, and to assist a little
in its rotation.

           2. Rectus Capitis Posticus Minor,
   Arises, by a narrow beginning, close to its fellow, from
a little protuberance  in the  middle of the back part of the
first vertebra of the neck, its outer edge being covered by
the rectus major.
   Inserted, somewhat broad, into the sides of a dimple in
the os occipitis, near its foramen magnum.
   Use.  To assist  the rectus major in moving the head
backwards.

             3. Obliquus Capitis Superior,
   Arises from the transverse process of the first vertebra
of the neck.
   Inserted, tendinous and fleshy, into the os occipitis be-
hindthe back part of the mastoid process of the temporal
bone, and under the insertion of the complexus muscle.
   Use.  To draw the head backwards.

             4. Obliquus Capitis Inferior,
   Arises, fleshy, from the spinous process of the second
vertebra of the neck, its whole length; and, forming a thick
fleshy belly, is
   Inserted into the transverse process of the first vertebra
of the neck.
   Use.  To give a rotatory motion to the head. 
                   side of the Neck.                223
  On the side of die neck are,

                  1. Scalenus Anticus,
  Arises from the fourth, fifth, and sixth transverse pro-
cesses of the first vertebra of the neck, by as many ten-
dons.
  Inserted,  tendinous  and fleshy,  into the upper side of
the first rib, near its cartilage.

                  2. Scalenus Medius,
  Arises, from all the transverse processes of the vertebrae
of the neck, by as many strong tendons; the nerves to the
superior extremity pass between it and the former.
  Inserted into the upper and outer part of the  first rib,
from its root, to within the distance  of an inch from its
cartilage.

                  3. Scalenus Posticus,
  Arises from the fifth and sixth transverse processes of
the vertebrae of the neck.
  Inserted into the upper edge of the second rib, not far
from the spine.
   Use of the three scaleni: to bend the neck to one side;
or,  when the neck is fixed, to elevate the ribs, and to di-
late the thorax.
  There are a number of small muscles situated between
the spinous and transverse processes of contiguous verte-
brae; which are accordingly named,

                 1. Interspinales Colli,
  The space between the spinous processes of the verte-
brae of the neck, most of which are bifurcated, is filled up
with fleshy portions; which 
  224              Muscles of the Spine.
    Arise, double, from the spinous process of the inferior
  vertebrae of the neck; and ascend to be
    Inserted, in the same manner, into the spinous process
  of the superior vertebra.  They are five in number.
    Use.  To draw these processes nearer to each other.

               2. Intertransversales Colli.
   They begin from the transverse process of the first ver-
 tebra of the back, and fill up the spaces between the trans-
 verse processes of the vertebrae of the neck, which are like-
 wise bifurcated; and, consequently, there are six distinct
 double muscles, which
   Arise from the inferior transverse process  of each ver-
 tebra of the neck, and first of the back, and are
   Inserted into the superior transverse processes.
   Use.  To draw these processes towards each other, and
 turn the neck  a little to one side.

        Interspinals Dorsi et Lumborum, and the
               Intertransversales Dorsi,
   Are rather small tendons than  muscles, serving to con-
nect the spinal and transverse processes.

             Intertransversales Lumborum,
   Are four distinct small bundles of flesh, which fill up
the spaces between the transverse processes of the verte-
brae of the loins, and serve  to draw them towards each
other. 
225
    Mu>eles of tlie Superior Extremities.
  THESE may be divided into the muscles that are situ-
ated on the scapula, on the os humeri, on the cubit or fore
arm, and on the hand.

            Muscles situated on the Scapula.
  These are called muscles of the os humeri; and are three
behind, one along its inferior costa, two before, and one
beneath it.
  Behind are,
                  1. Supraspinatus.
  Arises, fleshy, from all that part of the base of the sca-
pula that is above its spine; also from the spine and supe-
rior costa; passes under the acromion, and adheres to the
capsular ligament of the os humeri.
  Inserted, tendinous, into that part of the large protube-
rance on the head of the os humeri that is next the groove)
for lodging the tendon of the long head of the biceps.
  Use. To raise the arm upwards; and, at the same time,
to pull the capsular ligament from between the bones, that
it may not be pinched.

                  2. Infraspinatus,
  Arises, fleshy, from all that part of the base of the sca-
pula that is between its spine and inferior angle; from the
spine as far as the cervix of the scapula. The fibres ascend
and descend obliquely towards a tendon in the middle of
the muscle, which runs forwards, and adheres to the cap-
sular ligament.
  Inserted, by a thick and  short tendon, into the upper
and middle part of the large  protuberance on the head of
the os humeri.
  Vol. I.                 2 F 
226        Muscles situated on the Scapula.
  Use. To roll the humerus outwards; to assist in raising,
and in supporting it when raised; and to pull the ligament
from between the bones.
  N. B,  These two muscles are covered with a tendinous
membrane, from which a number of their fleshy fibres
arise. It serves  besides to strengthen their actions, and
keeps them  from swelling  too much  outwardly when in
action.

                   3. Teres Minor,
  Arises, fleshy, from all the  round edge of the inferior
costa of the scapula, and runs forwards along the inferior
edge of the infraspinatus muscle, and adheres to the liga-
ment.
  Inserted, tendinous, into the back part of the large pro-
tuberance on the head of the os humeri, a little behind and
below the termination of the last named muscle.
  Use, To roll the humerus outwards; to draw the hu-
merus backwards; and to prevent the ligament from being
pinched between the bones.
  Along the inferior costa of the scapula is,

                    Teres Major.
  Arises, fleshy, from the  inferior angle of the scapula,
and from all that portion of its  inferior costa that is rough
and jhicker  than the rest; its fleshy fibres are continued
over part of the infraspinatus muscle, to which they firmly
adhere.
  Inserted, by a broad, short,  and thin tendon,  into the
ridge at the  inner side of the groove for lodging the ten-
don of the long head of the biceps, along with the latissi-
mus dorsi. 
             Deltoides.—Coraco-Brachialis.        227
   Use.  To roll the humerus inwards, and to draw it back-
wards and downwards.
   The two before the scapula are,

                     1.  Deltoides,
   Arises, fleshy, from all the posterior part of the clavicle
that the pectoralis major does not possess; tendinous and
fleshy, from the acromion, and lower margin of almost the
whole spine of the scapula opposite to the insertion  of the
cucullaris muscle: from these origins it runs in three dif-
ferent directions, i.  e. from  the clavicle outwards and
downwards; from the spine of the scapula outwards, for-
wards, and downwards; and from the acromion straight
downwards; and  is composed of a  number of  fasciculi,
which form a strong  fleshy muscle that covers the anterior
part of the joint of the os humeri.
   Inserted, tendinous, into a rough protuberance  in the
outer side of the os humeri, near its middle, where the
fibres of this muscle intermix with some part of the bra-
chialis externus.
   Use.  To pull the arm  directly outwards and  upwards,
and a little forwards  or backwards, according to the dif-
ferent directions of its fibres.

                 2.  Coraco-Brachialis,
  Arises, tendinous and fleshy, from the fore part of the
coracoid process of the scapula;  adhering, in its descent,
to the short head of the biceps.
   Inserted, tendinous and fleshy, about the middle  of the
internal part of the os humeri, near the origin of the third
head  of the triceps,  called brachialis externus, where it
sends down a thin tendinous expansion to the internal
condyle of the os humeri. 
228            Subscapularis.—Biceps.
   Use.  To raise the arm upwards and forwards.
   N. B. There passes a nerve through this muscle, called
musculo cutaneus.
   The one beneath the scapula is,

                     Subscapularis.
   Arises, fleshy, from all the base of the scapula internally,
and from its superior and inferior costre, being composed
of a number of tendinous and fleshy fasciculi, which make
prints on the bone;  they all join together, fill up the hol-
low of the scapula, and pass over the joint, adhering to the
capsular ligament.
   Inserted, tendinous, into the upper part of the internal
protuberance at the head of the os humeri.
   Use. To roll the humerus inwards,  and to draw it to the
side of the  body; and to prevent the capsular ligament
from being pinched.


         Muscles situated on the Os Humeri.
   These are called

           Muscles of the Cubit or Fore Arm.
   They consist of two before, and two behind.
   Before are,

                1. Biceps Flexor Cubiti.
   Arises, by two heads.  The  first and outermost,  called
longus, begins tendinous from the upper edge of the gle-
noid cavity of the scapula; passes over the head of the os
humeri  within the joint; and, in its descent without the
joint, is inclosed in a groove  near the head of the os hu-
meri, by a membranous ligament that proceeds from the 
                 Brachialis Internus.              229
capsular ligament and adjacent tendons. The second, or
innermost head, called brevis, arises, tendinous and fleshy,
from the coracoid process of the scapula, in common with
the coraco-brachialis muscle. A little below the middle of
the fore part of the os humeri, these heads unite.
  Inserted, by a strong roundish tendon, into the tubercle
on the upper end of the radius internally.
  Use. To  turn the hand  supine, and to bend the fore
arm.
  N.  B.  At the bending of the elbow,  where  it begins to
grow tendinous, it sends off an aponeurosis, which covers
all  the muscles on  the inside of the fore arm, and joins
with another tendinous membrane, which is sent off  from
the triceps extensor cubiti, and covers  all the muscles on
the outside  of the fore arm, and a number of the fibres,
from opposite sides, decussate each other. It serves to
strengthen the muscles, by keeping them from swelling too
much outwardly, when in action;  and a number of  their
fleshy fibres take their origin from it.

                2.  Brachialis Internus,
  Arises,  fleshy, from the middle of theos humeri, at each
side of the insertion of the deltoid muscle, covering all the
inferior and fore part of this bone, runs over the joint, and
adheres firmly to the ligament.
  Inserted, by a strong short tendon,  into the  coronoid
process of the ulna.
  Use. To bend the fore arm, and to prevent the capsular
ligament of the joint from being pinched. 
 230        Triceps Extensor.—Anconeus.
   Behind, are
              1. Triceps Extensor Cubiti.
   Arises, by three heads; the first called longus, somewhat
 broad and tendinous, from the inferior costa of the scapu-
 la, near its cervix. The second head, called brevis, arises
 by an acute, tendinous, and fleshy  beginning, from the
 back part  of the os  humeri,  a little below its head, out-
 wardly. The third, called brachialis externus, arises by an
 acute  beginning, from the  back part of  the  os humeri.
 These three heads unite lower than  the insertion  of the
 teres major, and cover the whole posterior part of the hu-
 merus, from which they receive addition in their descent.
   Inserted into the upper and  external part of the process
 of the ulna, called olecranon, and partly into the condyles
 of the os humeri, adhering firmly to the  ligament.
   Use. To extend the fore arm.

                     2. Anconeus,
   Arises, tendinous, from the  posterior  part of the exter-
 nal condyle of the os humeri; it soon grows fleshy, and is
 continued from the third head of the triceps.
   Inserted, fleshy, and thin, into a ridge on the outer and
 posterior edge of the ulna, being continued some way be-
low the olecranon,  and  covered with a  tendinous  mem-
brane.
   Use. To assist in extending the fore arm. 
Palmaris Longus.
231
         Muscles situated on the Fore Arm.
    These may be divided into three classes, viz.
    1. The muscles which bend and extend the wrist, and of
      course the whole hand.
    2. Those which bend and extend the fingers exclusively.
    3. Those which act on the radius so as to roll it backwards
      and forwards on the ulna;  which are called supinators
      and pronators.
    The flexors both of the wrist and fingers, and the prona-
      tors, lie on the front of the fore arm.  The extensors and
      the supinators on the back.
    The flexors generally originate from the internal condyle
      of the os humeri, and the parts adjacent to it: the exten-
      sors from the external condyle of the  same bone, and the
      parts which are near it.
    In the following description they are arranged in the order
      in which  they occur in the dissection of the arm; begin-
      ning with those which originate from the internal con-
      dyle, without regard to their particular functions.


   Muscles on the Anterior part of the Fore Arm.

                  1.  Palmaris Longus,
  Arises, tendinous, from the internal condyle of the  os
humeri,  soon  grows  fleshy, and after a short progress,
sends off a long slender tendon.
  Inserted into the ligamentum carpi annulare, and into a
tendinous membrane that is expanded on the palm of the
hand, named aponeurosis palmaris; which, above, begins
at the transverse or annular  ligament of the wrist, and, be-
low, is fixed to the roots of the fingers. 
232            Muscles on the Anterior
   Use.  To bend the hand, and to stretch the membrane
that is expanded on the palm.
   N. B. This muscle is sometimes wanting;  but the apo-
neurosis-palmaris is always to be found.

               2. Pronator Radii Teres,
   Arises, fleshy, from the internal condyle of the  os hu-
meri, and tendinous from the coronoid process of the ulna.
   Inserted, thin, tendinous, and fleshy, into the middle of
the posterior part of the radius.
   Use, To roll the radius, together with the hand, inwards.

               3. Flexor Carpi Radialis,
   Arises, tendinous and fleshy, from the internal condyle
of the os humeri, and from the anterior part  of the upper
end of the ulna, where it firmly adheres to  the pronator
radii teres.
   Inserted, by a flat tendon, into the fore and upper part
of the metacarpal bone that sustains the fore finger,  after
running through a fossa in the os trapezium.
   Use. To bend the hand, and to assist in its pronation.

                4. Flexor Carpi Ulnaris,
   Arises, tendinous,  from the internal condyle of the os
humeri. It has likewise a small fleshy beginning from the
outer side of the olecranon; between which and the  con-
dyle the ulnar nerve passes to the fore arm; and a number
of its fleshy fibres arise from the tendinous membrane
which covers the fore arm.
   Inserted, by a short strong tendon, into the os pisiforme.
At a little distance from its insertion, a small ligament is
sent off to the metacarpal bone that sustains the little finger.
   Use. To assist the former in bending the arm. 
         i         part of the Fore Arm.             23:3
               5. Flexor Sublimis Perforatus,
    Arises, tendinous and fleshy, from the internal condyle
  of the os humeri; tendinous from the coronoid process of
  the  ulna, near the edge of the cavity that receives the head
  of the radius; fleshy from the tubercle of the radius; and
  membranous and fleshy from the middle of the fore part
  of the radius, where the flexor pollicis longus  arises. Its
  fleshy belly sends off four round tendons before it passes
  under the ligament of the wrist.
    Inserted, into the anterior and upper part of the second
  bone of each finger, being, near the extremity of the first
  bone, divided for the passage of the perforans.
    Use. To bend the second joint or phalanx of the fingers.

              6. Flexor Profundus Perforans,
    Arises, fleshy, from the external side, and upper part of
  the ulna, for some way downwards, and from a large share
  of the  interosseous  ligament. It splits into four tendons,
  a little before it passes under the ligamentum carpi annu-
  lare; and these pass through  the slits in the tendons of the
  flexor sublimis.
    Inserted into the fore and  upper part of the third or last
v  bone of all the four fingers.
    Use. To bend the'last joint of the fingers.

            7. Flexor Longus Pollicis Manus,
    Arises, by an acute fleshy beginning, from  the upper
  part  of the radius, immediately below its tubercle, and is
  continued down  for some space on the fore part of this
  bone. It has likewise generally another origin from the
  internal condyle of the os humeri, which forms  a distinct
  fleshy slip that terminates near the upper part of the origin
  from the radius.
    Vol. I.              2  G 
234           Muscles on the back part
  Inserted into the last joint of the thumb, after having
passed its tendon under the ligament of the wrist.
  Use.  To bend the last joint of the thumb.*

             8.  Pronator Radii §>uadratus,
  Arises, broad, tendinous, and fleshy, from the lower and
inner part of the ulna;  the fibres run transversely, to be
  Inserted into the lower and anterior part of the radius,
opposite to its origin.
  Use.  To  turn the radius,  together with the hand, in^
wards.


   Muscles of the External Side and Back of the
                        Arm.
              1. Supinator Radii Longus,
  Arises, by an acute and fleshy origin, from the external
ridge of the os humeri, above the external condyle, nearly
as far up as the middle of that bone.
  Inserted into the outer side of the inferior extremity of
the radius.
  Use.  To roll the radius outwards, and consequently the
palm of the hand upwards.

          2. Extensor  Carpi Radialis Longior,
  Arises, broad, thin,  and fleshy, immediately below the
supinator radii longus, from the lower part of the external
ridge of the os humeri, above its external condyle.

  * The thumb has but  one flexor muscle on the front of the arm,
although it has three extensors on the back part. 
                   of the Fore Arm.               235
  Inserted, by  a round tendon, into  the  posterior and
upper part of the metacarpal bone that sustains the fore
finger.
  Use. To extend and bring the hand  backwards.

          3.  Extensor Carpi Radialis Brevior,
  Arises, tendinous, from the  external condyle of the os
humeri, and from the  ligament that connects the radius to
it, and runs along the  outside of the radius.
  Inserted, by  a round tendon, into the upper and back
part of the metacarpal bone that sustains the middle finger.
  Use. To assist the last mentioned muscle.

              4. Extensor Carpi Ulnaris,
  Arises, tendinous, from the external condyle of the os
humeri; and, in its progress, fleshy from the middle of the
ulna,  where it passes  over the ulna. Its round tendon is
inclosed  by a membranous sheath, in a groove which is
situated at the extremity of the ulna.
  Inserted, by its round tendon,  into the  posterior and
upper part of the metacarpal bone that sustains the little
finger.
  Use. To assist the former in extending the hand.

           5. Extensor Digitorum  Communis,
  Arises, by  an acute,  tendinous, and fleshy beginning,
from the external condyle of the os humeri, where it ad-
heres  to the supinator  radii brevis.  Before  it passes under
the  ligamentum carpi annulare externum, it splits into
four tendons; some of which may be divided into several
smaller;  and  about the fore part of the metacarpal bones
they remit tendinous filaments to each other. 
236            Muscles on the back part
  Inserted into  the posterior  part of all the bones of the
four fingers, by a tendinous expansion.
  Use. To extend all the joints of the fingers.

              6. Supinator Radii Brevis,
  Arises, tendinous, from the  external condyle of the os
humeri; tendinous  and fleshy, from the external and up-
per part of the  ulna, and adheres firmly to the ligament
that joins these two bones.
  Inserted into the head, neck, and tubercle of the radius,
near the insertion of the biceps,  and ridge running from
that downwards and outwards.
  Use. To roll the radius outwards, and so bring the hand
supine.

                     7. Indicator,
  Arises, by an acute fleshy beginning, from the middle of
the posterior part of the ulna;  its tendon passes under the
same ligament with the extensor digitorum  communis,
with part of which it is
  Inserted into the  posterior part of the fore finger.
  Use. To extend the fore finger separately.

      8.  Extensor Ossis Metacarpi Pollicis Manus,
  Arises, fleshy, from  the middle and posterior part of
the ulna, immediately below the  insertion of the anconeus
muscle, from the posterior part of the middle of the radi-
us, and from the interosseous ligament.
  Inserted, generally by two tendons, into the os trapezi-
um, and upper  back part of  the metacarpal bone of the
thumb, and often joins with the abductor pollicis.
   Use,  To extend the  metacarpal bone of the thumb out-
wardly. 
                   of the Fore Arm.                237
             9.  Extensor Primi Internodii,
  Arises, fleshy, from the posterior part of the ulna near
the former muscle, and from the interosseous ligament.
  Inserted, tendinous, into the posterior part of the first
bone of the thumb; and part of it may be  traced as far as
the second bone.
  Use.  To extend the  first bone of the thumb obliquely
outwards.

            10. Extensor Secundi Internodii,
  Arises, by an acute, tendinous, and fleshy beginning,
from the middle back part of the ulna, and from the inter-
osseous ligament; its tendon runs through a small groove
at the inner and back part of the lower end of the radius.
  Inserted into the last bone of the thumb.
  Use.  To extend the  last joint of the thumb obliquely
backwards.


         Muscles on the Palm of the Hand.
    To obtain a full view of the muscles situated on the palm
      of the hand, it will be necessary to remove the annular or
      transverse ligament, which is stretched across from the
      projecting points of the pisiform and unciform bones on
      the inside of the wrist to the scaphoid  and trapezium on
      the outside; for the purpose of retaining the tendons of
      the flexor muscles in their proper situation. And also, to
      remove from the palm of the hand the aponeurosis pal-
      maris,  which has been described with  the palmaris lon-
      gus muscle.

                  1. Palmaris Brevis,
  Arises from the  ligamentum carpi annulare, and tendi-
nous membrane that is expanded on the palm of the hand. 
238
•  Muscles on the Palm
   Inserted, by small bundles of fleshy fibres, into the skin
 and fat that covers the abductor minimi digiti, and into
 the os pisiforme.
   Use. To assist in contracting the palm of the hand.

               2. Abductor Pollicis Manus,
   Arises, by a broad tendinous and fleshy beginning, from
 the ligamentum carpi  annulare, and from the os trape-
 zium.
   Inserted, tendinous, into the outer side  of the root of
 the first bone of the thumb.
   Use. To draw the thumb from the fingers.

  3. Flexor Ossis Metacarpi Pollicis, or Opponens Pollicis,
   Arises, fleshy, from the os trapezium and ligamentum
 carpi annulare, lying under the abductor pollicis.
   Inserted, tendinous and fleshy, into the under and ante-
 rior part of the metacarpal bone of the thumb.
   Use. To bring the thumb inwards, opposite to the other
 fingers.

            4. Flexor Brevis Pollicis Manus,
   Arises from the os trapezoides, magnum, and unciforme
of the carpus, and is divided into two portions by the ten-
don of the flexor pollicis longus.
   Inserted into the ossa sesamoidea and first bone  of the
thumb.
   Use.  To bend the first joint of the thumb.

              5. Adductor Pollicis Manus,
  Arises, fleshy, from almost the whole length of the me-
tacarpal bone that sustains the middle finger; from thence
its fibres are collected together. 
                     of the Hand.                 239
  Inserted, tendinous, into the inner part of the  root of
the first bone.
  Use.  To pull the thumb  towards the fingers.
  There are four small flexors, called, from their form,

                    6. Lumbricales,
  Which arise, thin  and fleshy,  from the outside of the
tendons of the flexor profundus, a little above the lower
edge of the ligamentum carpi annulare.
   Inserted, by long slender tendons, into the outer  sides
of the broad tendons of the interossei muscles, about the
middle of the first joint.
   Use. To increase the flexion of the  fingers while the
long flexors are in full action.

      7. Adductor Metacarpi Minimi Digiti Manus,
   Arises, fleshy, from the  thin edge  of the os unciforme,
and from that part of the ligament of the wrist next to it.
   Inserted, tendinous, into  the inner side and anterior part
of the metacarpal bone of this finger.
   Use. To bend and bring the  metacarpal bone of this
finger towards the wrist.

            8. Flexor Parvus Minimi Digiti,
   Arises, fleshy, from the outer  side of the os unciforme,
and from the ligament of the wrist which joins with that
bone.
   Inserted, by a roundish tendon, into the inner and ante-
rior part of the upper end of the first bone of this finger.
   Use. To bend the little finger, and assist the adductor.

            9. Abductor  Minimi Digiti Manus,
   Arises, fleshy, from the os pisiforme, and from that part
 of the ligamentum carpi annulare next it. 
240             Muscles on the Palm
   Inserted, tendinous, into the inner side of the tipper end
 of the first bone of the little finger.
   Use. To draw this finger  from the rest.

   The spaces between the metacarpal bones are occupied
 by muscles called, from their situation, interosseous. The
 four following are to be seen on the palm of the hand.


           Anterior Interosseous Muscles.
                    1. Prior Indicis,
   Arises, tendinous and fleshy, from the upper and outer
.part of the metacarpal bone that sustains the fore finger.
   Inserted into  the outside of that part  of the tendinous
 expansion from the extensor digitorum communis, which
 covers the posterior part of the fore finger.
   Use. To draw the fore finger outwards towards  the
 thumb, and extend it obliquely.

                  2.  Posterior Indicis,
   Arises, tendinous  and fleshy, from the root  and  inner
 part of the metacarpal bone that sustains  the fore finger.
   Inserted into the inner side of  the tendinous expansion
 which is sent off from the extensor  digitorum communis,
 along the posterior part of the fore finger.
   Use. To extend the fore finger obliquely, and to  draw
 it inwards.

                  3. Prior Annularis,
  Arises, from the root of the outside of the metacarpal
 bone that sustains the ring finger.
  Inserted into the outside of the tendinous expansion of
 the extensor digitorum communis which  covers the ring
 finger. 
                     of the Hand.                 241
   Use.  To extend and pull the  ring finger towards the
thumb.

              4.  Interosseous Auricularis,
   Arises from the root and outer  side of the  metacarpal
bone of the little finger; and is
   Inserted into the outside of the tendinous expansion of
the extensor digitorum communis, which covers the pos-
terior part of the little finger.
   Use. To extend and draw the little finger outwards.
   On the back of the hand three muscles of the same kind
are to be seen, which also appear on the palm.


          Posterior Interosseous  Muscles.
                   1.  Prior Medii,
   Arises, by two origins, from the roots  of the metacar-
pal bones that sustain the fore and middle  fingers exter-
nally, and next each other:  runs along the outside of the
middle finger; and, being conspicuous on both sides of the
hand, is
   Inserted into the outside of the  tendinous  expansion
from the extensor digitorum communis, which  covers the
posterior part of the middle finger.
   Use.  To extend, and to draw  the middle finger out-
wards.

                  2. Posterior Medii,
   Arises, by two origins, from the roots of the metacarpal
bones, next each other, that sustain the middle and  ring
fingers.
   Vol.  I.                  2 II 
242        Muscles of the back of the Hand.
  Inserted into the inside of the tendinous expansion from
the extensor digitorum  communis, which runs along the
posterior part of the middle finger.
  Lse. To extend and draw the middle finger inwards.

               3. Posterior Annularis,
  Arises, by two origins, from the roots of the metacarpal
bones that sustain the ring and little fingers, next each
other.
  Inserted into the inside of the  tendon on the back of
the ring finger.
  Use. To draw the ring finger inward.
  The following muscle  also appears on the back of the
hand.

               Abductor Indicis Manus,
  Arises, from the os trapezium,  and from the superior
part and inner side of the metacarpal bone of the thumb.
  Inserted, by a short tendon, into the outer and back part
of the first bone of the fore finger.
  Use. To bring the fore finger towards the thumb. 
243
     Muscles of tlie Inferior Extremities.
  THESE may be divided into the muscles situated ojp.
the outside of the pelvis, on the thigh, on the leg',  and on
the foot.
  Muscles on the outside of the pelvis, which are called
muscles of the thigh.
  These are composed of one layer before and three layers
aehind.
  The layer before consists, of five muscles:
  I. Psoas Magnus.  *)         „._
             °      J. see page 212.
  2. Iliacus Internus. J

                    3. Pectinalis,
  Arises, broad and fleshy, from the upper and anterior
part of the os pubis or pectinis, immediately above the fo-
ramen thyroideum.
  Inserted into the anterior and upper part of the linea
aspera of the os femoris, a little below the trochanter  mi-
nor, by a flat and short tendon.
  Use. To bring the thigh upwards and  inwards, and to
give it a degree of rotation outwards.

             4. Triceps Adductor Femoris,
  Under this appellation are comprehended three distinct
muscles:

             a. Adductor Longus Femoris,
  Arises, by a strong roundish tendon, from the upper
and anterior part of the  os  pubis, and  ligament of its
synchondrosis, on the inner side of the pectinalis. 
 244           Muscles of the Os Femoris.
   Inserted, tendinous, near the  middle of the posterior
 part of the linea aspera, being continued for some way
 down.

              b. Adductor Brevis Femoris,
   Arises, tendinous, from the os pubis near its joining
 with the opposite os pubis, below and behind the former.
   Inserted, tendinous and fleshy, into the inner and upper
 part of the linea aspera, from a little below the trochanter
 minor, to  the beginning of the insertion of  the adductor
 longus.

             c. Adductor Magnus Femoris,
   Arises, a little lower down than the former, near the
 symphysis of the ossa pubis; tendinous and  fleshy,  from
 the tuberosity of the os ischium;  the fibres run outwards
 and downwards.
   Inserted, into almost the whole length of the linea aspe-
 ra; into a  ridge above the internal condyle  of the  os
 femoris; and, by a roundish long tendon, into the upper
 part of that condyle, a little above which the femoral ar-
 tery takes a spiral turn towards the ham, passing between
 this muscle and the bone.
   Use of these  three muscles, or triceps. To bring the
thigh inwards and upwards, according to the different di-
rections of their fibres; and, in some degree, to roll the
thigh outwards.

                5. Obturator Externus,
   Arises, fleshy, from the lower fore part of the os pubis,
and fore part of the inner crus  of the ischium;  surrounds
the foramen thyroideum; a number of its fibres, arising
from the membrane which fills  up that  foramen, are coi- 
              Muscles of the Os Femoris.           245
lected  like rays towards a  center, and pass outwards
around the root  of the back part of the cervix of the os
femoris.
  Inserted, by a strong tendon, into the cavity at the in-
ner and back part of the root  of the trochanter major,
adhering in its  course to the  capsular ligament of the
thigh bone.
  Use. To roll the thigh bone obliquely outwards, and to
prevent the capsular ligament from being pinched.
  Behind are,

  First layer,
                  Gluteus Maximus,
  Arises, fleshy, from the posterior part of the spine of
the os ilium, a  little  higher up than  the joining of the
ilium with the os sacrum, from the whole external side of
the os sacrum, below the posterior spinous process of the
os ilium; from the posterior sacro ischiatic ligament, over
which part of the inferior edge of this muscle hangs in  a
folded manner; from the os coccygis. All the fleshy fibres
run obliquely forwards, and a little downwards, to form a
thick broad muscle, which is divided  into a number of
strong fasciculi.  The  upper  part of it covers almost the
whole  of the trochanter major, between which  and the
tendon of this muscle there is a large bursa mucosa, and
where it  is inseparably joined to the broad tendon of the
tensor vagina femoris.
  Inserted, by a strong, thick, and broad tendon into the
upper and outer part  of the  linea aspera, which is con-
tinued from  the trochanter major,  for some way down-
wards.
  Use. To extend the thigh, by pulling it directly back-
wards, and a little outwards. 
 246           Muscles of the Os Femoris.
   Second layer,
                    Gluteus Medius,
   Arises, fleshy, from the anterior superior spinous  pro-
 cess of the os ilium, and  from all the outer edge of the
 spine of the ilium, except its posterior part, where it arises
 from the dorsum of that bone.
   Inserted, by a broad tendon, into the outer and poste-
 rior part of the trochanter major.
   Use. To draw  the thigh bone outwards, and a little
 backwards; to roll the thigh  bone outwards,  especially
 when it is bended.
   N. B. The  anterior and upper part of this- muscle is
 covered by a tendinous membrane, from which  a number
 of its fleshy fibres arise, and which joins with the broad
 tendons of the gluteus maximus, tensor vaginae femoris,
 and latissimus dorsi.

   Third layer consists of four muscles.
                  1. Gluteus Minimus,
   Arises, fleshy, from a ridge that is continued from the
 superior anterior spinous process of the os ilium, and from
 the middle of  the dorsum of that bone, as far back as its
 great niche.  •
   Inserted, by a strong tendon, into the fore  and upper
part of the trochanter major.
   Use. To assist the former in pulling the thigh outwards
 and backwards, and in rolling it.

                    2. Pyriformis,
  Arises, within the pelvis, by three tendinous and fleshy
origins, from the second, third, and fourth  pieces of the
os sacrum; from thence growing gradually narrower, it 
              Muscles of the Os Femoris*           247
passes out of the  pelvis along with the posterior crural
nerve, below the niche in the posterior part of the os ilium,
where it receives a few fleshy fibres.
  Inserted, by a roundish tendon, into the upper part of
the cavity at the inner side of the root of the trochanter
major.
  Use.  To move the thigh a little upwards, and  roll it
outwards.
                      3.  Gemini,
  Arise, by two distinct origins; the superior from the
spinous process, and the inferior from the tuberosity of the
os ischium; also,  from the posterior sacro ischiatic liga-
ment. They  are both  united  by a tendinous  and fleshy
membrane, and form a purse for the tendon of the obtura-
tor internus muscle, which was formerly described.
  Inserted, tendinous  and fleshy, into the  cavity at the
inner side of the root of the trochanter major, on each side
of the tendon of  the obturator internus,  to which they
firmly adhere.
   Use.  To roll the thigh  outwards, and to preserve the
tendon of the obturator internus from  being hurt  by the
hardness of that part of the ischium over which it passes;
also, to hinder it from starting out of its place, while the
muscle is in action.

                4. ^uadratus Femoris,
  Arises, tendinous and fleshy,  from the  outside  of the
tuberosity of the os ischium;  and, running  transversely,
is
  Inserted, fleshy, into a rough ridge, continued from
the root of the large trochanter to the root  of the small
one.
   Use.  To roll the thigh outwards. 
248
Muscles of the Leg.
            Muscles situated on the  Thigh.
   These are called muscles of the leg: and consist of one.t
 on the outside; two, on the inside; four, before;  and four,
 behind.
   Previous to the description of the muscles that are situ-
 ated on the thigh and leg,  it is necessary to take notice of
 a broad tendinous fascia or sheath,  which is sent off from
 the back and from the tendons of the  glutei and adjacent
 muscles.
   It is a strong thick membrane on the outside of the thigh
 and leg; but, towards the  inside of both,  it gradually
 turns thinner, and has rather the  appearance of cellular
 substance, than a tendinous membrane. A little below the
 trochanter major,  it is firmly fixed to the linea  aspera;
 and, farther down, to that part of the head of the tibia
 that is  next the fibula; where it sends off the tendinous
 expansion along the outside of the leg.
   It serves to strengthen the action of the muscles, by
 keeping  them firm in their proper places while in action,
 particularly the tendons that pass over  the joints, where
 this membrane is thickest; and it gives origin to a number
 of the fleshy fibres of the muscles.
   On the outside is,

                Tensor Vagina Femoris,
   Arises, by a narrow, tendinous, and fleshy beginning,
from the external part of the anterior superior spinous
process of the  os ilium.
  Inserted, a  little below the trochanter major, into the
inner side of the membranous fascia which covers the out-
side of the thigh. 
                Muscles on the Thigh,             249
  Use. To stretch the membranous fascia, to assist in the
abduction of the thigh, and somewhat in its rotation in-
wards.
  On the inside are,

                     1. Sartorius,
  Arises, tendinous,  from the anterior superior spinous
process of the os ilium, soon grows fleshy, runs  down for
some space upon the rectus, and going obliquely inwards,
it passes over the vastus internus, and, about the middle
of the os  femoris, over part of the triceps, it runs down
farther between the tendon of the  adductor  magnus and
that of the gracilis muscle.
   Inserted, by  abroad and thin tendon, into the  inner side
of the tibia, near the inferior part of its tubercle.
   Use. To bend the leg obliquely inwards, or to bring one
leg across the other.
                      2.  Gracilis,
   Arises, by a thin  tendon, from the  os pubis near the
 symphysis of these two bones:  soon grows fleshy; and.
 descending by the inside of the thigh, is
   Inserted, tendinous, into the tibia under the sartorius,
   Use.  To assist the sartorius.
   Before are,
                       1.  Rectus.
   Arises, fleshy, from the inferior anterior  spinous pro-
 cess of the os ilium, and tendinous from the  dorsum of
 the ilium, a little  above the acetabulum; runs down over
 the anterior part of the cervix of the os femoris; the fibres
 not being straight, but running down like the plumage of
 a feather obliquely outwards and  inwards, from a tendon
 in the middle.
    Vol. I.                2 I 
£50            Muscles on the Thigh.
  Inserted, tendinous, into the upper part of  the  patella,
from which a thin tendon rutis down, on the fore part of
this  bone, to terminate in a thick strong ligament, which
is sent off from the inferior part of the patella, and inserted
into the tubercle of the tibia.
  Use, To extend the leg, and in a powerful manner, by
the intervention of the patella, like a pully.

                  2.  Vastus Externus,
  Arises, broad, tendinous and fleshy, from the root of the
trochanter major, and upper part of the linea aspera; its
origin being continued from near the insertion of the glu-
teus minimus,  the whole length of the linea aspera, by
fleshy fibres which run obliquely forwards  to a  middle
tendon, where they terminate.
  Inserted into a large share of the upper part of the pa-
tella; and part of it ends in an aponeurosis, which is con-
tinued down to the leg, and in its passage is firmly fixed
to the head of the tibia.
  Use, To extend the leg.

                  3.  Vastus Internus,
  Arises, tendinous and fleshy, from between the forepart
of the os femoris and root of the trochanter minor, and
from almost  all the  inside of the linea aspera, by fibres
running obliquely forwards and downwards.
  Inserted, tendinous, into the upper and inside of the
patella, continuing fleshy lower than the  vastus  externus.
Part of it likewise ends in an aponeurosis continued down
to the leg, and fixed in its passage to the upper part of the
tibia.
  Use, To extend the leg. 
Muscles qn the Thigh.
251
                     4. Cruralis,
  Arises, fleshy, from between the two trochanters of the
os femoris, but nearer the minor, and firmly adhering to
most of the fore part of the os femoris, and connected to
both, vasti muscles.
  Inserted, tendinous, into the tipper part of the patella,
behind the rectus.
  Use. To assist in the extension, of the leg.
  N. B.  These four muscles before, being inserted, into
the patella, have the same effect  upon the leg  as if they
were immediately inserted into it, by means of the strong
tendon, or rather ligament,  which is sent  off from the
Inferior part of the patella to the tibia.
  Behind are,
                   1. Semitend.inosus,
  Arises, tendinous and fleshy,  in common with the long
head of the biceps, from the posterior part of the tubero-
sity of the os ischium; and sending down a long roundish
tendon, which ends flat} is
   Inserted into the inside of the ridge of the tibia, a little
below its tubercle.
   Use. To be^d the leg backwards and a little inwards.

                  2. Sen^membranosus,
   Arises, tendinous, from the upper arid posterior part of
the tuberosity of the  ps Uph)u;ra.; sends d^wn a broad fiat
 teadop, whjch ends,  m a fleshy belly, and, in its descent,
 ruqs at first on the fore pajt of the biceps, and, lower, be-
 tween it and the semiten4inasus.
    Inserted, tendinous, into the inner ajid. back part of the
 head of the tibia.
    Use, To bend the leg, and bring it directly backwards. 
252             3Iuscles on the Thigh.
   N. B. The two last form what is called the inner ham-
string.

                3. Biceps Flexor Cruris,
   Arises, by two distinct heads. The first,  called longus,
arises, in common with the semitendinosus, from the up-
per and posterior part of the tuberosity of the os ischium.
The second, called brevis, arises from the linea aspera, a
little below the termination of the gluteus maximus, by a
fleshy acute beginning, which soon grows broader as it
descends to join with the first head, a little above the ex-
ternal condyle of the os femoris.
   Inserted, by a strong tendon, into the upper part of the
head of the fibula.
   Use. To bend the leg.
   N. B. This muscle forms what is called the outer ham-
string; and between it and the inner, the nervus popliteus,
the arteria and vena poplitea,  are situated.

                    4.  Popliteus,
   Arises, by a round tendon, from the lower and back part
of the external condyle of the os femoris; then runs over
the ligament that involves the joint; firmly adhering to it,
and part of the semilunar cartilage. As it runs over the
joint, it becomes fleshy, and the fibres run obliquely in-
wards, being covered'with a thin tendinous membrane.
   Inserted, broad, thin, and fleshy, into a ridge  at the up-
per and internal edge of the tibia, a little below its head.
   Use. To assist in bending the leg, and to prevent the
capsular ligament from being pinched. After the  leg is
bent, this muscle serves to roll it inwards. 
Muscles on the Leg.
25S
            Muscles situated on the Leg.
    These muscles may be arranged in the two general class-
      es of flexors and extensors of the foot, and flexors and
      extensors of the toes; but several of them, viz. the tibi-
      ales and the peronei, produce effects which are differ-
      ent from flexion or extension. For the accommodation
      of the student of anatomy, they may be studied in the
      order of their position, as they lie on the front, on the
      outside, and on the back of the leg.

          Muscles on the Front of the Leg.
                  1.  Tibialis Anticus,
   Arises, tendinous and fleshy, from  the middle  of  that
process of the tibia, to which the fibula is connected above;
then it runs down fleshy on the outside of the tibia; from
which, and the upper part of the interosseous ligament, it
receives a number of distinct fleshy fibres; near the extre-
mity of the tibia, it sends off a strong round tendon, which
passes under part of the ligamentum tarsi annulare near
the malleolus internus.
   Inserted, tendinous, into the inside of the  os cuneiforme
internum, and posterior end of the metatarsal bone  that
sustains the great toe.
   Use, To bend  the foot, by drawing it upwards, and, at
the same time, to turn the toes inwards.

          2. Extensor Proprius' Pollicis Pedis,
   Arises, by an acute, tendinous, and  fleshy beginning,
some way below the head and anterior part of the fibula,
along which it runs to near its lower extremity, connected
to it by a number of fleshy fibres, which descend obliquely
towards a tendon. 
 254             Muscle,* on the Leg.
   Inserted, tendinous, into the posterior part of the first
 and last joint of the great toe.
   Use. To extend the great toe.

         3. Extensor Longus Digitorum Pedis,
   Arises, tendinous and fleshy, from the upper and outei
 part of the head  of the tibia, and from the head of the
 fibula where it joins with the tibia, and from the interos-
 seous  ligament; also from the tendinous fascia, which
 covers  the upper  and outside of the leg by a number of
 fleshy fibres; and  tendinous and fleshy, from the anterior
 spine of the fibula, almost its whole lengthy where it is in-
 separable from  the peroneus tertius. It splits into four
 round tendons, under the ligamentum tarsi annulare.
   Inserted, by a flat tendon, into the root of the first joint
 of each of the four small toes; and is expanded over the
 upper side of the  toes, as far as the root of the last joint.
   Use, To extend  all the joints of the four small toes.
   N, B. A portion of this muscle, which is called

                 4. Peroneus Tertius,
   Arises from the  middle of the fibula, continues down to
 near its inferior extremity, and sends its fleshy fibres for-
 wards to a tendon, which passes under the annular liga-
ment, and is
   Inserted into the root of the metatarsal bone that sus-
tains the little toe.
   Use. To assist in bending the foot. 
Muscles on the Leg.
255
        Muscles on the Outside of the Leg,
                1. Peroneus Longus,
  Arises,  tendinous and fleshy, from the fore part of the
head of the perone, or fibula, the fibres running straight
down;  also from the upper and external part of the fibula,
where it begins to  rise into  a round  edge;  as also, from
the hollow between that and its anterior edge, as far down
as to reach within a hand's breadth of the ankle, by a num-
ber of fleshy fibres, which run outwards towards a tendon,
that sends off a long round  one, which passes  through a
channel at the outer ankle, in the back part of the inferior
extremity of the fibula; then, being reflected to the sinuo-
sity of the os calcis, it runs  along a groove in the os cu-
boides, above the muscles in  the sole of the foot.
  Inserted, tendinous,  into the outside of the root of the
metatarsal bone that sustains the great toe, and by some
tendinous fibres in  the os cuneiforme internum.
  Use, To move  the  foot outwards, and to extend it a
little.

                  2. Peroneus Brevis,
  Arises, by an acute fleshy beginning, from above the
middle of the external part of the fibula; from the outer
side  of the anterior spine of this bone;  as also, from its
round edge  externally, the  fibres running obliquely out-
wards towards a tendon on its external side: it sends off a
round tendon which passes through the groove at the outer
ankle, being there included under the same ligament with
that of the preceding muscle; and a little farther, it runs
through a particular one of its own.
  Inserted, tendinous, into the root and external part of
the metatarsal bone that sustains the little toe. 
256              Muscles on the Leg.
   Use. To assist the former in pulling the foot outwards,
and extending it a  little.

          Muscles on the Back of the Leg.
        1. Gastrocnemius Externus, seu Gemellus,
   Arises, by two distinct heads. The first head arises from
the upper and back part of the internal condyle of the os
femoris, and from that bone, a little above its condyle, by
two distinct tendinous  origins.  The second head arises
tendinous from the upper  and back  part of the  external
condyle of the os femoris. A little below the joint, their
fleshy bellies unite in a middle  tendon; and, below the
middle of the tibia, it sends off a broad thin tendon, which
joins a little above  the extremity of the tibia with the ten-
don of the following.

         2. Soleus, seu Gastrocnemius Internus,
   Arises by two origins. The first is from the upper and
back part of the head of the fibula, continuing to receive
many of its fleshy fibres  from the posterior part of that
bone for some space below its head.  The other origin be-
gins from the posterior and upper part of the middle of the
tibia; and runs  inwards along the inferior edge of the
popliteus  towards  the inner part of the tibia, from which
it receives fleshy fibres for some way down. The flesh of
this muscle, covered by the tendon of the gemellus, runs
down near  as far  as  the  extremity of the tibia; a little
above which the tendons of both gastrocnemii unite, and
form a strong round chord, which is  called tendo Achillis.
   Inserted into the upper and posterior part of the os cal-
cis; by  the  projection of which the tendo Achillis > at a
considerable distance from the tibia. 
            Muscles on the Back of the Leg.        257
   Use.  To extend the foot, by bringing it backwards and
downwards.

                    3. Plantaris,
   Arises, thin and fleshy, from the upper and back part of
the root of the external condyle of the os femoris, near the
inferior extremity of that bone,  adhering to the ligament
that  involves the joint in  its descent. It passes along the
second origin of the soleus, and under the gemellus, where
it sends off a long, slender, thin tendon, which comes from
between the great extensors, where they join tendons; then
runs down by the inside of the tendo Achillis.
   Inserted into the inside of the posterior part of the os
calcis, below the tendo  Achillis.
   Use.  To assist the former, and to pull the capsular liga-
ment of the knee from  between the bones. It seems like-
wise to assist in rolling the foot inwards.

     4.  Flexor Longus Digitorum Pedis, Profundus,
                      Perforans,
   Arises, by an acute tendon, which soon becomes fleshy,
from the back part of the tibia, some way below its head,
near the entry of the medullary artery; which  beginning
»s  continued  down the inner edge of this bone by short
fleshy fibres, ending in its tendon; also by tendinous and
fleshy fibres, from the outer edge  of the tibia; and between
this double order of fibres,  the tibialis posticus muscle lies
inclosed. Having passed under two annular ligaments, it
then passes through a sinuosity at the inside of the os cal-
cis;  and, about the middle of the "sole of the foot,  divides
into  four tendons, which pass through the slits of the per
foratus; and, just before its division, it  receives a consi-
derable tendon from that of the flexor pollicis longus.
  Vol. I.                 2  K 
 258              Muscles on the Foot.
   Inserted into the extremity of the last joint of the four
 lesser toes.
   Use. To bend the last joint of the toes.

                  5.  Tibialis Posticus,
   Arises, by a narrow fleshy beginning, from the fore and
 upper part of the tibia, just under the process which joins
 it to the fibula;  then passing through a perforation in the
 upper part  of the  interosseous ligament,  it continues its
 origin from the back part of the fibula next the tibia, and
 from near one  half of the  upper  part of  the last named
 bone; as also, from the interosseous ligament, the fibres
 running towards a middle tendon, which sends off a round
 one that passes in a groove behind the malleolus internus.
   Inserted, tendinous, into the upper and inner part of the
 os naviculare, being further continued to the os cuneiforme
 internum and medium; besides, it  gives some  tendinous
 filaments to the  os calcis, os cuboides-, and to the  root of
 the metatarsal bone that sustains the middle toe.
   Use. To extend the foot, and to turn the toes inwards.

            6. Flexor Longus Pollicis Pedis.
   Arises, by an acute, tendinous,  and fleshy beginning,
 from the posterior part of the fibula, some way below its
 head, being  continued down the same bone, almost to its
 inferior extremity, by a  double  order of oblique fleshy
 fibres; its tendon passes under an annular ligament at the
 inner ankle.
   Inserted into the last joint of the great toe, and generally
 ■sends a small tendon to the os calcis.
   Use. To bend the last joint of this toe.

   On the upper surface of the foot, there is one muscle;
•■viz. 
             Muscles on the Sole of the Foot.        259

           Extensor Brevis Digitorum Pedis.
  Arises, fleshy and tendinous, from the fore and upper
part of the os calcis; and soon forms  a fleshy belly, divisi-
ble  into  four portions, which send off an equal number of
tendons that pass over the upper part of the foot,  under
the tendons of the former.
  Inserted, by four slender tendons, into the tendinous ex-
pansion  from the extensor longus which covers the small
toes,  except the little one; also into the tendinous expan-
sion from the extensor pollicis, that covers the upper part
of the great toe.
  Use. To extend the toes.


           Muscles on the Sole of the Foot.
    On the sole of the foot there is a strong tendinous mem-
       brane called Aponeurosis Plantaris, which originates
       from the tuberosity of the os calcis, and proceeds for-
       ward to the toes, increasing gradually in breadth.
     It is divided into  three portions. That in the middle is
       the  largest; it protects and covers the  short flexor
       muscles, and the tendons  in the middle  of the foot.
       That on the  outside, which covers  the abductor, and
       the flexor of the little toe, is next in size. The inter-
       nal portion, which covers the abductor of the great toe,
       is the smallest.           «
    The edges of these portions dip down so as to separate
       the  muscles  they cover  from each other. They  are
       divided into five processes, corresponding  with  the
       heads  of the  metatarsal bones; each of these portions
       is divided into two bands, which are inserted into each
       side of the head of each metatarsal bone, and the ten-
       dons, nerves, and arteries, pass between them.
     Immediately under the middle portion of this aponeurosis
       are the common short flexors of the toes, viz. 
260        Muscles on the Sole of the Foot.
  1. Flexor Brevis Digitorum Pedis, Sublimis Perforatum,
   Arises, by a narrow fleshy beginning, from the inferior
and posterior part of a protuberance of the os calcis, be-
tween the abductors of the great and little toes, soon forms
a thick fleshy belly, which sends off four tendons that split
for the passage of the flexor longus.
   Inserted into the second phalanx of the four lesser toes.
The tendon of the little toe is often wanting.
   Use. To bend the second joint of the toes.

   2. Flexor Digitorum Accessorius, seu Massa Carnea
                    Jacobii Sylvii,
   Arises, by a thin fleshy origin, from most  part of the
sinuosity at the inside of the os calcis, which is continued
forwards, for some space on the same bone; also by a thin
tendinous beginning, from before the tuberosity of the os
calcis externally; and, soon becoming all fleshy, is
   Inserted into the  tendon of the flexor longus, just at its
division into four tendons.
   Use, To assist the flexor longus.

                 3. Lumbricales Pedis,
   Arise, by four tendinous and fleshy  beginnings, from
the tendon of the flexor profundus, just before its division,
near the insertion of the massa carnea.
   Inserted, by four slender tendons, into the inside of the
first joint of the four lesser toes, and are lost in the tendi-
nous expansion that is sent from the extensors to  cover
the upper part of the toes.
   Use, To  increase the flexion of the toes, and to draw
them inwards. 
             Muscles on the Sole of the Foot.         261
   On the inside of the foot, and under the common flex-
ors, are the muscles which are considered  as exclusively
appropriated to the great toe, viz.

              1. Abductor Pollicis Pedis,
   Arises, from the internal side of the tuberosity of the os
calcis, and from a ligament which extends from this tube-
rosity to the sheath of the tendon of the tibialis posticus
muscle, and also from the internal and inferior side of
this sheath.  It likewise arises from that portion of the
aponeurosis plantaris, which separates it from the short
flexor of the toes, and many of its fibres appear to be  con-
nected with the ligaments which pass  from the posterior
to the anterior bones of the foot:  as it passes under the
cuneiform bone  a portion  of  its lower surface is tendi-
nous.
   It is inseparably connected to the  flexor of the great
toe, and is inserted into the internal sesamoid bone, and the
inferior and internal part of the root of the first bone of
the great toe.
   This muscle not only separates the great toe from the
other toes, but it must increase the curvature, or arched
form of the foot.

            2. Flexor Brevis  Pollicis Pedis,
   Arises, tendinous, from the under and fore part of the
os calcis where it joins with the os cuboides, from the os
cuneiforme  externum, and is inseparably united with the
abductor and adductor pollicis.
   Inserted into  the external os sesamoideilm and root of
the first joint of the great toe.
   Use, To bend the first joint. 
262        Muscles on the Sole of the Foot.
               3. Adductor Pollicis Pedis,
   Arises, by a long thin tendon, from the os calcis, from
the os cuboides, from the os cuneiforme externum, and
from the root of the metatarsal bone of the second toe.
   Inserted into the external os sesamoideum, and root of
the metatarsal bone of the great toe.
   Use, To bring this toe nearer the rest.

   Near the outer edge of the foot, under the second por-
tion of the aponeurosis plantaris, are the muscles peculiar
to the little toe, viz.

           1. Abductor Minimi Digiti Pedis,
   Arises, tendinous and fleshy, from the semicircular edge
of a cavity on the inferior part of the protuberance of the
os calcis, and from the root; of the metatarsal bone of the
little toe.
   Inserted into the root of the first joint of the little toe
externally.
   Use, To draw the little toe outwards from the rest, and
assist in  preserving the arched form of the foot.

         2.  Flexor Brevis Minimi Digiti Pedis,
   Arises, tendinous, from the os cuboides, near the sulcus
or furrow for lodging the tendon of the peroneus longus;
fleshy from the outside of the metatarsal bone that sustains
this toe, below its protuberant part.
   Inserted into  the  anterior extremity of the metatarsal
bone, and root of the first joint of this toe.
   Use, To bend this toe. 
External Interosseous Muscles.        263
    Between the metatarsal bones are four external and three
      internal interossei: and one muscle which is common to
      all the metatarsal bones.

           Interossei Pedis Externi, Bicipites.
               1. Abductor Indicis Pedis,
  Arises, tendinous and fleshy, by two origins,  from the>
root of the inside of the metatarsal bone of the fore toe,
from the outside of the root of the metatarsal bone of the
great toe, and from the os cuneiforme internum.
  Inserted, tendinous, into the inside  of the root of the
first joint of the fore toe.
  Use.  To pull the fore toe inwards from the rest of the
small toes.
               2. Adductor Indicis Pedis,
  Arises, tendinous and fleshy, from the roots of the me-
tatarsal bones of the fore and second toe.
  Inserted, tendinous, into  the outside of the root of the
first joint of the fore toe.
  Use. To pull the fore toe outwards towards the rest.

             3. Adductor Medii Digiti Pedis,
  Arises, tendinous and fleshy, from the roots of the me-
tatarsal bones of the second and third  toes.
  Inserted, tendinous, into the outside of the root of the
first joint of the second toe.
  Use.  To pull the second toe outwards.

           4. Adductor Tertii Digiti Pedis,
  Arises, tendinous and fleshy, from the roots of the me-
tatarsal bones of the third and little toe.
  Inserted, tendinous, into the outside of the root of the
first joint of the third toe.
  Use.  To pull the third toe outwards. 
 264         Internal Interosseous Muscles.
                 Interossei Pedis Interni.
             1. Abductor Medii Digiti Pedis,
   Arises, tendinous and fleshy, from the inside of the root
 of the metatarsal bone  of  the middle toe internally.
   Inserted, tendinous, into the inside  of  the root of the
 first joint of the middle toe.
   Use. To pull the middle toe inwards.

            2. Abductor Tertii Digiti Pedis,
   Arises, tendinous and fleshy, from the inside and infe-
 rior part of the root of the metatarsal bone of the third
 toe.
   Inserted, tendinous, into the inside of the root of the
 first joint-of the third toe.
   Use. To  pull the third toe inwards.

            3. Abductor Minimi Digiti  Pedis,
   Arises, tendinous  and fleshy, from  the inside  of the
 root of the metatarsal bone of the little toe.
   Inserted,  tendinous,  into the inside of the root  of the
 first joint of the little toe.
   Use. To pull the little toe inwards.
   The common muscle,

                  Transversalis Pedis,
   Arises, tendinous, from the under part of the anterior
extremity of the metatarsal bone of the  great toe, and
from the internal os sesamoideum of the first joint, adher-
ing to the adductor pollicis.
   Inserted, tendinous, into the under and outer part of the
anterior extremity of the metatarsal bone of the little toe,
and ligament of the next toe.
   Use. To contract the foot, by bringing the great toe and
the two outermost toes nearer each other. 
ALPHABETICAL  ARRANGEMENT
OF THE
MUSCLES.
                           Page
 ABDUCTOR indicis  ma-
           nus,            242
         indicis pedis,      263
         minimi  digiti  ma-
           nus,            239
         minimi  digiti  pe-
           dis,        262, 264
         oculi,             173
         pollicis manus,     238
         pollicis pedis      261
         medii digiti pedis,  264
         tertii digiti pedis,   264
 Accelerator urinae,         205
 Adductor brevis femoris,    244
         indicis pedis,      263
         longus femoris,    243
         medii digiti pedis,  263
         magnus  femoris,   244
         metacarpi minimi
           digiti  manus,    239
         oculi,             173
         pollicis manus,     238
         pollicis pedis,      262
         tertii digiti pedis,   263
 Anconeus,                  230
 Ani sphincter,        206,  209
   levator,           207,  209
 Anterior auris,             1 70
 Arytenoideus obliquus,      192
             transversus,     id.
 Arytseno-epiglottideus,       id.
Attollens aurem,            170
Auris retrahentes,           171
Azygos uvulae,              189
Biceps flexor cubiti,	228
flpxor cruris,	252
Brachialis internus.	229
Buccinator,	178
Vol. I.	
                           Page
 Capitis obliquus superior,   222
        obliquus inferior,     id.
 Cervicalis descendens,      218
 Circumflexus, or Tensor pa-
   lati,                      187
 Clitoridis erector,          208
 Coccygeus,                213
 Colli longus,                193
      transversalis,         221
      semispinalis,          id.
      interspinales,         223
      intertransversales,     224
 Complexus,                219
 Compressor naris,           175
 Constrictor isthmi faucium,  188
           pharyngis,   189,  190
 Coraco-brachialis,          227
 Corrugator supercilii,       170
 Cremaster,                204
 Crico-arytenoideus lateralis,  191
      arytenoideus posticus,  id.
      thyroideus,           185
 Cruralis,                   251
 Cubit,or fore-arm,muscles of, 233
 Cuculearis,                214
 Cutaneus,                  181

 Dartos,                    204
 Deltoides,                  227
 Depressor anguli oris,      177
          labii inferioris,     id.
          labii superioris  a-
           laequenasi,      176
          oculi,            173
 Diaphragma,               209
 Digastricus,                182
 Dorsi interspinales,         224
      latissimus.            215
      spinalis,              217
2  I. 
266
Alphabetical Arrangement  of the  Muscles.
                            Page
Dorsi longissimus,           2is
      scmispinalis,           220
Erector clitoridis,	208
penis,	204
Extensor brevis digitorum	
pedis,	259
carpi radialis brevior,	235
carpi radialis longior,	234
carpi ulnaris,	235
digitorum communis,	id.
longus digitorum pe-	
dis,	254
ossis metacarpi pol-	
licis manus,	236
primi internodii pol-	
licis manus,	237
proprius pollicis pe-	
dis,	253
secundi internodii pol-	
licis manus,	237
Extremities superior, mus-	
cles of,	225
inferior, mus-	
cles of,	243
Eyeball, muscles of,	172
Eyelids, muscles of,	171
Faucium isthmi constrictor,	188
Flexor accessorius digitorum	
pedis,	260
brevis digitorum pe-	
dis,	id.
brevis minimi digiti	
pedis,	262
brevis pollicis manus,	238
brevis pollicis pedis,	261
longus digitorum pe-	i
dis,	257
carpi radialis,	232
carpi ulnaris,	id.
longus pollicis manus,	233
longus pollicis pedis,	258
ossis metacarpi polli-	
cis,	238
parvus minimi digiti	
manus,	239
profundus perforans,	c\ o n 400
sublimis perforatus,	id.
Gastrocnemius externus,	Page 256
internus,	id.
Gemellus,	256
Gemini,	247
Genio-hyo-glossus, Genio hyoideus, Gluteus maximus,	183 id. 245
medius,	246
minimus, Gracilis,	id. 249
Humeri os, muscles situated
  on                       228
Hyo-glossus,                184

Jaw lower, muscles of,     179
Iliacus internus,            212
Indicator,                   236
Infra-spinatus,              225
Intercostales externi,        196
             interni,         id.
Interosseus auricularis,     241
Interspinales colli,          223
         dorsi et lumborum, 224
Intertransversales  colli,      id.
                dorsi,        id.
                lumborum,   id.
Isthmi faucium constrictor,  188

Labii inferioris depressor,   176
      inferioris levator,       id.
      superioris alaeque nasi
        levator,             176
Latissimus dorsi,            215
Leg, muscles situated on,   253
Levator anguli oris,         176
        ani,             207, 209
        labii inferioris,      177
        labii superioris alae-v
          que nasi,         176
        oculi,               173
        palati,              187
        palpebrae superioris, 172
        scapulae,            220
Lingualis,                  184
Lips, muscles of,           175
Longissimus dorsi,          218
Longus colli,                193
Lumborum intertransversa-
  les,                      224 
Alphabetical Arrangement of the Muscles.
267
	Page		Page
Lumborum quadratus,	212	Palato-pharyngeus,	188
Lumbricales manus,	239	Palmaris, brevis,	237
pedis,	260	longus,	231
		Palpebrae superioris levator,	172
Masseter,	180	Palpebrarum orbicularis,	171
Mouth, muscles of,	175	Pectinalis,	243
Multifidus spinae,	220	Pectoralis major,	194
Musculus cutaneus.	181	minor,	195
Mylo-hyoideus	183	Penis erector,	204
		Perinei transversus, 205	, 208
Naris compressor,	175	Peroneus brevis,	255
Nose, muscle of,	id.	longus,	id.
		tertius,	254
Obliquus ascendens internus	201	Pharynx, muscles on the pos-	
capitis inferior,	222	terior part of it,	189
capitis superior,	id.	constrictor, 189,	190
descendens externus,	* 197	Plantaris,	257
inferior oculi,	174	Platysma myoides.	181
superior, seu troch-		Popliteus,	252
Iearis,	id.	Posterior annularis,	242
Obturator internus,	213	indicis,	240
externus,	244	medii,	241
Occipito-frontalis,	169	Prior annularis,	240
Oculi abductor,	173	indicis,	id.
adductor,	id.	medii,	241
depressor,	id.	Pronator radii quadratus,	234
elevator,	id.	teres,	232
obliquus inferior,	174	Psoas magnus,	212
» superior,	id.	parvus,	id.
Omo-hyoideus,	184	Pterygoideus externus,	181
Opponens pollicis,	238	internus,	180
Orbicularis oris,	179	Pyramidalis,	203
palpebrarum,	171	Pyriformis,	246
Oris anguli depressor,	177		
levator anguli,	176	Quadratus femoris,	247
orbicularis,	179	lumborum,	212
Palati circumflexus,	187	Rectus,	249
levator,	id.	abdominis,	202
tensor,	id.	capitis internus major,	193
  * The following account of the use of the obliquus externus abdo-
minis was by  accident  omitted, viz.  These muscles compress the
abdomen,  and therefore contribute to  the evacuation of  its contents:
if the diaphragm is in a  passive state they force it upwards, by press-
ing the abdominal viscera against  it; and thus  assist in  producing
expiration and its various modifications of coughing, sneezing, Sec.
  They bend the spine forwards, or approach the thorax tp the pelvis.
  When one acts separately, it bends the trunk obliquely to the side
on which it is situated. 
268
Alphabetical Arrangement of the Muscles.
Page
Rectus capitis internus minor, 193
            lateralis,
            posticus major,
            posticus minor,
Retrahentes auris,
Rhomboideus,
194
221
222
171
216
Sacro-lumbalis,              218
Sartorius,                   249
Scalenus anticus,            223
         medius,             id.
         posticus,            id.
Scapulae levator,             220
Semimembranosus,          251
Semispinalis colli,           221
            dorsi,           220
Semitendinosus,             251
Seminis ejaculator,          205
Serratus magnus,           195
         posticus inferior,    215
         posticus superior,   217
Soleus,                     256
Sphincter ani,          206, 209
         vaginae,           208
Spinalis dorsi,               217
Spinae multifidus,            220
Splenius,                   216
         capitis,             217
         colli,                id.
Sterno-cleido-mastoideus,    182
Sterno-hyoideus,            184
Sterno-thyroideus,           185
Stylo-glossus,                186
Stylo-hyoideus,               id.
Stylo-pharyngeus,            id.
                           Pag«
Subclavius,                 195
Subscapularis,               228
Supercilii corrugator,        170
Supinator radii brevis,       236
          longus,           234
Supra-spinatus,              225

Temporalis,                 179
Tensor palati,               187
       vaginae femoris,      248
Teres major,                226
      minor,                id,
Thigh, muscles situated on,  248
                            191
                            192
                            185
                            253
                            258
                            219
                            202
                            221
                            264
                       205,  208
Thyreo-arytenoideus,
Thyreo-epiglottideus,
Thyreo-hyoideus,
Tibialis anticus,
        posticus,
Trachelo-mastoideus,
Transversalis,
             colli,
             pedis,
Transversus perinei,
Trapezius, seu Cucularis,   21 -
Triangularis,               197
          or Sterno-costalis,  id.
Triceps adductor femoris,   243
        extensor cubiti,     230

Vastus externus,           250
       internus,             id.
Urinae accelerator,         205
Uvulae azygos,              189

Zygomaticus major,        178
             minor,         id. 
SYSTEM  OF ANATOMY.

             PART  III
OF  THE  LIGAMENTS  AND  MEMBRANES AVHICH
  CONNECT  THE DIFFERENT  PARTS OF  THE
  BODY  TO  EACH  OTHER--AND OF  THE  AR-
  TICULATIONS.


                  CHAPTER I.
            OF LIGAMENTS IN GENERAL.

THE tendons and the strong membranes connected with
them  called  aponeuroses; the fascia which  bind  down
some of the muscles and afford an origin to many of their
fibres;  and the membranes which confine the tendons,
appear to be composed of the  same substance.
  They consist of fibres which are flexible but extremely
strong, and in general have but little elasticity; their sur-
faces are smooth and polished; their colour is whitish
and silverlike.
  The vessels  which enter into their composition do not
commonly  carry red blood; and although it seems certain
that they must have nerves, many very expert anatomists
have declared that no nerves could be traced into them. 
270           Of Ligaments in General.
   In  a healthy state they  are entirely void of sensibility,
and can  be cut and punctured, or corroded with caustic
applications, without pain. When  inflamed, they are ex-
tremely painful.
   The ligaments, which connect the different bones to each
other, have a very strong resemblance to these tendinous
parts, not only in their structure but in  their qualities
also.  Many of them appear rather more firm in  their
texture and more vascular.  Their vessels are also larger:
their colour sometimes inclines to a dull white, and when
examined chemically, they appear to differ in some res-
pects  from tendons.
   They agree however with the tendinous parts as to their
insensibility in a sound state, and the extreme pain which
occurs when  they are  inflamed.  No nerves  have been
traced into their structure.
   Notwithstanding the ordinary  insensibility of  these
parts, it was asserted by M. Bichat  that several animals
who seemed to suffer no pain from  cutting, puncturing,
or corroding the ligaments of their joints, appeared to be
in great agony when these parts were violently stretched
or twisted; and he declared this to be the case when all
the nerves which passed  over  the ligaments, and  could
have  been affected by  the process,  were cut away. He
explained by this the pain  which sometimes occurs instan-
taneously in sprains, in the reduction of luxations, and
in other analogous processes.
   The ultimate structure of these parts is perhaps not
perfectly understood.
   An anatomist of the highest authority, Haller, appears
to have considered them as formed of membrane,  while
a late  writer who has paid great attention to  the subject,
and is also of high authority, M.  Bichat, has satisfied
himself that their structure is essentially fibrous. 
              Of Ligaments in  General.           271
  If a tendon, or a portion  of  tendinous membrane, be
spread out, or forcibly extended, in a direction which is
transverse with respect to its fibres, it will seem to be con-
verted into a fine membrane, and the fibres will disappear
to the naked eye.  The same circumstances will  occur
when a ligament is treated in a similar  way; but  much
more force is required.
  Thus constructed, these parts are perfectly passive por-
tions of the animal fabric, and  have not more  power of
motion than the bones with  which many  of  them are
connected.
   But notwithstanding their ordinary insensibility, they
often induce a  general violent  affection of  the system,
when they are diseased. A high degree  of fever, as well
as severe pain, attends their acute inflammations; and hec-
tical symptoms, in their greatest extent, are often induced
by  their suppurations.
   There is another circumstance in their history which is
very difficult to reconcile with their ordinary insensibility.
They are the most common seats of gouty painful affec-
tions.
   In these  cases, pain does  not seem to be the  simple
effect  of  inflammation; it often occurs as the first  symp-
tom of the disease; it frequendy exists with great  vio-
lence for  a short time and goes off without inflammation;
and it is frequently vicarious with affections  of the most
sensible and irritable parts.
   Parts of a tendinous and ligamentous structure do  not
 appear retentive of life, but lose their animation very
readily, in consequence of the inflammation and other cir-
cumstances which attend wounds.
   When  thus deprived of life, they retain their usual
 appearance and their texture  a  long  time.  The dead 
 272           Of Ligaments in General.
 parts separate from the living in large portions, in a way
 which has a considerable analogy with the  exfoliation of
 bones.
  The tendons and their expansions, and the various fascia,
 have  the  same chemical composition.  If  boiled a  long
 time, they dissolve completely, and  form the substance
 called by chemists,  gelatine, or pure glue.
  The  ligaments  differ from them in some respects.
 When boiled they yield a portion of gelatine, and do not
 dissolve entirely; but  are said to retain their form and
even their strength, after very long boiling.  The composi-
tion of the part so insoluble in water, has not yet been
 ascertained. 
273
                   CHAPTER  II.
A GENERAL ACCOUNT OF ARTICULATIONS AND OF BURS.E
                      MUCOSA.

                    SECTION  I.
                  Of Articulations.
 1 HOSE surfaces of bones which form the movable arti-
culations are covered  with  cartilaginous  matter, which
has been already described.*  They  are retained in their
relative situations by ligaments, such as have been lately
mentioned, which are exterior to  the cavities of the arti-
culations, and placed in such situations that they permit
the motions the joints are calculated  to perform, while
they keep  the  respective bones  in their proper  places.
They are invested in  a particular manner by a thin deli-
cate membrane, which in some joints, as those of the hip
and shoulder, seems to be the internal lamen of a stronger  ,
ligament called the capsular;  and  in other joints, the knee
for example,  appears  to be  independent  of any  other
structure.  In each case, this synovial membrane, as it has
lately been called, forms  a complete sack or bag, which
covers the articular surface of one bone, and is reflected
from it to the corresponding  surface of the  other; adhe-
ring firmly to  each of the articulating  surfaces, and  ex-
tending loosely from the margin of one surface to that of
the other.
  In this distribution it supplies  the place of perichon-
drium to the cartilages, and of periosteum to those surfa-
ces of bone with which it is connected.
                     « See page 4.
  Vol.  I.              2 M 
274          Of Articulations in general.
   It seems greatly to resemble the membranes which line
the abdomen and thorax, and invest the parts contained
in these cavities; and like them it may be termed a reflect-
ed membrane.
   It is thin and very flexible, but dense and strong.
   It secretes, or effuses from its surface, a liquor called
synovia; which is particularly calculated to lubricate parts
that move upon each other.
   This fluid is nearly transparent: it has the consistence
of a thin syrup, and is  very tenacious  or ropy. It mixes
with cold water, and when  heated  becomes  milky, and
deposits some pellicles without losing its viscidity. It ap-
pears to be composed of eighty parts  in one hundred of
water; above eleven parts of fibrous matter; and between
four and five parts of albumen.  It also contains  a  small
portion of soda,  of muriate of soda,  and of phosphate
of lime.
   There are in many of the joints  masses of fat which
appear to project into the cavity, but are exterior to the
synovial membrane, and covered by it; as the viscera in
the abdomen are covered by the peritoneum.
   They are generally situated so as to  be pressed gendy,
but not bruised, by the motions of the bones.
   In some joints they appear like portions of the common
adipose membrane;  in others they appear more vascular,
and have a number of bloodvessels spread  upon them.
Small processes  often  project  from  their sides  like
fringe.                      '
   These masses have been considered as synovial glands;
but they do not appear like glands; and it is probable that
the synovia is secreted  by the whole internal surface of
 membrane.
   The synovial membrane,  like  the other parts of joints. 
                   Of Bursa Mucosa.              275
 is insensible in a sound state,  but extremely painful when
 inflamed.  The synovia which is secreted,  during the
 inflammation  of this membrane, has a purulent appear-
 ance.

                    SECTION II.
                 Of Bursa Mucosa.
   THERE are certain membranous cavities called bursa
 mucosae, which are found  between tendons  and bones,
 near the joints, and in other places also; which have so
 strong a resemblance to the synovial membrane,  and are
 so intimately  connected with some of the articulations,
 that they ought tow to be mentioned.
   They are formed of a thin dense membrane, and are at-
 tached to the surrounding parts by cellular substance;  they
 contain a fluid like the synovia;  and sometimes there are
 masses of fat, which although exterior to them, appear to
 project into their cavities.
   There is commonly a thin cartilage, or tough  membrane,
 between them  and the bone on which they are placed.
   They often communicate with the cavities of joints,
 without inducing any change in the state of the part.
   As they are always situated between parts that move
 upon  each other, there is the greatest reason to believe
that they are intended to lessen friction.*
   These bursae mucosas are very numerous, as will appear
 from a subsequent account of them.
   Several of them are very interesting on account of their
connexion with very important joints.
  * For further information respecting this subject, as well as joints in
general, the reader is referred to a Description of the Bursae Mucosae
of the Human Body, by Alexander Monro; to whom the world is so
much indebted for the elucidation of many important point* in anatomy
»nd physiology 
276
                  CHAPTER  III.

           OF PARTICULAR ARTICULATIONS.

     The Connexion of the Head zvith the Vertebra.

 1 HE condyles  of the occipital bone,  and  the corres-
ponding  cavities  of the atlas, are covered with cartilage.
The condyle and  cavity on each side are invested with a
synovial ligament, as described in the general account of
articulations.
   An anterior ligament descends from the front part of
the great occipital foramen, and is inserted into all the front
part of the atlas,  between its articulating processes. That
portion of this ligament which is in the  middle, and in-
serted into the tubercle of the atlas, appears stronger,  and
is distinct from the rest of it.
   A posterior ligament passes from the posterior margin
of the occipital foramen to the upper edge of the posterior
arch of the atlas.
   From  each  side of the upper end of the toothlike pro-
cess of the vertebra dentata, a ligament passes upwards
and outwards, to be inserted into the internal side of the
basis of each condyle of the occipital bone.
   From the anterior margin of the great occipital fora-
men, a ligament  passes down on the inside of the  verte-
bral cavity, over  the toothlike process,  which is inserted
in the body  of the vertebra dentata  and the ligaments
connected with it.
   There is also a ligament  which runs across from  one
side of the atlas to the other, to confine the toothlike  pro- 
Particular Articulations.
277
cess in its anterior cavity.  This  ligament adheres above
to the occipital bone,  and below to the body of the ver-
tebra dentata. The anterior surface of the toothlike pro-
cess plays on the anterior arch of the atlas; the posterior
surface plays on this ligament. A synovial capsule is pla-
ced on each surface of the toothlike process.
  The articulating surfaces of the oblique processes of the
atlas and vertebra dentata on each  side, are invested by a
synovial membrane.  There are  also additional ligaments
placed before and behind these processes, that have an ef-
fect on their motions.
     The uses of these different ligaments are very  obvious
      when  they are dissected. The transverse ligament of
      the atlas, with the synovial membranes, forms an arti-
      culation for the toothlike process, which is of a peculiar
      kind. The ligaments that pass  from this process, to  the
      bones of the condyles of the occipital bone, must have
      an effect in restraining the rotation of the head and at-
      las on this process, and therefore have been called mo-
      derator ligaments.

     The Articulations oft/ie Vertebra with each other.
  To acquire a perfect idea of  the construction of the Spine,
     it is necessary to examine  at least two preparations of it;
     in one of which the bodies of the  vertebrae should be
     sawed off from the processes, so  that the spinal canal may
     be laid open.
   The bodies  of all the vertebra, except the atlas,  are
connected to each other by the intervertebral cartilaginous
matter described in page 72, which unites them very firm-
ly, at the same time that it allows of some motion, in con-
sequence of its elasticity  and compressibility. This con-
nexion is strengthened by two ligaments, which  extend 
  '278          Articulations of the Vertebra.
  the whole length of the spine,  from  the second cervical
  vertebra to the sacrum.
    The first of these, denominated the anterior vertebral
  ligament, covers a considerable part  of the anterior sur-
  face of the  bodies  of the  vertebrae;  it is thickest in the
  middle, and varies in its breadth, in different parts of the
  vertebral column; it adheres very firmly to -the interver-
  tebral substance,  and not so  firmly to the  bodies of the
  vertebrae. It  has the shining silverlike appearance of ten-
  don, and seems to consist  entirely of longitudinal fibres.
  There  are many fibres which appear to be connected with
 it, that do not extend the whole length of the spine.
   On the posterior surface of the bodies of the vertebras,
 in the cavity which contains the spinal marrow, is the pos-
 terior or internal vertebral ligament, which like the ante-
 rior, extends from the upper  part of the spine to the sa-
 crum.
   In its progress downwards it  is broader  where it is in
 contact with the intervertebral matter, and narrower about
 the middle of each  of the bodies of the vertebrae. It ap-
 pears to consist of  longitudinal  tendinous  fibres, which
 are similar to  those of the anterior ligament.
   The  oblique processes of the vertebras are covered with
 cartilage, and are invested with a  synovial  membrane,
 like  the other movable  articulations.  In  the neck and
 back these membranes are thin  and delicate; but in the
 loins  they are blended  with  ligamentous fibres, which
 give them additional strength.
   Some of the most curious and  interesting ligaments of
the spine, or indeed  of the body, are those which are at-
tached to the bony  plates or arches  that  extend from
the oblique to the spinous processes  of each vertebra.
These plates form a great portion of the posterior part of 
             Articulations of the Vertebra.         279
the vertebral canal; and the vacant spaces between them
are filled up by these  ligaments, which  extend from the
plates of each upper vertebra to those of the next vertebra
below.
  They are situated  between the spinal process and the
oblique processes on each side.
  There are,  therefore, two distinct ligaments between
the two vertebrae,  one on each side of the spinal process,'
and as they extend only from the plates or arches of one
vertebra to those  of  the other, they must necessarily be
very short. They are much more conspicuous on the in-
ternal surface of the vertebral cavity than they are exter-
nally.  They are thick and substantial, and very elastic;
their colour resembles that of yellowish adeps; and from
that circumstance they  are called by  some  anatomists
the yellow ligaments.  They complete the  cavity for the
spinal  marrow.
   As  the plates or arches to which they are connected
must recede from each other, when the  spine is bent for-
wards, it seems necessary that they should be elastic.
   There are also ligaments between the spinous processes,
which extend from the under surface of one spinous pro-
cess to the upper surface of the spinous process below it.
These are composed  of tendinous shining fibres, and are
sufficiently loose to permit the anterior flexure of the ver-
tebral column.  From  their situation they are denominated
interspinal ligaments.
   There is also a thin  and narrow ligamentous band, which
extends from the spinous process of the  seventh cervi-
cal vertebra to  the spinous processes of the os sacrum,
and adheres to the ends of the intermediate spinous pro-
cesses. It is exterior  to the tendinous origins of the tra-
pexii and latissimi dorsi muscles. The upper portion is 
 280        Articulation of the Lower Jaxv.
 slightly connected to the trapezius the lower part adheres
 more firmly to the'latissimus dorsi.
   The ligamentum  nucha, as it has  been denominated,
 is a narrow but firm strip, which extends from the spinous
 process of the last cervical vertebra, to the occipital bone,
 at or near its protuberance. That portion of the trapezius
 muscle, which is between the occipital bone and the se-
 venth cervical vertebra, originates from it,  or is intimately
 connected with it; and a portion of the splenius muscle is
 also connected with it.
   From the internal surface of this ligament, a thin ten-
 dinous  membrane arises,  whose fibres run obliquely up-
 wards and forwards, and are inserted into the spinous pro-
 cesses of each of the cervical  vertebrae above the seventh,
 and also  into the atlas  and the os occipitis. Attached to
 the ligamentum  nuchae and to the spine, this membrane
 seems like a partition between the muscles which  lie on
 each side of the back of the neck.
     After inspecting the different ligaments of the spine, it
      will be obvious that the yellow ligaments are among the
      most important of them, in consequence of their posi-
      tion, their strength, and their elasticity.

            Articulation of the Lower Jaw.
  The  glenoid cavity of  the temporal bone with the tu-
bercle before it, and the condyle of the lower jaw, are co-
vered with cartilages. A cartilage is placed between them,
which being flexible, is accommodated  to the convexity of
the condyle and hollowness of the glenoid cavity, and also
to the figure of the aforesaid tubercle  to which  it is ex-
tended.  A synovial capsule  or bag invests the glenoid
cavity and the tubercle, and covers the upper surface of
the cartilage. A second capsule of the same kind is attach- 
         A rticulation of the Clavicle and Sternum.    281
 ed to the condyle of the lower jaw and the lower surface
 of the cartilage. A few ligamentous fibres extend from the
 circumference of the cavity and tubercle of the temporal
 bone, over both synovial capsules and the cartilage between
 them, to the lower jaw below the condyle, and appear to
 be attached to the cartilage.
   These fibres are collected in such numbers, on the ex-
 ternal and internal sides of the articulation, that they have
 been called the external and internal lateral ligaments.
   Another  ligament  is mentioned which arises from the
 styloid process of the temporal bone,  and is inserted into
 the lower jaw near its angle;  but this seems rather appro-
 priated  to the stylo-glossus muscle than to this articula-
 tion.
   In consequence of this structure, the condyle of the lower
jaw moves  out of the  glenoid cavity upon the tubercle,
 when the mouth is opened widely.

         Articulation of the Clavicle and Sternum.
   The connexion of  the clavicle  and sternum resembles
 strongly that of  the  lower jaw and  temporal bone. A
 movable cartilage is placed between the articulating  sur-
 faces, with a distinct synovial capsule on each side of it,
 applied in the usual manner to  the corresponding surface
 of the clavicle and of the sternum. Exterior to these cap*
 sules and the intervening cartilage, are many ligamentous
 fibres, which are most numerous on the anterior and pos-
 terior surfaces, but  diverge from each  other as they pro-
 ceed from the clavicle to the sternum,  and are therefore
 called Radiated Ligaments.
   There is  a strong ligament, called the Interclavicular,
 which passes across the sternum internally, from one cla-
 vicle to  the other*
   Vol. I.                2 N 
 282         Articulation of the Shoulder.
   And another ligament, which arises from the interior
 rough surface of the clavicle, near the sternum, which is
 inserted into the cartilage of the  first rib.  This is called
 the  Rhomboid, or Costo clavicular ligament.

         Articulation of the Clavicle and Scapula.
   The small surfaces of the clavicle and scapula which are
 in contact with each other, are furnished with the appara-
 tus  of a  movable articulation.   They are  covered with
 cartilage, and are invested with  a small synovial capsule.
 The upper and lower surfaces of the extremities of the
 clavicle and acromion are covered by a ligamentous mem-
 brane, which is called, from its situation, the superior and
 inferior ligament of this articulation.  But these bones are
 more firmly connected by the ligament which passes to the
 coracoid process of the scapula from the under side of the
 clavicle,  and is  very strong. Some of the  fibres which
 compose this ligament are so arranged that they have the
 appearance of an inverted cone: the remaining fibres ap-
 pear like another ligament, and therefore they have been
 called the Trapezoid and Conoid ligaments.
  By their situation and strength they are enabled  to re-
 tain  the bones in their proper  relative positions, at the
 same time that they permit a peculiar  rotatory motion.

       Articulation of the Os Humeri and Scapula.
  The spherical portion of the upper  extremity of the os
 humeri is the part of that bone which  is  principally con-
 cerned in  the articulation, and is covered  with cartilage;
 as is also the glenoid cavity of the scapula.
  The glenoid cavity of the scapula, which is so small in
trie dried bone when compared with the  head  of the os
humeri, is enlarged by the long tendon of the biceps mus- 
               Articulation of the Shoulder.          283
 tie, which is attached to the upper edge of its margin, and
 then divides and passes down on each side of the cavity,
 increasing the  breadth of it considerably.  It appears to be
 blended with  the cartilage that lines the cavity, and also
 with the capsular ligament which is exterior to it.
   The articulating surface, thus composed, is  perfectly
 regular and uniform.
   The synovial ligament in this articulation, is so blended
 with an external stronger ligament that it cannot be sepa-
 rated in the recent subject;  but notwithstanding, it is ap-
 plied to the articulating surfaces in the same way that it
 is applied to  the other joints forming a  capsule. The
 stronger exterior lamen is of course only applied  to  that
 part of the synovial capsule which proceeds from the mar-
 gin  of one cartilaginous articulating surface to the other;
 it appears to be most intimately connected with  the peri-
 osteum, and is  rendered more firm and thick in particular
 parts by the addition of fibres from the tendons of the su-
 pra  and infraspinatus,  and  subscapularis  muscles  with
 which it is blended.
   It arises from the scapula at a small distance from the
 margin or edge of the glenoid cavity, as formed by the
 tendon of the biceps, and is inserted into the os humeri at
 a small distance from the edge of the cartilaginous articu-
 lating surface; and if dissected away from the bones, would
 appear like a cylindrical bag with both extremities open.
  The long tendon of the biceps  muscle, in the groove at
 the head of the os humeri, appears  to penetrate this liga-
 ment, but it is not within the cavity of the synovial mem-
 brane; for this membrane sends down a process  like  the
 finger of a glove, which lines the groove, and is  reflected
from its surface upon the surface of the tendon,  and  co-
vers  it during  its whole extent, being reflected from the 
284.           Articulation of the Elbow.
tendon, at its upper termination, to the adjoining surface:
so that the tendon is in fact outside of the synovial capsule,
which, xiiu'refore, confines the synovia completely.
   Tr is capsular ligament, which is one of the strongest,
would not avail much in keeping the bones in their proper
situations, if the muscles and their tendons were not dis-
posed in such a manner that, when the muscles act, their
power is excited to the same effect.  In some cases of pa-
ralytic affection, where the muscles exert no influence, the
weight of the arm, when it is allowed to hang without sup-
port, draws  the head of the os humeri below the glenoid
cavity, notwithstanding the  capsular  ligament.  At the
same  time it ought to be observed, that this ligament must
be lacerated in every case of complete luxation of the os
humeri, as it cannot possibly distend sufficiently to permit
the separation of the bones to the  extent which then takes
place.

             The Articulation of the Elbow.
  Those surfaces of the os humeri, ulna, and radius, which
move upon each other, are covered with cartilage.
  The motion of the ulna and radius on the os humeri is
that of simple flexion and extension. The cylindrical head
of the radius performs a part of a revolution, nearly on its
own axis, without moving from the depression  in the side
of the ulna, with which it is  in contact.
   The synovial membrane adheres very firmly  to the sui *
fece covered with cartilage on each of  the bones, and is
reflected from the margin of this surface on one bone, to
that of the others. As the principal motion performed is
hingelike, the principal ligaments are on the sides. There
is also a circular ligament, which arises from the ulna and
invests the narrow part of the radius immediately below 
               Articulation of the Wrist.            285
its cylindrical head, like a loop, to confine the radius  in
contact with the ulna, and at the same time permit its mo-
tion.
  This ligament is so blended with the synovial membrane
that it sometimes cannot be separated from it.
  The lateralligaments are denominated from their origin
and insertion, Brachio radial, and Brachio cubital, or Inter-
nal and External. The ligament which invests the neck of
the radius is called Coronary, or Orbicular.
  There are also some ligamentous bands, which run up-
on  the front and back parts of the joint to strengthen it,
which are called  Anterior and Posterior accessary  liga-
ments. Within the synovial membrane, in the  upper mar-
gins of the depressions for the olecranon and coronoid pro-
cesses of the ulna,  are the adipose substances usually
formed in joints.

               Articulation of the Wrist.
    The structure of the wrist is particularly complex, he-
       cause it consists of three articulations, which are con-
       tiguous to each other, viz. That of the ulna and radius;
       of the radius and first row of carpal bones; and of the
       first and second row of carpal bones with each other.
   An oblong convex head is formed by the upper surfaces
of  the scaphoides and lunare, and a portion of the upper
surface of the cuneiform bone. This head is covered by
one cartilage, which is so uniform that the different bones
cannot be distinguished from each other. The lower end
of  the radius is articulated with this head, but does not
cover the whole of it; a portion of it therefore is under the
ulna, but not in contact with  that bone; for the cartilage
which lines the  concavity of the radius is continued be-
yond the radius, so as to cover the remainder of the head. 
286           Articulation of the Wrist.
The  lower end of the ulna is in contact with the upper
surface of this cartilage, and is articulated laterally with
the semilunar cavity of the radius. This semilunar  cavity
is lined by a cartilaginous process, continued from the up-
per surface of the aforesaid cartilage; so that the extremity
and the side of the ulna play upon the cartilage continued
from the radius. This articulation of the ulna and radius
is distinct from that of the radius and carpus.
  A synovial membrane covers the articulating head form-
ed by the three bones of the carpus, and is reflected from the
margin of their cartilaginous surface, to the cartilage at the
end of the radius.  A plait or fold of this membrane passes
from the  head of the carpus, at the  junction of the sca-
phoides and lunare, to the opposite part of the  cartilage of
the radius, and has been called the Mucous ligament.
  A strong ligament is placed on the internal  side of this
articulation, which arises from the styloid process of the
ulna, and  is inserted into the anterior transverse  ligament
which confines the flexor tendons, and into the  ligament of
the pisiforme.
  Another ligament, on the  external side, arises from the
styloid process of the radius, and is inserted into the sca-
phoides, some of its fibres being continued into the afore-
said transverse ligament, and the trapezium.
  There are two broad irregular ligamentous membranes,
one of which arises from the anterior margin of the articu-
lating surface of the radius, and the other from the poste-
rior margin; one of them is inserted anteriorly, and the
other posteriorly, into  the margin of the corresponding
surface of the  scaphoides, lunare, and cuneiforme. They
adhere to  the synovial membrane, but in some places this
membrane appears through  apertures which are  in them.
  The surfaces bv  which the first and  second  rows of 
          Of the Carpal and Metacarpal Bones.      287
carpal bones are articulated with each other, are very ir-
regular. The magnum and part of the unciforme form  a
prominent oblong head, on each side of which is a much
lower surface, formed by the trapezium and trapezoides
externally, and the remaining portion of the  unciforme
internally.*
  The scaphoides, lunare, and cuneiforme, form a cavity
which correspond  with this head, and also with the lower
surface formed by the unciforme; while another surface of
the scaphoides is articulated with the trapezium and tra-
pezoides. These corresponding surfaces, formed by the
two rows of carpal bones, irregular as they are, compose
but one articulation, which is capable of a limited flexion
and extension. It has  a synovial membrane, with two late-
ral ligaments, and an anterior  and posterior ligament;
these last, however, are short, and can be best examined
from within, by cutting open the articulation.
   The bones of each row  move laterally upon each other.
Their lateral surfaces, which are in contact, are covered
with cartilage; and the synovial sack which exists between
the first  and second row of bones, sends off processes be-
tween these surfaces, which are disposed like the ordinary
synovial  membranes  in other articulations; adhering to
each of the cartilaginous surfaces, while they communicate
with the larger cavity between the two rows.

     Articulation of the Carpal and Metacarpal  Bones,
   The metacarpal bones are connected to the last row of
the carpus by surfaces which are covered with cartilages,
and supplied with synovial membranes as the most mova-
ble articulations are; but the ligaments which connect these
s The palm of the hand is supposed to present for^vd 
 288           Articulation of the Finger.*.
 bones do not permit much motion between  them. The
 irregularity of the  articulating surfaces of the metacarpal
 bones of the index and middle finger also contribute to re-
 strain their motion; and these  bones accordingly move less
 than  the other two metacarpal bones, whose surfaces are
 better calculated for motion.

              Articulation of the Fingers.
   The first joint of the fingers has a large synovial mem-
 brane, which invests the head  of the metacarpal bone and
 the corresponding  cavities of the bones of the first pha-
 lanx.  On each side  is a strong lateral ligament, which ari-
 ses from the side of the head  of the metacarpal bone and
 is inserted into the  side of the base of the  first phalanx.
  Anteriorly there is also a ligament, which, although thick
 and strong, is very  flexible: posteriorly  the  expansion of
 the tendons of the extensor muscle, and the tendons of the
 interossei,  have the effect  of a  ligament.
   The different phalanges are articulated  with each other
 in a similar manner. The lateral ligaments  are very strong:
 the tendon of the  extensor covers the articulation poste-
 riorly; and anteriorly, under the flexor tendons, there is
 a soft, but  thick ligamentous  substance. The  metacarpal
 bone of the thumb differs greatly from the other metacar-
 pal bones in its articulation with the wrist, as respects its
 motions. The articulating surfaces are calculated for late-
 ral motion as well as flexion and extension; and there are
 no ligaments which  prevent it.  The first joint of the thumb
 resembles considerably that of the fingers,  and the second
joint resembles the  last of the  phalanges. 
Hip Joint.
289
                Articulation of the Ribs.
   The ribs are connected to the bodies of the vertebrae
 and the intervertebral cartilages, by one articulation, and
 to  the  transverse processes of the vertebrae by another:
 these articulations have the  ordinary apparatus for motion,
 with capsular ligaments, which in one case pass from the
 heads of the ribs to the bodies  of the vertebrae, and in the
 other from the tubercles to the transverse processes. They
 are  also secured in  their  positions by ligaments which
 arise from  the  transverse  processes,  and are called the
 Internal and External Transverse ligaments; and  also by
 ligaments which arise from the oblique processes. These
 ligaments permit the motions  necessary for respiration,
 and restrain all othe rs
  The connexion of the ribs  anteriorly with their cartilages
 is such as admits of no motion whatever between  them;
 but the extremities of the cartilages are articulated with
 the sternum, at the pits on the edges of that bone. In many
 instances there is no appearance of synovia between the
 ends of the  cartilages and  the sternum; but this  fluid is
 mostly  to be found in the pits, on the  lower extremity of
 the sternum.

                    The Hip Joint.
  The acetabulum is lined with cartilage; and the brim or
 margin of it is much enlarged, and the cavity deepened, by
 the addition of fibrous cartilaginous matter, which forms a
 regular smooth edge.  This cartilaginous ring is continued
 across the upper part of the notch in the acetabulum; so
 that it completes the  circular margin  of the  cavity, but
leaves the under part of the notch open. The head of the
os femoris is  covered with cartilage; but the depression in
 it is still visible. From  this  depression a strong ligament
  Vol. I.                 2 0 
290                 Hip Joint.
arises, which appears to pass into the depression, near the
center of the acetabulum; but actually terminates in the
lower edge of the cartilaginous ring or margin, where it
crosses over the notch, and not in the bone. The thin mem-
brane with which this ligament is invested extends to the
center of the acetabulum, and has given rise to the opi-
nion that the ligament was inserted in  the bottom of the
acetabulum.  There is therefore an  analogy between the
termination of this ligament and that  of the long tendon
of  the biceps flexor  cubiti,  at the  glenoid cavity of the
scapula.*
   This ligament allows the head of the os femoris to rise
out of the acetabulum; but  it is  probably  torn in every
luxation of the os femoris.
   The capsular ligament, which contains these articula-
ting parts, is the strongest in the  body. It  arises around
the acetabulum, near the basis of the  cartilaginous brim;
but it does not adhere to the cartilaginous edge; and it is
inserted into the os femoris, near the roots of the trochan-
ters,  so that it includes  a large portion of the neck of the
bone. It is not every where  of the same thickness and
strength; for, in various places, there are additional liga-
mentous fibres.  The largest portion of these  additional
fibres appears to arise from the inferior anterior spinous
process of the ilium.
   The synovial membrane forms the internal lamen of this
ligament: it  invests the articulating surfaces in the usual
manner, and being reflected from the internal surface of
the capsular ligament to  the neck of the os femoris, it is
in  the place of periosteum to that part of the bone.
   It  seems  probable that this membrane is so reflected
* See page 283. 
                       Knee Joint.                 291
 and arranged, that the internal  ligament is covered  by it
 also; and, of course,  that this ligament is exterior to the
 synovial membrane.
   There is  a considerable quantity of adipose matter,
 near the termination of the  aforesaid internal ligament,
 which is also exterior to the synovial membrane :* some of
 this can be pressed out of the acetabulum, at the vacuity
 in the notch under the cartilaginous margin.

                Articulation of the Knee.
   The synovial membrane of the knee joint  is, in some
 places, without the  support of a proper capsular ligament,
 or external lamen; so that it is easier distinguished in this
 articulation than in  many others.
   It adheres firmly  to the cartilaginous surfaces of the os
 femoris, tibia, and patella, and is reflected in the usual
 manner, from one to the other of these surfaces. It arises
 closely from the edge  of the  cartilaginous surface at the
 top of the tibia; but on the anterior part of the os femoris,
 it is continued to some distance from the  margin  of the
pulleylike surface,  and the edges of the  condyles.   On
 each of the portions of the cartilaginous surface of the ti-
bia is  a  cartilage of a semilunar form, so  placed, that  its
convex edge rests on the margin of the cartilaginous sur-
 face; and its  concave  edge is internal. These cartilages
 are thick at their external, and very thin at their internal,
edges; so that they form two superficial concavities on the
top of the tibia.
  Their extremities are attached by ligaments to the cen-
tral  protuberance of the tibia;  and their anterior extremi-
ties are also connected by a ligament to each other.
  The synovial membrane is  so  reflected as to cover the
whole surface of  these  cartilages,  except the exterior 
292                 Knee Joint.
edge, which  is connected with the external ligaments of
the articulation.
   The use of these cartilages is evidently to form conca-
vities on the top of the tibia, for accommodating the con-
dyles of the os femoris: and, upon examination, they will
not appear so anomalous as they are at first view; for there
is a considerable analogy between them and the cartilagi-
nous edges of the glenoid cavity, and of the acetabulum.
   The patella appears to project into the cavity of  the
joint; and its internal surface is  very prominent: around
the margin of this surface, and especially at the under part
of it, the adipose substance found in joints is very abundant.
On  each  side of the adipose mass, under the  patella, is a
plait of the synovial membrane, called ligamentum alare
minus, and majus; and a process of the membrane, called
hgamentum mucosum, passes from the neighbourhood of
the adipose mass to the os femoris between the condyles.
   These processes retain the adipose substance in its pro-
per place, during the motions of the joint.
   There are two very strong ligaments, called the crucial,
which arise from the middle protuberance of the tibia, one
of which is inserted posteriorly into the external condyle,
and the other into the internal.  These ligaments decus-
sate each other partially; on which account the name cru-
cial is applied to them. They are in a state of tension when
the leg is  extended, and prevent it  from moving further
forward:  when it is bended they are relaxed. They  add
greatly to  the strength of the  connexion between the os
femoris and tibia.
   These  ligaments are generally supposed to be in the
cavity of the joint; but the synovial membrane is reflected
round them in such manner that they are exterior to it.
   In addition to the crucial ligaments, this articulation has
the following external supports. 
         Articulation of the Tibia and Fibula.       293
   1. Two strong lateral ligaments, one on each side of the
knee. The external of which arises from the tubercle above
the external condyle of the os femoris, and is attached to
the fibula  a  little below its head; and the internal, from
the upper part and tubercle of the internal condyle, and is
inserted into the upper and inner part of the tibia.
   2. The posterior ligament, whose  fibres run obliquely
from the external condyle to the back part of the internal
side of the head of the tibia.  This ligament also prevents
the leg from being drawn too far forwards.
   When the leg  is extended, these ligaments are tense:
they therefore  prevent rotation  in  the  extended  state.
When the leg is bent, they are relaxed, and therefore ad-
mit of that motion.
   3. The connexion of the tendons of the extensor muscles
of the leg, with this articulation, has a great effect upon
it. Their insertion into the patella places them in the situ-
ation of the upper part of an anterior ligament, of which the
very strong ligament, that passes from the lower margin
of the patella to the tubercle of the tibia, is only the lower
portion; while the patella may be considered as an indura-
ted part of the ligament.

          Articulation of the Tibia and Fibula.
   The surfaces of the upper extremities of the tibia and
fibula, which are articulated with each other, are very small.
When the  bones are in their natural position, these sur-
faces are nearly horizontal: that of the tibia looking down,
and  that of the fibula looking up: they are covered  with
caniLiges, and have a synovial membrane. This^articula-
tion is supported by some ligamentous fibres, which have
been called anterior and posterior ligaments;  but  it  is
Strengthened by the external lateral ligament of the knee, 
 294        Articulation of the Leg and Foot.
 and by the tendon of the biceps muscle which is inserted
 into the upper end of the fibula.
   Attheir lower extremities, the cartilaginous crust, which,
 on each of them, forms part of the articulating surface with
 the astragalus, is turned up on their lateral surfaces, which
 are in contact with  each other; so that a small portion,
 (equal in breadth only to one-sixth of an inch) of the con-
 tiguous  surfaces, is covered with cartilage:  the  other
 parts  of  these surfaces, which are very considerable, are
 attached  to  each  other by the intervention of fibrous or
 membranous matter; and there is very little motion of the
 bones on  each other.
   There are very strong external ligaments, anteriorly and
 posteriorly, which connect the fibula to the tibia; and from
 the  posterior end of the fibula a small  short ligament
 passes to the nearest part of the tibia, which resembles the
 margins of the  glenoid cavity and acetabulum; for it en-
 larges the articulation with the astragalus, while it serves
 as a ligament of the tibia and fibula.

            Articulation of the Leg and Foot.
   It should be  observed that the  tibia and fibula are so
 firmly connected with each other below, that they may be
 considered as forming but one member of this articulation.
   The varied surfaces formed by the tibia and  fibula, and
 by  the astragalus, when it is contiguous to them, are in-
vested with the usual apparatus of articulation.  The syno-
vial fluid  is generally  observed  to be very redundant in
this joint.
  A lateral ligament passes downwards from the tibia, at
the internal  malleolus,  and is inserted into the inside of
the astragalus, and also into the os  calcis and naviculare.
Some of the fibres are blinded with those  of the  sheath 
         Of the Astragalus with Os Calcis, &fc.      295
for the tendon of the flexor communis; and some of them
have a radiated arrangement, in consequence of which this
has been called the deltoid ligament.
   From the fibula three ligaments arise. The middle liga-
ment, which is strong and thick,  passes downwards from
the end of that bone, to be inserted into the outside of the
os calcis.
   The anterior and posterior ligaments pass also from the
external malleolus, and are inserted  into the anterior and
posterior portions of the astragalus.

       Articulation of the Astragalus and Os Calcis.
   The astragalus is attached firmly to the os calcis by very
strong and short ligamentous fibres, which arise from the
fossa on its under surface, and are inserted into the fossa
between the upper articulating surfaces  of the os  calcis.
This ligament separates the posterior articulations  of the
astragalus and os calcis from the anterior.  The posterior
articulation has a synovial membrane exclusively  appro-
priated to it.  The anterior articulation is supplied by an
extension of the membrane which also invests the articu-
lating surfaces of the astragalus and  naviculare.
   The connexion of the  astragalus, with the os calcis, is
supported by the  lateral ligaments of the ankle joint, and
also by many irregular ligamentous fibres.

  Articulation of the Astragalus with the Os Naviculare.
   This articulation  appears calculated for considerable
motion, as well from the form of the  two surfaces concern-
ed in it, as the perfect state  of their articulating invest-
ments.  Their motions are restrained, to a certain degree,
by ligaments, which are situated on the upper and internal
surfaces of the foot. 
 296    Articulation of the Os Calcis and Cuboides.
    The ligaments which pass from the anterior internal ex-
      tremity of the os calcis to the os naviculare, and sup-
      port the head of the astragalus, ought to be observed
      with attention during the examination of this joint.

        Articulation of the Os Calcis and Cuboides.
  The  articulating surfaces of this joint are arranged in
the usual manner.
  There are two additional ligaments:  one placed on the
upper, and the other on the under, surfaces of the bones.
The upper ligament is thin; but the under ligament is one
of the strongest of the  foot; and its fibres are blended with
those which form the sheath for the tendon of the pero-
neus longus, as it passes along the groove in the cuboides. 
297
                  CHAPTER  IV.
OF PARTICULAR LIGAMENTS, AND OF THE SITUATION OF
          THE INDIVIDUAL BURSAE MUCOSiE,

                    SECTION  I.
Enumeration of the most important ligaments, which
              have not been described.
           Ligaments proper to the Scapula.
1 ilE triangular ligament arises,  broad, from the external
surface of the coracoid process,  and becomes narrower
where it is fixed to the posterior margin of the acromion*
It confines the tendon of  the supraspinatus muscle, and
assists in protecting the upper and inner part of the joint
of the humerus.
  The posterior ligament of the scapula is sometimes dou-
ble, and is stretched across the semilunar notch of the sca-
pula, forming that notch into one  or two holes for the pas-
sage of the superior posterior scapulary vessels and nerves.
It also gives rise to part of the omo-hyoideus muscle.

      The Interosseous Ligament of the Fore Arm
  Extends between the sharp ridges of the radius and ulna,
filling up the  greater part of the space between these two
bones, and is  composed of small fasciculi, or fibrous slips,
which run obliquely downwards and  inwards. Two  or
three of these, however, go in the opposite direction; and
one of them, termed  oblique ligament, and chorda trans-
versalis cubiti, is stretched between the tubercle of the ulna
and under part of the tubercle of the radius.  In different
parts  of the  ligament there are perforations for the pas-
  Vol. I.                 2 P 
 298            Ligaments of the Hand.
 sage of bloodvessels from the fore to the back part of the
 bone; and a large opening is found at the upper part of it,
 which is filled up by muscles.  It prevents the radius from
 rolling too  much outwards, and furnishes a commodious
 attachment for muscles.

   Ligaments retaining the  Tendons of the Muscles of the
       Hand and Fingers in their proper positions.
   The anterior annular ligament of the wrist is stretched
 across from  the projecting points of the pisiform and un-
 ciform bones, to  the os scaphoides and trapezium, and
 forms an arch which covers and preserves in their places
 the tendons of the flexor muscles of the fingers.
   The  vaginal  ligaments of  the flexor  tendons are
 fine  membranes, connecting the tendons of the sublimis,
 first to each  other, and then to those of the profundus;
 forming, at the same time, bursae mucosae which surround
 the tendons.
   The vaginal, or  crucial ligaments of the phalanges,
 arise from the ridges on the concave side of the phalanges,
 and run over the tendons of the flexor muscles  of the fin-
 gers. Upon the body of the phalanges, they are thick and
 strong, to bind down the tendons; but over the joints they
 are rhin, and have, in some parts, a crucial appearance, to
 allow the ready motion of the joints.
   The accessory  ligaments of the flexor tendons of the
fingers are small tendinous  fraena, arising  from  the
 fiist and second phalanges of the fingers. They run ob-
 liqiu 1\  forwards within the vaginal ligaments,  terminate
 in the tendons of the two flexor muscles of the fingers, and
 assist in keeping ihem in their places.
   The  posteror annular  ligament of thet wrist is part
 of the  aponeurosis  of  the fore arm, extending across 
               Ligaments of the Sternum.           299
the back of the wrist, from the extremity of the ulna and
os pisiforme to the extremity of the radius.  It is connect-
ed with the small annular ligaments which  tie down the
tendons of the extensores ossis metacarpi etprimi interno-
dii pollicis, and the extensor carpi ulnaris.
  The vaginal ligaments adhere to the last mentioned
and serve as sheaths and bursae mucosae to the extensor
tendons of the hand and fingers.
   The  transverse ligaments, of the  extensor tendons,
are aponeurotic slips running between the tendons, near
the heads of the metacarpal bones, and retaining them
in their places.

     Ligaments on the Anterior part of the  Thorax,
   The  membrane proper to the sternum is  a  firm expan-
sion, composed of tendinous fibres running in different di-
rections, and covering the anterior and posterior surfaces
of the bone, being confounded with the periosteum.
   The  ligaments of the cartilago ensiformis  are part of
the proper membrane of the sternum, divided into strong
bands, which run obliquely from the under and fore part of
the second bone of the sternum, and from the cartilages of
the seventh pair of ribs, to  be fixed to the cartilago ensi-
formis. The ligaments covering the sternum serve consi-
derably to strengthen that bone.
   There are  also  thin tendinous  expansions which run
over the intercostal muscles at the fore part of the thorax,
and connect the cartilages of the ribs  to each  other.

          Ligaments of the  Bones of the Pelvis.
   The two transverse  ligaments of  the  pelvis  arise
from the posterior part of  the spine  of the os ilium, and
run transversely. The superior is fixed to  the transverse 
300            Ligaments of the Pelvis.
process of the last vertebra of the loins; the inferior to the
first transverse process of the os sacrum.
   The  ilio-sacral  ligaments arise  from  the  posterior
spinous process of the os ilium, descend obliquely, and
are fixed to the first, third, and fourth, spurious trans-
verse processes of the os sacrum.
   These, with the two transverse ligaments, assist in bind-
ing the bones together, to which they are connected.
   The two sacro-ischiatic ligaments are situated in the uni
der and back part of the pelvis. They arise in common from
the transverse processes of  the os sacrum, and likewise
from the under and lateral part of that bone, and from the
upper part of the os coccygis. The first, called the large,
external, or posterior, descends obliquely, to be fixed to
the tuberosity of the  os  ischium. The  other, called the
small,  internal,  or  anterior, runs transversely to be fixed
to the spinous process of the os ischium. These two liga-
ments assist in binding the bones of the pelvis, in support-
ing its contents, and in giving origin to part of its muscles.
   There are two membranous productions which are con-
nected with the large  sacro-ischiatic ligament, termed its
superior and inferior appendices.
   The superior appendix, which is tendinous, arises from
the back part of the spine of the os ilium, and is fixed
along the outer edge of the ligament, which it increases
m breadth.
   The inferior, or falciform appendix, situated within the
eavity of the pelvis, the back part of which is connected
with the middle of the large external ligament, and the
rest of it is extended round the curvature of the os is-
chium.
   These two productions  assist the large sacro-ischiatic
ligament in furnishing a more commodious situation for, 
                Ligaments of the Pelvis,           301
and insertion of, part of the gluteus  maximus, and  ob-
turator internus muscles.
  Besides the  ilio-sacral, and  sacro-ischiatic ligaments,
several other slips are observed upon the back  of the os
sacrum,  which descend in an  irregular  manner,  and
strengthen the connexion between that bone and the os
ilium.
  The large holes upon the back part of the os sacrum are
also surrounded with various ligamentous expansions, pro-
jecting from one tubercle to another, and giving origin to
muscular fibres, and protection to small vessels and nerves
which  creep under them.
  A general covering is sent down from the ligaments of
the os sacrum, which spreads over and connects the dif-
ferent  pieces of the os coccygis together, allowing consi-
derable motion, as already mentioned in the description of
this bone.
  The longitudinal  ligaments  of the  os  coccygis  de-
scend from those upon the dorsum of the os sacrum, to be
fixed to the back part of the os coccygis. The ligaments of
this bone prevent it from being  pulled too much forwards
by  the action  of the coccygeus muscle, and they restore
the bone to its natural situation, after the muscle has ceased
to act.
  The ligamentous  cartilage, which unites  the two  ossa
pubis so  firmly together as to admit of no motion, except-
ing in the state of pregnancy, when it is frequently found
to be so much softened as to yield a little in the time of
delivery.
  The obturator membrane, or ligament of the foramen
thyroideum, adheres to the margin of the foramen thyroi-
deum, and fills the whole of that opening, excepting the
oblique notch at its upper part for the passage of the ob- 
 302            Ligaments of the Foot.
 turator vessels and nerve.  It assists in supporting the con-
 tents of  the pelvis, and in  giving origin  to the obturator
 muscles.
   The interosseous ligament of the leg fills the space be-
 tween the tibia and fibula  like the interosseous ligament
 of the fore arm, and is of a similar structure; being formed
 of oblique fibres, and perforated in various places for the
 passage of vessels and nerves.
   At the upper part of it there is a large opening, where?
 the muscles of the opposite sides are in contact; and where
 vessels and nerves pass to the fore part of the leg.
   It serves chiefly for the origin  of part of  the  muscles
 which belong to  the foot.

  Ligaments retaining the Tendons of the Muscles of the
         Foot and Toes, in  their proper positions.
   The  annular ligament of the  tarsus is  a  thickened
 part of the aponeurosis of  the leg, splitting into superior
 and inferior portions, which bind down the tendons of the
 extensors of the toes upon the fore part of the ankle.
   The vaginal ligament of the tendons of the peronei mus-
 cles behind the  ankle is common to both, but divides at
 the outer part of the foot and becomes proper to each.
 They preserve  the  tendons in  their places, and are the
 bursae of these tendons.
   The laciniated ligament*arises  from the  inner ankle,
 and  spreads in  a radiated manner, to be  fixed partly
 in the cellular substance and fat, and partly to the os cal-
 cis, at the inner  side of the heel.  It incloses the  tibialis
 posticus  and flexor digitorum longus.
   The vaginal ligament of the tendon of the extensor pro-
prius pollicis  runs in a crucial direction.
   The vaginal ligament of the tendon of the flexor longus 
                   Bursa Mucosa,                303
pollicis surrounds this tendon in the hollow of the os cal-
 cis.
   The vaginal and crucial ligaments of the tendons of the
flexors of the toes inclose these tendons on the surfaces
 of the phalanges, and form their bursae mucosae.
   The accessory ligaments of the flexor tendons of the toes,
 as in  the  fingers, arise  from  the phalanges,  and are
 included in the sheaths of the tendons in which they ter-
 minate.
   The transverse ligaments  of  the  extensor  tendons
 run between them, and preserve them in their places be-
 hind the roots of the toes.


                    SECTION II. .
     Enumeration of the most important Bursa
                      Mucosa.
   Those about the articulation of the shoulder are situated
   1. Under the clavicle, where it plays upon the coracoid
 process.
   2.  Between the triangular ligament of the scapula and
 the capsular ligament of the humerus.
   3. Between  the point of the coracoid process and cap-
 sular ligament of the humerus.
   4. Between the tendon of the subscapularis muscle and
 capsular  ligament of the humerus, frequently communi-
 cating with the cavity of that joint.
   5. Between the origin of the coraco-brachialis and short
 head  of  the biceps muscle, and capsular ligament of the
 humerus.
   6. Between  the tendon of the teres major and the os
 humeri, and upper part of the tendon of the latissimus
 dorsi. 
304    Bursa Mucosa of the Upper Extremity,
   7. Between the tendon of the latissimus dorsi  and os
humeri.
   8. Between the tendon of the long head of the biceps
flexor cubiti and the humerus.
    The bursae marked 3 and 5 are sometimes absent.

      Near the articulation of the Elbow there are,
   1. With apelaton of fat, between the tendon of the bi-
ceps and tubercle of the radius.
   2. Between the tendon common to  the extensor carpi
radialis brevior, extensor digitorum communis, and round
head of the radius.
   3. A small bursa, between the tendon of the triceps ex-
tensor cubiti and olecranon.

        On the Fore Arm and Hand are situated,
   1. A very large bursa surrounding the tendon of the
flexor pollicis longus.
   2. Four long bursae lining the sheaths which inclose the
tendons of the flexors upon the fingers.
   3. Four short bursae on the fore part of the tendons of
the flexor  digitorum sublimis in the palm of the hand.
   4. A large bursa between  the tendon of the flexor pol-
licis longus, the fore part of the radius, and capsular liga-
ment of the os trapezium.
   5. A large bursa between the tendons of the flexor digi-
torum profundus, and the fore part of the end of the radius
and capsular ligament of the wrist.
    These two last mentioned bursae arc sometimes found to
      communicate with each other.
   7, A bursa between the tendon of the flexor carpi radi-
alis and os trapezium.
   8. Between the tendon of the flexor carpi ulnaris and
os pisiforme. 
              Bursa Mucosa of the Thigh.         305
  9. Between the tendon of the extensor ossis metacarpi
pollicis and radius.
  10. A large bursa common to the extensores carpi radi-
ales, where they cross behind the extensor ossis metacarpi
pollicis.
  11. Another common  to the extensores carpi radiales,
where they cross behind  the extensor secundi internodii
pollicis.
  12. A third at the insertion of the tendon of the exten-
sor carpi radialis brevior.
  13. A bursa for the tendon of the extensor secundi in-
ternodii  pollicis,  which  communicates with  the second
bursa common to the extensores carpi radiales.
  14. Another bursa between the tendon of the extensor
secundi internodii  pollicis  and metacarpal bone of the
thumb.
  15. A bursa between the tendons of the extensor of the
fore, middle, and ring fingers, and ligament of the wrist.
  16. For the tendons of the extensor of the little finger.
  17. Between the tendon of the  extensor carpi ulnaris
and ligament of the  wrist.

 Upon the Pelvis and upper part of the Thigh there are,
  1. A very large bursa  between the iliacus internus and
psoas magnus muscle, and capsular ligament of the thigh
bone.
  2. One between the tendon of the pectinalis muscle and
the thigh bone.
  3. Between the gluteus  medius and trochanter major,
and before the insertion of the  tendon of the pyriformis.
  4. Between the-tendon of the gluteus minimus and tro-
chanter major.
  Vol.  I.                  2 Q 
306     Bursa Mucosa of the Thigh and Knee.
  5, Between the gluteus maximus and vastus externus.
  6. Between the gluteus medius and pyriformis.
  7. Between the obturator internus and os ischium.
  8. An oblong bursa continued a considerab e way be-
tween the obturator internus, gemini, and  capsular liga-
ment of the thigh bone.
  9. A small bursa at the head of the semimembranosus
and biceps flexor cruris.
  10.  Between the origin of the semitendinosus and that
of the two former muscles.
  11.  A  large bursa between the tendon of  the gluteus
maximus and root of the trochanter major.
  12.  Two small bursae between the tendon of the gluteus
maximus and thigh bone.

             About the joint of the Knee are,
   1. A large bursa behind the tendon of the extensors of
the leg, frequently found to communicate with the cavity
of the  knee joint.
   2. Behind the ligament which joins the patella to the
tibia, in the upper part of the cavity of which  a fatty sub-
stance projects.
   3.  Between the tendons of the sartorius, gracilis, semi-
tendinosus, and tibia.
   4.  Between the tendons of the  semimembranosus and
 gemellus, and ligament of the knee. This bursa contains
 a small one within it, from which a passage leads into the
 cavity of the joint of the knee.
   5.  Between the tendon of the semimembranosus and the
 lateral internal ligament of the knee, from which also there
 is a passage leading into the joint of the knee.
   6.  Under the popliteus muscle, likewise communicating
 with the cavity of the knee joint. 
              About the Ankle and the Foot.         307
               About the Ankle there are,
   1.  A bursa between the tendon  of the tibialis  anticus,
and under part of the tibia and ligament of the ankle.
   2.  Between the tendon of the extensor proprius pollicis
pedis, and the  tibia and capsular ligament of the ankle.
   3.  Between the tendons of the extensor digitorum lon-
gus, and ligament of the ankle.
   4.  Common to the tendons of the peronei muscles.
   S.  Proper to the tendon of the peroneus brevis.
   6.  Between the tendo achillis and os calcis, into the ca-
vity of which apeloton or mass of fat projects.
*► 7.  Between the os calcis and flexor pollicis longus.
   8.  Between the flexor digitorum  longus and the tibia
and os calcis.
   9.  A bursa between the tendon of the tibialis posticus
and the tibia and  astragalus.

             On the Sole of the Foot are also,
   1.  A second bursa for the tendon of the peroneus lon-
gus, with an oblong peloton of fat within it.
   2.  One common to the tendon of the flexor pollicis lon-
gus,  and  that  of the flexor digitorum profundus, at  the
upper end of which a fatty substance projects.
   3.  Another for the tendon of the tibialis posticus*
   4.  Several for the tendons of the flexors of the toes. 
APPENDIX
         TO THE THREE PRECEDING PARTS

       Observations on the Motions of the Skeleton.
  THE falling down of the body during life, when mus-
cular action is suspended, as well  as the examination of
the artificial skeleton, evinces that this machine is not con-
structed to preserve the erect position  of itself; but thi^*
when unsupported, it bends at the  joints, and invariably
falls  forward.
  It is retained in the erect position  by the action of mus-
cles; and that the muscles should produce this effect, it is
necessary that they should have a fixed basis to act from.
This basis is the feet, and they are fixed to the ground by
the weight of the body.
  To keep the body from falling it is necessary that the
center of gravity should be immediately over the center of
the common basis.
  All our movements, both in walking,  standing, and
rising from our seats, are regulated by this principle; and
whenever we move the body, so that the center of gravity
is changed, we must  change the position of the feet, that
the center of the basis may be directly under it.
  If this proposition were not almost self-evident, it might
be illustrated by several very easy experiments.
   If a person stands against a wall, with his heels and the
back parts of his  legs and thighs in  contact with it, and in
this  situation attempts to stoop forward, he will fall upon
his face; there is no power in his muscles, or in any other 
          Adjustment of the Center of Gravity.      301>
part of the body, when thus circumstanced, to prevent it;
but a small movement forward of one foot, will enable him
to stoop with ease by altering the basis of his body.
   When we sit in such a position that we cannot bring the
center of gravity over the feet, the lower limbs are divested
of all  power of elevating the body: this is always the case
when we sit with the thighs and legs at right angles with
each other.  Bend the knees to an acute angle, so that the
feet are placed under the body, and we rise with ease.
   When we wish to stoop forward without advancing one
of our feet, we acquire the power in a small degree, by
placing our hands behind us, to preserve the equilibrium.
   Some old persons, whose spines curve forwards in con-
sequence of age, bend their lower limbs, so that the pelvis
may be projected backwards beyond the center of the base
of the body, and form a counterpoise to the upper part of
the trunk.
   Bending  the  knees alone without  projecting the pelvis
backwards, will not produce this effect; for a person who
stands with his back to a wall will bend his knees without
obtaining this advantage, while the heels and back part of
the pelvis are in contact with the wall.
   When we stand with the toes pointing directly forwards,
the base of the body is a square; of which the feet are two
of the sides. As the positions of the feet are changed,  the
figure of the base and its  center necessarily changes also.
When the  feet are placed one immediately before  the
other, the center is between the toes of the one and  the
heel  of the other. When the position of  the feet is such,
that  the  toes point directly outwards, and the heels  are
opposed to each other, the center of the base is between
the heels. 
310      Adjustment of the Center of Gravity.
   In these cases, when the situation of the center of the
base is changed, we immediately change the center of gra-
vity. Thus, as we turn the toes outwards, the center of the
base  moves  backwards; we therefore immediately make
the body more erect;  and by that means keep the center
of gravity over the center of the base.
   We move  the  center of gravity laterally, as well as
backwards and forwards,  in conformity to this principle.
Thus, when we raise  one foot from the ground, the body
inclines so much in the opposite direction, that the center
of gravity is directly  over the other.  If  the spine is dis-
eased in one spot, and assumes a lateral curvature, placing
the center of gravity  on one side of the  natural center of
the base;  another curve  is formed by muscular action, in
a sound part of the spine, to counteract the first, and keep
the center of gravity in its natural position.
  The perception of a tendency to fall, when the center
of gravity is in a wrong situation, first induces us to make
efforts to  resist this  tendency; we learn  by experience
what these efforts ought to be; and by habit we  at length
make them without consciousness.
  As the natural tendency of the skeleton, when we stand,
is  to bend at the articulations, and therefore to fall for-
wards; the muscles which have the principal effort in keep-
ing the body erect, must be the extensors.
  Thus, the muscles on the back of the leg, and  particu-
larly the soleus, keep the tibia erect: while the muscles on
the front of the thigh, the vasti  and crureus, produce the
same effect upon  the os femoris: the bones being kept
steady by the occasional  counteraction of the antagonist
muscles.
  The whole lower limb is thus made erect by an exertion 
           Muscles which keep the Body erect.       311
which  begins  at the foot, while the foot is fixed to the
ground by the weight and pressure of the body above it.
  The trunk of the body has a strong tendency to bend
forward at the articulations of the thigh bones and the ossa
innominata. This tendency  is  resisted by the muscles
which lie on the back part of the ossa femoris, and extend
the trunk on those bones, viz., the glutei maximi.
  The muscles which arise  from the tuberosity  of the
ischium, and are inserted into the leg, the semitendinosus,
semimembranosus, and the long head of the biceps flexor
cruris, have also this effect.
   The flexure of the thoracic and lumbar portions of the
spine is counteracted by the  sacro-lumbalis, and longissi-
mus dorsi, which act from the sacrum and back parts of
the pelvis.  The yellow ligaments, which are elastic, must
also cooperate to this effect: so that with regard to the
spine,  there is an additional agent distinct from the mus-
cular power.
   Indeed, respecting the vertebral articulations in general,
it may be observed, that the connexion of the bodies  of
the vertebrae,  by  the intervertebral  cartilaginous matter,
and of the plates behind, by the elastic ligament, renders
these articulations perfectly anomalous; and very different
in their principles from the articulations in general.
   In no part of the skeleton is this tendency to bend for-
ward more strongly perceived than in the head.  When we
 are awake, and the muscles in a healthy situation, it is effec-
 tually  restrained, and the head kept erect, by the splenius
 and complexus, and other muscles,  which act  from the
 spine below, upon the back part of the head and the ver-
 tebras  of the neck.
   When we stand on one foot, some very different mus-
 cles are called into action; the tendency of the body is to 
 312     Muscles employed in rising from a Seat.
 fall sideways, towards the foot which is raised from the
 ground. To counteract this tendency, the two larger pero-
 nei muscles, which are situated on the outside of the leg,
 act from the foot, to keep the leg erect. The vastus externus
 acts upon the same principle from the leg upon the os fe-
 moris.  The gluteus medius and minimus, and the muscle
 of the fascia lata,  act from the os femoris upon the pelvis
 and trunk; while the quadratus lumborum, and those ab-
 dominal muscles which draw the spine to that side, con-
 tinue the operation: and so do likewise the muscles which
 act on the same side of the neck and head.
  In rising from a seat, the tibialis anticus acts very pow-
 erfully, to keep  the tibia erect, and prevent it from incli-
 ning backwards. The two vasti,and the  crureus, raise up
 the os femoris: while the gluteus maximus, the semiten-
 dinosus, and semimembranosus, and the long head of the
 biceps, extend the  trunk of the body.
  There are several modes of walking, which are different
 from  each other, in a small degree.
  We may walk, for example, with the  knee of the hind
 limb straight or bent, as we bring it forward. This circum-
 stance is merely  a  matter of accommodation. But there
 are two essential processes in walking, viz. 1, Projecting
 one foot forward, and placing it on the ground while thus
 projected; and 2, Moving the body over that foot.
  The mode of projecting the foot requires no explana-
 tion;  but  the manner of bringing it to the ground when
 thus advanced, ought to be noticed.
  If,  after standing  with both  feet on the same line, we
 move one  foot forwards, suppose the right foot, it cannot
be applied flat to the ground, unless we either incline the
bod) forward: or move the pelvis on the  left thigh, so that
the right side may present obliquely forward: or lower the 
              Motions necessary in Walking,         313
 right side of the pelvis, so that it  may be  nearer the
 ground.
   When we incline the  body forward, and thus bring the
 right foot to the ground, we perform the second essential
 process in walking along with the first; for we. move the
 body over the fore foot.  The muscles on the front part of
 the  hind leg, and particularly the tibialis anticus, seem to
 produce this effect, by bending, or inclining forward, the
 tibia on the foot.
   When the foot is brought to the ground by a rotation of
 the  pelvis, it  is likewise  the tibialis  anticus,  and the
 muscles on the front of  the hind leg, that move the  body
 over it, or that begin the motion.
   The gastrocnemius and soleus, and  the flexors of the
 toes, particularly that of the great toe, occasionally coope-
 rate with  great effect.  By  raising the  heel, and  thus
 lengthening  the hind limb, they push the body forward,
 and  continue its motion in that direction after the effect
 of the tibialis anticus  ceases.  The length  of the step
 appears therefore  to require this elevation of the  heel,
 and  depression of the toes; but  it should be observed,
 that when we take long steps, we also'turn the pelvis partly
 roundK presenting the side obliquely forward; and in this
 manner increase the anterior projection of the front leg.
  Although the action of the gastrocnemius, &c. seems
 necessary to walking with long steps; we can walk without
 their operation.  This is proved incontestably by the act of
 walking on the heel: when the gastrocnemii and the  flex-
 ors are so far from acting, that they are in a state of exten-
 sion. In this operation,  the principal  effort seems to be
 made by the tibialis anticus, and the muscles on the front"
 of the  leg;  and the  extensor muscles on the front of the
thigh.
  Vol. I.               2 R 
314        Motions necessary in Jumping.
  Notwithstanding these facts, the action of the gastroc-
nemius and soleus is essential whenever we raise the heel
from the ground, while the weight of the body presses
on the front part of the foot; and it then acts with a force
which equals, if it does not exceed, the weight of the body.
  Jumping, at the first view of it, appears an extraordina-
ry operation; but if a man who lies on the ground, with
his feet against a wall, makes a muscular exertion, such as
is necessary for jumping, the nature of the operation is
very intelligible. It is a sudden extension of the feet and
knees, and sometimes of the trunk of the body.  The stroke
is  made  against the wall; but as that does  not yield, the
whole motion is imprest upon the body; which is projected
from the wall horizontally,  in the  same way that in jump-
ing, it is projected from the ground vertically. 
SYSTEM OF ANATOMY.
            PART IV.
 OF THE BRAIN AND  SPINAL MARROW: OF THE
               EYE AND THE EAR.

                  CHAPTER  I.
                   OF THE BRAIN.
 1 HE whole of the soft mass, which fills the cavity of the
cranium,  is called the brain. This mass is covered by
three membranes: two of which were called meninges, or
maters, by the ancient anatomists; who believed that all
the other membranes of the body originated from them.
  These membranes  are  denominated  the Dura Mater,
Tunica Arachnoidea,  and  Pia Mater,

                   SECTION I.
   Of the Membranes of the Brain, and Sinuses of
                 the Dura Mater.
  The Dura Mater  incloses the  brain and all its appen-
dages, and lines the different parts of the cranium. It con-
sists of one membrane of a very dense texture, which in
several places is composed of two or more laminae.  It  is
the thickest and strongest membrane of the body, and  is
composed of tendinous fibres, which have  a shining ap-
pearance, particularly on its inner surface. In many parts
these fibres  run in a variety of directions, and decussate
each other at different angles. 
316
Dura Mater.
   The dura mater adheres every where to the surface of
 the cranium, in the same manner as the periosteum ad-
 heres to the bones iri the other parts of the body; but it is
 more firmly connected at the sutures and foramina than
 elsewhere; and so much-more  firmly in children than in
 adults, that in  separating it from the cranium, it is apt to
 bring along with it some of the fibres of the bone to which
 it is attached. In the adult, the separation of the bone from
 the membrane is less difficult, in consequence of many of
 the fibres being obliterated;  although in old age the adhe-
 sion is sometimes very strong.
   The inner surface of the dura mater, which is remarka-
 bly smooth, is in close contact with the brain, but adheres
 only where the veins go into the sinuses; and is lubricated
 by a fluid discharged  through its vessels,  which guards
 the brain from danger, according as it may be affected by
 the different states of respiration.
   The dura mater serves as a  defence to the brain, and
 supplies the place of a periosteum to the inside of the cra-
 nium; giving nourishment to them, as is evident  from the
 numerous drops of blood which appear after removing a
 portion of it.
   The proper bloodvessels of the dura mater are not very
 numerous.  Its arteries are derived partly from the exter-
 nal carotids, and partly from the internal carotids, and the
 vertebral arteries.  Corresponding veins accompany these
 arteries; but the dura mater forms also reservoirs, that
 contain the venous blood, which  is brought from  the sub-
 stance  of the brain. These are called sinuses, and are very
different from common veins.
   Nerves have  not been distinctly traced into  the dura
mater; and there have been disputes respecting its sensi-
bility;  but there is reason to believe that in a sound state
 it has very little sensibilitv. 
           Tunica Arachnoidea—Pia Mater,       317
  The Tunica Arachnoidea is an exceedingly thin, tender,
and transparent, membrane, in which no vessels have been
hitherto observed.
  It is spread uniformly over the surface of the brain, in-
closing all its convolutions, without insinuating itself be-
tween any of them.
  Atthe upper part of the brain, it adheres so closely to
the subjacent  coat by fine cellular substance, that it can
scarcely be separated from it; but in different parts of the
base of the brain, particularly about the tuber annulare and
medulla oblongata, it is merely in contact withthe^mem-
brane under it,  and may readily be raised from it by the
assistance of the blow-pipe.
  The Pia Mater, named from its tenderness, is some-
what of the nature of the former covering, but is extremely
yascular.
  It covers the brain in general, enters double between all
its convolutions, and lines the different  cavities called
ventricles.
  It serves to conduct and support the vessels of the brain,
and  allows  them  to divide into sueh minute parts, as to
prevent the blood  from entering the tender  substance of
this  viscus with too great force.
  The arteries of the pia mater are the same with those of
the brain, and are  derived from the internal carotids and
vertebrals.
  The veins differ in no respect from those  of the other
viscera, excepting in this, that they do not accompany the
arteries.
  From the dura mater certain membranous processes go
off, forming incomplete partitions, which partially divide
the cavity of the cranium; and in the same partial manner
separate the parts  of the brain from each other: thus pre- 
318                    Falx.
venting them from pressing upon each other, and keeping
them steady.
   They are formed of the internal lamen or layer of the
dura mater, like a plait, and therefore each of them con-
sists of a double membrane.
   The most conspicuous of these is denominated the falx,
which extends from  the  anterior to the posterior part of
the  cranium, and divides the upper part of the brain into
two hemispheres;  but it is not sufficiently deep to divide
the whole of the brain; for between the under edge of it,
and the base of the cranium, there is a large space occu-
pied by a portion of the brain, which is undivided; and,
therefore, common to both hemispheres.
   The falx begins at the middle of the sphenoid bone, and,
continuing its origin from the crista galli  of the ethmoid
bone, runs along the upper and middle part of the head;
adhering first to the  frontal, then to the joining of the
parietal, and afterwards  to the middle  of the  occipital,
bone.
   In its passage it becomes gradually broader; and ter-
minates behind, in the middle of the tentorium.
   It runs from before backwards  in a straight direction,
and has some resemblance in  shape  to a sickle or sithe,
placed with its edge downwards; from which circumstance
it has obtained the  name of falx.
   After extending  backwards as far as the center of the
crucial ridge, on the internal surface of the occipital bone,
it extends to each side, and forms a horizontal partition,
which partially divides the lower part of the cavity from
the upper;  but it does not extend  so far forward as to se-
parate completely the mass which is  under it, or the cere-
bellumj from the upper part of the brain, or cerebrum. 
                  Tentorium—Sinuses.             319
  This horizontal membrane is called the tentorium, and
also the transverse septum: it is connected behind to the
inner transverse ridges and grooves of the occipital bone,
and, at the  fore and outer edges, to the ridges and great
angles of the temporal bone3, and terminates at the poste-
rior clinoid process of the sphenoid bone.
  Between the inner edge of the tentorium and the poste-
rior clinoid process of the sphenoid bone, there is a large
notch, or foramen ovale, where the brain and cerebellum are
united, or where the tuber annulare is chiefly situated.
  The tentorium keeps the falx tense, and forms a floor or
vault over the cerebellum, which prevents the brain from
pressing upon it.
  The falx minor,  or  septum cerebelli, is placed be-
tween the lobes of the cerebellum. It  descends from the
under and back part of the falx in the middle of the ten-
torium, adheres to the inferior longitudinal spine of theos
occipitis, and terminates insensibly at the edge of the fo-
ramen magnum of that bone.
  Besides the processes of the dura mater already descri-
bed, there are four of inferior consideration: two of which
are situated at the  sides of the sella turcica, and two at the
edges of the foramina lacera.
  As these  partitions arise like plaits from the internal
surface of the dura mater, there must necessarily be a ca-
vity, larger or smaller, between the external layer of the
dura mater, which lines the  internal surface  of the crani-
um, and the basis of the partition which rises from it: this
cavity must continue along the whole  basis  of the parti-
tion; and a section of it will be triangular.
  This cavity is of considerable size at  the upper edge of
the falx, where it  rises from the  dura mater; and  also
where it forms the tentorium; and at the posterior edges
of the tentorium, where it adheres  to the occipital bone. 
320                    Sinuses.
   The  cavity at the upper edge of the falx is called the
longitudinal sinus; that at the posterior edge of the tento-
rium forms two cavities, called the transverse sinuses;
and that which is at the junction of the falx and tentorium
has the name of the torcular or press of Herophilus.
   The veins of the brain open into these sinuses; and the
blood flows through them into the internal jugular veins.
They differ from veins principally in this: that they are
triangular, and, by the tension of the dura mater, are pro-
tected from pressure.
   The principal sinuses are,
   1. The  longitudinal sinus, which begins at the crista
galli, and, running along the upper edge of the falx until it
arises at the tentorium, increases  gradually in size, and
terminates in
   2. The two lateral sinuses which run in depressions of
the occipital and  temporal bones, until they terminate in
the internal jugular veins at the foramen lacerum.
   3. The  torcular Herophili which receives a large vein
from the interior of the brain, and is situated at the junc-
tion of the falx and tentorium, opening into the longitudi-
nal sinus, where it divides into the lateral sinuses.
   These are the largest sinuses of the dura mater; but, in
addition to these, there are several small sinuses: as,
   4. The  inferior longitudinal sinus, which is situated at
the under edge of the falx, and receives blood from the
central parts of the cerebrum:  it terminates in the torcular
Herophili, near the beginning. The other small sinuses are
situated under the brain, viz.
   5. The circular sinus of Ridley,* which frequently sur-

  * An English anatomist, who published near the end of the lrth
ccnturv.' 
                      Cerebrum.                   321
rounds the pituitary  gland, and carries the  blood  from
the contiguous parts to the
  6. Cavernous sinuses, which  are placed at the sides of
the sella turcica, surrounding the carotid arteries and the
sixth pair of nerves,  and receive blood from the circular
sinuses and several contiguous parts, and discharge it into
the
  7. Inferior petrous sinuses, which are placed at the
bases of  the partes petrosae, and discharge this blood into
the ends of the lateral sinuses. To these, should be added
  8. The superior petrous sinuses, which are situated on
the upper edges of the petrous bones.  They communicate
both with the lateral and the cavernous sinuses, and re-
ceive some small veins from the adjacent parts.
  There are  also several small sinuses near the great oc-
cipital foramen, which communicate with the lateral sinus-
es,  and  also with the vertebral veins. They are  called
occipital sinuses.

  The brain, or the whole of the soft substance contained
within these membranes, is composed of four portions, viz.
cerebrum, cerebellum, tuber annulare or pons  Varolii^ and
medulla oblongata.

                    SECTION II.
                  Of the Cerebrum.
  The cerebrum completely fills the upper part of the cavi-
ty of the cranium. It has some resemblance to the half of an
egg which has been divided horizontally; and is composed
of two equal parts, which are separated vertically from each
other by the falx. This vertical separation does not extend
through the center of the cerebrum, although it divides it
completely before and behind. A portion of the central part
of the cerebrum, which is situated deeper than the under
edge of the falx, is not divided.
  Vol. I.                 2 S 
322                 Cerebrum.
  The upper  surface of the two hemispheres is convex.
The under surface is rather irregular: it is divided in each
hemisphere into three lobes: the anterior, the middle, and
the posterior.
  The anterior lobes of the brain  are situated on the front
part of the base of the cranium, principally on the orbitar
processes of the os frontis.
  The middle lobes are lodged in the fossae formed by the
temporal and sphenoid bones.
  The posterior  lobes  rest chiefly upon the tentorium,
over the  cerebellum.
  Between the anterior and middle lobes is a deep furrow,
corresponding  to the base of the cranium on which they
rest, which is called the fossa Sylvii.
  The surface of the brain resembles that of a mass of
small intestines, or of a convoluted cylindrical tube: it is
therefore said to  be convoluted. The fissures between
these convolutions do not extend  very deep into the sub-
stance of the brain.
  The whole surface of the  brain, thus convoluted, is co-
vered by pia mater;  which is connected to every part of
the surface by an infinite number of small vessels and pro-
cesses, that appear when this membrane is peeled off from
the surface- of the brain.
  The mass of brain consists of two substances of different
colours:  one of which is, for the most part, exterior to the
other. The exterior substance is of a light brown colour,
and is therefore called cineritious, or cortical, from  its
situation.
   The internal substance  is white, and is denominated tht
medullary.
   The proportion of this medullary part is much greater
than that of the cortical. The cortical, however, surround? 
                       Cerebrum.                 323
it, so as to form the whole of the surface of the cerebrum,
that can be strictly said to be exterior.
  The colour of the cortical part appears to be derived
from blood; as its intensity seems regularly proportioned
to the quantity of blood in the head. In subjects who have
been plethoric, or have  had a determination of blood to
the head, it is uniformly high-coloured; in pallid and ex-
hausted subjects it is of a brighter colour.
  The medullary matter is uniformly white; but small red
points appear upon its surface, when cut,  which are the
sections of vessels thatcarry red blood; and these points
are larger  and more numerous  in plethoric, than in ex-
hausted subjects. It is rather firmer than the cortical sub-
stance.
  These two substances are most intimately connected in
the cerebrum, and indeed seem to be a  continuation of
each other. In some parts they are blended together; and
in other places, there are portions of cortical matter within
the medullary.
  The division of the cerebrum into two hemispheres ex-
tends to a  considerable depth from above, and also to a
considerable distance internally, from its anterior and pos-
terior extremities; of course, the part which is undivided
is in the center.
  The cortical part covers alsothe surfaces, which are inthe
great fissure that forms the two hemispheres, and is occu-
pied in a great degree by the falciform process of the dura
mater. Towards the bottom of this fissure, and below the
falx, these surfaces being opposed to each other, and in
contact, are slightly united by adhesion of the membranes
that cover them.
  The central part which is not divided, and  which must
appear at the bottom of  the fissure, when the  two hemis- 
324              Lateral Ventricles.
pheresare separated from each other, is medullary; being
evidently a union of the medullary matter of each hemis-
phere. This undivided  medullary part is equal to about
one half of the length of the hemispheres;  the fissures at
each extremity extending inwards about one-fourth of their
length.  On each side of it, a fissure, equal to it in length,
extends  horizontally into  the medullary matter  in each
hemisphere, about half an inch; and the whole of  this un-
connected surface, the middle of  which is directly at the
bottom of the great fissure, is termed corpus callosum.
   When the hemispheres are cut away to the level of this
surface,  and the corpus callosum is examined, two raised
lines  appear in the middle, which  extend from one end of
it  to the other; and between them is a  small groove  of
the same length. This groove is called the raphe, or su-
ture of the corpus callosum. From  the raised lines  or
bands on each side of the  raphe,  small lines less eleva-
ted pass across the corpus callosum,  and are lost in the
medullary matter.  The hemispheres being thus cut off  at
the level of the corpus callosum, on the cut surface is to be
seen the  interior mass of medullary matter, with the corti-
cal part exterior, its edge exhibiting the convoluted  sur-
face of the brain, and  the pia mater following the convolu-
tions.
   The medullary surface thus exhibited, with the,corpus
callosum in the center, is denominated the centrum ovale.
   In  the brain there are four  cavities called ventricles:
three of these are formed in the substance of the cere-
brum; the fourth is situated between the cerebellum, the
pons Varolii, and  medulla oblongata. The two largest are
called the  lateral ventricles, from their situations; the
others are named, from the order in which they occur, the
third and the fourth ventricles. 
                  Lateral Ventricles.              325
  The lateral ventricles are cavities of an extremely irre-
gular figure: they are situated in each hemisphere a little
below the level of the corpus callosum; and, with the ex-
ception of the partition which separates them, are directly
under it. They commence anteriorly, nearly on a line with
the termination of the fissure that separates the two hemi-
spheres anteriorly; and continue backwards almost as far
as the commencement of the fissure that separates them
posteriorly: when they have attained this length posteri-
orly, they form a considerable curve, first outwards, then
downwards, and afterwards forwards; so that they termi-
nate almost as far forwards as they commenced; but much
deeper.
   At the posterior part of their curve, when they incline
outwards, previous to their turn downwards, a process or
continuation of the cavity extends backwards, almost as
far as the cerebrum  itself.  These  elongations are called
the posterior cornua or sinuses, or the digital cavities.
   Each ventricle  may therefore be divided into three
parts, viz. The portion under the corpus callosum; the
portion which continues outwards  and  downwards, and
terminates below it;  and the posterior portion.
   It has  been compared to  a ram's horn, by some who
have contemplated particularly the upper and lower por-
tions of the cavity; and by others, who have had the whole
extent in view, it has been called tricornis.
   The bottom, or lower surface of these cavities, is varied
in almost every part of its extent.  The front part of the
bottom of each ventricle is a broad and convex eminence,
which becomes narrower as it proceeds backwards; so that
it resembles a portion of a pear. It inclines outwards as
well as backwards, so that the narrow posterior extremi- 
326
Fornix.
 ties of the two bodies are further from each other than the
 anterior broad extremities.
   The colour of these bodies is cineritious externally; but
 they are striated with medullary matter within, and there-
 fore are called corpora striata.
   Between their posterior extremities are two other emi«
 nences, which incline to the oval form, and have a white
 or medullary colour; although their  substance, when cut
 into, is slightly striated: they are called the thalami nervo-
 rum opticorum. These bodies are very near each other;
 and, being convex in  form, are in  contact at the  center:
 they adhere slightly to each other;  and  this adhesion is
 called the soft commissure.
   The corpora striata, and the thalami nervorum optico-
 rum, join  each at the exterior sides of the thalami: where
 they are in contact, there is the appearance of a narrow me-
 dullary band,  which continues during the whole extent of
 their connexion: it has been called, by some, tenia semicir-
 cularis, from its form;  by others, centrum geminum semi-
 circulare.
   These surfaces constitute the bottom or floor of the first
 portion of the  ventricles, which  is under the corpus callo-
 sum: upon this floor is laid a thin lamen of the medullary
 matter, of a triangular form, called the fornix, which co-
 vers the thalami nervorum opticorum, and is attached to
 them by  a membrane;  so  that  when  the ventricles  are
 opened, the bottom appears to consist of the corpora striata,
 and the fornix.
   The upper surface or roof of the ventricles is  concave;
from the middle of it, immediately under the raphe of the
 corpus callosum, there proceeds downwards  a partition of
medullary matter,  which separates the two ventricles from
 each other. This is called septum lucidum, from  its being 
                  Plexus Choroides.              327
nearly transparent: below, it adheres to the fornix, posteri-
orly; and anteriorly, it is continued into the medullary mat-
ter, between the corpora striata. This septum lucidum is
formed of two laminae or plates, which are separated from
each other in the anterior portion of the septum, and thus
form a small cavity, which has no communication with the
other cavities of the bfain.
  The fornix is not perfectly flat; but, accommodating  to
the surface of the thalami nervorum opticorum,  its under
surface is  rather concave, and  its upper surface convex.
The anterior angle passes down between the most anterior
parts of the thalami nerv: optic: and is divided into two
small portions  called its crura, which can be traced some
distance in that part of the brain.
  The body of the fornix is  attached to the surfaces of the
thalami nervorum opticorum; on which it rests,  by a very
vascular membrane, which is spread over the thalami, and
called tela choroidea, and velum interpositum. At the edges
of the fornix,  there are many bloodvessels in this mem-
brane, arranged close to each other, which are  called the
plexus choroides.
   The posterior side or edge of the triangular fornix ter-
minates in the  corpus callosum, or  the medullary  matter
which is above it at that place; but the under surface is
attached throughout to the parts on which  it lies,  by the
aforesaid membrane.
   The two posterior angles  of the  fornix form what are
called the crura; and they terminate in the following way.
   The surfaces of the inferior portions of the lateral ven-
tricles are not uniformly concave; but at  the  bottom  of
each, there is a prominent body, which begins where this
portion of the cavity winds outward and forward, and con-
tinues its whole extent.  This prominence has a curved 
328
Third Ventricle.
 form, and is marked by transverse indentations, towards
 its extremity: hence it has been termed the hippocampus,
 or cornu ammonis.
   A similar prominence, but smaller, and without the
 transverse indentations, is  to be found in the posterior
 portion of the ventricle: this has also been called hippocam-
pus;  but the terms minor and major are applied to distin-
 guish them.
   The posterior angles of the fornix terminate in the large
 hippocampi; and the margin, or thin edge of the two ante-
 rior sides of the fornix, is continued to form an edge to the
 hippocampus; and is called the tania hippocampi, or cor-
pus flmbriatum.
   The  word fornix was the ancient name of a vault or
arch; and from its supposed resemblance to an arch, this
part has been called  by that name.
   When the fornix  is raised up, (which must be done by
dividing it at the anterior angle, and detaching it from the
thalami nervorum opticorum, by dissecting the  membrane
which connects them*, called velum interpositum, or tela
choroidea^) the thalami are brought fairly  into  view; and
appear like oval bodies placed parallel to each other. They
adhere slightly at their upper surfaces, and, when separa-
ted,  a fissure appears  between them; which is the third
ventricle. At the upper and front part of this third ventricle,
near its commencement, before the anterior crura of the
fornix, and very near them, is a white chord, like a nerve,
which passes across the ventricle, and can be traced to
some distance  on each side into the medullary matter of
the brain.

  * It is to be observed that the parts of the brain are here described in
the order in which they occur, when successive layers of the organ are
cut away: beginning with the upper surface. The fornix of course must
be raised up, after it is brought into view. 
               Commissures of the Brain.           329
  This chord is called the anterior commissure of the brain.
 The thalami  nerv:  optic: being  of an oval form, and
touching each other in the middle, there must be a vacu-
ity between them at their extremities. This vacuity is be-
hind the anterior crura of the fornix, and has been called
Vulva, Iter ad Infundibulum, and Iter ad Tertium Ventri-
culum.
  It leads of course into the third ventricle; but a pas-
sage continues from it downwards and rather forwards, to
the infundibulum; which is a process  somewhat resem-
bling a funnel that is composed principally of cineritious
substance, and passes from the lower and front part of the
third ventricle, towards the sella turcica; in which is situ-
ated the small body called the Pituitary Gland.
  The infundibulum is  hollow at its commencement, and
solid at its extremity near the  gland.
  The adhesion of the thalami  nerv: optic: to each other,
at the upper part of the third ventricle, has been denomi-
nated the Commissura Mollis.  The recession from each
other at their posterior extremities, in consequence  of
their oval  figure,  forms another opening into the third
ventricle when  the fornix  and  tela  choroidea is  raised,
which is closed when they are in their natural situations
upon it.
  In the back part of the third ventricle is another medul-
lary chord called the posterior Commissure, which appears
much like the anterior commissure; but does not  extend
into the substance of the brain in the same way. Under
this  chord, or posterior commissure, is a passage which

  This mode of examining the brain was employed by Vesalius, and has
been adopted by a majority of anatomists; but Willis and Vieussens had
each a different method
  Vol. I.                 2 T 
330    Tubercula ^uadrigemina—Pineal Gland.
leads to the fourth ventricle, called Iter ad §>uartum Ven-
triculum, or Aqueduct of Sylvius.
   Behind the third  ventricle, and  terminating it poste-
riorly, are four convex bodies, called Tubercula §>uadri-
gemina, or Nates and Testes: the nates are uppermost and
most convex; the testes are immediately below, and some-
what oval transversely.
   The nates and testes are situated so far backwards that
they are near the anterior part of the upper surface of the
cerebellum, and the anterior edge of the middle of the ten-
torium. The posterior part of the fornix is directly over
them, but it unites with the medullary matter of the cere-
brum above it; there would therefore be a passage into the
lateral  ventricles from behind, between the back  of the
fornix which is above,  and the nates and testes which are
below; but a fine membrane passes  in  from behind, and
attaches the lower surface of the fornix to all the parts on
which it lies; and thus closes the ventricles at  this place.
The membrane, however, is continued in the ventricles,
and is spread over the thalami nerv: optic: The fornix of
course lies upon it, and is attached by it to the surfaces of
the thalami;  in this membrane, immediately over the pos-
terior end of the  fissure called the third  Ventricle, and in
contact with the nates, is the Pineal Gland.  This body is
not so large as a pea, and formed like a pine apple, or the
cone of a pine tree.
   When the  fornix is raised, by dissecting the membrane,
it  may be elevated with the membrane and fornix.
   The nature of this body is not understood: it resembles
a small gland in its appearance;  but it is very soft; and
particles of sandlike matter are often found in it.
   There is a small chord on each edge of the third  ven-
tricle, which appears to proceed from the  pineal gland and 
     Communication of the Ventricles— Vena Galeni.  331
continues on the edge of the ventricle to the anterior crura
of the fornix, which it unites to. These chords join each
other under the pineal gland: they are called the pedun-
xula, or footstalks of the pineal gland.
  The membrane connected with the pineal gland, is the
tela choroidea, or velum interpositum, in which the plexus
choroides is placed, at the edges of the fornix. This mem-
brane is extended, somewhat thinner and less vascular, so
as to line the surfaces  of  the ventricles. The plexus cho-
roides appears to begin at the end of  each of the inferior
portions of the ventricles, where the pia mater penetrates
from the basis of the brain: it proceeds into the upper por-
tions of the ventricles, and, continuing along the edge of
the fornix, passes  under that body  at its inferior angle,
and  meets the plexus  of  the opposite side. Between this
meeting of the plexus, and the crura of the fornix, is a va-
cuity of an oval figure, which forms a communication be-
tween  the ventricles of the brain. Under  this vacuity or
foramen, the thalami nerv: optic: recede from each other,
and  form the  anterior  passage into the third ventricle de-
scribed at page 329, so that at this place the three ventri-
cles  communicate with each other.
   From the plexus choroides of each side, where it has
passed under the fornix at the anterior angle, a large vein
is turned backwards, so as to run nearly over the fissure
of the third ventricle towards  the pineal gland. Several
veins from the surface  of  the ventricle join this vein near
its commencement; thus formed it passes along with the
corresponding vein from  the opposite side, sometimes in
contact, and sometimes separated to a small distance; near
the pineal gland, these veins unite  into  one trunk, the
great internal vein of the brain, called the  Vena Galeni;
which  terminates soon after in the torcular Herophili. 
332
Arbor Vita.
                    SECTION III.
                 Of the Cerebellum.
   THE cerebellum is situated in the lower and posterior
part of the cavity of the cranium, in contact with that por-
tion of the os occipitis which is below the grooves for the
lateral sinuses.  It is of course much less than the brain.
   It is covered above by the tentorium, and is divided be-
low into two lobes, by the falx minor.
   The surface of the cerebellum differs in  some respects
from that of the  cerebrum. Instead of the convolutions
there are small superficial depressions, which are nearly
horizontal,  tending to  divide the cerebellum into strata.
The pia mater extends into these depressions; and  the
tunica arachnoidea passes over them, as in the cerebrum.
   The exterior part of the cerebellum is composed of cine-
ritious or cortical, and the internal of medullary, matter, as
is the case with the cerebrum: but the proportions of these
substances in the cerebellum, are the reverse of what they
are in the cerebrum.
   If sections are made in the cerebellum, the medullar)-
matter is so arranged that it appears like the stem or trunk
of a plant, with ramifications extending from it. This ap-
pearance has been called the Arbor Vita.
   On the  basis of the brain is a part called Tuber Annu-
lare, or Pons Varolii, which is formed by processes  from
the cerebrum and cerebellum;  and is in contact with the
anterior and inferior portion of the cerebellum in the mid-
dle. From this part the medulla oblongata proceeds down-
wards and backwards, under the cerebellum: and between
the cerebellum, the medulla oblongata, and the pons Varo-
lii, is the vacuity, called tht fourth Ventricle of the brain. 
                  Valve of the Brain.              33S
  When the brain is in its natural situation this cavity is
below and behind the nates and testes; and from the cere-
bellum there passes up to the testes a lamen of medullary
matter,  which closes  it above. This lamen is called the
Valve of Vieussens, or the Valve of the Brain.  Below, the
ventricle is closed by a membrane which connects the me-
dulla oblongata to the  cerebellum.
  There is a passage into this cavity from the third ven-
tricle, which passes under the posterior commissure and
the nates and testes, and enters it below the testes.


                    SECTION IV.
  Of the Basis of the Brain and the Nerves which
                   proceed from it.
   WHEN the brain is detached from the basis of the cra-
 nium, and inverted; which can be readily done, if the nerves
 that proceed  from it  are divided, as it is inverted. The
 tunica arachnoidea appears  more conspicuous on the basis
 than it is on the upper part; and the pia mater is disposed
 round the  convolutions  in the same manner that it is
 above; but the nerv«s and vessels connected  with the sur-
 face of the brain are  so much involved  with these mem-
 branes, that considerable dissection is required to expose
 them properly.
    The anterior and middle lobes of  the  brain are very
 conspicuous on the inverted  surface.  The anterior lobes
 appear separated from each other by the extension  of the
 great fissure which forms the two hemispheres.  The mid-
 dle lobes appear at some distance from each other in the
 center; and the cerebellum forms the posterior and most
 prominent part of the surface. 
334  Olfactory and Optic Nerves—Corpora Albicantia.
  When the brain has been carefully  detached from the
cranium and the  nerves adhering to it  are preserved,
the olfactory  or first pair,* of  nerves, appear on the
anterior  lobes, running nearly parallel to each other at a
small distance  from the great fissure. They are flat and
thin, and soft, in their texture: their breadth is rather more
than one-sixth of an  inch. They pass in three divisions
from between the anterior and middle lobes of the cere-
brum, which soon unite and run to the cribriform plate of
the ethmoid, where  they expand into soft bulbous lobes,
from which proceed  the fibres that perforate the  cribri-
form plate, and are spread upon the schneiderian mem-
brane.
  Behind the olfactory nerves are the optic. Each of which
comes out between the  anterior  and middle lobes of the
cerebrum; and after bending so as to meet its fellow, turns
off and passes through  the optic foramen in the sphenoidal
bone. These nerves can be traced in the brain to the tha-
lami nerv:  optic:.
  In the angle  formed by the optic nerves posteriorly, is
a mass of softish cineritious  matter; and also the infundi-
bulum which passes to the sella turcica.
  In this soft cineritious matter are two round white bo-
dies that resemble peas; which are called the Corpora Albi-
cantia of Willis, or the Eminentia Mammillares.  Behind
these bodies are two large medullary processes, called the
Crura Cerebri, which are best seen if some of the cortical
part of the adjoining middle lobes is dissected away. They
come from the medulla of the opposite sides  of the brain,
and gradually approach each other until they  arrive at the
tuber annulare, or pons Varolii.
* The nerves are numbered from before. 
           Pons Varolii—Medulla Oblongata.       335
  The Pons Variolii is a mass of considerable size, which
has a medullary appearance externally, but is striated with-
in: it is formed by  the union of the two above mentioned
crura cerebri, and of two similar processes derived from the
cerebellum, called also its Crura. It lies over a part of the
body of the sphenoid bone, and of the cuneiform process of
the occipital bone, and under a portion of the middle lobes
of the cerebrum and of the cerebellum. There is a longitu-
dinal depression on its surface, made by the vertebral arte-
ry; and there are also many transverse streaks on it.
  The crura  of the cerebellum, which run into this sub-
stance, are evidently continued from the arbor vitae, or me-
dulla of the cerebellum.
  The anterior edge of the cerebellum, part of which is in
contact with the pons varolii, is remarkably prominent on
each side of it.  These prominences are called the Vermes
of the cerebellum.
  The medulla oblongata is continued backwards from the
posterior side of the tuber; and  somewhat  resembles  a
truncated cone inverted.
  It lies on the cuneiform process of the occipital bone,
and extends to the foramen magnum. It is indented length-
ways,  both anteriorly and posteriorly, by fissures which
are very evident: it is  composed of medullary matter ex-
ternally, and cineritious  matter within.
  On  each side of the  anterior fissure, which is in view
when the brain is inverted, are two oblong convex bodies:
those which are next to the fissure are called the Corpora
Pyramidalia, and are the longest: the two exterior  are
called Corpora Olivaria,  and are not so long.
  The third pair of nerves come from between  the
crura of the  cerebrum,  and pass forward, diverging from 
336    Fourth, Fifth and Sixth pair of Nerves.
each other.  They proceed by the cavernous sinus, and,
after penetrating the dura mater, go out of the cranium at
the foramen lacerum.
  The fourth pair, the smallest nerves of the brain, resem-
ble sewing thread in their size and appearance. They come
out between the cerebellum and pons Varolii, but can be
traced backwards as  far as the testes. They proceed for-
wards by the sides of the pons Varolii, and, after penetra-
ting the dura mater near the posterior clinoid apophysis,
pass through the foramen lacerum to the trqchlearis mus-
cles of the eye.
  The fifth pair, the largest of the brain, arise from the
crura of the cerebellum,  where they unite with the pons
Varolii: they pass forwards and downwards, and penetrate
the dura mater near the point of the petrous portion of the
temporal bone.
   This nerve appears like a  bundle of fibres; and, under
the dura mater, forms a plexus; from which its three great
branches proceed to their destination.
   The sixth pair arise from the medulla oblongata, where
it joins the  pons Varolii. It is often composed of two
chords on each side, one of which is very small; they pass
under the pons Varolii,  and through the cavernous sinus,
with the carotid artery: after emerging from this sinus
they proceed through the foramen lacerum to the abductor
muscles of the eye. In this course a small twig passes from
it, which accompanies the carotid artery through the  ca-
nal in the petrous portion of the temporal bone, and, with
a twig from the fifth pair, is the origin of the intercostal
nerve.
   The seventh pair appears at the side of the medulla ob-
longata, near the pons  Varolii. It is composed on each 
                 Eighth Pair of Nerves.           337
side of two chords, called Portio Dura and Portio Mollis,
and of one or more small fibres between them, called Por-
tio Media. The portio mollis can be traced to the fourth
ventricle. The portio dura seems to arise from the place
of union of the pons Varolii  with the medulla oblongata
and the crura cerebelli. The portio media appears to origi-
nate in the  same neighbourhood, and may be considered
as an appurtenance of the portio  dura. They all proceed to
the meatus auditorius internus, as it has been called, in the
temporal bone.
  The eighth pair of nerves arise from the corpora oliva-
ria on the side of the medulla oblongata. They are com-
posed on each  side of one chord  called the Glosso-Pharyn-
geal, and of a considerable number of small filaments,
which  unite and  form another chord called  the Par Va-
gum.
  With these nerves is associated a third chord called the
Spinal Accessory Nerve of Willis, which passes  up  the
spinal cavity, being composed of twigs from the posterior
and anterior portions of almost all the cervical  nerves.
The par vagum, with this nerve and the glosso-pharyn-
geal, proceeds from its  origin  to  the  foramen lacerum
formed by the occipital and temporal bones; where they
all pass out of the cranium; separated from each other and
from the internal jugular vein,  by small processes of the
dura mater.
  Their  destination  is extremely different.  The glosso-
pharyngeal is  spent upon the tongue and pharynx; the
par vagum upon the contents  of the thorax and abdomen,
&c; while the accessory branch, which seems to have no
connexion with them,  perforates the sterno mastoid mus-
cle, and is distributed among the muscles of the shoulder.
  Vol. I.                 2  U 
338            Ninth Pair of Nerves, fcrY.
   The ninth  pair arise from the corpora pyramidalia by
many filaments  that are united on each side into three or
four fasciculi, which perforate the dura mater separately,
and then unite to pass out of the anterior condyloid fora-
men of the occipital bone: this pair is spent upon the mus-
cles of the tongue.

   Within the last three or four years, there have been many allusions
in the public papers, to the discoveries of Dr. Gall, formerly of Vienna,
respecting the brain.  For  information concerning these discoveries,
the reader is  referred  to a very  learned and judicious Memoir, pre-
sented  to the class of Mathematical and Physical Sciences of the
National Institute  of France, by Messrs*  Tenon,  Portal,  Sabatier,
Pinel, and Cuvier.
   A translation of this report has been published in the fifth volume of
the Edinburgh Medical and Surgical Journal for 1809. 
339
                    CHAPTER II.
                OF THE SPINAL MARROW.

  1 HE medulla oblongata is continued from the cavity of
 the cranium, through the great foramen of the occipital
 bone, into the great canal of the spine; when it takes the
 name of Medulla Spinalis, or Spinal Marrow.
   The dura mater passes with it through the great fora-
 men, and incloses the whole of it. At the commencement
 of the spinal canal  this membrane is attached to the sur-
 rounding bones, viz.: to  the margin of the great occipital
 foramen, and to the atlas; but below this it is loosely con-
 nected by a membrane which sometimes appears to contain
 a little adeps.  The  tunica arachnoidea and the pia mater
 also invest the medulla spinalis. The arachnoidea appears
 unconnected with the dura mater; and it can easily  be re-
 moved from the pia mater.  The pia mater adheres  rather
 firmly to the substance  it  incloses.
   The spinal marrow consists of medullary matter exter-
 nally, and cineritious or cortical matter internally.
   The fissures, which are observable, anteriorly, and pos-
 teriorly, in the medulla oblongata, are continued down the
 spinal marrow; dividing  it partially into two lateral por-
 tions:  these  fissures penetrate to a  considerable  depth.
 Each of the lateral portions is marked on its external sur-
 face, by a more superficial fissure, which partially  divides
 it into an anterior and posterior part;  so that a transverse
 section of the spine has  a cruciform appearance.
  The nerves go off in fasciculi from the anterior and pos-
terior surfaces of each lateral portion of the spinal marrow;
so that each nerve is formed of two  fasciculi: one  from 
340  Ligamentum Denticulatum. Cauda Equina.
before, and the other  from behind. The fasciculi are of
different sizes in different parts of the spine.  The  lower-
most of the neck are large and broad; those  of the back
are slender; and those of the loins, and upper part  of the
sacrum are very large.
   The uppermost of the  fasciculi of the spine proceed,
almost at right angles with the medulla spinalis, to the fo-
ramina through which they pass; those which are lower
pass off in a direction obliquely downwards;  and the low-
ermost are almost perpendicular. Betv/een  the anterior
and posterior fasciculi, a fine ligamentous chord passes;
which is attached above to  the dura mater, as it passes
through the  foramen magnum,  and continues to the os
coccygis. It passes between the tunica arachnoidea and
pia mater, attached to the pia mater by cellular membrane.
It sends off a small process in a lateral direction, to be at-
tached to the  dura  mater  in the interstice between the
places where the fasciculi pass through the dura mater,
and nearly in  the middle between the upper and lower
fasciculi.
   The spinal marrow  terminates in a point near the up-
permost lumbar vertebrae. The ligamenta denticulata of
the opposite sides join  each other at this point, and form a
small  chord,  which, continuing downwards, is inserted
into the os coccygis.
   These ligaments may support, and keep fixed, the me-
dulla and the nerves, as they originate from it.
   As  the  spinal marrow terminates at the upper lumbar
vertebrae, the lumbar and sacral nerves go off above: they
pass down like a bunch of straight twigs, and are called
Cauda Equina; from a fancied resemblance  to the tail of
the horse. The sheath, formed by the dura mater for the 
            Arteries of the Spinal Marrow.        341
spinal marrow, continues of its original size, and incloses
them in one cavity.
  The posterior and anterior fasciculi pass out separately
from the dura mater: after they are out, the posterior fas-
ciculus forms a  ganglion;  from which one nerve passes
that joins the  anterior fasciculus, and thus forms the spi-
nal nerves.
   When the nerves go off, either from the spinal canal, or
the cavity of the cranium, the external lamen of the  dura
mater where they pass out, attaches itself to the bone or
the periosteum; while an internal lamen, together with the
pia mater, and perhaps the tunica arachnoidea,  is continu-
ed with the nerve.
   This  process  from the dura mater becomes so much
changed that it has been considered as cellular membrane.
The pia  mater and tunica  arachnoidea  seem  also to
invest, not only the nerve in general, but the fibres of which
it is composed.  On this account, probably, the nerves are
larger after passing through the dura mater, than they are
when they leave the  brain and spinal marrow.
   The arteries  of the spinal  marrow proceed from the
head, and, with several additions, continue downwards to
the lumbar vertebrae.
   There  is generally one  artery on the front surface of
the medulla, which is formed by the union of two branches,
that arise from the vertebral arteries within the cranium.
This artery proceeds downwards and communicates with
those of the neck, and with the intercostal arteries, by the
intervertebral foramina, so that it preserves  its  size.
   It terminates with the spinal marrow;  and the cauda
equina below  it  is supplied by branches from the internal
iliac, which enter through the foramina of the sacrum. 
342        Veins of the Spinal Mdrrow.
  There are generally two  arteries on the posterior sur-
face of the medulla spinalis, which also pass out from the
cranium; arising from the vertebral arteries, or inferior
arteries of the cerebellum: they have a serpentine arrange-
ment;  and  communicate with each other, and  with the
ramifications of the anterior spinal artery.
  All of these arteries are dispersed upon the spinal mar-
row and its membrane, and  the parts immediately  conti-
guous.
  The veins correspond with the ramifications of the arte-
ries; but they are collected into two larger branches called
the Sinus Venosi; which are  situated exterior to  the dura
mater, on the front and lateral sides of the spinal  canal.
They extend the whole length of the canal, and, entering
the  great occipital foramen,  communicate with the lateral
and occipital sinuses. 
343
                  CHAPTER III.

                     OF THE EYE.
    It will be very proper to read the description of the orbit
      of the eye in page 54 of this volume, as an introduction
      to the following description of the organ.
    In addition to that account of the bones, it is to be ob-
      served, that processes of the dura mater pass through
      the foramina optica and lacera,  which line the cavity of
      the orbit and unite with the periosteum at the margin
      of it.
  THE eye is an optical instrument of a spherical form,
which lies in the orbit, in a bed of adipose membrane, more
or less filled with adeps for the convenience of its motions.
Connected with the  ball of the eye, are several auxiliary
parts, which are calculated for  its motion and protection,
as well as accommodation in other respects.

                     SECTION I.

         Of the Parts auxiliary  to the Eye.
  ABOVE the upper margin of the orbit, on the promi-
nences of the os frontis, called the superciliary ridges, the
adipose membrane is commonly more full than it is in the
other contiguous places; and the skin which covers it is
thereby rendered prominent.
  The supercilia or eyebrows grow out  of this prominent
skin. The hairs which compose  them are placed obliquely,
with their  roots  towards the nose. Their principal  use
seems to be to defend the eye from sweat, and other matters
which roll  down the forehead. They  are moved by the
corrugator  muscle, and thus express certain passions; and 
344                The Eyelids.
they are  also moved by the occipito-frontalis and  orbicu-
laris palpebrarum.

                The Eyelids or Palpebra,
   Are formed by a slit or orifice in the skin: immediately
under the skin, surrounding this orifice, is a portion of the
orbicularis muscle, (see page  171), in the upper eyelid:
under this portion of the muscle, there is a plate of cartil-
age; and under the cartilage, a portion of tunica conjunc-
tiva, or membrane that covers  the front part of the ball of
the eye and lines the eyelids.
   The upper eyelid, therefore, is composed of the skin,
of some fibres of the orbicularis muscle, of the cartilagin-
ous plate, and of the tunica conjunctiva. The  under eye-
lid is formed in the same way, with the exception of the
cartilage, which, in it, is confined to the margin.
   These cartilages form the margin of each eyelid, which
is called Tarsus. The upper cartilage is broad in the mid-
dle, and narrower at each extremity, and  accommodated
to the form of the eyeball and eyelid.  The  under cartilage
is a narrow flat rim, which does not extend far from the
margin of the eyelid. A thin delicate membrane is extend-
ed from the upper and lower margins of the orbit to these
cartilages, and has been considered as forming  ligaments
for them.
  Their  edges are formed  obliquely, and apply to each
other in such way, that when the lids are closed, a groove
is formed between them and the eye; by which the tears
are conve)red towards the nose.
  The use of these cartilages is to keep the eyelids pro-
perly expanded; and to form margins that apply accurately
to each other.
  These  cartilages are covered internally by the  tunica
conjunctiva. 
                  Tunica Conjunctiva.              345
   The levator palpebrae muscle, which arises from the bot-
 tom of the orbit, at the upper part of the foramen opticum,
 and passes over the superior muscle of the eyeball; is insert-
 ed by a broad thin tendon or  aponeurosis into the cartilage
 of the upper eyelid; and draws it upwards, within the up-
 per margin of the orbit, when the eyelids are opened.
   The tunica conjunctiva, that lines the eyelids, is conti-
 nued from them, without any interruption of the surface,
 over the anterior part of the  ball of  the  eye; in the same
 manner that the reflected membranes are continued from
 one surface to another.
   Although this membrane is a continuation of the skin,
 it is essentially different from it in its structure; being ex-
 tremely thin, flexible and sensible, and also transparent. It
 abounds with vessels, which do not carry red blood in their
 natural state, but receive it largely when they are inflamed
 or much relaxed. It adheres  firmly to the cartilage at the
 edges of the  eyelids; and becomes more loose in its adhe-
 sion to the lids, as it proceeds backwards.  It is so reflected
 to the ball of the eye, that it  covers and adheres to about
 one third of it anteriorly. Where it first joins the eye, the
 adhesion  is  loose; but this adhesion becomes firmer as it
 advances over the eye; and it cannot be separated from
 the cornea without maceration, and a slight degree of pu-
 trefaction. The part immediately  connected with the cor-
 nea is extremely thin and delicate.
   This membrane closes the orbit of the eye, and com-
 pletes the cavity which contains the muscles, lachrymal
 gland, &c. which are by this means precluded from contact
 with the external air.
   On the inside of each eyelid, apparently between the
tunica conjunctiva and the cartilages, are a number of
lines running inwards from the edge of the  lid. These
  Vol. 1.                  2 X 
 346    Glands of Mcibomius—Lachrymal Gland.
 lines are of various lengths, from one fourth to near hall
 an inch; the  longest are in the middle of the upper lid.
 Some of them are straight; and others are serpentine:  their
 colour is a yellowish white. There  are generally more
 than  thirty in the upper eyelid, and  more than twenty in
 the lower. They are called the glands of Mcibomius. By
 pressure a sebaceous substance can be forced out of them,
 in the form of fine threads, from orifices on the edges of
 the eyelids. They are follicles into which the  sebaceous
 substance  is secreted. This substance appears to have a
 twofold effect: it prevents  the tears from running over
 the eyelid, as any other unctuous  matter would do; and it
 prevents the eyelids from adhering to each other, in con-
 sequence of their contact during sleep.
   The  eyelashes or cilia are placed  near the outer  edge
 of the lower part of the cartilages of each eyelid. They
 are.always more  or less curved; and their convexities are
 opposed to each other.  By this  arrangement  the eye is
 defended from small external objects, and from light to a
 certain degree, without closing the lids completely.
   It  is necessary for the perfection of the eye, that the
 whole surface covered by the tunica conjunctiva, viz. the
 anterior part of the eyeball and the internal surfaces of the
 eyelids, should be kept perfectly  flexible and moist; for
 this purpose the  lachrymal fluid is constantly secreted, in
 varying quantities, by t.he lachrymal gland, formerly called
Glandula Innominata.             \
   This body is situated in a depression, in the upper sur-
 face of the  orbit, near its external margin: it is exterior to,
 and above, the tunica conjunctiva.  It is of an irregular ob-
 long form,  and rather flat; but it has some thickness.  The
under surface is lobulated, and forms  two principal lobes.
   From the anterior edge of the gland the excretory ducts, 
                Tears—Lachrymal Sac.            347
to the number of six or seven, pass off. They terminate
at a short distance from the gland, near the upper edge of
the cartilage, and near the external angle of the eye.  They
do not communicate with each other.
   These ducts are so small that they are often not to be
seen by the naked eye; but there is sometimes a chain of
smaller glands, which lie between the gland and the eye-
lid, nearly in the direction of the ducts.
  The fluid secreted by this gland, (viz. the tears) is trans-
parent; but it is always salt to the taste.  When evapora-
ted,'by exposure to the air, some cubic crystals, and a small
quantity of mucilaginous matter, remain. Chemistry has.
ascertained that these crystals contain muriate of soda and
soda uncombined; and that phosphate of  lime and phos-
phate of soda  may be  obtained by burning inspissated
tears; but the whole of the saline matter does not amount
to one hundredth part of the tears in which they are dis-
solved.  The tears therefore consist of  these salts, and of
mucus, dissolved in a large proportion of water.
   The tears are carried from the eye by two small canals,
which commence, one on each eyelid, at the  internal ex-
tremities of the cartilages; opposite to each other.
   The orifices of these canals, being in the cartilages, are
always open, and are called the Puncta Lachrymalia.
   Each of these canals runs, within the edge of each eye-
lid, from the place of  its commencement  to the lachrymal
sac; which is a larger membranous canal  situated in  the
depression formed by the anterior portion of the os unguis
and  the corresponding portion  of the upper maxillary
bone; and extending thence along the bony canal,  which
continues from this depression into the nose, and termi-
nates under the inferior spongy bone near its anterior ex-
tremity. 
 348   Caruncula Lachrymalis-^-Valvula Semilunaris.
   These canals  are very small at their commencement at
 the puncta lachrymalia; but this small portion is very short;
 it forms an angle with the remainder of the canal,  which
 is considerably larger.
   The canals gradually approach each other as they pro-
 ceed towards the lachrymal sac; into which they enter, in
 contact with each other, but by distinct orifices, behind the
 tendon of the  orbicularis muscle.
   About  one fourth part of the lachrymal sac is situated
 above  the junction of the two eyelids, or the tendon of the
 orbicularis muscle, and the remainder  below.  After it de-
 scends below the orbit of the eye, it sometimes contracts
 and takes the name of the Lachrymal Duct.
   The sac and duct have some resemblance to the schnei^
 derian membrane in structure; and are defended with a
 similar mucus. The membrane, of which they are compo-
 sed, adheres to the periosteum of the bony canal.
   The tears appear to enter  the puncta lachrymalia upon
 the principle  of capillary attraction; and to be propelled
 forwards by the motion of the eyelids and the pressure of
 the orbicularis muscle.
   Between the puncta lachrymalia and the termination of
 the eyelids, at their junction with  each other, is a small
 angular space, which is occupied by  a body called the Ca-
 runcula Lachrymalis; which is of a reddish colour, with a
 few small hairs  growing out of it:  it is supposed to  be
 glandular, and to secrete a sebaceous substance.  It has an
 effect in directing the tears to the puncta lachrymalia.
   Between the caruncula lachrymalis and the  cornea, the
 tunica  conjunctiva, in many persons, forms a plait or fold;
 which  is very  obvious when the eye  is directed  inwards:
 this has some analogy with the membrana nictitans of cer-
tain animals, and has been called the Valvula Semilunaris. 
                 The Ball of the Eye.             349
  The muscles of the eye, described at page 171, &c. are
to be ranked among the auxiliary appurtenances of that
organ.
  The tendons of the  four recti muscles, being spread up-
on the anterior part of the ball of the eye, constitute a par-
tial covering, which  has been called Tunica Albuginea.
This tendinous expansion does not extend to the edge of
the cornea, but stops short of it by several lines.*

                     SECTION II.
               Of the Ball of the Eye.
  THE spherical figure of the eyeball depends upon a
strong and  firm external coat called the Sclerotica; which
has an aperture in its anterior part, filled up with a trans-
parent substance, denominated Cornea, that closes it per-
fectly.
  The sclerotica is lined by a thin and delicate membrane,
the Choroides; which is in close contact with it, but does
not extend over the whole internal surface of the eye, and
is deficient in the whole of the part occupied by the cornea.
  On  the internal surface of the choroides is spread the
pulpy expansion of the optic nerve, called  the Retina;  the
natural consistence of which is not much  more firm than
mucus.
  Within these coats  is a cavity, that corresponds with the
figure  of  the  sclerotica  and cornea, but is divided by an
incomplete membranous partition  that separates the  an-
terior part of it, which is covered by the cornea, from the
remainder.  This  partition is called Iris;  and it has a  cir-
cular vacuity in the center, directly opposite to the middle
of the  cornea, which is denominated the Pupil. Rays of
* By line, is meant one twelfth of an inch. 
350               Tunica Sclerotica.
light, which penetrate the transparent cornea, pass through
the pupil into the posterior part of the eye.
  The eye, thus formed, is filled with several transparent
substances, called Humors. The greatest part of the cavity,
posterior to the iris, is occupied by the vitreous Humor,
which is thus denominated, from its apparent resemblance
to melted glass.
  In front of the  vitreous humor, and directly behind the
pupil, is a small body with double convex surfaces, called
the Crystalline Lens.
  In the  space  between the lens and cornea  is a  thin
fluid, denominated from its consistency, the  Aqueous  Hu-
mor.
  Several of the parts, above enumerated, have exquisite
delicacy of structure, and require a very minute descrip-
tion.
               Of the Tunica Sclerotica.
  The Tunica Sclerotica,  or external coat of the ball of
the eye, derives its name from a Greek word, which signi-
fies to make hard. It is composed of opake white fibres, of
great firmness; which form a membrane of very  close tex-
ture, that supports  the globular figure of the  eye.  It is
thicker behind than it is before; but the expansion of the
tendons of the recti muscles give  it a partial additional
covering.
  It has been considered,by many anatomists, as continued
into the cornea; but it can be separated from it by putre-
faction; and it is essentially different from it in  structure.
  The aperture in  it, which is occupied by the  cornea, is
not perfectly circular;  but inclines somewhat to* the  oval
form: the transverse diameter being rather longer than the
vertical.
  Posteriorly, it is  intimately connected with the optic
nerve; which enters it, not directly at the  extremity of the 
                      The Cornea.                 35 \
axis that passes through the center  of the cornea and
pupil, but on the inside of this spot.
   The optic nerve has a firm coat, which invests it rather
loosely: this coat seems to be continued into, or expanded
upon,  the sclerotica.  Within it, the delicate nerve dimi-
nishes considerably before it perforates the sclerotica, and
appears to be composed of fibres. At the small place of its
penetration, the sclerotica is very thin: and it seems that
the nerve does not penetrate  through one  aperture, but
these fibres pass separately through very small foramina,
in this thin part. The foramina are necessarily very small,
as the diameter of the whole  perforated portion, in some
eyes, does not exceed two lines or one sixth of an inch.
   The sclerotica, in its natural state, has few, if any, ves-
sels, that carry red blood. The great vascularity, which is
so evident in ophthalmia, is in the tunica conjunctiva.

                      The Cornea.
   The transparent membrane, which fills up the vacuity in
the anterior part of the sclerotica, is denominated Cornea;
from its resemblance to horn.  It is said to be superior in
strength to  the  sclerotica; and  it is also very firm. It is
formed of lamina,  that  are separable from each other;
which  are supposed to  be connected by a very delicate
cellular membrane.
   This cellular membrane appears sometimes to contain a
fluid; for if a section be made  of the coats of the eye, and
pressure be applied to the  cornea, an exudation will be
perceived, both  upon its internal and external surfaces.
  The cornea is covered by the tunica conjunctiva; which
adheres firmly to it, but may be separated  after macera-
tion. It can  also be separated from  the sclerotica after
maceration, and  a slight degree of putrefaction; especially 
 352                  The Cornea.
 if the parts, when in this situation, are suspended a short
 time in boiling water.
   The cornea is lined internally by a fine membrane, called
 the  Capsule of the aqueous humor; which will be evident
 if the coats of the eye are boiled. In this case, the cornea
 hardens;  and the capsule of the aqueous humor appears
 detached from it, like the cuticle raised by vesication.
   In a sound state, the sensibility of the cornea varies con-
 siderably.*  The  vessels in its structure  do not carry red
 blood: it is however much charged in  its structure by in-
 flammation; and it is said that blood has been found between
 its laminae, in consequence of violent strokes upon the eye.
   It is the segment of a smaller sphere than the scleroti-
 ca;  and therefore is more convex.  The degree of convex-
 ity is very different in different persons: those in whom it
 is very great are necessarily short sighted.  It  is not per-
 fectly  circular,  but rather  oval; the transverse diameter
 being the  longest.
   The cornea and sclerotica are connected to each other
 by sloping surfaces. The edge of the  sclerotica projects
 over the internal lamen of the cornea;  and the edge of the
 cornea passes under the external surface of the sclerotica.
   The separation above mentioned proves the cornea and
 sclerotica to  be distinct from each other.  And although
 their structure is  essentially different  in the human spe-
 cies, it is much more so in some fishes and in some birds.
   From what has been already stated, it appears that there
 are pores  in the cornea, through which  the fluid situated
 between its laminae may be pressed.
   It is probable that an  exudation  through  these pores
 takes place after death; as a pellicle then forms on the cor-
  * It is the opinion of Dr. Physick, whose numerous and successful
operations on the eye have afforded him many opportunities of judging,
that the incision of the  cornea always occasions some pain; which is very
different, as to its intensity, in different persons 
                   Tunica Choroides.               353
nea; which, upon examination, appears to originate from
the drying of a fluid effused there.  This has been consi-
dered as a proof of death; but there are few practical phy-
sicians who have not seen a similar  pellicle, during life, in
persons who were very weak.

                   The Choroid Coat.
  The sclerotica and cornea compose a firm external shell
for the eye; upon which its form depends.
  The sclerotica is lined by a thin flexible very vascular
membrane, denominated  Choroides; which  is in contact
with it nearly throughout its whole extent.
  The  choroides has been supposed to be  derived from
the pia  mater; but this sentiment is not confirmed by ob-
servation:  for the pia mater appears to be connected with
the interior surface of the sclerotic coat.
  It is so delicate a membrane, and so vascular, that it
has been considered by some anatomists as a texture com-
posed entirely of vessels and nerves.
  It has three sets of arteries which are derived from the
ophthalmic branch of the internal carotid, viz:
  1st. The long ciliary arteries, which are generally two
in number: they penetrate the sclerotic coat at the poste-
rior part of the eye, and pass, one on each side of the ex-
ternal surface of the choroides, dividing at the ciliary cir-
cle, each into two  branches, which inosculate with  each
other around the great circumference of the iris.
  2d. The short ciliary  arteries, which are very nume-
rous: they  penetrate the sclerotic  coat  near  the optic
nerve; are spread upon the choroides, and anastomose very
frequently with each other: in their progress forwards they
penetrate from the external to the internal surface of the
choroides, and supply the iris and ciliary processes.
  Vol. I.                2 Y 
354  Bloodvessels—Nerves—Pigmentum Nigrum.
  3d.  The anterior ciliary arteries, which are not very
numerous; and  penetrate the sclerotic coat no great way
behind the  cornea.   These  are  distributed among  the
branches of the long ciliary arteries on the iris.
   The veins of the choroides are very peculiar: besides
those, which accompany.the arteries above described, there
are several veins which are situated more internally than
the arteries and nerves, and about the middle of the eye:
their branches are not arranged in the usual manner, but
run from the main trunk, nearly in a semicircular curve,
are  almost parallel to  each  other, and very numerous:
from  this arrangement of their branches they are called
the  Vasa  Vorticosa.
   The nerves, which appear on the choroides, come from
the ophthalmic ganglion: they pass very obliquely through
the sclerotica, and run forwards; having a very flat appear-
ance in proportion to  their size: five or six of them are of
this description; some others are very small.
   The internal surface of this coat is covered with a black
paste, denominated Pigmentum Nigrum. This  appears to
be spread most thickly on the anterior part of it, and thin-
ner behind, near the optic nerve:  it is said to be thinner
and less  dark  in old persons. It seems to resemble the
matter of the rete mucosum of negroes, when that is soft-
ened by putrefaction.  It is asserted that the colour of this
pigment has never been changed by the ordinary chemical
agenls, or by  moderate  heat. When it is washed away,
the internal surface of the choroides appears to be villous.
   There  is also a portion of this substance  on the external ,
surface of the choroides.  It is said that, in very recent sub-
jects, this matter appears to be inherent in the structure of
the internal surface, and does not come off when it is rub- 
                   Ciliary Ligament.               355
bed gently, or even  when  immersed in  water; but it is
certain, that  a considerable quantity of it sometimes ap-
pears on the exterior surface of the choroides, in eyes that
are not very recent.
   The celebrated Ruysch, and many anatomists after him,
have  considered the choroides as composed of two lami-
nae; but it seems to be the opinion of the anatomists of the
present day, that it consists of but one membrane;  and
there are some who consider it as a  mere tissue of ves-
sels.
   In  the white  rabbit, and some other animals, the pig-
mentum nigrum is entirely deficient: and the pupil of the
eye appears of a red colour, owing to the bloodvessels of
the choroides.
   The general connexion between the choroides and scle-
rotica is  very slight; depending upon a fine cellular  sub-
stance, and very small bloodvessels and nerves.
   But immediately around the margin of the cornea, the
choroides and sclerotica are firmly connected to each other;
by the intervention  of  a portion of cellular  substance,
which, although soft, is dense  and compact, and  of some
thickness.  As this substance extends round the circum-
ference of the cornea, it necessarily forms a ring; which is
between  one  and two lines broad. This substance, thus
placed, constitutes the Ciliary Ligament; which has, to the
great  perplexity  of students, been called by many differ-
ent names; as Orbiculus Ciliaris, Annulus Gangliformis, &c
   It is very distinguishable from  the choroides, the scle-
rotica, and the iris; and appears generally of a gray colour;
but contains the ciliary nerves and arteries, in great num-
bers, as they pass to the iris.
   In this circular band is a small canal, discovered by the 
356
The Iris.
 Abbe Fontana, which is moistened by a pellucid fluid; but
 its use is not known.*
   All of the choroides, which is posterior to the ciliary
 ligament, is in close contact with the  internal surface of
 the sclerotica; but the choroides continues anterior to the
 ligament; and this anterior portion takes a different posi-
 tion.  It no longer lines the internal surface of  the shell of
 the eye;  but is reflected inwards; and  takes a transverse
 direction, as if it were to form a partition. This reflected
 part forms the ciliary body and the ciliary processes, which
 will soon be described.
   The choroides begins to take  this reflection inwards,
 at the place where it is connected with the ciliary liga-
 ment. Immediately anterior to the ligament, the cornea is
 continued from the sclerotica; and being more convex than
 the sclerotica,  it projects  externally and  anteriorly.  As
 the ciliary ligament is situated between the sclerotica and
 choroides, very near to the place where the sclerotica unites
 to the cornea, and where the choroides is reflected inter-
 nally to form the ciliary processes, the edge of the ciliary
ligament must lie in the angle formed by the cornea, which
 is anterior and external, and the reflexion of the choroides,
which is internal. To this  edge of  the ciliary ligament is
fixed the circumference of the circular membrane, called
 Iris, which is now to  be described.

                       The Iris
  Is a flat membrane, which does not partake of the sphe-
rical figure of the sclerotica and cornea,  or of the cho-
roides; but extends across a portion of  the cavity of the

 ' * See Fontana on the poison of the viper, vol. 2, page 310:  and also
 Adolph Murray, Nova Acta Upsal, vol. 3. 
                       The Iris.                   357
eye, and forms a  septum. As it is circumscribed by the
ciliary ligament, it is necessarily circular. It has a round
foramen near its center, which is called the Pupil; which,
in the healthy subject, varies continually in size, according
to the degree of light to which the eye is exposed.
  The situation of the iris, in the cavity of the eye, is such,
that, at its circumference, it is nearly in contact  with the
circumference of the cornea: it is actually in contact with
the  anterior edge of the ciliary ligament, and with the an-
terior surface of that part of the tunica choroides, which is
reflected inwards and forms the ciliary processes.
  As the iris is flat or plain, and the cornea is the seg-
ment of a sphere, there  must be a considerable vacuity
between them.  This vacuity constitutes the anterior cham-
ber of the eye.
  The  iris therefore is a septum, passing across the eye
at its anterior part; and separating that portion of the cavity,
which is bounded exteriorly by the cornea, from the larger
portion formed by the sclerotica.
  The  anterior, or external, surface of this membrane is
very remarkable for its colour: in persons of a light com-
plexion it is generally of a light blue intermixed  with
white; or of a gray, or light hazel, &c. In those whose
complexions are  dark, it  is almost invariably dark also.
These colours are  so arranged, that frequently there is an
appearance of lines, sometimes nearly radiated, more fre-
quendy curved  in various  directions, but tending from the
circumference towards the pupil or center: and when the
general colour of  the iris is blue,  these lines are'often
whitish.
  When this surface is examined in water with a magni-
fying glass, it  appears to be covered with very fine  villi;
which probably have the effect of increasing  its lustre. 
358                  The Iris.
  From a supposed resemblance of these colours to those
of the rainbow, this membrane has been called Iris; and is
generally known by this name: but unfortunately another
appellation has been given to its internal and posterior
surface, which is  covered with a black pigment like the
choroides, and has been commonly called Uvea.
  This black pigment, on the internal or posterior surface
of the iris, has been supposed to have a great effect in de-
termining its general colour: and there is some reason for
this opinion, as the iris is partly transparent; but there is
a colour inherent in it, which is most evident  when the
black pigment is very carefully washed away.
  Thus, the light hazel colour remains unchanged after
the black pigment  is removed; and it is not  probable that
light blue is much  influenced by the black pigment.
  The  iris  is capable of dilatation  and contraction to a
very considerable  degree; by which  the pupil,  or central
vacuity, is enlarged or diminished. By this means it regu-
lates the quantity of light admitted  into the eye. Upon
the first exposure to strong light, the pupil of every healthy
person is observed to be diminished;  and, upon the dimi-
nution of light, to  be enlarged.
   It has been ascertained  by experiment, that this motion
of the iris is not excited by the action of light immediately
upon it, but on the  interior surface of the eye: and this cir-
cumstance  has occasioned the greatest attention to the
structure of this extraordinary and important membrane.
   Anatomists of the greatest respectability hold opinions,
extremely different indeed, respecting the structure of the
iris. They agree that there are many radiated fibres on the
posterior surface, commencing at its circumference; which
can be  readily seen when the  black pigment  is washed
awav; but, while many respectable anatomists declare that 
                       The Iris.                   359
they have not been able to see any circular  fibres, Dr.
Monro describes them minutely; and has published a plate
of them.  He considers them as forming a circle  imme-
diately round the pupil;  which circle makes about one
fifth part of the breadth of the iris.*
  In the human subject, the iris does not appear to be di-
visible into laminae. It is abundantly supplied with arteries;
which form two circles upon it! and it has also a large
supply of nerves.
  The operations of the iris, in contracting the pupil upon
exposure to light, and dilating it, when light is diminished
or withdrawn, have been  explained very differently by
persons who have different sentiments respecting its struc-
ture. Some of those persons, who do not believe in the ex-
istence of muscular fibres in the  iris, suppose its motions
to depend upon the sudden turgescence or depletion of its
bloodvessels: while others impute it to a peculiar quality,
exclusively enjoyed by this membrane.
  Dr. Monro, who refers the contraction of the pupil to
the action of the circular fibres, which is excited by the
stimulus of light applied to the retina,  considers this ope-
ration as analogous to that of the abdominal muscles, in
those cases of coughing, which are produced by irritation
of the glottis. The action of the muscles, in these instances,
being excited by substances applied to the glottis, which
would have produced no irritation if they had been appli-
ed to the muscles themselves.
  The  dilatation of the pupil appears, in the human spe-
cies, if not  in other animals, to depend  upon a different
cause. It seems to be  a  passive state of the eye, which

  * See his publication, intitled Three Treatises.  On the Brain, the
Eye, and the Ear. 
 360             The Ciliary Processes.
 takes place when the stimulus is withdrawn, and the conse-
 quent action ceases. There is some elasticity in the iris;
 and  a great many, perhaps all, of  its natural or healthy
 motions in the human species, may be explained by con-
 traction of circular fibres, induced by irritation; and by
 the contraction of the rest of the  membrane in  conse-
 quence of its  elasticity;  which always exhibits its effects
 when the muscular action ceases.
   The  elastic power in this case  may have some analogy
 to the elasticity of the arteries, which certainly produces
 some of the contraction of those vessels; but  there is ano-
 ther  principle  of  contraction superadded to this,  which
 produces effects different from  those of mere elasticity.
   In the foetus, prior to the seventh month after concep-
 tion, the pupil is closed by a delicate vascular membrane,
 called the Membrana Pupilaris; which, after this period,
 completely disappears.
   The iris was formerly supposed to be a continuation of
 the choroid coat;  but it is now generally agreed that it is
 a distinct membrane; for, when the  eye is very slightly
 affected by putrefaction, it can  be pulled off,  and the cho-
 roides left entire.
   The choroides, on the  contrary, cannot be separated
 from the ciliary processes  without laceration;  and when
 the pigment is washed away from its internal surface, it
 is very obvious that these  processes  are continued from
 the substance of the choroides, and  reflected inwards, so
 as to form a projection into the cavity of the  eye.

      Of the Ciliary Body, and the Ciliary Processes.
  This  internal projection forms a ring or circle, which
has the ciliary ligament before described, near its circum-
ference, and anterior to it. 
                 The Ciliary Processes.             361
  It is so disposed that the whole of its internal or poste-
rior  surface  appears to be formed into radiated plaits
which extend from the circumference to the central vacu-
ity, where they terminate.
  The whole of this structure, or the membrane thus
plaited, is called the ciliary body, while the plaits are called
the ciliary processes.
  In a natural  state  of the eye the ciliary body is covered
With a large portion  of the pigmentum nigrum. It may be
seen very well  by placing the eye on the cornea, and re-
moving the posterior part of all the coats, without deran-
ging the humors. When thus viewed from behind, it has
a black surface, and appears like a ring formed of radiated
lines; it  has been compared to  a  flower  with radiated
petals.
  When the black  paint is washed off, and the humors
of the eye removed with proper caution, the plaited struc-
ture of these radiated processes will be very apparent; it
then will appear that the membrane of the choroides is so
arranged  as  to form radiated plaits; and that these plaits
are the ciliary processes.
  These plaits  or processes do not lie  upon each other,
but are placed on their edges, one edge looking into the
cavity of the eye, and the other edge anteriorly towards
the iris.
  Each ciliary process seems to originate from two lines
or smaller plaits, called the ciliary stria, which soon unite
and  form it.  The process or plait, thus formed, is rather
larger at  its central extremity than at any other part: and
their central extremities are not of equal lengths, but alter-
nately longer and shorter. ,
  The ciliary processes do not extend to the center of the
circle of which they are radii, but stop short of  it; and
  Vol. I.                  2 Z 
362             The Ciliary Processes.
thus include a circular vacuity or aperture; whioh is larger
than the pupil of the iris, and situated a little way within
or behind it. This aperture is occupied by the crystalline
lens (to be hereafter described): but the central extremi-
ties or terminations of the ciliary processes do not adhere
to the lens,  for they are loose and movable; but they arc
in contact with its anterior surface, near the margin.
   It is however to be  observed that the  ciliary processes
are loose only at their central extremities;  for, towards
their other extremities, they seem to adhere, anteriorly, to
the iris; and posteriorly, to the retina, and to the capsule of
the vitreous humor.
  ,The ciliary body, (or the radiated ring  formed by all the
processes) is about two lines broad in the human subject:
but the part next to  the nose is rather narrower than the
rest of it.
   The black pigment is spread over the whole of the pos-
terior, or internal surface, of the ciliary body; but it is much
more abundant towards the circumference than towards
the center.  It is also  more abundant in the furrows be-
tween the ciliary processes than it is in the processes them-
selves:  and  as the membrane, of which the processes  or
plaits are formed, is of a whitish colour, the processes, at
their central extremities, have a whitish cast.
   The black pigment is also spread over the anterior sur-
face of the processes; on all that part which  is  loose and
not in contact with the  posterior surface of the iris.
   When the pigment is completely washed  away,  the co-
lour of the ciliary body appears grayish; but if the  eye has
been successfully injected, it will appear  to  be composed
almost entirely of vessels; and to have a villous surface. 
363
                     The Retina.
  Within the tunica choroides, and in contact with its in-
ternal surface, is a third coat of the eye: the Retina. This
coat is evidently derived from the optic nerve, although
its texture appears somewhat different.
  Before the optic  nerve arrives at the ball of the eye, a
small branch of the  ophthalmic artery penetrates its coats:
and when the nerve perforates the tunica sclerotica, as de-
scribed in page 351, this artery passes with it.
  On the internal surface of the choroides, the nerve forms
a small prominence: and from this, the retina expands,
with many ramifications of the aforesaid artery in it.
  The retina has the appearance of mucus, and the semi-
transparency of a surface of ground glass; but when im-
mersed in water, it  floats like a membrane.
  By particular management, when  the retina floats  in
water, a  considerable  quantity of the soft substance may
be removed; and a  delicate, soft, transparent membranous
substance, with the  vessels, will remain.
  The retina,itherefore, seems to consist of a delicate, vas-
cular, membranous web,  with a medullary pulpy matter
spread upon it, and supported by it.
  Thus  constituted, the retina extends from its origin, at
the optic nerve, to  the commencement of the ciliary pro-
cesses.
  It  lines the choroid coat,  and is  therefore in contact
with  the pigmentum nigrum, on its internal surface; but
it is simply  in contact with it,  and is not tinged by it. No
vessels pass from it to the choroides; and, when a poste-
rior section of the eye is made, it slips from it without any
appearance  of  adhesion; being attached only to the optic
nerve.
   Most  anatomists agree respecting these circumstances;
but there is the greatest difference of opinion respecting 
564                  The Retina.
the extent of the retina. Several distinguished anatomists,
of the century lately past, thought very differently from
each other on this subject:  and two of the first anatomists
of the present day have embraced opinions entirely oppo-
site.  Monro is convinced that it extends, under the ciliary
processes, to the crystalline lens: and Soemmering asserts
positively, that it terminates at  the commencement of the
ciliary processes. Some of the* anatomists of London in-
cline to the  opinion embraced  by Soemmering:  and the
late  ingenious Bichat  adopted the opinion embraced by
Monro.
  Both parties confide  in their own observations, and refer
to the eye.  An object which appears so  very different to
different persons, who have good sight, cannot be very dis-
tinct. The pulpy substance of the retina appears to termi-
nate at the commencement of the ciliary processes; but a
membrane,  of a very different  texture,  seems continued
from  it to the crystalline lens.
  Although the eye and the retina have  long been objects
of anatomical  attention, professor Soemmering made an
interesting discovery respecting  it, so  lately as the year
1791, viz.: that  at the posterior part of the retina, in the
axis of the eye, and of course  a little exterior to the en-
trance of the optic nerve, there is a spot of a circular or
oval figure, about one line  or rather mare, in diameter, of
a yellowish or saffron colour, which is brightest about the
center.
  In  the center  of this spot is a round hole, equal, in di-
ameter, to one fourth of the spot.  There are generally se-
veral small plaits of the retina about this place: one of these,
which is very constant, extends  from the optic nerve to
this spot.

  * See the New Cyclopedia, by Dr. Rees and others; article Eye, 
The Vitreous Humor.
365
  The colour of this  spot is pale  in children, bright in
young persons of mature age, and pale at an advanced
period of life.
  The foramen is to  be found in the foetus, but not the
yellow spot.  The colour of the spot diminishes when vi-
sion is obstructed; and the spot disappears when vision is
lost.
  There is the greatest reason to believe that the retina
is the seat of vision: but it has been ascertained, most de-
cisively, that the extremity of the optic nerve, from which
the retina originates, is insensible to the rays of light.

                    SECTION III.
             Of the Humors of the Eye.
  THE  three humors of the eye, viz. the Aqueous, the
Crystalline, and the Vitreous, are separately invested with
a membranous capsule; which is very delicate, and per-
fectly transparent.
                  The Vitreous Humor
  Occupies almost all  the cavity of eye which is posterior
to the iris.  It of course possesses a spherical form. It has a
depression in the center of its anterior surface, in which
the  posterior surface of  the crystalline  lens is received.
It is covered by the retina as far as the retina extends.
  The peculiar consistence of this body, which resembles
that of melted glass, is owing to its membrane;  which is a
spherical sac, divided  by many septa, or partitions; that
form small irregular cavities, in which a fluid is contained.
This membranous sac is most perfectly transparent, and
very flexible: it has,  however, some strength; as it will
support the weight of all the  fluid it contains; and may be
suspended from a hook or forceps. The fluid may be se-
parated from the membranes, by beating the vitreous hu- 
366              Tunica Hyaloidea.
mors in a cup with a spoon;  or by  suspending the vitre-
ous humor, and then puncturing it.  In either case the
fluid, escapes; but the internal arrangement of the mem-
branes is not visible.
  It is said that when this body is frozen, the portions of
fluid in the different cavities, have sometimes been distin-
guishable from each other, as distinct pieces of ice: and
that their form is that of  small wedges; with their edges
directed to the crystalline  lens as a center, and their bases
to the circumference of the  vitreous humor, it is also
said, that if this body be immersed in a solution of potash,
the membranes will become opake, while the fluid continues
transparent: and that the appearance of the cells, thus ex-
hibited, agrees with the form of the pieces of ice above
mentioned.
  This membrane is now generally called the Tunica Hy-
aloidea, from two Greek words which imply a resemblance
to glass.
  Its particular structure is not  perfectly understood.
Vessels are not generally seen on it in the adult; but, in
the foetus, the artery in the optic nerve, (or the central ar-
tery,) sends a branch through the vitreous humor to the
crystalline lens:  and some branches of this artery are to
be seen on the tunica hyaloidea.
  Throughout the greatest part of its extent it appears to
consist of but one lamen; but at the front part, near the
ciliary processes, there are two lamina.  The internal, or
posterior, seems  to be a portion of the proper tunica hya-
loidea, and passes behind  the crystalline lens. The exter-
nal, or anterior, passes over and before  the lens; or at
least is attached to the  anterior part of the capsule, in
which the lens is contained. It is supposed by some anato-
mists, that this  membrane is continued completely over
the crystalline lens; but it has not been separated. 
             Fluid in the Tunica Hyaloidea.        367
  As this lamen extends round the crystalline lens, it is in
contact with the ciliary processes; or with a production
from the retina, which is supposed by some anatomists to
pass between them. It is impressed with radiated plaits
by the ciliary processes, and some of the pigmentum  ni-
grum of these processes adheres to it.
  As these lamina  of the tunica hyaloidea are  separated
by the crystalline lens, there  is a vacuity  between them,
around the margin of the lens: and this vacuity must  ne-
cessarily be circular in its course.
  It is not probable that any considerable quantity of fluid
is contained in this  vacuity; for the two lamina concerned
in its formation, appear in contact with each other. It  can
be readily demonstratedby puncturing the external lamen,
and blowing into it through a small pipe. When thus dis-
tended, there appear to be  incomplete partitions in  the
canal; or partial adhesions of the lamina forming it, which
have the effect of partitions;  these partitions are placed in
a radiated direction, at some distance from each other,
and give the canal a peculiar indented appearance. It is
called by the name of the celebrated  Petit who discover-
ed it.
  The anterior lamen of the tunica hyaloidea, which forms
part of this canal, seems to adhere to the coats of the cili-
ary processes; for if a section is made behind the ciliary
ligament of all the  coats of  the eye, the vitreous  humor
will be found adhering to the anterior portion of the sec-
tion, when it is lifted up.
  When the fluid contained in the tunica hyaloidea is dis-
charged and collected, it appears to resemble, in all its
properties, the fluid in the anterior chamber of the eye;
which, from its consistence, has been  called the Aqueous
Humor.  This circumstance  proves that the  particular 
368               Crystalline Lens.
consistence of the vitreous humor is derived from the
arrangement of its internal membranes.
  The fluid, thus obtained, consists of water slightly im-
pregnated; 1st, with albumen, 2d, with gelatine, and 3d,
with muriate of soda.
  The vitreous humor appears  necessary, to give the ball
of the eye the necessary size, for the performance of its
optical functions: to keep the retina properly distended:
and to retain the crystalline lens at the proper focal di#-
tance from the retina.

                 The Crystalline Lens
  Is a solid body; although it is considered  as one of the
humors of the  eye.  It is of asoftish consistence; and has
been compared to gum half dissolved; but is more firm in
the center than about the circumference.
  When sound, it is perfectly  transparent in  young and
middle aged persons, but  is yellowish in old age.  It is
convex on both surfaces, but the convexity of the different
surfaces is different. The  anterior surface, which is the
least convex, is the segment of a sphere,' whose diameter
varies from six to nine lines. The posterior surface, which
is most convex, is the segment of a sphere, whose diame-
ter  varies from four lines and  a half, to five lines and a
half. This lens is most convex in young subjects.
  It is invested with a tunic of  the same lenticular form
with itself; which has some firmness; but  in a healthy
state, is also perfectly transparent. The lens either does
not adhere at all  to this tunic, or so slightly, that it pro-
jects from it with very slight pressure, as in the operation
of extracting the cataract.
  The posterior surface of this tunic adheres firmly to the
tunica hyaloidea, with which it is in contact: and this last
membrane is generally ruptured in the attempt to separate 
                   Crystalline Lens,               369
them although the separation can sometimes be effected
without rupture.
  The anterior  surface is so intimately connected with
that lamen of the hyaloid tunic which passes before it from
the canal of Petit, that it is not separable without laceration;
and it therefore has not been ascertained whether this
lamen extends completely over the surface.
  As the capsule  of the lens  is thus connected with the
tunica hyaloidea, and this last mentioned  tunic adheres
to the ciliary body, it necessarily follows that  the lens is
confined in its proper position behind the pupil.
  Notwithstanding  the soft consistence of the exterior
portion of the lens, there is reason to believe that it has a
peculiar organization; for if it be immersed some time in a
diluted solution of the nitrate or muriate of  alumine, or in
several other fluids, and then dried, it will be found to be
composed of concentric lamellae, which resemble those of
the bulbous roots; and these lamellae will appear to consist
of fibres.
   It  has  been supposed that muscular fibres entered into
the  composition of the crystalline lens, but this opinion
has never been generally adopted.*
   Between  the  lens and its capsule a small quantity of a
transparent  fluid  is  sometimes found, which escapes
whenever the capsule is punctured.  This fluid is supposed
to be most abundant on the anterior surface.
   The lens is said by chemists to be composed of albumen
 and gelatine, with some phosphate of lime; and it  is as-
 serted that the proportion of gelatine is much smaller in
 the center than in the exterior  parts.
   No bloodvessels are to be seen in any of  the humors
  • See Dr. Young's  Memoir in the Philosophical Transactions for 
370               Aqueous Humor,
of the eye, or their capsules, excepting those of the foetus.
In the fcetus a branch can be traced from the central artery
of the retina, through the vitreous humor, to the posterior
surface of the crystalline capsule, on which it ramifies.  In
similar subjects vessels have been seen passing from the
ciliary processes to the anterior surface of the capsule; and
it is also asserted by very respectable anatomists that they
have  seen  vessels passing from  the capsule into the sub-
stance of the lens.
   The use of the crystalline lens is to concentrate the rays
of light, so as to form a  distinct image at  the  bottom of
the eye.

                  The Aqueous Humor
   Occupies the space which is between the crystalline lens
and central extremities of the  ciliary  processes and the
cornea. This space is divided by the iris into two cham-
bers, very dissimilar in figure, which communicate with
each other by means of the pupil. The posterior chamber
is much smaller than the anterior, and its existence has
been doubted;  but it is easily proved by freezing the eye,
when it is  found filled with a part of the aqueous humor
in a state of congelation.
   The  aqueous humor,  in a natural  state, is perfectly
transparent; but in the  foetus, and for a short time after
birth, it is reddish  and turbid. It consists of water impreg-
nated with albumen, gelatine, and muriate of soda; and of
course resembles the fluid of the vitreous humor.
   It is probable that this fluid has also a capsule appropri-
ated to it; for after  boiling an eye, a delicate membrane
can be found lining the internal surface of the cornea, and
extending from it over the anterior surface of the iris.  It
has not yet been traced as  far as the pupil, but it is proba- 
                  Dissection of the Eye.             371
ble that it extends through the pupil, and lines the poste-
rior chamber also.
   The aqueous humor is quickly renewed after it has es-
caped in consequence of wounds or operations: and blood
accidentally effused into its cavity is often absorbed.
   This fluid  preserves  the  convexity of the cornea, and
admits the free motions of the iris; allowing at the same
time a ready passage to the rays of light.


   It will be very beneficial to every student of anatomy to dis-
sect this delicate organ  himself, as he  will thereby acquire
more accurate and precise ideas of  its structure than he can
possibly obtain from the ordinary demonstrations.
   The eyes of sheep and oxen will serve very well for begin-
ners, as many of them will be required, and they can be easily
obtained. They resemble  the  human eye in many  respects;
and  the circumstances in which they differ may be readily
ascertained by the diligent student; especially if he dissects the
human eye afterwards.
   For  this purpose it will be requisite to have forceps, finely
pointed; with  Knives and scissors that are equally delicate in
structure; and also a pair of strong scissors, bended like those
in the cases of pocket instruments.
   When removing the exterior parts, it  will be useful to pre-
serve a portion of the optic nerve, to take hold of.
   The dissection of the coats of the eye can be best performed
when the  eye is placed in a vessel of water; which should be
shallow or deep, according to the different stages of dissection.
   In some dissections it will be serviceable to form  a bed of
jelly, to support the eye, as proposed by Mr. C. Bell.
  As the first process in this operation, the sclerotica coat can
be readily separated from the choroides, and the cornea with it.
  After examining the external surface of the  choroides, the
ciliary  ligament, and the iris, the iris may be peeled off  from
the choroides. 
 372             Dissection of the Eye.
   The choroides,  by a careful process, may then be separated
 from the retina, which it leaves  surrounding the vitreous hu-
 mor. The  ciliary  processes, being a part of  the  choroides,
 come away with it.
   The preparation being in water, may now be suspended by
 the optic nerve. It consists of the vitreous and  crystalline hu-
 mors, and  the retina. The retina, originating  from the optic
 nerve, adheres anteriorly also,  with so much firmness that it
 will support the part inclosed.
   The retina may  be removed without lacerating the tunics of
 either of the humors; and  the pigmentum nigrum which often
 adheres to  that part of the vitreous humor which was con-
 nected with the ciliary processes, may be washed away with a
 piece of soft sponge. By this washing, the radiated  grooves in
 the vitreous humor, which  were connected with the ciliary
 processes, will be very apparent.
   To examine the iris in its natural situation, an aperture may
 be made in the cornea of  a fresh eye near its circumference,
 and the cornea cut out with the strong scissors.  Tftis exposes
 the anterior surface of the iris.
   The iris may then be  easily  removed, and  the  crystalline
 lens, with the  central extremities of the ciliary processes sur-
 rounding it, will be exposed to view.
   To examine the ciliary processes on the other side, a lancet
 may be plunged into  another  eye, somewhat anterior to the
 middle, and the eye divided by means of the strong scissors.
 The anterior section should then  be laid on the cornea, and the
 ciliary processes will appear very  distinctly, seen through a
portion of the  vitreous humor.  The retina may  also  be seen at
the same time, and a judgment may be formed of its extent.
 The view will be more distinct, if part of the vitreous humor
 should be cut away with the scissors and forceps, so as to lessen
the quantity, without deranging the  parts under  it.
  Several methods have  been  proposed  for  rendering  the
structure of the vitreous humor, and the processes of the tunica 
                   Dissection of the Eye,             373
hyaloidea, more distinct.  None  of them have been very suc-
cessful: but if the vitreous humor be suspended in water by
means of a thread passed through that part which surrounds
the crystalline lens, and some large incisions be made into the
most  depending part of it; after some days of suspension, its
bulk will be diminished, by the discharge of the fluid. If, in this
situation, it be immersed in a solution of nitrate of silver, the
tunica hyaloidea will become very apparent; and by various
degrees of exposure to light, may have its color varied from a
whitish opacity to a dark brown.
  The appearance of the retina is also much changed by im-
mersion in the solution of nitrate of silver.  This effect of the
solution,at first sight,appeared calculated to decide the question
respecting the extent of the retina; but after several applica-
tions it could only be said, that the pulpy  substance of the reti-
na appeared to terminate at the commencement of the ciliary
processes, while a membrane  of a different texture seemed
continued from it to the crystalline lens. 
374
                  CHAPTER  IV.
                    OF THE EAR.
THE organ of hearing is composed  of three distinct
parts, viz. 1. The exterior portion, which, although merely
auxiliary, is denominated the External Ear, 2. A cham-
ber, situated in the petrous portion of the temporal bone,
which is called the Cavity of the Tympanum. 3. A deeper
seated cavity in the same bone, which, from its complica-
ted form, is denominated the Labyrinth.


                    SECTION  I.
               Of the External Ear.
   THE  External  Ear consists of the expanded portion,
exterior to the head, commonly called the Ear: and a wide
tube passing from it to the cavity of the tympanum, called
Meatus Auditorius Externus.
   The form of the Ear is so familiar to every one that it is
not necessary to describe it. The uppermost and longest
portion is denominated Pinna. The  small pendulous part
below is called Lobus.
   The form, as well as the firmness of the pinna, depends
entirely upon a cartilage: the lobus  consists of skin and
cellular membrane.
   The skin which covers the pinna is particularly delicate;
and when  the cuticle is separated from it by maceration,
it appears  to be perforated with an unusual number of
foramina, which are the orifices of the  sebaceous glands.
 It is connected to  the subjacent cartilage by a dense cellu-
lar membrane, which, in most places, is free from adeps. 
                  The External Ear.              375
  The cellular membrane of the lobus contains adeps very
delicately arranged.
  The circumference of the ear is formed by a fold of the
margin  of  the cartilage:  and this folded edge is denomi-
nated Helix, from its winding direction.  It commences in
the cavity called Concha, to be  presently described; and
after  proceeding forwards and upwards, it turns round
backwards  and downwards.
  Within this prominent margin is a second prominence,
called the Antihelix, which appears to be formed by a con-
vexity of the surface of the cartilage, but is found in every
ear.  It is nearly semicircular, with its concavity towards
the meatus; and it forms the  margin of the cavity called
Concha, above mentioned. The upper portion of the anti-
helix consists of two superficial ridges which unite after
forming  between them  a shallow depression, the Fossa
Navicularis, or Scapha.
  The helix and antihelix form therefore three cavities or
depressions, viz. 1. A sulcus, occasioned by the  fold of
the helix,  which is sometimes called Fossa Innominata.
2. The Fossa Navicularis: and 3. The Concha, which may
be considered as the proper orifice of the ear.
   Besides  these  prominences and fossae there are  two
other eminences, called Tragus and  Antitragus,  formed
also  by this cartilage. The Tragus is anterior to the mea-
tus auditorius, and  covered by a continuation of the skin
of the face.  It projects backwards, so as pardy to cover
the meatus. On the inside of it there is commonly a tuft
of hair, from which its name is derived.
   The Antitragus is opposite to the  tragus, on the poste-
rior  margin of the concha.
   On the posterior surface of the ear the convexity of the
concha is very conspicuous. 
376              The External Ear.
  When the skin and  cellular membrane is carefully re-
moved, and the cartilaginous skeleton of this structure is
examined,  its form will not appear so regular as that of
the undissected ear; for there are several deficiencies or
vacuities in it;  the most remarkable of which is between
the tragus and the helix.
  The cartilage, thus formed, is attached to the bones of
the face  and cranium by three ligamentous membranes,
which connect it to the zygomatic and the mastoid pro-
cesses of the temporal bone, and to the aponeurosis on the
squamous portion of the same bone.
  In addition to the common muscles of the ear, described
at page  170, there are a few  muscular fibres,  which, in
some subjects, may  be discerned on particular parts of the
cartilage, and therefore are considered as muscles proper
to these portions of the  ear.
  There are five of these portions of fibres: two on the
helix, one on the tragus, one near the antitragus, and the
fifth on the other side of the ear.
  The Major Helicis is on the anterior and most promi-
nent part of the helix above the tragus.  The Minor Helicis
is lower down on the helix, in the concha.
  The Tragicus lies on the tragus, and the Antitragicus
behind the antitragus, while the Transversus Auris is on
the other side  of  the  ear, on the prominence formed by
the concha near its circumference.
  It may be observed  respecting the muscles of the ear,
that even the common muscles, which are by far the largest,
are unable, in many persons, to move that organ; and the
proper muscles, in a large majority of mankind, cannot be
perceived to produce any effect at all.
  There are difficulties in explaining the form of the car-
tilage; for, notwithstanding the well known opinion of the 
            The Meatus Auditorius Externus.       377
Geometrician, said to have been employed by Boerhaave,
that the line of reverberation  is directed to the  meatus
auditorius externus from every part of the ear; in many
persons the cartilage is so situated, that the concha appears
to be the principal, if not the only part, from which sound
can be reverberated into the meatus.
  It may be questioned whether the backward position of
the ear, which is commonly observed at the present day,
is altogether natural; as a more prominent position seems
much better calculated for the reverberation of sound; but
this position of the cartilage is observable in many infants
at birth.
  It is asserted by some comparative anatomists that the
cartilage is  stronger and more elastic in proportion to its
size, in man, than in  any other animal; and that the lobus
is peculiar to the human ear.
  The Meatus Auditorius Externus is a  tube, extending
from the concha to the membrana tympani; the external
extremity of which is principally composed of cartilage,
and the internal of bone. The cartilage in the external
portion of  the tube  is a  continuation of the substance of
the concha.  It does not solely form a complete tube, for
when  the meatus is opened longitudinally and spread out,
this cartilage appears triangular in shape; a fibrous mem-
brane being joined to it to complete the tube.
  In addition to the  deficiency thus arising, there are two
others, one of which, that has a transverse position, is of
considerable size. These deficiencies are called Incisura;
and the fibrous structure  which closes that which is trans-
verse, has  been  called by Santorini, who described it,
Musculus Incisura Majoris.
  The cartilage is attached to  the bony portion pf the me-
  Vol. I.                 "  B 
378         Meatus Auditorius Externus.
atus at the lower part of  its margin, and forms about one
half of the length of the meatus.
  The skin covering the external ear is continued into the
meatus, and lines it throughout:  extending over the inci-
surae, and also over the membrana tympani. It  adheres
more firmly to the  periosteum of the bony part of the me-
atus than to any other portion of the canal. Some fine hair
is often observable  growing out of it at the external extre-
mity.  As  the skin  advances deeper in the meatus it be-
comes more and more delicate and sensible.  The extreme
pain excited by the penetration of an insect, or the intro-
duction of an instrument, into the  ear, evinces the great
degree of  sensibility with which it is indued.
  Exterior to the skin, in the cellular membrane which sur-
rounds it,  are many small glands of a yellowish  colour,
whose ducts open upon the surface of the meatus, and pour
upon it the substance called cerumen or ear  wax. These
glands  are most numerous about the middle of the meatus,
and at those places in which the cartilage is deficient. The
cerumen is fluid at first, and gradually thickens: in some
diseases of the meatus it has the appearance of pus. The
use of  this secretion is probably to exclude  insects, for
which it is well calculated by its tenacity and bitterness;
and also to defend the delicate surface upon  which it is
spread.
  The direction of the meatus is inwards and forwards: it
is also  curved, with the convexity upwards; but it is very
easy, by management of the external ear, to admit the rays
of the  sun to the  bottom  of the meatus, and bring the
membrana tympani into view.
  A vertical section of the meatus is of the oval figure. In
the foetus the bony part of this duct is not formed, and the
meatus consists entirely of cartilage. 
The Cavity of the Tympanum.         379
                     SECTION II.
          Of the  Cavity of the Tympanum.
   THE meatus auditorius externus is terminated abruptly
by the membrana tympani, which forms a septum that
closes it completely.
   On the inner side of this septum is the Cavity of the
Tympanum, which may be regarded as the continuation of
the bony meatus.
   It  differs however from  the form of this canal, for its
diameter is greater, and it is not so regularly cylindrical.
   It is not deep, as the distance from the membrana tym-
pani, which constitutes the external side, to the  opposite
internal side, is seldom more than  three or four lines.
   The breadth of the cavity of the  tympanum is therefore
greater than its depth.
   It is situated immediately between the membrana tym-
pani, and the labyrinth, which is on the  inside of it.
   In its natural state this cavity has two  apertures: one
which communicates with the fauces,  by means of the
Eustachian Tube;  and another which leads into  the cel-
lular structure of the mastoid process.
   There are also two deficiencies in the bony plate, which
separates it from the labyrinth, called the Foramen Ovale,
and Foramen Rotundum; but in the natural  state of the
parts these deficiencies are  closed, and there is no direct
communication of the tympanum either  with the labyrinth
or the meatus auditorius externus. The only direct com-
munications being those above mentioned, with the fauces
and the mastoid cells.
  That deficiency in the bone between the tympanum and
the labyrinth, which is called Foramen Ovale, is closed by 
380        The Cavity of the Tympanum.
one of the small bones of the ear, called the Stapes. The
other deficiency called Foramen Rotundum, is covered by
the membrane which lines the tympanum.
   In the cavity of the tympanum are four of the smallest
bones of the body, which are articulated with each other
so as to form one flexible piece. This piece is attached by
one end  to the Membrana Tympani, and the other to the
Foramen Ovale; and it is  moved by small muscles con-
nected with it.
   The cavity of the tympanum  is lined by a membrane
which has been considered as similar to the  periosteum;
but it is asserted by Bichat that this membrane, when in-
flamed, resembles the mucous membranes; and that in it6
natural state it secretes a mucus which passes into the
fauces by the Eustachian tube.
   This lining  membrane  is continued over the internal
surface  of the  membrana tympani, and was supposed by
the aforesaid author to be reflected so as to cover the small
bones of the ear.
   The opinion of Bichat, respecting the  nature of the
membrane, is rendered probable  by analogical reasoning,
viz. The internal surface of the cavity must be in want
of  mucus or cuticle, as it is  in contact with the air. The
membrane is very sensible in a sound state, and therefore
is very different from periosteum, which it was supposed
to resemble.

               The Membrana Tympani
   Appears to  be fixed in a bony  ring in the meatus audi-
torius, and is nearly circular in form. It is not perpendicu-
lar to the  meatus,  but has an oblique position in  it;  the
inferior margin projecting further inwards than the supe-
rior. 
               The Membrana Tympani.           381
  The external surface forms a conical concavity, being
apparently drawn in by the malleus, one of the small bones
of the ear, to which it is attached.
  It is asserted by several anatomists, that this membrane
may be separated into  four laminae, viz. 1. The Cuticle;
and 2. The Cutis;  which are continued from the skin of
the meatus externus. 3.  The proper Membrana Tympani:
and 4. The Lining Membrane  of the Tympanum;  which
is extended over the internal surface of the membrana
tympani. Notwithstanding these laminae, it is almost trans-
parent in the living subject, when in a healthy state, and
appears highly polished on its external surface, when light
is thrown upon it. It has been injected so  as to appear
vascular in every part; and one or two vessels are some-
times  seen even  in common injected preparations.  In
some  cases  of inflammation  it  has been  uniformly red.
   It was formerly  asserted by Rivinus, a professor at
Leipsic,that there was a natural aperture in this membrane;
but  although this opinion has had several votaries, it is
certainly erroneous. At the same time it is to be observed,
that an aperture, occasioned by accident  or  disease, is
sometimes perceived in persons who enjoy the faculty of
hearing to a considerable degree. Some persons thus cir-
cumstanced, are accustomed to force tobacco smoke from
the mouth through the ears.
   It is asserted by a respectable anatomist* that the mem-
 brana tympani, when viewed  in a microscope, which will
 magnify twenty-three times, appears to be supplied with
 muscular fibres arranged  in  a radiated manner.  These
 fibres are on the internal side of the membrane.  He thinks

   *  See Mr. Home's Memoir on the structure and uses of the Mem-
 brana Tympani, in the Philosophical Transactions for 1800. 
 382        Eustachian Tube—-Mastoid Cells.
 that under favourable circumstances they can be seen with
 the naked eye.

                 The Eustachian Tube.
   The communication between the cavity of  the tympa-
 num and the fauces is formed by the Eustachian Tube, a
 canal which consists of bone at one extremity, and of car-
 tilage at the other. It commences in the  upper and ante-
 rior part of the cavity of the tympanum, and continues for-
 wards and  inwards through a part of the  petrous portion
 of the temporal bone, above the  fissure in the cavity for
 receiving the condyle of the lower jaw.  The bony canal
 terminates  in a very rough and irregular orifice, which is
 united to a tube composed of cartilage and of membrane,
 that terminates  by a large orifice behind the inferior tur-
 binated bone of the nose, and on a line with it.
  This tube is lined by a continuation of the membrane of
 the posterior nares, which becomes more thin  as it pro-
 ceeds towards the cavity of the tympanum.
  Above the Eustachian Tube, and separated from it by a
 thin plate of bone, is a small  canal which is nearly parallel
 to it, and continues so to the  end of the petrous bone; this
 contains the internal muscle of the malleus.

                  The Mastoid Cells.
  In the  upper and back part of the cavity of the tympa-
num, nearly opposite to the orifice of the Eustachian Tube,
is an  opening which communicates with  the cells of the
mastoid process. These cells do not appear different from
those  in other bones, and are lined with a membrane ap-
parently similar.  Their size is proportioned to that of the
mastoid process, and consequently they do not exist  in
the  foetus. 
The Cavity of the Tympanum.
383
     Foramina and Protuberances of the Tympanum.
  That part of the surface of the cavity of the tympanum
which is  opposite to the membrana  tympani, is very irre-
gular; but  it contributes to the formation of several parts
which are very important in the structure of the ear.
  When the lining membrane is removed, the aperture
called Foramen Ovale, appears in a conspicuous situation,
rather  above the  middle  of this surface. It would open
directly into the Vestibule, or middle chamber of the Laby-
rinth;  but it is closed by the base of the stapes.
  Above the foramen ovale is a prominency of the sur-
face, in which passes the canal for the Portio Dura of the
seventh pair of nerves.
  Under the above mentioned foramen is a more striking
protuberance called the Promontory; within which is  a
part of the  Cochlea, the anterior division of the Labyrinth.
  At the under  and posterior part  of the promontory is
the  Foramen Rotundum, which  opens into the  Cochlea.
This foramen is smaller than the foramen ovale; and in
its  recent state is covered by the membrane which lines
the tympanum.
  Behind the foramen ovale is a protuberance with a per-
foration in  it.  This is called the Pyramid. It is excavated,
and contains the muscle of the stapes, which passes out
through the perforation.

                 The Bones of the Ear.
  The four small bones in the cavity of the tympanum are
denominated Malleus, Incus, Orbiculare, and Stapes.
  The Malleus resembles a crooked club more than any
of  the hammers now in use. It consists of an irregular
roundish head, a neck, and a long tapering body, called 
384             The Bones of the Ear.
the Manubrium or handle. It has also two processes; one
arising from the  neck which  is long  and slender, like a
bony fibre, and therefore called Gracilis. The other called
Brevis arises from the upper end of the handle.
   The Incus  resembles a molar tooth, with  two roots,
widely separated from each other. On the  body is  a de-
pression which is  connected with the head of the malleus.
One of the roots or crura is much longer than the other.
   The Os Orbiculare is equal in size to a small grain  of
sand.  It  is connected to the extremity of the long crus of
the incus, and to the upper part of the stapes.
   The Stapes has a strong resemblance to the  common
stirrup. The upper part is  called its head, the lower part
its base, and the two lateral portions  its crura.  One of the
crura is longer than the other.  The base is applied to the
Foramen  Ovale.
   The situation of these bones is such, that the head of the
malleus and the body of the incus  are in  an  upper and
anterior part of the cavity of the tympanum, which extends
above the membrana tympani. The malleus is the most
anterior of the two bones: its manubrium projects down-
wards, and is included between the internal lamina of the
membrana tympani and the membrane itself. Its long pro-
cess extends horizontally, inwards and forwards, into the
fissure of the glenoid cavity.
   The incus is so placed that the depression on its body
receives the head of the malleus. The shortest leg projects
backwards horizontally, and is attached by a ligament to
a point in the opening into the mastoid cells.  While the
long leg projects downwards like the handle of the mal-
leus, but  behind it, and at a small distance inwards from
the membrana tympani.
i 
            Muscles of the Bones of the Ear.        385
   The situation of the stapes is almost at right angles with
the long leg of the incus, projecting inwards. Between the
bead  of the  stapes and the long leg of the incus, the os
orbiculare intervenes.
  When these bones are viewed in their natural position,
the short leg of the incus projects horizontally backwards,
the long process of the malleus horizontally forwards; the
handle of the malleus, and the long leg of the incus, di-
rectly  downwards, one  connected with  the  membrana
tympani, and the  other  with  the foramen ovale, by the
intervention of the os orbiculare and stapes.

          The Muscles of the Bones of the Ear.
  The aforesaid bones  appear to be regularly articulated
for motion with each other, and they are furnished with
several muscles.
  One of these muscles runs in the bony canal above the
Eustachian tube, and is inserted into the posterior side of
the handle of the malleus, below the root of the long pro-
cess.  Its effect is  to  draw in  the malleus and membrana
tympani. It is therefore called Tensor Tympdni, or Inter-
nus Auris.
   Another muscle, as it is supposed to be, runs in the fis-
sure on the outside of the Eustachian tube, and is inserted
into the long process of the malleus.
   This is supposed  to  draw  the malleus  obliquely  for-
ward, and of course  to relax  the tympanum.  It is there-
fore called  Laxator  Tympani, or Externus Mallei; but
there are the strongest doubts  respecting the  muscularity
of this organ.
   Morgagni, Haller, Lieutaud,  and  Meckel, could not
satisfy themselves that it was muscular: and Sabatier also
   Vol. I.               * 3 C 
386              Chorda Tympani.
doubts of it; while Bell, Fyfe, Hume, Bichat and Gavard,
appear to adopt the opinion of its muscularity.
   Some anatomists describe a third muscle of the malleus
as arising from the superior posterior margin of the meatus
auditorius, where the  membrana tympani adheres to it,
and uniting to the neck of the malleus. It is supposed to
draw the  malleus and membrana tympani  upwards and
forwards.  This however is noticed by few authors.
   The stapes is also supplied with one muscle  called the
Stapedius, which lies in the  cavity of  the pyramid. Its
tendon pssses through the foramen in that protuberance,
and is inserted into the posterior part of the head of the
stapes. It pulls  the head of the stapes upwards and back-
wards.

                The Chorda  Tympani.
   In the upper and posterior part of the cavity of the tym-
panum is a small nervous  cord which enters by a foramen
near the basis of the pyramid, and passing downwards and
forwards, goes out at an aperture in the fissure of the ca-
vity for the head of the lower jaw. In this course it crosses
the long leg of the incus,  and the manubrium of the mal-
leus, and passes between them, being in contact with the
manubrium.
   This nerve comes off from the portio dura immediately
before it emerges from the  foramen stylo-mastoideum,
and after  passing a short distance through a small canal,
enters the  cavity of the  tympanum as above described.
After passing out of the cavity of the tympanum it joins
the lingual branch of the fifth pair of nerves.
   It  was  believed by  the  late Mr. John  Hunter that
the chorda tympani is not simply a branch of the Portio
Dura, but that it is the twig of*the reflected branch of the 
      Observations on the Membrana Tympani, &?c.  387

spheno-palatine fierve, which entering the os petrosum by
the Vidian Foramen joins the portio dura; and after pass-
ing wit.h it a considerable distance, leaves it at the  place
above described.

    There is the greatest reason to believe that the principal
      object of the structure above described, is to transmit
      to the labyrinth those impulses of the air  which occa-
      sion  sound. The membrana tympani, with the small
      bones and their muscular appendages, seem to be  the
      agents for this purpose. The Eustachian tube, and the
      mastoid cells, are subservient parts. The effect of the
      chorda tympani in the cavity, has not been ascertained.
    With this view of the subject it is surprising that persons
      in whom the membrana tympani has been destroyed,
      should enjoy the sense of hearing in a very considera-
      ble degree of perfection. Such, however, is the fact.
    It is necessary that there should be a communication be-
      tween the cavity of the tympanum and the external air,
      in order that the function may be duly performed. This
       is evinced  by the  deafness which results from the ob-
       struction of the Eustachian tube, and the cure of this
       deafness by relieving that obstruction; as well as by the
       salutary  effects of opening the membrana tympani;*
       and even of instituting a communication through the
       mastoid  cells, in  cases where the obstruction  of the
       Eustachian tube could not be removed.
     It has  been supposed that  the Eustachian tube has the
       effect of transmitting sound to the ear, and particularly
       the voice of the individual of whose structure it is a part:
       and it is certain that we hear our voices very distinctly,
       (although peculiarly  modified,) when the external ori-

   • See Dr. Sim's paper on this subject in the first volume of Memoirs
 of the Medical Society of London: and Ashley Cooper's in the London
 Philosophical Transactions. 
388                The Labyrinth.
      fices of the ears are closed: but the well known fact that
      a small watch,  when placed in the mouth, and not in
      contact with any part of it, is scarcely heard, if heard at
      all, renders this opinion very doubtful. It ought, how-
      ever, to be  remembered, during the  investigation of
      this subject, that persons who  hear with difficulty are
      almost invariably in the habit of  opening their mouths
      when they listen.


                    SECTION III.
                  Of the Labyrinth.
   THOSE parts of the organ of hearing which have been
already described seem  calculated  for  concentrating the
vibrations of air; and for  communicating, with some modi-
fication, the motion they occasion, to  the Labyrinth.
   This important portion of the ear consists of three very
dissimilar parts, which communicate with  each other and
form one general cavity.
   The central part of this cavity is a chamber of a form
which approaches to the oval, and has been compared to
that of a grain of barley. It is called the Vestibule.
   At one extremity of this chamber are three  tubes, each
of which is  curved so as to  form a large portion  of a cir-
cle.  These tubes communicate with the vestibule by each
extremity; but they form only five orifices, because two
of their  extremities are united  before they open into the
vestibule. These tubes are denominated the Semicircular
Canals.
   At the other extremity, of the vestibule is a conical tube
convoluted like the  shell of a snail. This is called the
Cochlea.  It also communicates with the  vestibule. 
                     The Vestibule.                 389
   The Ijabyrinth, thus complicated in its form, is situated
on the inner side of the cavity of the tympanum.  Its posi-
tion is such that the Vestibule and the Cochlea are opposite
to the Membrana Tympani, and the Semicircular Canals
are posterior to it. The apex of the cochlea is on  the side
of the labyrinth which is next to the tympanum, the basis
of the cochlea is next to the brain.
   The texture of the bone which  immediately surrounds
these cavities is much harder than that of the other parts
of the os petrosum; and if the bone of a foetus  be used,
these softer parts  may be cut away so as  to leave behind
the bony substance which  surrounds these cavities, cor-
responding exactly to their form.
   The Labyrinth, when thus prepared, may be consider-
ed as a solid body which has been inveloped in a softer
substance, and is  brought into view by  detaching the soft
substance which surrounded it.
   In the foetus it  is nearly as large as in the adult, so that
the structure of the ear can be investigated with great ad-
vantage in such subjects.

                     The Vestibule
   Is situated within  the Foramen  Ovale.  There are two
remarkable depressions of its internal surface;  one, which
is in the superior part, is called Semi Elliptical; the other,
which is below, has the name of Hemispherical.
   When  the  dried preparation is  examined there are
several foramina in this cavity, viz. The Foramen Ovale,
already mentioned. A round aperture, by which  it com-
municates with one of the cavities of the cochlea, and the
five  openings, of the semicircular canals. Besides these,
there are several small perforations from the Meatus Au-
ditorius Internus for the transmission of nerves. 
390
The Cochlea.
   The vestibule,  as  well  as  the other parts of the laby-
 rinth, is lined by a fine  membrane which has been consi-
 dered as the periosteum.

                      The Cochlea
   Commences at  the anterior part of the vestibule. It
 is a conical tube, so convoluted that it has the  form of the
 shell  of a  snail, making two circuits and an half round a
 center.
   It may be considered  as wound in  a spiral  direction
 round a pillar of bone. To  this central pillar the name of
 Modiolus  is applied.  It  commences at the cavity called
 Meatus Auditorius Internus;  and its base is somewhat
 excavated. It gradually diminishes  in diameter as it pro-
 ceeds towards the apex of  the cochlea, and is therefore
 conical in form; but it does not preserve this  form to its
 termination, for near the apex it gradually becomes broad-
 errand thus forms a second cone inverted. This last por-
 tion of the central pillar is called the Infundibulum.  It is
 hollow; and the portion of bone which covers its cavity,
 constitutes the basis of the inverted cone and the apex of
 the cochlea. It is called the Cupola.
   The tube thus wound round the modiolus, or the coch-
 lea, is divided from the beginning to the end by a partition.
   The cavities are called Scala, and the partition Lamina
 Spiralis.
   The Lamina Spiralis is made up of four  parallel strips,
 which compose its breadth.
   1st. A plate of bone.
   2d. Outside of this, a softer plate which  appears carti-
laginous.
   3d. A cellular portion, which appears to contain a pellu-
cid fluid. 
           Lamina Spiralis and Scala of the Cochlea.    391
      4th. A thin membranous strip, which  completes  the
    septum or partition.
      These parts may be distinguished from each other when
    magnifying glasses of sufficient power are used.
      The  bony plate is composed of two laminae with small
    cancelli'between  them, in which  are canals for the trans-
    mission of the fibres of nerves. These canals are extended
    into the cartilaginous part.
      The  membranous part which  completes the septum is
    continued into the lining membrane on the surface of the
    cochlea.
      The  bony portion of the scala does not extend towards
    the apex of the  cochlea so far as  the cartilaginous  and
    membranous portions; and none  of them  continue to the
    apex, for the lamina spiralis terminates in  the infundibu-
    lum  before it has arrived at the apex. Its extremity has
    the form of a hook, and is therefore termed Hamulus.
      As this septum does not extend to the apex of the coch-
    lea, the two  scalae necessarily communicate with each
    other at the apex.
      These  different bands or strips which compose  the
    lamina  spiralis, are called its Zones, and are termed Zona
    Ossea,  Zona Coriacea, Zona Vesicularis, and Zona Mem-
    branacea.
      From what has been stated it follows that there are two
    cavities in the cochlea, each of which continues throughout
    its whole extent. One  begins at the vestibule;  the other
    at the tympanum. But a membrane extended over the fo-
    ramen  rotundum separates  this last from the tympanum.
    They communicate with each other at their terminations.
*   From their origins they are denominated Scala  Vestibuli,
    and Scala Tympani. 
392
Meatus Auditorius Internus.
   As  both the cochlea and the vestibule are filled with a
fluid, it is evident that a vibration produced on the mem-
brane  of the  foramen rotundum may be communicated
through the two scalse to the vestibule.

              The three Semicircular Canals
   Are placed obliquely behind the vestibule. Their posi-
tion is such  that  one is Superior, another  Posterior, and
the third Exterior.  The superior and  posterior are  so
placed that  one extremity of  each may be  considered  as
internal and the other external. They unite at their inter-
nal extremities, which therefore form but  one orifice  in
the vestibule. Their other extremities being separated  to
a considerable distance, form each one orifice. While the
external canal, which is smaller than the others, opens by
two orifices.
   Each of these canals is nearly of the same  diameter, viz.
rather  more than two lines.
   At one of  their extremities each of them has an en-
largement, which is called Ampulla; and there is no other
variation of their diameters.
   The cavity of the labyrinth, thus complicated, is perfo-
rated by many small foramina, through which  various
nerves are transmitted.
  These foramina communicate with the large  canal on
the posterior side of the petrous bone called Meatus Audi-
torius Internus; which continues very near  to the basis  of
the cochlea, and transmits the  seventh pair of nerves.
   The bottom of this cavity is  divided by a  ridge into two
unequal fossae; the uppermost  of which is the least.
   In the Upper Fossa are  two foramina; the  anterior,
which is the largest, serves to transmit the Portio Dura, a.
part of the seventh pair, to be  hereafter described, which 
                Contents of the Labyrinth.           393
 passes through the petrous bone to  the face. The  poste-
 rior  foramen forms a pit with a cribriform bottom, which
 admits nervous fibrillae to the vestibule.
   The anterior part of the Inferior Fossa is also cribri-
 form; its perforations  lead  to the cochlea;  one of them
 which passes  through  the modiolus to the infundibulum
 is larger than the rest.  The posterior part of this fossa is
 occupied by foramina,  which pass  to the vestibule and
 semicircular canals; but they are not so numerous as those
 "which lead to the cochlea.

                Contents of the Labyrinth.
   This interesting cavity is lined throughout by a delicate
 membrane. It contains  sacs and tubes,  and a plexus of
 delicate  nerves, which  constitute a soft  labyrinth within
 that which is composed pf bone.
   In the cavity of the Vestibule are two sacs distinct from
 each  other, and also from the lining membrane.
   One of  these, denominated Sacculus Sphericus, or Sao
 cuius Vestibuii, is situated partly in the Hemispherical Ca-
 vity of the vestibule, and has no direct communication
 with any other part.
   It  contains a limpid fluid, and is said to have so much
-firmness, that when  opened with the point of a lancet it
 will retain its form.
   The other sac is situated partly in  the depression  called
 Semi-elliptical, nearly opposite to the foramen ovale; it is
 so transparent that  it is sometimes  seen with difficulty,
 and appears like a bubble of air in a fluid. All the mem-
 branous semicircular canals, which are soon to be descri-
bed, communicate with it by each of their extremities; it
 has been called Alveus Communis  by Scarpa, and Utriculus
 by Soemmering.
  Vol. I.                3D 
394             The Auditory Nerve. ">
  In the bony canals already described are three Membra-
nous Semicircular Canals, which resemble them in form.
They have an ampulla at  one extremity,  as they arise
from the sac above mentioned, and are cylindrical during
the remainder of their  course;  they are transparent, and
have smaller diameters than  the bony canals, although
they are rather larger.

                 The Auditory Nerve.
  Upon this structure, viz. the Sacs in the Vestibule, the
Membranous  Tubes in  the  Semicircular Canals, and the
Lamina Spiralis of the Cochlea, are expanded the fibres of
the Auditory Nerve.
  This nerve, with the Portio  Dura, and  its  appendage,
the Portio Media, composes the seventh pair of nerves of
the brain.
  It is called Portio Mollis, and is very distinct from the
Portio Dura, although they pass together along the Mea-
tus Auditorius Internus.
  Corresponding to the foramina and the cribriform struc-
ture of the bottom of the  Meatus Auditorius Internus,
the Auditory Nerve passes into  the Labyrinth in branches,
or fibrillae, of various sizes. One portion of them enters
the Vestibule, and has been traced upon  the  Alveus or
Utriculus,  and its internal surface;  and also upon the
Semicircular membranous tubes. Another portion seems
exclusively appropriated to a part of these tubes. And a
Third  is spent upon the Sacculus Sphericus.
  These nervous fibres seem to terminate in a pulpy ex-
pansion on the internal surface of the aforesaid sacs and
canals, in a way  which has  some analogy with the termi-
nation of the optic nerve. 
                    The AqueduSts.                395
  A large bundle of these fibrillae enters the Cochlea at its
base; and the largest of them passes through a foramen,
mentioned before, along the center of the Modiolus to the
Infundibulum.
  These fibrillae divide  most minutely, and passing be*
tween the  plates of the Lamina Spiralis, as well as the
other parts of the bony structure of the Cochlea, at length
form a plexus, which has the appearance of a pulpy menir
brane, that is extended over the whole of the Lamina Spi-
ralis. Thus is the Auditory Nerve distributed.
  To complete the account of  the Labyrinth, it is to be
observed that a pellucid fluid certainly exists in it; exterior
to the sacs in the Vestibule, and to the Membranous Semi-
circular Canals. So that the Membranous Labyrinth may
be said to be immersed in a fluid.
   This fluid fills also the Cochlea.

                    The Aqueducts.
   It is probably on account of this fluid,  that two small
 canals exist; which are called, after the anatomist who first
 suggested their use, the Aqueducts of Cotunnius.*
   One of these commences in the Scala Tympani of the
 Cochlea, near  the foramen ovale; and terminates in the
 jugular fossa, by a small orifice, situated  before the  spine
 that separates the eighth pair of nerves from the internal
 jugular vein. It is called the Aqueduct of the Cochlea.
   The other originates in  the Vestibule,  under the com-
 mon orifice of the two canals; and terminates on the pos-
 terior surface of the petrous bone, by a small orifice, which
 is situated at some distance behind  the Meatus Audito-
 rius Internus.  It is called the Aqueduct of the Vestibule.

   •  See Sandifort's Thesaurus Dissertatlonum, Stc. vol. I. 
396
Portio Dura.
   To this account of the ear it ought to be added, that the
Portio Dura, after  entering into the petrous bone by the
foramen in the upper fossa of the Meatus Auditorius In-
ternus, proceeds, in  a canal which is called the Aqueduct of
Fallopius, through  the  bone, to the Foramen Stylo Mas-
toideum, on its inferior surface; where it emerges, and is
distributed to  the  face. It is therefore  called the Facial
Nerve by some anatomists.
   In the course of this nerve from the Meatus through the
solid bone,  it forms a remarkable angle, and then passes,
between the Cochlea and the Semicircular Canals, to the
foramen Stylo Mastoideum,
   In this course it soon receives the Vidian Nerve already
mentioned; and it sends-off the Chorda Tympani, imme-
diately before it passes out at the Foramen Stylo Mastoi-
deum. It also sends off small fibrils to the muscles of the
bones of the ear.
   It has not been ascertained whether the Portio Dura,
the Vidian  Nerve, and the  Chorda Tympani, have any
effect upon the  function of hearing.

     The situation of those branches of the Auditory Nerve
      which are expanded in the Vestibule and the Semicir-
      cular Canals,  is somewhat different from the situation
      of those  which are in the  Cochlea;  but it has not yet
      been ascertained how far their functions are different.
     The information on  this subject derived from compara-
      tive anatomy,  is very interesting; but for want of more
      acquaintance with  the state of this function in the dif-
      ferent animals, no  very decisive inferences have been
      drawn from it.
     The Vestibule and Semicircular Canals occur much more
      frequently than the Cochlea, which  is to be found in
      few animals, if any, besides those of the classes of Mam- 
Functions of the different parts of the Labyrinth. 397

   maha and of Birds. It is therefore supposed necessary to
   that perfect state of hearing which the animals of these
   classes enjoy. But there  remains a considerable diffi-
   culty on this subject; the Cochlea is not by any means
   so  perfect in  birds  as in quadrupeds; yet many birds
   appear to have  clear perceptions of musical sounds,
   and some birds imitate articulate sounds with consider*
   able accuracy.
 That  the  impression which produces hearing is made on
   the nervous expansions in the Labyrinth,  does not ap-
   pear to be doubted by any one.  The structure  of  the
   whole organ, and the analogy between it  and the eye.
   induce a strong  belief that this is the case.
 This belief  is confirmed by a dissection recorded by Mr.
   Haighton,* in which  Original Deafness was found to de-
   pend  upon a  quantity  of cheese-like matter, which
   filled the whole Labyrinth, and was attended  with  a
   considerable diminution  of the  size of the Auditory
   Nerve: while all the other parts of the organ were in a
   perfectly natural  state.

  "See Memoirs of the Medical Society of London, vol. 3 
SYSTEM OF ANATOMY.

            PART  V.
OF THE GENERAL INTEGUMENTS: OR THE CEL-
       LULAR MEMBRANE AND THE  SKIN.


                  CHAPTER I.
           OF THE CELLULAR MEMBRANE.

A. HAT substance which is situated between the skin and
the muscles, which  is insinuated between the different
muscles, and between the fibres which compose these;
which also connects the different parts of the body to each
other, is denominated the Cellular Membrane, or Tela Cel-
lulosa.
   As it extends over the whole of the body, and is most
intimately connected with the skin, it is considered as one
of the integuments, although it is found in great quantities
in some of the  internal parts.
   It appears to be composed  of membranous laminae, ex-
quisitely fine and delicate in their structure, which are so
connected to each other that they compose cells  or cavi-
ties of various  forms and sizes. 
                The Cellular Membrane.           399
   When these cavities are empty, this arrangement of the
cellular membrane is not apparent; but when they are dis-
tended by water or air it is very evident.
   The  laminae which  pass from  one contiguous part to
another are of different lengths, according to the motions
performed by the different parts; thus, about the muscles
and their tendons they are of considerable length, and be-
tween the coats of the eye they are very short.
   In  some places these laminae are compressed together,
and form a dense  membrane somewhat resembling ten-
don;  but  whenever they  are  separated  from  each other
they appear pellucid, and extremely delicate.
   These laminae, when in a healthy state, appear to have
no sensibility; but so many nerves pass through them, that
pain is generally felt when incisions are made in the cellu-
lar membrane.
   No vessels can be seen in their composition when they
are free from disease, although many pass through them.
On this account they have been considered by some very
respectable physiologists as inorganic; but there are good
reasons for regarding this sentiment as erroneous.
  If a portion of cellular membrane, in the living subject, be
brought into view by a surgical operation or a wound, and
be allowed to remain sometime, covered by an emollient
cataplasm, or a soft plaster, a complete change of color
will gradually take place; it will become uniformly red, in
consequence  of the great number of  minute  vessels into
which blood has penetrated during inflammation; and gra-
nulations will form on its surface.
  These vessels must have existed previously in the sound
state of the membrane, and conveyed a transparent fluid;
although no structure of this kind was visible.  This single
fact therefore proves completely its organization. 
 400            The Cellular Membrane.
   In  some parts of the body, this cellular membrane ap-
 pears to be moistened by a small quantity of fluid, or hali-
 tus, in its cells; which seems merely sufficient to keep it soft
 and flexible.  In other places it is loaded with fat.
   There is great reason to believe that the fat is contained
 in cavities which are somewhat different from the ordina-
 ry cavities of the cellular membrane.
   The cells or cavities which contain the moisture or ha-
 litus communicate with each other, over the whole body.
 Thus, air insinuated into the cellular membrane exterior
 to the pleura, in consequence of a fractured rib, will be dif-
 fused over the whole body; and produce the disease called
 emphysema. In  a patient  who is affected with that spe-
 ties of dropsy called anasarca, a portion of the fluid will
 be effused in the head and upper parts of the body, after he
 has passed a night in bed in a horizontal position; but af-
 ter Jie has been in an erect position for some time, the fluid
 will be accumulated in the legs and  feet, or most  depend-
 ing parts of the body, in consequence of its gravity.
   It is well  known in dissecting rooms, that the effused
 water may be completely discharged from anasarcous sub-
jects, by making incisions in the feet, and placing the sub-
ject erect.
   Blood effused in the cellular membrane is sometimes
 dispersed in the same way: an ecchymosis often appears in
 the eyelids, in consequence of a coatusion on the upper
 part of the head; and similar appearances occur in almost
 every part of the body, in consequence of effusions of blood
 at a distance  from them.
   The fat or  adipose matter is not diffused in this man-
 ner: wherever it is first effused, it remains;  uninfluenced
 by gravity, or the ordinary pressure.
   Fat is not observed in every part of the body;  it is ne- 
         The Reticular and Adipose Membranes.     401
ver seen in the cellular membrane of the eye lids; of the
penis; of the lungs; or of the parts within the cranium; as
well as of several other places. The inconvenience which
would result from the  accumulation of fat in these places
is very obvious: and it is equally certain that the  cellular
membrane, in them, must be different from that in which
fat is produced.
  From these peculiar circumstances, relative to the adeps,
it has been inferred, that there was a peculiar apparatus for
the production and retention of fat, superadded to the cel-
lular membrane; and  some anatomists, with a view to
precision, have called the  part  containing fat, Adipose
Membrane, and the other part Reticular Membrane.* They
state that in dropsical subjects, who are much emaciated,
the membrane, which in a healthy state contained adeps, is
more ligamentous than the ordinary cellular membrane.
  It seems to be proved, by reasoning, that there must be
a considerable difference between these different parts of
the cellular membrane; but it ought to be observed that
those parts of the omentum which are especially appropri-
ated to the production of adeps, do not exhibit any pecu-
liarity of structure.
  This  adipose substance is  distributed in unequal pro-
portions in different parts of the body.  In corpulent per-
sons there  is a considerable quantity of it immediately
under the skin, and especially under the skin of the abdo^
men.
   It is also between the muscles; in the orbits of the eyes;
in the omentum and  mesentery; in the joints and  the
bones; as well as about the kidneys, and the heart also, in
elderly persons. In the  foetus, and for some time after

  • See remarks on the cellular membrane, &c. by Dr. W. Hunter, in
the London Medical Observations and Inquiries, vol. JI
  Vol. I.                3 E 
402  Connexion of the Cellular Membrane and Skin.
birth, it appears to be confined to the parts immediately
under the skin, but it soon becomes more diffused.
  It is observed by  dissectors that there  are no subjects,
however emaciated, which are entirely free from fat; ex-
cept those which have been affected with anasarca.
  The cellular membrane has been already observed to
form granulations very promptly; and it has been asserted
that the granulations, which arise from  all the different
parts of the body, when wounded, originate from the cel-
lular membrane in those parts.
  Whether this  proposition be true or not, to the extent
above stated, it is a fact that granulations, in some instan-
ces, seem to have a cellular structure; as the following case
will prove.
  A patient with a compound fracture of the leg, which
was attended with a large wound, covered with  luxuriant
granulations, was attacked with an oedematous swelling of
the limb,  which increased suddenly  to  a great degree.
While this was going on, the granulations on the surface
of the wound tumified with the limb; and upon examina-
tion, appeared somewhat pellucid with an effused fluid;
indenting  by pressure, precisely as the skin was indented.
  The cellular memSrane appears to have a most intimate
connexion with the  skin;  and cannot be completely sepa-
rated from it by dissection. It is  said that in certain cases
of disease, where it is reduced to a slough, while the tex-
ture of the skin remains unchanged, as in some species of
anthrax or carbuncle, this separation may be completely
effected;  In such cases the under surface of the skin will
appear to be composed of pits or excavations,  which pene-
trate very deep into  its substance, and were occupied by
the cellular or adipose membrane while it was in its natu-
ral condition. 
403
                   CHAPTER II.
                     OF THE SKIN.
The skin is composed of three dissimilar laminae, which
  are denominated the Cutis Vera, the Rete Mucosum,
  and the Cuticula.

                    SECTION I.

                 Of the Cutis Vera.
JL HE innermost of the above mentioned laminae is much
more substantial than the others, and therefore is called
Cutis Vera.
  It is an elastic, dense, and strong membrane; which con-
tains in its texture a large proportion of fibres that appear
to be tendinous, and  are woven together in an intricate
manner.
  Blended with these fibres is an immense number of ves-
sels  which enter into the texture of the skin; these ves-
sels do not generally convey red blood, and therefore they
are not very visible; yet they may be readily brought into
view, by the application of rubefacients during life; and, by
fine injections, in the dead subject. Their existence is also
demonstrated  in the vigorous infant, at  birth, by the uni-
versal redness of the skin, which is observable at that time.
  Nerves are  also distributed to  every  part of the skin.
They can be traced to it very easily; and as there is no part
of the  skin,  into  which the finest needle can be pushed
without pain, it is certain that their distribution must ex-
tend to every part. 
404
Cutis Vera.
   It is highly probable that the processes of  absorption
and exhalation are effected by small vessels which origi-
nate or terminate on the surface of the skin, and of course
form a part of its texture.
   The skin,  thus constructed, extends over the whole of
the body, and is continued into those cavities which open
upon  the surface, as the. mouth, nose, &c, although its
texture changes immediately upon its reflexion.
   It varies in thickness in different parts; thus, it is thicker
on the back  than the front of the body.  It is thin on  the
insides of the arms and legs, where opposite surfaces touch
each other.
   It is in general thinner in women than in men.
   The elasticity of the skin is made evident by its yielding
to distension, and returning  to its usual size;  as in preg-
nancy, dropsy, &c: but it is particularly demonstrated in
some cases of parturition, when the skin of the perinaeum
stretches immensely, and, after labour, very  quickly reco-
vers its natural size.
   The external surface of the  skin is very generally divi-
ded by superficial grooves or sulci, into small spaces of
various angular forms; most commonly rhomboidal.  On
the palms  of the hands and soles of the feet, instead of
these figures, we perceive the whole surface  composed of
furrows and ridges, which in some places are rectilineal
and in, others oval and spiral.
   There are also a number of depressions or grooves
Which seem formed to accommodate  the various articula-
tions, particularly about the fingers and toes.
   There are  other furrows, occasioned  by muscles,  as
those on the forehead;  and some depend on the subjacent
cellular membrane. 
             Pores, &?c. of the Cutis  Vera.         405
  On the external surface of  the true  skin, when the two
exterior laminae are removed, many papillae are to be seen.
They differ in size in different parts of the body:  they are
vascular, and, on the ends of the fingers, appear like villi,
when examined with a magnifying glass.
  There are  many perforations or pores to be seen on the
skin with the naked eye, which are probably the ducts of
sebaceous glands, and the passages which transmit hairs.
Other pores,  different from either of these, are to be seen
when magnifying glasses are used; as those on the fingers:
these probably are the exhaling or absorbing pores, but
their connexion with the vessels which perform these func-
tions has not  yet been demonstrated.
  The internal surface of the skin, when carefully dissect-
ed from  the subjacent cellular membrane, in a subject of
ordinary  corpulency, appears to  have some adipose sub-
stance in its texture; but, as has been  already mentioned,
when the cellular membrane is destroyed, these portions of
adipose matter disappear, and the  surface of  the skin ap-
pears pitted.  It is probable that this  connexion  of the
cellular membrane and skin may occasion that delicacy of
skin which appears in some hydropic patients.
  In some places on the under surface of the  skin are
small glands  called miliary, from their resemblance to the
millet seed; these glands are supposed to secrete a seba-
ceous matter, but they are not so general as has been sup-
posed.
  There are sebaceous follicles or ducts which open on the
external surface of the skin, and contain  an oily substance,
which sometimes has  the consistence of suet or tallow:
when these ducts are filled with sebaceous matter, their
orifices are often covered by a black substance which acci-
dentally adheres to the surface of the matter,and forms very 
406
Cutis Anserina.
 small black spots in the skin.  These often occur on the
 nose and ears, and may be removed by pressing out the
 sebaceous substance, which rises up in the form of small
 worms.   Sometimes this  secretion accumulates  in  the
 ducts in such quantities that it forms small tumors in the
 skin.
   Muscular fibres have been supposed by some persons
 to exist in the skin, but such fibres have never  been  de-
 monstrated in it. The skin of the scrotum is often much
 contracted,  but the fibres which produce this effect are ve-
 ry visible in the cellular membrane, and have a  muscular
 appearance.
   Although the skin is not muscular, it sometimes chan-
 ges its appearance in a surprising manner.
   When the surface  of the body is suddenly exposed to
 cold, or when  the chill of fever exists  to a considerable
 degree, the skin will contract very sensibly; and at the
 same time a great number of conical papillae will project
 from its surface. This constitutes the Cutis Anserina; and
 is supposed  to be produced by a sudden contraction of the
 vessels in the skin, which forces out their contents, and of
 course diminishes its bulk; while the papillae do  not con-
 tract in the same degree, and therefore are somewhat pro-
jected.
  When the skin is  free from  disease, the two exterior
 laminae may be separated from it completely, after macera-
 tion or putrefaction, and the surface will appear smooth; but
 in an inflamed skin, a network of vessels has been injected;
 which is considered by Mr. Cruikshank* as an additional
 lamina. In this lamina the pustules of smallpox originate.
 When the skin is injected they appear to be formed at first

 * See Experiments on Insensible Perspiration, &c. by W. Cruikshank. 
       Vessels on the External Surface of the Skin.   407
by very small vessels, arranged in a radiated manner, with
a white uninjected substance  in the center, which is sup-
posed  to be a slough, occasioned by the irritation of the
variolous  matter.  Mr. Cruikshank  after removing this
lamella was able, by continued maceration of the same skin,
to separate another, which was  also vascular. It is to be
observed that this skin had been preserved for some time
m spirits, and was macerated in putrid water a week du-
ring the heat of summer, before the first  lamella was re-
moved.
  The colour of the healthy skin is invariably white, when
all the lamellae exterior to it are removed.  This is the case
not only with the European, but with the  blackest African,
and the people of all the intermediate colours.
  The variety of colours in the human species depends
upon the lamella next to the cutis, which is now to be de-
scribed. 
408
                     SECTION  II

               Of the Bete Mucosum.
   IMMEDIATELY  in  contact with the external sur-
face of the cutis vera is a thin stratum, of a pulpy or mu-
cilaginous consistence, which appears  to be spread uni-
formly over it, but cannot be detached  without deranging
its own texture.*
   It can be  best examined after the cuticle is raised in a
blister.  In this case it  appears like a pulpy substance,
spread upon a membrane of a soft and  delicate  texture.
This is the Rete or Corpus Mucosum.
   In this pulpy substance resides the pigmentum, or  co-
louring matter, which gives the peculiar complexion to the
different races of men.  The cutis vera is white,  and the
cuticle is nearly transparent in them all; but this substance
is black in the negro; copper-coloured, yellow, or tawny,
in many of the Asiatics; and yellow, with  a tincture of red,
in the aborigines of America; while  it is transparent, or
whitish, in the people of Europe and their descendants.
   It can therefore be best examined in the negroes; and
if it be inspected immediately after the cuticle of a blister
is removed it will appear as above described, with a black
matter diffused through it.
   The particular structure of this substance has not been
ascertained; although anatomists have paid a good deal of
attention to it. It is generally believed by them  that no
vessels can be injected in it; but Dr. Baynham of Virginia,
while he was engaged in anatomical pursuits in London,

  * It has been asserted that the rete mucosum of the scrotum can
sometimes be exhibited in a separate state. 
      Vessels between the Rete Mucosum and Cutis.   409
made a preparation which excited the attention of the Bri-
tish anatomists, on account of its particular relation to this
subject.
  He injected one of the lower extremities, the os femoris
of which was diseased with an exostosis; and with a view
to an examination of the lamina? of the skin, he  removed
a portion of it from the leg; and after immersing it a few
seconds in boiling water, to thicken the laminae, he macer-
ated it in cold water for some days.  Upon separating the
cuticle, after this treatment, he discovered a texture of ves-
sels  on the surface of the cutis vera, which  was distinct
from the cutis itself.  This has often  been  mentioned as
injection of the rete mucosum.
  It is to be regretted  that Dr.  Baynham, who is particu-
larly qualified to decide, has not published his opinion on
the subject. Mr. Cruikshank', to  whom he  afforded the
most satisfactory opportunity of  examining  his prepara-
tion, believes that the aforesaid vessels were not a part of
the rete mucosum; but that the rete mucosum was to be
seen on the epidermis (being raised with it when  it was
separated from the cutis),  while this texture remained on
the surface of the cutis. He considers these  vessels as be-
longing to the additional lamellae already mentioned, of
which he says Dr. Baynham is the discoverer.
   There is therefore every reason to believe that there is
a texture of vessels, either in the rete mucosum, or between
the cutis vera and the  rete mucosum.
   After putrefaction, or  maceration for a long time, trie
cuticle separates readily from the cutis vera; and the rete
mucosum  sometimes  adheres to the skin, and sometimes
to the cuticle.  If the parts are much softened by putrefac-
tion, the rete mucosum can be  washed away, like the pig- 
410         Change of Colour in Negroes.
mentum nigrum of the eye; leaving the cutis white, and
the cuticle nearly transparent.
   In the negroes the black colour  of  the rete mucosum
is  greatly diminished, on the palms of the hands, and soles
of the feet, and under the nails; but it is perceptible. It is
said that the black colour does not appear in the cicatrices
of the blacks.  This is the fact with respect to recent cica-
trices; but those of long standing are often dark coloured,
although not so black as the original skin. The pits of the
smallpox in their skins,  although  white at first, become
finally as dark as the original surface.
   In Europeans and their descendants the colour of the
rete mucosum becomes darker, as they are more exposed
to  the air and the rays of the sun; and soon changes again
to  its original fairness, by confinement to the house.
   In negroes, the skin loses some of its deep glossy black
colour during the winter season of  cold climates; and re-
covers it again in summer.
   The rete mucosum sometimes undergoes very  impor-
tant changes;  there have been several  instances in  the
United States, where large portions of the skin of the
African have changed from black to white;  owing proba-
bly to an absorption of the black pigment from the rete
mucosum; or perhaps to an absorption  of the rete  muco-
sum itself.
   There is now in Philadelphia a female, between thirty
and forty years of age, in whom this process is going on.
One of her parents was a negro and the  other a mulatto;
and her original complexion accorded with  her  origin.
But a change of colourbegan during her childhood, in small
spots, which have gradually increased so  much,  that at
this time the  whole of her body  and limbs are nearly
white, with the exception of her hands and feet. A large 
    Changes of the Rete Mucosum in White Persons.  411
proportion of her face is also white, and the remainder of
it much lighter than it was originally.  At this time, some
part of her face has an unnatural whiteness; but the skin
of her fore-arms appears like that of an European in a per-
fectly healthy state. This change of colour is attended with
no unusual sensation;  so that if she did not see the altera-
tion, she would not suspect that her skin was any way dif-
ferent now from what  it had originally been. She  does
not appear sensible that the white parts are more suscep-
tible of irritation from the rays of the sun than they were
originally; but they are so much  covered by her dress that
the experiment has not yet been  fairly made.
  The first appearance of a change is slight diminution of
the dark  colour;  this change goes on gradually, and then
small spots appear, which are perfectty white. They  gra-
dually increase, and run into each other, and thus a large
white spot is formed.
  In a former  case, where this process  had gone on to a
great extent, it is said that the black pigment was again
deposited, and the skin resumed its original blackness.
  These  circumstances in negroes have been considered
as great deviations from the ordinary course of nature, but
a process very analogous to it sometimes goes on in  per-
sons  who are white. Thus, there are some in whom the
skin becomes much browner than natural in some parts of
the body, particularly on  the  arms;  and in these brown
portions, spots are formed which are much more white
than the natural colour of the skin.
   In such cases there appears to be a deposition of colour-
ing matter in the rete mucosum of the brown places; while
the  white spots are rendered more white than natural,
either by an absorption of the rete mucosum, or by a de-
position of whiter matter in it. 
412  Changes of the Rete Mucosum in White Persons.
   The colour of the rete mucosum sometimes undergoes
a temporary change in particular places. Thus, at a certain
period of pregnancy, a dark circle forms round the nipple.
   In some cases, where the peculiar whiteness occurs, the
skin becomes very  susceptible of irritation from the rays
of the sun; so as to be blistered,  if exposed to them for a
short time: this circumstance renders it probable that the
colouring matter in the rete mucosum of the. blacks, was
originally designed to protect their skins from the very
powerful rays of the sun to which they are exposed.
   There are  some persons to be found, among most of the
different races of men, who are born with  this peculiar
whiteness of the whole skin, which continues  during life.
In these persons, the hair has a remarkable white colour,
and the eyes are  without the pigmentum nigrum.  They
appear to be in a state  of imperfection, and are unable
to endure the ordinary light of day.  They are generally
designated by the epithet of Albinoes.
   The texture  which exists between the cutis vera and
the epidermis is probably the principal seat of several im-
portant cutaneous diseases; as the Scarlatina, Pemphigus,
&c.;* and from what has been stated, there is  good reason
to believe  thnt  the  smallpox also commences in it. It is
therefore much  to be wished  that its structure* was more
precisely ascertained.

  * In severe cases of the scarlatina, at the termination of the disease,
large portions of the cuticle are sometimes detached from the cutis, so
that several practitioners have seen the whole cuticle of the hand come
off like a glove. As the texture of the cutis does not appear to be alter-
ed in these cases, and the cuticle is also unchanged, the cause of this
separation must exist in the intervening-structure which connects them 
413
                    SECTION III.

              The Cuticula or Epidermis
  HAS been examined with the greatest care by several of
the most successful anatomists; but notwithstanding their
labours, the structure of this substance is by no means un-
derstood.
  It appears  to  have some resemblance to the matter of
the nails, and of horn;  but is rather more flexible, even af-
ter  allowing for the difference  of thickness.
  In those parts where it is thinnest it is semitransparent.
  It is insensible, and  no vessels can be seen in it.*
  It extends over the  whole external surface of the body,
except the parts covered by the nails; and is accommoda-
ted to the surface of the skin, by forming ridges or furrows,
corresponding to it.
  It adheres most closely to the cutis; and when abraded
by mechanical violence, the surface  of  the skin  appears
moistened by effusion.
  It is not certain that its mode of union with the skin is
perfectly understood;  the adhesion of these membranes to
each other is as uniform  as that of two smooth surfaces
glued  together, but it.is generally said  that the cuticle is
attached to the cutis by very numerous and fine filaments.
  It has often been asserted  that these filaments are the
exhaling and absorbing, vessels, which  pass  through the

  *  In the early part of the last century an anatomist of the name of St.
Andre exhibited a preparation of the cuticle which appeared to be in-
jected  with  mercury. Ruysh  declared the thing impossible, and in-
vited him to an investigation of the subject. This invitation was not ac-
cepted, and the affair has been generally considered as a mistake or an
imposition. 
414              Pores of the Cuticle.
cuticle, to and from the skin. This sentiment appears verj
reasonable, but no vessels that pass in this way can be in-
jected.
  There are innumerable processes which pass from the
cuticle to the skin.  Many of these are  the linings of the
cavities which contain the roots of the hairs; but they are
reported by microscopical observers to be, like the fingers
of a glove, closed at their extremities.
  There are also many processes  which contain a seba-
ceous substance that may be pressed out of them in the
form of worms:  these are the  ducts of sebaceous glands.
  Besides these, there is an immense number of whitish
filaments which are as fine as the most delicate thread of a
spider's web.  These  filaments can  be best seen while the
cuticle is separating from the skin of the sole of the foot,
as suggested by Dr.  William  Hunter.* They are suppo-
sed to be vascular, but they have never been injected.
  When the cuticle is in its natural situation, in union with
the skin, there appear to be three species of foramina, or
pores, on its external surface: viz. 1. Those formed by the
passage of the hairs;  and 2. Those which are the orifices
of the ducts of the  sebaceous glands;  each of which has
been already mentioned. And 3. Such pores as exist  on
the ends of the fingers and the inside of  the hands.
  It is sajd that these last are very visible, when magnified
to, twice or thrice their original bulk, and drawings of them
have  accordingly been  made  by Dr. Grewf and by Mr.
Cruikshank.:j:  Small specks of fluid can be seen with the na-
ked eye, in the same situations, in warm  weather, or when
the ends of the fingers are made turgid by a ligature. It is

  * See the London Medical Observations and Inquiries, vol. II.
  | In the Philosophical Transactions, vol. III. Lowlhrop's Abridgment.
  \  See his Experiments on  Insensible Perspiration. 
    Question respecting the Outlets of Perspiration.  415
 probable that they are formed by the accumulation of fluid
 at these orifices.
   The above described pores are situated on the ridges at
 the  ends of the fingers and not in the furrows;  and it is
 probable that similar pores are distributed over the surface
 of the bodj-.
   Notwithstanding, the appearance  of these foramina,
 when the cuticle is in its natural situation, several of the
 most successful investigators of the subject have declared
 that they could not discover any pores or foramina in the
 cuticle, when it was separated from the cutis.
  The late  professer Meckel of  Berlin, who was one of
 this number, was induced to believe that the matter of ex-
 halation, and of absorption, soaked through the cuticle,  as
 the vapour of warm water passes through leather.*
  In support of this doctrine he states, that perspiration
 goes on through the cuticle on the palms of the hands and
 soles of the  feet when it is very thick; and observes, that if
 it were transmitted by delicate vessels, the vessels in the
 feet must be torn by the weight  of the body, in  persons
 who walk;  and those in the hands would experience the
 same fate, in labourers, who work with heavy hammers, &c.
  On the other hand, Mr. Cruikshank, who could likewise
 find no pores in the separated cuticle, contends strenuous-
 ly for their existence notwithstanding;  and explains their
 non-appearance by the following facts, among others, viz:
 that  no foramen will appear in the separated cuticle al-
 though it has been punctured by a  needle;  and that when
 the cuticle has been peeled off, from portions of the cutis
 on which were hairs, which must necessarily have perfora-
ted it, no foramina have appeared in it.
  * Sec Memoirs  of the  Royal Academy of Sciences of Berlin, vol.
 XIII. for 175" 
416       Peculiar Permeability of the Cuticle.
   M.-Bichat took very different ground: he asserted that
the pores of the separated cuticle were to be seen distinctly,
in large numbers, by looking through it towards the light;
he also believed that  the course of the exhalent vessels,
through the cuticle, might be seen in the same manner; and
that they passed obliquely.
  That the cuticle is pervious, is proved incontestably by
the functions  of perspiration and sweating, as well as of
absorption; but there  are good reasons for believing that
the perforations of the cuticle have a peculiar structure;
and  are not simple  foramina. Thus,  when a vesicle is
formed by  the operation of cantharides or any other pro-
cess, if the cuticle is not lacerated, it will confine the effu-
sed fluid for a considerable time; without any appearance
of its escape through these pores.
  This fact, which is strongly opposed to the hypothesis
of Meckel, is  explained by Cruikshank upon the supposi-
tion that the pores of the skin are lined by processes of the
cuticle, and that when the cuticle ,is  separated from the
cutis, these processes go with it, and act like valves in con-
fining the fluid.
  Bichat supposes the oblique vessels to produce  the same
effect upon analogous principles; and compares their situ-
ation to that of the ureters, which pass obliquely between
the coats of the bladder.
  This peculiar quality of the cuticle, in admitting of per-
spiration and sweat, and also absorption, while it prevents
evaporation from the parts which it incloses, is of immense
importance.
  If a portion of skin be deprived of cuticle a short time
before  death, by a  blister  for example, this  portion will
in a few days become perfectly dry and hard, like horn; 
            Causes which produce Vesication.        417
While the other parts of the skin of the subject, covered
by the cuticle, retain their moisture and flexibility.
  It may therefore be admitted, that the use of the cuticle
is to keep the skin soft and flexible, by confining its mois-
ture, as  well as to defend it. And it is  probable that the
sebaceous matter is secreted for the purpose of preserving
the cuticle in a state of flexibility.
  As the cuticle is capable of confining fluid, and resisting
the action of chemical  agents, it is surprising that epispas-
ties and rubefacients should act through it, upon the skin,
with so much certainty as we find they  do; and that can-
tharides  should produce vesications, when applied dry.
  The thickness of the cuticle on every part of the body-
is much  increased by long continued  pressure, forming
corns and excrescences of its own nature. By this cause
also it is rendered very thick on  the palms of the hands
and soles of the feet; although it is originally  thicker there
than in other parts.
   It is said that, after long boiling, these thick portions of
cuticle may be separated into distinct laminae.
   In the living subject, the cuticle,  when immersed in
warm water, seems to absorb some  of that fluid; as is
evinced  by the hands when they have  been  long in that
situation; and also by those parts of the skin to which poul-
tices have been applied.
   Notwithstanding the uniform adhesion of the cuticle to
the  cutis, it is observed, in the  living subject, to be separa-
ted, and formed into vesicles, by a variety of causes, viz.
   1. Pinching of the skin, or violent mechanical irritation'
such as labouring with hard instruments.
   2. By the application of cantharides, and  certain other
substances which produce vesications. Sometimes these
substances appear to inflame the skin;  but on other occa-
   Vol.  I.                3 G 
418           Separation of the Cuticle.
sions the vesication is produced while  the  skin  appears
unchanged in colour, and free from inflammation. The pro-
cess appears  different from that of simple inflammation;
for certain rubefacients often inflame the skin considera-
bly, without vesicating or blistering it.
   3. The boiling heat will very generally produce vesica-
tion.
   4. Certain diseased processes seem to occasion vesica-
tion in a manner which is not well understood, viz.  ery-
sipelas, zona or shingles, pemphigus, and some  other
eruptions which  have no name. In erysipelas thefe is an
obvious inflammation of the skin; but in  some of the other
diseases the vesication takes place without the appearance
of inflammation.
   5. Vesications often appear when there is a tendency to
gangrene.
   6. They also occur in some  cases  of simple fracture,
where there is considerable injury.  In these cases the fluid
effused is often tinged with blood.
   After death the cuticle is separated from the cutis:
   1. By putrefaction; in which case  large vesicles  are
sometimes formed.
   2. By long continued maceration.
   3. By boiling,  and
   4. By violent dry heat.
   The cuticle appears to be least deranged when it is sepa-
rated by putrefaction and maceration: in these  cases  the
internal surface corresponds to  the surface of the  skin;
and the processes which contain the hairs, as well  as those
which are the ducts of the sebaceous glands, are  particu-
larly obvious.
   The external surface of the cuticle varies in different
places, according to the surface of the skin. In some places 
            Chemical Qualities of the Cuticle.        419
it appears scaly at times, and has therefore been supposed
to consist entirely of scales; but in other parts, when ex-
amined attentively, it appears like a  half transparent con-
creted substance, with a rough surface.
  When the skin has continued dry  for a long time, bran-
like scales can  be rubbed off from it. These are probably
composed of the residuum of the secretion deposited on
the skin, and of a portion of the external surface of the
cuticle. The same substance appears upon the first wash-
ing of the skin,  after that process has been discontinued for
any length of time.
  Many speculations have arisen respecting the manner in
which the cuticle is originally formed, and reproduced; but
none of these are perfectly satisfactory.
  It is also a question whether the cuticle is endued with
vitality, or is merely an inanimate unorganized  concrete.
No decisive arguments have been adduced in favour of its
vitality; and it has already been stated, that neither nerves,
nor vessels, can be demonstrated in it.
  It appears particularly calculated for protecting the skin
which it covers; for it is insoluble in water, and resists the
action of several powerful chemical agents. Thus, it is not
affected by immersion for a considerable time in the sul-
phuric and  muriatic acids; although the  nitric acid acts
upon it.
  It resists for a short time, but is at length dissolved, by
the pure fixed alkalies, and by lime.
  It is supposed by the chemists to consist of albumen, in
a peculiar state of modification.

                      The Nails.
  The roots of the nails appear to originate in a fold of
the cutis vera, from the epidermis which lines the fold; 
420
The Nails.
  but the bodies of the nails adhere firmly to the cutis on
  which they lie; and appear to cover  it, in the place of the
  cuticle. The  papilla? of those parts of the cutis which are
  covered by the nails are very conspicuous when the nails
  are removed.  It has been supposed that there was no rete
  mucosum between the nails and cutis;  but this opinion is
  probably erroneous, as the black pigment is  perceptible
  under the nails of some negroes.
    The nails can  be separated from  the cutis by all those
  processes which separate the cuticle from it. When this is
  effected, they remain  connected  with the cuticle, which
  appears to be continued into them:  and on this account,
  as v/ell as their insensibility, and their resemblance to the
  horny  excrescences of the cuticle, they are considered as
  appendages of it.
    The root is opake, and appears  white.  The body  is
  transparent, and in health shows the  florid colour of the
  cutis which it covers;  but the colour of this portion of the
1  cutis depends upon the  state of  the circulation; and be-
  comes livid when the blood is disoxygenated, or when the
  circulation ceases  there;  and this  colour  also appears
  through the nails.
    The nails are unquestionably organized, although their
  ultimate structure is not known. They appear to be com-
  posed of lamellae, and these lamellae, of fibres. They grow
  rapidly, and when they are not  pared or worn away, they
  sometimes acquire an immense size.
    As a remarkable instance of this, it is related, that a nail
  of the  great toe was sent from Turin, to the academy of
  sciences at Paris, which measured four inches and one half,
  in length.                          ^
    The growth seems to take place altogether at the roots. 
                      The Hair.                  421
   The nails, when chemically examined, appear to consist
of a modification of albumen; and thus resemble cuticle
and horn, in their composition.

                      The Hairs
  Originate from bulbs which are situated at the bottom
of pores or cavities  in the skin. These pores appear to be
lined by a production of the cuticle, and the extremities
of the bulbs project  beyond them into the cellular mem-
brane.  In some cases, where the cuticle is separated after
putrefaction, it seems that these lining  processes of the
cuticle come away completely, and bring the hairs and their
roots with them; but in other cases, the cuticle separates
from the cutis, and  leaves the  hairs in their natural situa-
tion.
  When viewed in a  microscope,  the bulb appears half
transparent, and whitish; and of a softer consistence than
the hair itself. The extremity  of it is remarkably flexible,
and sometimes much darker than the rest of the bulb. The
hair does  not appear to extend completely to the end of
the bulb.  Neither bloodvessels nor nerves have been tra-
ced to  these bulbs,  although it is  probable  they extend
there;  for the operation of extracting hair by the roots is
generally  very painful; and blood  sometimes appears in
the pore, from which the hair is extracted.
  The body of the hair appears to be composed of smaller
fibres,  inclosed in a membrane which often is imperfect at
the extremity; in consequence of which the fibres often
separate from each  other, or split.
  Within the  hair is diffused the substance upon which its
colour depends: this does not appear to be essential to the
strticture, as in the  advance of life, the hair is so gene- 
422        Vicarious connexion of the Skin.

rally without it, while its structure continues unchanged;
although it becomes less flexible.
  The colour of the hair appears to have some connexion
with the colour of the rete mucosum, as it is so generally
black when the rete mucosum is dark coloured.
  The sudden change of colour in consequence of fright
or grief, is a very rare occurrence indeed;  but Bichat re-
lates  an instance which came under his observation, ia
which the hair became perfectly white in one night, in con-
sequence of grief.

    The SKIN, constructed as above described, answers a
      fourfold purpose in the animal economy.  It is the or-
      gan  of touch. It  covers and protects the whole  struc-
      ture. It is the outlet for a large proportion of the insen-
      sible perspiration,  and it performs absorption.
    Many facts have been noticed  by practitioners of medi-
      cine which prove that it has a connexion with the lungs
      and stomach,  which is not yet explained by anatomy.
    As  one of these, an  effect of the urticaria or nettle rash
      may be mentioned. This eruption sometimes  relieves
      completely the  spasmodic croup; and in other  cases,
      nausea and vomiting.
    Some children,  when affected with this species of croup,
      are  relieved by  rubbing  the  skin with  harsh  woollen
      cloth.
    In some places the urticaria and the affection of  respira-
      tion are so much regarded  as symptoms  of the  same
      disease, that the term hives is  used as the name for
      each of them.
END OF THE FIRST VOLUME. 
 
 
 
 
 
 
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