N 
A
SYSTEM OF ANATOMY

            >.■ OR THE USE OF

     STUDENTS OF MEDICINE.
                -----r~~
         BY CASPAR WISTAR, M. D.
1A.TE PROFESSOR OF ANATOMY IN THE UNIVERSITY OF PENNSYLVANIA
    FOURTH EDITION.


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

ADJUNCT PROFESSOR OF ANATOMY IN THE UNIVERSITY OF PENNSYLVA-
  NIA, MEMBER OF THE AMERICAN PHILOSOPHICAL SOCIFTY, &£.
EN TWO VOLUMES—VOL. I.
        PHlLrAlJELPHIA:
CAREY, LEA & CAREY—CHESNUT WW.

              1*37, 
  as
WSHs
     EASTERN  DISTRICT OF PENNSYLVANIA, TO WIT;

                BE IT REMEMBERED, that on  the  twentieth day
              of August in the  forty-ninth year of the Independence o£
              the United States of America, A. D. 1825, H. C. Carey
              &  I. Lea, of  the said district, have deposited in this office
              the title of a book,  the right whereof  they claim as Pro-
              prietors, in the words following, to wit:

  " A System of Anatomy  for the  use  of Students of  Medicine.   By
    " Caspar Wistar, M. D.  Late Professor of Anatomy in the Universi-
    " ty of Pennsylvania.  Third edition.  With notes and additions.   By
    " William Edmonds Horner, M. D. Adjunct Professor of Anatomy
    " in the University of Pennsylvania, and  member  of  the American
    " Philosophical Society,  &c.   In two volumes, Volume I."

  In  conformity to the act of the Congress of the United States, entitled,
" An Act  for the  Encouragement of Learning, by securing the copies of
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daring the  times therein mentioned."  And also to the act, entitled, " An
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authors and proprietors of such copies during the times therein mentioned,"
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etching historical aad other prints."
                                            D.  CALDWELL,
                     Clerk of the Easttm District of Pennsylvania.-
 
PREFACE  BY THE  EDITOR.
   The value of the present work having  been
 sufficiently tested by its very diffused  use  in the
 profession, and by a third edition being now call-
 ed for, the editor has been induced to superinten :
' the latter, with a hope that its utility and the pub-
 lic conviction in its favour  have been in no wise
 diminished.  The closeness of the connexion be-
 tween himself and its lamented author,  furnished
 also another and a very powerful  reason, why he
 should endeavour by such means as  he  command-
 ed, to contribute to perpetuate the memory of a
 man whose  literary and professional  care::'  had
 been so conducive to the reputation of  his coun-
 try, and whose  philanthropy  and  suavity of man-
 ners had established him so firmly in the affections
 and confidence of all who knew him.
   Several amendments have  been introduced by
 the way  of corrections,  alterations and additions.
 The  latter  for  the most  part, appear between
 brackets and in  the  form of notes, but there are
 many which could not be marked in such .nanne.
 without giving the texta garbled appearance,  s
 therefore appear as  portions of the original w.u. 
IV
PREFACE.
The whole mass of matter introduced as amend-
ments, is greater indeed, than a superficial perusal
of the work would intimate; and the only way for
the reader to arrive at it, will be by a careful com-
parison of the last with  the present edition.   The
editor, however, has been  careful not to allow the
spirit of change or improvement to affect the work
in any points excepts  such as seemed to him abso-
lutely to  require it,  and where  he was fully war-
ranted by the best authorities in Descriptive Ana-
tomy.  It would have been sufficiently easy for him
to have  extended the work considerably beyond
its present dimensions;  but from  its having been
originally designed as  a text book for the course of
Lectures on Anatomy in the University of  Penn-
sylvania,  and for the  benefit  of practitioners, who
are always most  assisted by condensed views on
this subject, he was apprehensive of  perverting or
of frustrating its objects  by such extension.  In
consequence of which he has principally confined
himself to adding where additions were called for
by the recent discoveries in Anatomy,  and by the
omissions of older ones.
Philadelphia. Oct. 10, 1823. 
CONTENTS  OF  VOL.  I.
                    PART I.

                   OSTEOLOGY,

                   CHAPTER I.
                   SECTION I.

Structure of Bones......'

                   SECTION  II.
Cartilages and their Structure     -                  (■

                   SECTION III.
Formation of Bone......

                   SECTION IV.
Terms used in the description of Bones and their ar-
  ticulations  .....-   -    -     9

                   CHAPTER II.
Of the Skeleton and its different parts, and the indif-Jchrjj,
            bones of which it is composed.

                   SECTION I.
Of the Head.....• •   -'    -    22

                   SECTION  II.
Of .he Trunk.....            ^

                   SECTION III.
Of the-Superior Extremities.....H5

                   SECTION IV.
Of the Inferior Extremities   -    -    -   -    -    H3 
VI                    CONTENT.-;.


                    PART II.

                     MYOLOCxY.

                    CHAPTER I.

                    Of the Muscles.

Muscles of the Face......173
Muscles of the Neck.....-    185
Muscles of the Front  of the Thorax     -    -    -197
Muscles of the Front  of the Abdomen   -    -    -    200
Muscles of the Posterior part of the Trunk   -    -    217
Muscles of the Superior Extremities     -    -    -    227
Muscles of the Inferior Extremities     -    -    -    244

                    PART III.

                    CHAPTER I.

Ligaments in General......270

                    CHAPTER IF.

A General Account  of Articulations and  of Bursie
   Mucosae........284

                    SECTION I.
Articulations........284

                    SECTION II.
Bursse Mucosae    -    -.....286

                    CHAPTER III.

Particular Articulations      _..---   287

                    CHAPTER IV.

 Particular Ligaments and the situation of  the indivi-
   dual Bursae Mucosas......297
 Appendix on the motions of the Skeleton     -   -   308 
                    COXTES'lS-                  "> i-

                   PART IV.
Of the Brain and Spinal Marrow; of the Eye and the
  Ear.........315
                  CHAPTER I.
Of the Brain........315
                   SECTION I.
Of the Membranes of the Brain and of the Sinuses of
  the Dura Mater.......31j
                   SECTION II.
Of the Cerebrum   -        -    -    -    -    -   323
                  SECTION  III.
Of the Cerebellum.......331
                  SECTION IV.
Of the Basis of the Brain and the Nerves which pro-
  ceed from it.......33°
                  CHAPTER II.
Of the Spinal Marrow......339
                  CHAPTER III.
Of the Eye.......«  343
                   SECTION I.
Of the Parts auxiliary to the Eye   -       . -   -  343
                   SECTION II.
Of the Ball of the Eye  -                    -350
                  SECTION III.
Of the Humours of the Eye.....368
                  CHAPTER IV.
Of the Eur    -                     -   '      ^ 
via
iOM'fiX'iiii
                  SECTION I.
0f the External Ear.....       'irr
                  SECTION II.
Of the Cavity of the Tympanum   -   .   -   -   S82
                 SECTION  III.
Of the Labyrinth  -......391
                   PART V.
          UF THE GENERAL INTEGUMENT-
                  CHAPTER I.
Of the Cellular Membrane   -----   401
                 CHAPTER II.
OfthcSkiix      .....-       406
                  SECTION I.
Of the Cutis Vera.......406
                  SECTION II.
Of the Rete Mucosum......410
                 SECTION III.
Of the Cuticle.......415 
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
                 DESCRIBING BONES.

                    SECTION 1.

             Of The Structure of Bones.

  The human bones, in a recent  adult subject, are
of a dull white colour; their texture is varied, not on-
ly in different parts of the skeleton,  but in different
places of the same bones.   Thus, in long bones, the
middle portion is compact with a cavity in the centre,
the extremities are  cellular  or spongy, and the cen-
tral cavities are occupied by  a network  formed of
thin plates and fibres.  In flat bones, the external sur-
faces are composed  of firm plates, but the internal
substance is cellular.
  [The cellular structure of bones is attended with
several  important advantages.   In the  cylindrical
bones it gives great additional strength, by increasing
their diameter, without adding to  their  weight; and
by swelling out their articular extremities, it produ-
ces much greater security of the joints, by obviating
  voi. i.                 1 
2
Structure of the Bones.
 the tendency to dislocation, and rendering their move-
 ments more steady.   A simple experiment will satisfy
 any one  that the increase of volume in the extre-
 mities of the long bones, is not attended with an in-
 crease of .osseous matter;  for in the dried bone,  the
 section of an inch from the centre will weigh as much
 as  the  same  length  from  the extremities, notwith-
 standing the greater size of the latter. Dr. Physick has
 pointed out another very important advantage of the
 cellular structure of bones, besides those of its making
 them nearly as strong as if they were solid, and at the
 same time diminishing what otherwise would have
 been a weight too oppressive for the muscular powers,
 He thinks that thereby the concussion of the brain,
 and of the other viscera is frequently prevented; and
 in nearly all cases diminished, in falls and in blows,  J
 He illustrates  the position by showing, first, the  cor£
 cussion which takes  place through a series of ivory
 balls suspended by threads; if one be drawn to some
 distance from the others, and allowed, to impel them
 by falling.   The momentum in  this case  impels  the
 ball at the further end of the row, almost to the dis-
 tance from which the first one fell.  But  if a ball of
 the same size, composed of the cellular  structure of
 bone, be substituted for one of the ivory balls, and the
 experiment be repeated, the  momentum of the first
,ball is lost almost entirely in the cellular structure of
 the substitute; particularly if the latter be well soaked
 previously in water, so as to give it  a condition in
 point of moisture allied to the living state. Adopting
 this experiment as  demonstrative  of the fact,  Dr.
 Physick asserts, that  in falls from an eminence upon
 the feet, the percussion,  by the time it  has passed
 through the cellular structure of the foot, leg, thigh,
 vertebral column and the condyles  of the occiput, is
 very much diminished in force, and carries much less
 impulse upon  the brain.  Again, in blows on the head, 
Structure of the Bones.              3
the brain, though much protected from external injury
by the arched form of the cranium, has an additional
security from the interposition of the diploe, which
weakens the force of the blow.
  In all the* bones there are  canals, independent of
the cellular structure, which penetrate to a greater or
less extent between the  lamina, and go in various di-
rections, some longitudinal, others oblique and trans-
verse.  These canals transmit the blood vessels, and
were first pointed  out  with  exactitude by Clopton
Havers, an  English  anatomist.  But he assigned a
wrong application to them, as he believed  that  the
marrow ran through them, in order to make the bones
supple, and  to unite their lamina  more  strongly.  S.
B. Albinus corrected the mistake,  by demonstrating
that they were filled with blood  vessels.  These  ca-
nals in a vertebra are particularly  large,  and  open
on  the posterior face of its body, by one or two large
foramina.  In the cranium they are remarkably well->*
seen; but their discovery is of more modern date.  M.
Portal says, that in the bones each kind of vessel has
a particular canal for itself alone; those of the arteries
are therefore to be readily  distinguished from such as
belong to the veins and to  the nerves; and this  takes
place both in the large and in the small canals.   Oc-
casionally the vessels dip  into a  common canal,  but
if any one will take  the trouble  to follow  them,  he
will find  them ultimately separating from each other.]
  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.
  In the firmness of their texture and  their general
aspect, bones resemble  inorganic  matter, but  there
are the strongest proofs of their  organization.
  For example, if a bone  be  macerated  in certain 
 4             Structure of the Bones.

 acid liquors, the earthy matter will be dissolved, and a
 membranous or cartilaginous substance will remain,
 resembling the bone in form and sizc.#
   If the bones of  a young subject, after being inject-
 ed, be treated in the same way, this membranous sub-
 stance will appear to be very vascular—when the in-
 jection has been successful, it will appear uniformly
 reddened by the great number of vessels  which are
 filled with the matter of injection.  These vessels  dis-
 charge blood when the periosteum is removed from
 the surface of bones, in the living subject, and they
 also form granulations upon bony surfaces 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.
   [The French anatomists have occasionally traced
 branches of the fifth pair of nerves going along with
 the nutritious arteries into some of the bones; but as
 yet no other nerves have been seen  by them.   Mr.
 Portal speaks in familiar  terms of the  existence of
 both nerves and lymphatics in the  bones, as if he had
 often noticed them; he, however, has omitted to in-
 form us of the source, from which the former come.]
 In a sound state bones have no  sensibility, but pain
 is often felt in them when diseased.
   Modern chemistry has ascertained that the earthy
 matter 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 carti-
 laginous  matter.
   Bones are invested with a firm membrane denomi-

  • One part of muriatic acid to thirty of water is a  good mixture for this
purpose,  by taking care to keep up the strength of the mixture, by addi-
tions of the acid from time to time___Ed. 
Structure of the Bones.
■)
nated periosteum, which is  of a fibrous texture,  and
in some  places may  be separated into different la-
mina.  The external surface of periosteum is con-
nected with the contiguous  parts by cellular  mem-
brane, the internal surface is connected with the bone
by a great number  of fibres and  of blood vessels.
The orifices of these vessels appear  when  the peri-
osteum 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 capsular ligaments of joints; those, which are
occupied by the insertion of tendons and ligaments,
and the bodies of the teeth.  It appears most  inti-
mately connected with the .surfaces 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 principle use of the perios-
teum 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 portion of bone.*
  At the extremities of the long bones, the foramina
for the transmission of blood vessels and fibres are
much larger than they are in the  middle;  but- there
is an oblique canal near the middle  of these  bones,
which transmit vessels 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

  * Dr. Physick thinks that the periosteum frequently prevents the  bones
from participating in contiguous disease, as the pleura turns off an abcess in
the parietes of the thorax from its cavity, or the peritoneum from the cavity
of the abdomen.—En. 
b'
Cartilages and their Structure.
the medullary  matter that is  always found in their
cavities.  [This is the internal periosteum or the me-
dullary membrane of the bones.  Mr. Portal  denies
that it exists as a distinct membranous sac, but asserts,
that it is derived from  the  envelope of the vessels
which is sent  in  along  with them  from the perios-
teum.]
  It has been said that in  some  circumstances this
membrane 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.

                    SECTION II.

           Of Cartilages and their  Structure.

  CartilactEs  are  white elastic  substances, much
softer than bones, in consequence of a smaller quan-
tity 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
asunder,  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  cancelli, nor  internal  mem-
branes, for lodging marrow; no  nerves can be traced
into them;  nor  do they  possess any sensibility in the
sound state. 
                Formation of Bone.               7

  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 pur-
poses to cartilage as this does to bone.
  Upon the surface of articular cartilages, the peri-
chondrium is a reflection of the inner surface of the
capsular ligament, and is so very  thin, and adheres
so closely, as to appear like part of the cartilage it-
self.
   One set of cartilages supplies the place of bone, and
by their  flexibility admit of a certain  degree  of  mo-
tion,  while their elasticity recovers  their   natural
position,  as in  the  nose, larynx, cartilages of the
ribs, <fec.
   Another set, in children, supplies the place of bone,
until bone can be formed, and affords 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
smoothness and lubrication of their  surface, allow the
bones to move  readily,  without any abrasion, as in
the cartilages of the joints.
   A fourth set supplies  the office  both of cartilage
and ligament, giving the elasticity of the former and
the 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 mem-
branes, and the teeth in distinct bags.
   When ossification is about to begin in  a particular 
8
Terms used in the
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 ori-
gin, 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 surround-
ing 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
osseous fibres issue in rays.
  The ossification of long bones, as in  those of the
extremities,  begins by central rings, from which the
fibres extend towards the ends of the bones.
  The ossification of spheri-formed bones begins  by
one nucleus, as in the wrist;  and that of irregular
shaped bones by different nuclei, as in the vertebra?.
  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 are  joined to the body of the  bone by carti-
lages,  which are thick  in children,  but gradually 
                Description of Bones.              9

become thinner  as ossification advances, till at last,
in,the adult, the external 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
difficult 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.
  The word process signifies any  protuberance  or
eminence arising from  a bone.
  Particular processes receive names from their sup-
posed resemblance to certain objects; and their names
are very often composed of two Greek words; thus
the term  coracoid, which  is applied  to a well known
process, is derived from the Greek words *«e*g, a crow,
and "he, resemblance.
  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. 
10
Tcnns used in the
  Words of this kind have been used most profusely
in the descriptions of  articulations,  and here  also
their utility is  doubtful.   Therefore, for many terms
used on this occasion, the reader is referred to the
glossary; but the following are necessary to be under-
stood.

  Symphysis does not merely imply the concretion of
    bones  originally separate,  as  its  derivation im-
    ports;  but it is understood also to mean the con-
    nexion  of bones  by  intermediate  substances.
    Thus there are three species of symphysis, par-
    ticularly noticed, viz.
  Synchondrosis, when bones  are connected to each
    other by cartilage;  as the  ribs and sternum.
  Synneurosis, when they are connected by ligaments,
    as in the moveable  articulations.
  Syssarcosis, when they are connected by muscle.
    The different articulations  are of two kinds, viz.
    Synarthrosis and Diarthrosis.

  Synarthrosis is the name of that kind of articula-
    tion which docs not admit  of motion. There are
    three species of synarthrosis, vk.
  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.
  Shindylesis, when the thin  edge of one bone is re-
    ceived into a narrow furrow of another, as the
    nasal plate of the ethmoid  in the  vomer.

  Diarthrosis is the name of that kind of articula-
    tion which admits of motion.   Of these articu-
    lations 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. 
Description of Bones.              11
  .Lilirodia, when a head is connected with a super-
    ficial 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 pe-
culiarities that they  cannot be  understood without
studying them separately. It may therefore be doubt-
ed whether the classification and arrangement of joints
is any way necessary. 
12
                  CHAPTER II.

 OF THE sKELi/lON AND ITS DIFFERENT PARTS, AM) THE
   INDIVIDUAL BONES OF WHICH THEY ARE COMPOSED.

  The 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 allowed to remain for that purpose.
  It is called artificial, when the bones are connect-
ed with wire, or an^foreign substance.
  The artificial  skeleton is best calculated for study-
ing 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 ani-
mals do not admit of  the  preparation necessary for
an artificial skeleton, as their epiphyses would sepa-
rate, and they are therefore formed into  natural  ske-
letons.
   The study of the skeleton and its mechanical pro-
perties, as a piece of machinery, is absolutely neces-
sary to a perfect understanding of many motions  of
the body, and of the action and co-operation  of mus-
cles; but any observations on this subject will be bet-
ter understood after the individual bones and the mus-
cles have been  described.
   The skeleton is divided into the head, the trunk, the
superior and the  inferior extremities.

                     SECTION I.

                   Of the Head.

   The head comprehends  the Skull, or Cranium, and
Face. 
The Head.
13
  The cranium consists of eight distinct bones, which,
when placed in their  natural  order,  form  a large
spheroidal 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 structure  between them, called  meditul-
lium, or diploe.  The external table is more firm
and thick than the internal.  The latter is compara-
tively very  brittle, whence it  is  called the  vitreous
table.   [Between the two tables which compose the
flat  bones  of the cranium  and running through the
diploe,  are  several sinuses, which are occupied by
veins in the recent subject.  They were discovered
by M. Fleury about  twenty years ago, while he was
Prosector at the  school of Medicine in Paris, and
engaged in  some inquiries relative to the structure of
the cranium at the instigation of M. Chaussier.  The
account which M. Chaussier gives of these veins is
as follows:  they are  situated  in  the  middle  of the
diploe between the  two  tables of the skull,  and like
all  other veins are  intended to return the  blood  to
the  heart.   They are furnished with small valves,
have extremely thin  and  delicate  parietes, and com-
mence  by  capillary ramifications  coming  from the
different points of the vascular membrane which lines
the  cells of the diploe.  Their roots are at first  ex-
tremely  fine and  numerous, form  by their  frequent
anastomoses a kind  of network, and produce by their
successive  junction, ramuscles, branches, and large
trunks, which, becoming still more voluminous, are
directed towards  the base of the cranium.  Some
varieties exist  in regard  to the  number, size, and dis-
position of these trunks, but generally one or two of
them are found in each side ot the frontal bone, two
in the parietal  bone, and  one in each side of the occi-
pital bone.  Anastomoses exist between these seve- 
M
The Head.
 ral  trunks by which the veins  in the parietal  bone
 are joined to those in the frontal and in the occipital.
 Branches from the right side of the head also anas-
 tomose with  some from the  left side.   Besides the
 branches already mentioned,'one or  two  smaller than
 the  others are directed towards the top  of the  head
 and terminate in the longitudinal sinus.
   The descending veins of the diploe communicate
 in their passage with the contiguous superficial veins,
 and empty into them the blood which  they receive
 from the several points of the diploe.   These  com-
 munications  are produced through  small  foramina
 which penetrate from the surface of the  bone to the
 diploe.  The trunks of such diploic veins as are con-
 tinued to the base of the cranium,  open partly into
 the  sinuses of the  dura mater, and partly into the
 venous plexus at the base of the pterygoid apophyses,
 and  form  there  the  venous communications called
 the  emissaries of  Santorini.   Moreover there  are
 communications sent from the diploic veins through
 the porosities of the internal table of the skull to the
 veins of the dura mater.  This  fact is rendered very
 evident by tearing off the skull cap, when the sur-
 face of the dura mater will be studded with dots of
 blood, and the internal face of the bone also, particu-
 larly in apoplectic subjects.  It appears  indeed that
 the arteries of the cranium are principally distributed
 on its  external surface and the veins on its internal
 surface and diploe.
  In the  infant the diploic veins are small,  straight.
 and  have but few branches: in the  adult they  cor-
respond with  the description just given; and  in old
age they  are  still more considerable, forming nodes
and  seeming  varicose.  In children,  when the bones
are diseased,  they partake of the latter character. In
order to see them fully, the external table  of the skull 
The Sutures.
I:»
must be  removed  with  the  chisel and mallet, both
from its vault and base.]
  The periosteum, which is on  their external surface
is  called pericranium.   Internally, #the dura mater or
membrane which covers the  brain, supplies the place
of periosteum.
  There are eight of these bones, which are thus de-
nominated:  Os Frontis,  Ossa Parietalia, Ossa Tempo-
rum, Os Occipitis,  Os  Sphenoides, and Os Ethmoides.
The*two last are  called common bones, to denote
that they are connected 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 between the orbits of the
eyes, and the sphenoides extends across the base  of
the cranium.
                   The Sutures.

   The above bones are joined to each other by five
sutures;  the names of which are the Coronal, Lamb-
doidal, 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 inden-
tations 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 
16
The Sutures.
letter a and are now generally said to  extend them-
selves to the base of the skull:  but formerly, anato-
mists reckoned the proper lambdoidal suture to ter-
minate at the squamous sutures: and the portion con-
tinued from them on each side, where the  indenta-
tions are less conspicuous than in the  upper part of
the suture, they called  additamentum  sutursc lamb-
doidis.
   This suture  is  sometimes very irregular, being
made up of a great many small sutures,  which' sur-
round a number of insulated bones, that are general-
ly more conspicuous on the external surface of the
skull  than internally.   These bones are  commonly
called triquetraor wormiana; their formation is owing
to a greater than ordinary number of points of  ossi-
fication in the skull, or to the ordinary bones of the
cranium not extending  their  ossification far enough,
or soon enough; in  which case, the unossified inter-
stice between such bones begins a separate ossifica-
tion, in one or more points;  from which the ossifica-
tion is extended to form as  many distinct bones as
there were points which are  extended into the large
ordinary bones, and into each other.
   The sagittal suture  is placed longitudinally, in the
middle of the upper  part of the skull, and  commonly
terminates at the middle of the coronal and of the
lambdoidal sutures;  between  which it is said to be
placed,  as an arrow 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 semicir-
cular 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 fur- 
The Sutures.
17
rows, which  are  indented 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 squamosa?.
  The squamous suture is not confined to the conjunc-
tion 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 su-
ture just now described, one of which  runs perpen-
dicularly downwards and  the  other horizontally for-
wards;  and also the lower part of the coronal sutuie
already taken notice of, may all be justly said to  per-
tain to the squamous suture.
   This structure  appears to depend upon the pressure
of the temporal muscle externally, afld the resistance
of the brain within,  which make the  bones so thin,
that their edges opposed to each other are  not suffi-
ciently thick to stop the extension of their fibres in
length, and thus  to cause the common  serrated ap-
pearance 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
provided  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 pa-
rietal, and this last supporting the  sphenoidal, while
both mount on the frontal, from  which disposition it
   Vol. i.                3 
18
The Sutures.
 is evident, that while the temporal muscle is con-
 tracting, 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 struc-
 ture 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 cra-
 nium; 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 with-
 out.  By this mechanism, there is no risk of the sharp
 points of the  bones growing inwards, since the exter-
 nal serrse of each of the  conjoined  bones  rest upon
 the internal smooth edged table of the other.
   The advantages of  the sutures are these:  1. The
 cranium 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 partu-
 rition, the bones  of the  cranium, instead of being
 only  brought into  contact, are  sometimes made  to
 mount one upon the other.
   [The sutures which unite  the  bones of the cra-
 nium, are generally said "to be  made by the  radii  of
 ossification, from the  opposite  bones  meeting and
 passing each  other,  so as  to form a serrated  edge.
 This explanation is however insufficient,  for  the fol-
 lowing reasons: we  always find  the  sutures in the
same relative situation,   and  observing  the  same
 course in the  cranium; if they, then, depended exclu-
sively on so mechanical a  process, as the shooting of
the rays of bone across each other when they met, in
ossification on one side of the head occurring sooner
or faster than on the other, we ought to  find the sa- 
The Sutures.
19
gittal suture to one side of the middle line; it should
also,  in many instances, be found  crooked.   More-
over, in all cases where bones arise from different
points of ossification and meet, particularly in the flat
bones, the serrated edges ought to be formed; this,
however, is not the case.  The os occipitis, which is
formed originally from four points of ossification, and
has therefore as many bones composing  it in  early
life, never joins these bones together by the serrated
edge;  the acromion process of the scapula is never
united to its spine by suture;  the three bones of the
sternum never unite by suture; and the same obser-
vation holds good in many other instances.  Bichat,
who rejects this mechanical doctrine, adfTLnces an
opinion much better founded.   The dura  mater and
the pericranium before ossification commences, form
one membrane,  consisting of two lamina; it is^jene-
rally known that the flat bones of the cranium are se-
creted between these two lamina; now the outline of.
each bone, long before it has reached its  utmost ;i-
mits, is marked off by partitions passing between these
two  membranes.  The peculiar shape of the bony
junction, or of the suture in adult life, will therefore
depend upon the original shape of the partitions; when
the latter are serrated, the points of ossification will
fill up these serrai; but when they are simply oblique,
the squamous suture will be formed.  This also ac-
counts for cases where the mode of  junction is inter-
mediate to the squamous and serrated suture;  for the
formation of the  ossa triquetra, and why in  some
skulls they  do not exist, whereas in others their extent
and number are very  considerable.  The  inference
will also be drawn from this, that  in all ossifica-
tions  from  different  nuclei,  where these original
membranous septa do not exist,  a suture will not be
formed; but the  bones will join each other, as  in a
ease of callus  between the  broken extremities of 
20
Os Frontis.
bones.   When these septa become weak or thin,
either from  original tendency, as in the case of the
sagittal suture, which  in early life is continued to the
root of the nose frequently; or from advanced age,
as in the case of nearly all sutures, the bones of the
opposite  sides amalgamate, and no appearance of su-
ture is left.   It is easy to  make a preparation illus-
trative of these facts,  and one now exists in the mu-
seum of  the university of Pennsylvania, in which,  by
removing the bone from between the membranes by
means of an acid, and afterwards rendering the mem-
branes transparent  with oil of "turpentine,  the septa
are seen sufficiently distinctly.]
                    Os Frontis.
   The os frontis, as its name imports, forms the front
part^pf the cranium, and the upper portion of the or-
bits qf the eyes.
   The external surface of this bone is smooth at its
upper convex part;  but several processes and cavities
are observable below: for at the angles of each orbit,
the bone projects to form four processes, two internal,
and as  many external; which are denominated an-
gular.    Between the  internal and external  angular
processes on each side, an arch 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 of the superciliary ridges,  the frontal
bone runs  a great  way backwards: these parts are 
Os Frontis.
•2\
called  orbitar processes, which,  contrary to the rest
of this bone, are concave externally, 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
observed, where the  glandula lacrymalis is  lodged.
Near each internal angular process, a small pit  may
be remarked, where the cartilaginous pully of the su-
perior  oblique muscle of the eye is fixed.  Between
the two orbitar  processes, there is  a large  vacuity
which  the cribriform  part of  the os ethmoides occu-
pies.   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
surface 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 pass a branch of the ophthal-
mic artery and a small nerve.
  In the  internal edge of each orbitar process are
two  other foramina denominated  anterior  and poste-
rior orbitar foramina, which lead to the nose; some-
times they are  only  notches  or  grooves,  which join
with similar grooves in the bones below, and form fo-
ramina.
  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 low-
er 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  superior longitudinal sinus;  at its  commence- 
•).)
Os Fronds.
 ment is a ridge to which the beginning of the falci-
 form process of the dura mater is  attached.  At  the
 root of this ridge is a small foramen, sometimes form-
 ed jointly  by  this bone  and the ethmoid:  it is  de-
 nominated foramen ccecum; in it a small  process of
 the  falx  is inserted, and here the longitudinal sinus
 begins.
   The frontal sinuses are formed by the  separation
 of 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 exter-
 nal table  commonly recedes  most from the general
 direction of the bone.  ~
   These cavities are divided by a perpendicular bony
 partition, which is sometimes perforated and admits
 a  communication between them.   Their  capacities
 are often  very different in different persons, and on
 the different sides of the  same person.  In some per-
 sons whose foreheads were very  flat, they are said to
 have been wanting. They communicate with the nose
 by means of a canal in the cellular part of the os eth-
 moides.
   The os frontis is composed of two tables, and an
 intermediate diploe, as the other bones of the cranium
 are: it is of a mean thickness between the os occipi-
 tis and the parietal  bones;  and  is nearly equally
 dense  throughout, except 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  di-
ploe 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  ca-
vities is  evidently composed of two plates, which
easily separate. 
Ossa Parietalia.
23
  Each of the  frontal  sinuses opens into one of the
uppermost 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 na-
sal,  maxillary,  unguiform  and malar  bones  of the
face.

                  Ossa Parietalia.

  Each of the two  ossa  Parietalia  is  an irregular
square; its upper and front edges being longer than
the one behind or below.   The  inferior edge is con-
cave, the middle part receiving the upper round part
of the temporal bone.  The angle formed by the un-
der and anterior edges is so extended as to have the
appearance of  a process.
  The external surface  of each os  parietale  is con-
vex.    Upon it, somewhat  below the  middle height
of the bone, there is  a transverse arched ridge, gene-
rally 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 to-
wards  a centre.  From this ridge  of each bone the
temporal  muscle rises: and, by the  pressure of its
fibres,  occasions the furrows just now mentioned.
Below these we observe, near the semicircular edges,
a  great  many risings  and  depressions,  which are
joined  to  like  inequalities  on  the inside  of the tem-
poral 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 longitu-
dinal sinus.
  On the  inner concave surface of the  parietal bones 
24
Ossa Parietalia.
we see a great  many deep furrows, disposed some-
what  like the branches  of trees; the  furrows  are
largest and deepest at the lower edge of each os pa-
rietale,  especially near its anterior angle, where  a
complete canal is sometimes formed.
   [These furrows are made by the ramifications of
the great middle artery of the dura mater; they have
been commonly attributed to the pulsation of the ar-
tery causing the  absorption of the bone, but it is more
probable that the deposition of the bone has been
prevented where the artery beats, and  thus the bone
becomes modelled over the artery in the  same way
that it is made to conform to the surface of the brain.
If it were exclusively an absorption  and not  a depo-
sition, we should scarcely find the artery occasionally
surrounded perfectly by bone.]
   On the inside of the upper edge  of the ossa parie-
talia there  is a large sinuosity,  frequently larger in
the bone of one side than of the other, where the up-
per part of the falx  is fastened, and the superior lon-
gitudinal sinus is lodged.  Part of the lateral sinuses
generally makes  a depression near the angle formed
by the lower and posterior edges of these bones; and
the pits made by the convolutions of the brain are in
no part of the skull more frequent or more conspicu-
ous, 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
frontis;  at their long inferior angles, to the sphenoid
bone; at their lower edge, to the ossa temporum; be-
hind to  the os occipitis, orossatriquetra; and above,
to one another. 
Ossa Tciiiftorum.
2")
                 Ossa Temporum.

  The ossa temporum are situated at the lateral and
inferior parts of the cranium;  each of them is divid-
ed into three portions, a superior or squamous, a pos-
terior 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
appears pared away to form the squamous suture with
the corresponding edge  of the parietal bone.  Its ex-
ternal surface is covered by the temporal muscle. At
the lower and anterior part of this  surface the zygo-
matic process arises, it  proceeds forward to join the
cheek  bone and form an arch under which  the tem-
poral muscle passes.
   At the base of the process is the cavity for the con-
dyle of the lower jaw. Immediately before this cavity
is a tubercle or protuberance, which forms part of the
articular 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 arti-
culation 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 anterior muscle of the mal-
leus, 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 correspond with  the convoluted surface of the
 brain, and also by impressions of  the arteries of the
 dura mater, as they go towards the parietal bone.
   The  mastoid or occipital portion  is  the  smallest  ot
 the three parts of the bone;  it consists of an angular
 portion, which occupies a vacuity between  the occi-
 pital and parietal bones;  and of the mastoid process.
 The mastoid process has some resemblance to the
 nipple;  it is composed  internally of cells which com-
   Vol.  i.                 x 
2b
Ossa Temporum.
municate 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 insert-
ed.  Behind this process is the mastoid hole, which
transmits a vein, and sometimes a  small artery.
   On the internal  surface 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 pyra-
mid lying on one of its sides.   When in its  proper
position it  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 divides the  fossa
for the middle lobes of the  brain, or cerebrum 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 cor-
respond with the  convolutions of  the brain.  Near
the middle of the anterior side is a small furrow, and
a foramen  denominated Innominatum or Hiatus Fallo-
pii, which transmits the vidian nerve to the aqueduct
of Fallopius.
   About the midle of the posterior side is the laro-e
aperture called meatus  auditorius internus.  The bot-
tom of this cavity is perforated by  several foramina;
the largest and uppermost of which is  the orifice of
a  winding  canal, called  improperly  the  aqueduct  of
Fallopius,  which transmits  the portio dura of the
seventh pair of nerves.   The other foramina trans-
mit the fibres of the portio  mollis of the same nerve.
Posterior to the orifice of the  meatus internus is an
oblong depression, with a foramen in it, covered by
a  shell of bone, which is the orifice of a proper aque- 
Ossa Temporum.
27
duct 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 hy-
oides, and of the pharynx, and also to  several liga-
ments.  [The base of this process  is  surrounded by
a flat projection of bone, occasionally called the va-
ginal process.]
   On the inside of this process, and rather before it,
is the jugular fossa, which, when applied to a corres-
ponding  part of the occipital bone,  makes the poste-
rior foramen lacerum, through which the internal ju-
 gular vein, and  the eighth pair of  nerves pass out.
 A  small spine often projects  into this foramen from
 the temporal bone, and separates 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 com-
 mencement of the  carotid canal, which  makes a
  curve almost semicircular, and then proceeds in a ho-
  rizontal  course to the anterior extremity of the bone;
  through this winding canal passes the carotid artery,
  and the  filam^ts from the fifth  and sixth pair of
  nerves,  which  are the  beginning of the intercostal
  nerve.
    * This orifice should not be confounded with one which is nearer to the
  meatus internus, and situated on the angle made by the  two sides of the
  bone.—En. 
.10
1<J
Os Occipitis.
   Between the carotid canal and the cavity for the
 condyle of the lower jaw, at the junction of the an-
 terior part of the squamous portion with the petrous
 portion of this  bone, is a very  rough aperture, the
 bony  margin of which appears  broken; this is the
 orifice of  the bony part of the Eustachian  tu^3, or
 passage from the throat to the ear.  This canal is di-
 vided lengthwise  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
 body part  of the Eustachian tube.
   The external passage to ihe ear, called JM^atus
 Auditorius  Exte^nus, is situated between  the zygoma-
 tic and the mastoid processes.   The orifice is large
 and smooth above, but  rough below, and  is  some-
 times called the auditory process. The direction of
 the canal is obliquely inward and forward.
   The temporal is articulated with the parietal, occipi-
 tal and sphenoidal bones, and by its zygomatic process
 with the malar bone.

                   Os Occipitis.

   The occipital bone is situated at the posterior and
 inferior 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 attacheaMo this line, and ex-
 ternally, on each side, the occipitd frontalis,  and the
 sterno mastoideus.  Under this  line is a depression,
 on each side, into which are insertefethe 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 
Os Occipitis.                  29
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 ex-
tremity of this spine is the great  occipital foramen,
which forms the communication between the cavities
of the cranium, and the vertebral column.  This great
opening transmits the medulla spinalis with  its mem-
branes, the accessory nerves of Willis, and the verte-
bral arteries  and veins.
   It is rather of an oval form, and the occipital con-
dyles 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 down-
ward and  outward; they  are received into corres-
ponding cavities of the atlas,  or first cervical  verte-
bra, and form with them the articulation of the head
and neck.  From  the oblique position of their articu-
lating surfaces, as well as the  length of  their liga-
ments and the inclination of their axes towards each
other, it results, that their motion is confined to flex-
ion and extension. On the internal sides of these con-
dyles is a rough surface to which are attached the
strong ligaments  that come from the processus den-
tatus of the second vertebra of the neck.
   Behind each condyle  is a depression in which is
situated the posterior  condyloid foramen, for trans-
mitting the cervical veins; and at  their anterior ex-
tremities are  two large foramina, through which pas-s
the ninth pair of nerves.
  On the internal surface of the os occipitis is the
crucial ridge, to which are attached the fal.v, or ver-
tical, and  the tentorium, or horizontal process of the
dura mater.
  The groove  made by  the longitudinal sinus  con-
tinues from the sagittal  suture along the upper limb 
30
Os OcCiptfls\
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 centre of the cross, the
groove  for the longitudinal sinus divides into two
grooves, for the lateral sinuses; these form the hori-
zontal limbs of the  cross, and proceed towards the
foramen lacerum 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 centre to the great occipital foramen, and  sup-
ports the falx of the cerebellum.  The internal sur-
face of the bone is divided by the cross into four por-
tions, each of which is considerably depressed; the
two upper by the posterior lobes of the cerebrum,
and the lower by those of the cerebellum.
  This  circumstance occasions great inequality in
the thickness of the bone, as the depressed portions
are extremely thin,  while the ridge adds greatly to
the thickness, especially at the centre of the cross,
which is opposite to the great external protuberance.
  Before the great  occipital foramen  is the cunei-
form process, 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 some-
what excavated, and forms a large superficial 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 ser-
rated, to articulate with those  of the  parietal, and
form the lambdoidal suture.  The inferior edges are
divided into  two portions  by a  small  prominence
called  the jugular eminence;  the upper  and poste-
rior portion  is also serrated for articulation with the
mastoid portion of the temporal; the inferior portion,
which is not serrated, applies to the petrous portion 
()s Ethmoides.
31
   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 in-
   closed in  the  os frontis, betwixt the orbitary pro-
   cesses of  that bone.  One horizontal plate receives
   the olfactory nerves, which perforate that  plate w ith
   such a number of small holes, that  it resembles a
   sieve; whence the bone is  named  cribriform,  or
   ethmoid.  Other plates are so arranged  that they
   form  a cellular structure,  on  which the  olfactory
   nerves are expanded by means of a particular mem-
   brane; while  {in additional plate,  appropriated  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 the  perpendicular plate is to be found in
   the septum of the nose.
      The ethmoid bone, for the  purposes of descrip-
   tion,  may be divided into three parts, viz.  the  cribri-
   form 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 extrem-
   ity the crista  galli projects  from its  upper surface. 
32
Os Ethmoides.
dividing it into two lateral portions, each of which is
rather concave, and occupied by the bulbous extrem-
ity 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  nervous fibre
derived from the ophthalmic 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 frontis 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
continued downwards from the crista  galli through
the cribriform  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 in-
clined to one side, so that the nostrils are  not of
equal size.
  At a small distance from this perpendicular plate,
on each side of it, the cellular portio?is originate from
the lower surface  of the  cribriform plate-, they  ex-
tend from before backward, and are as long as the
ethmoid bone; their breadth,  between the eye  and
the cavity of the 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 sur-
face of the orbit of the eye, and is called os planum;
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 brittleness of the bony plates of which it 
Os Ethmoides.                33
 is composed.   When the bone is perfect, the upper-
 most half part of this internal surface  is uniformly
 flat, and rather rough; but below it, about the mid-
 dle of the bone, a deep groove begins, which extends
 downwards and backwards, to the posterior extremi-
 ty: this is the  upper channel or meatus of the nose.
 The  edge of the  surface immediately above it pro-
 jects 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 meatus, which is
 immediately below the ethmoid bone.  The internal
 surface of this spongy bone, which 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 turbinated 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 ex-
 tends from the cellular part of the ethmoid so  as to
 cover a part of it.
  Vol. i.                 r> 
3-1
Os Ethmoides.
  The cellular portions of the ethmoid are composed  of
plates thinner than the shell of an egg;  they are en-
tirely hollow,  and  the cells  are  very various,  in
number, size and shape.   Some cells of the upper-
most row communicate with those of the os frontis,
formed  by the separation 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 surface of the  body of the os sphenoides,
one on each side of the azygos process, and often di-
minish the opening into the sphenoidal cells. These
plates are sometimes triangular in form, the bases
uniting  with the cribriform plate.  They have  been
described very differently by different authors, some
considering them as  belonging to the os ethmoides,
and  others  to the sphenoid  bone.   To the perfect
ethmoid bone there are attached two triangular pyra-
mids, in place of the  triangular bones; these pyra-
mids are hollow,  the azygos process of the os  spe-
noides 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 trian-
gularia, 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 di-
rectly into the nose, near the situation of the opening
of the sphenoidal  sinues, in the bones of adults;  and
the  other in each of  the sides  in contact  with the
azygos  process.

  * This may be considered as  an original observation of the  la-
mented Wistar.  The merit of it  has been denied to him, more par-
ticularly by the anatomists  of Paris,  under an impression that  he
had been anticipated in it by Bertin,  who has  written  an excellent
and minute treatise on osteology.  The extent  to which the claims
of other anatomists interfere with his,  he was fully aware of; and it 
.-» I
                          Os Sphenoides.


    The os  sphenoides,  or  pterygoidcs, resembles a  bat

with its wings extended.  It consists.


will be seen by the following communications to  the  American  Philoso-
phical Society, that these are placed  in as important  a light as  they de-
serve, at the same  time that  he vindicates  his own pretensions, to  have
first observed the  "cornets sphenoidaux"  in the form of triangular hollow
pyramids, as constituting part of the perfect ethmoid bone.   Ed.

Observations on those Processes of the  Ethmoid Bone -which  originally  form
  the Sphenoid Sinuses.   By  C IVistur, .M. D  President  of the  Society,
  Professor of Anatomy in the  University  of Pennsylvania.__Read.  Nov.
  4, 1814.

  It had been  long believed that the Sinuses, or cavities in the the body of
the Os Sphenoides, were exclusively formed by that bone, when W'mslow
suggested that a small portion of the orbitar processes of the Ossa Palati
contributed to their formation.*
  Many years after Winslow's  publication, Monsieur Bertin described
two bones which form the anterior sides of those sinuses, and contain the
foramina by which they communicate  with the nose.j-
  These bones he denominates  " Cornets Sphenoidaux," and states that
they are most  perfect and distinct between  the ages of four  years and of
twenty; that they are not completely  formed  before this period,  and that
after it, they appear like a part of  the Sphenoidal  bone—According  to
his  account they are lamina  of a triangular form,  and are  originally in
contact with the anterior and inferior surface of  the  body of the Os Sphe-
noides, so that they form a portion of the surface of  the cavity of the nose.
—He believed, that as  they  increase in size, they become convex and
concave, and  present their concave surfaces to the body of the sphenoidal
bone, which aho becomes concave, and presents its concavity to those
bones ; thus forming the sinuses.
    This account of M. Bertin has been adopted by Sabatier,  and also by
Buyer, who has improved it by the  additional observation,  that these tri-
angular bones  are sometimes united to the  ethmoid,  and remain attached
to that bone when it is  separated from the Os  Sphenoides.   Bichat and
F>fe, have confirmed the description of Boyer.
  The specimens of Ethmoid  and  Sphenoid bones, herewith  exhibited  to
the  society, will demonstrate, that in certain subjects,  about two  years of
age, there are  continiud from the posterior part of the cribriform  plate of
the  Ethmoid, two Hollow Triangular Pyramids which, when in their pro-
per situation, receive between them the' azygos process of  the  Os Sphe-
noides—(See  Piute X. Figures 1, 2,  3, with the explanation.)
  The internal side of each of these pyramids applies to the aforesaid

  * In his description of the Ossa Palati, printed in the Memoirs of the Academy of Sciences,
for 1720.
 t See Memoirs of the Academy of Sciences for 1774. 
36
Os Sphenoides.
   1st,  Of a body with two processes arising  from it,
called  the lesser icings, or apophyses  of Ingrassias.
   2dly, Of two  large lateral  processes,   called  the
greater wings, or temporal processes;  and,
   3dly, Of two vertical portions, denominated ptery-
goid processes.
azygos process; the lower side of each forms part of the upper surface of
the Posterior Nares; the external side at its basis is in contact  with the
Orbitar Process of the Os Palati. The base of each pyramid forms also a -
part of the surface of the Posterior Nares, and contains  a  foramen which
is ultimately the opening into the Sphenoidal Sinus of that side.
  In the Sphenoidal Mones which btlong to such  Ethmoids as are above
described, there are no cells or Sinuses ;  for the pyramids of the Ethmoid
bones occupy their places.   The azygos process, which is to become the
future septum between the Sinuses, is remarkably thick, but there are no
cavities or Sinuses in it.
  The sides of the pyramids which are in contact with this process are ex-
tremely thin, and sometimes have irregular foramina in them, as if their
osseous substance bail been partially absorbed.* That part of the external
side of the pyramid which is in contact with the orbitar process of the Os
Palati is also thin, and sometimes has an irregular foramen, which commu-
nicates with the cells of the aforesaid orbitar process.
  Upon comparing these perfect specimens of the Ethmoid and Sphenoi-
dal Bones of the subject about two years of age, with the Os  Sphenoides,
of a young subject who  was more advanced in years, it appears probable,
that the azygos process and the sides of the pyramid applied  to it, are so
changed, in the progress of life, that they simply constitute the septum
between the Sinuses; that the external side of the pyramid  is also done
away, and that the front side and the basis of the pyramid only remain ;
constituting the Cornets Sphenoidaux j- of M. Bertin.
  If this be really the case, the  origin of the  Sphenoidal  Sinuses is very
intelligible.
        Explanation of the Figures in the Plate referred to above.

                             FIG. I.

   Represents the upper surface,  or cribriform plate of the Ethmoid
Bone.
  a. Crista Galli.
  b b b b. Cribriform plate.
  c. Surface denominated Os Planum.
  d d.  Hollow Triangular Pyramids.
  e. Space between the Pyramids for  receiving the Azygos Process of
     the Os Sphenoides.

  * See e, fig. 3.
.u+!!£°rU.ehL'S ,he wo.rd aPP1ied,by «eve™1 French anatomists to the Ossa Turhinnta of
the nose, they seem to have intended to express by it a convoluted lamina or plate of bone. 


r


sr;
>H: st>'>',i I /''■' 
 
Os Sphenoides.                  37
   The body is  situated near the centre  of the cra-
nium, in contact with the cuneiform process of the
occipital bone; the greater wings extend laterally be-
tween the frontal and temporal bones as high as the
parietal;  while  the pterygoid processes  pass down-
wards on each side of the posterior opening of the
nose, as low as the roof of the mouth.   It is there-
fore in contact with all the other bones of the crani-
um, 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 cu-
neiform process of the occipital bone; and laterally
it is extended into the great wings,  or temporal pro-
cesses.
   On the upper surface of the body, the lesser wings
or the aphophyses of Ingrassias,* project from the  la-
teral and anterior  parts;  these  wings consist of two
triangular plates, each of which is joined to the other

                         FIG. n.
                 A lateral View of the Bone.
   a. Christa Galli.
   c. Os Planum.
   d. Triangular Pyramid.

                        FIG. III.
                     The Bone inverted.
   a. The Nasal Plate of  the Ethmoid Bone, which constitutes the upper
    portion of the Septum of the nose.
   g g. Those portions of the Ethmoid which are called Superior Turbi-
    nated Bones.
   //. The Cellular Lateral portions of the Bone.
   d d. The Triangular Pyramids.
   e. Space between the Pyramids for the Azygos Process of the Os Splie-
     noides—a foramen on the internal side of one of the Pyramids.
   The fine drawing of the Ethmoid Bone, for this plate, was done by iny friend M. Lesuenr,
 whoie talemt ar>-so conspicuous in the plates attached to Pcruu's '• Voyage de Descouveites
 aux Tcrres Australes.
* A physician of Palermo, who died in 1580, aged 70.  Ed. 
38
Os Sphenoides.
 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 fo-
 ramen lacerum of the orbit of the  eye; this edge is
 thick and prominent  at  its internal extremity,  and
 these prominences are called  the anterior or clinoid
processes; immediately before them are the optic fora-
 mina, 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 some-
 times a  foramen,  made by the  carotid  artery.  A
 groove made by the optic nerves, is often seen extend-
 ing across the body of the bone, from one of the optic
 foramina to the other.   Behind 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 supposed
 resemblance to the supporters of a  bed; and  the
 depression for the pituitary gland is  called cella tur-
 cica,  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 cuneiform process of the os oc-
 cipitis.
   On the anterior and  inferior surfaces  is  a  spine,
 called the azygos process, which  is received into the 
Os Sphenoides.                39
base of the vomer, and extends forward until it meets •
the nasal plate of the ethmoid bone; on each side of
this spine, in the  anterior surface,  are  the orifices of
the sphenoidal cells.  Those orifices  appear very dif-
ferently in different bones; in some  very perfect spe-
cimens, they are irregularly  oval, being closed be-
low, 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 communica-
tion with the cavity of the nose on its respective side,
by the orifice above described.  The sinuses do not
exist during infancy ;^key 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   *
processes.   These great  wings compose  the j^igest
part of the  bone, and their  internal surface'forms a
portion of the middle  fossa of the  base of the  cra-
nium.   Externally, the surface of each great wing is
divided into two portions: one  of  which is lateral,
and unites to the frontal, temporal,  and malar bones,
foiling part of the smooth surface for the temporal
muscle; the other portion forms part of the orbit of
the eye, and  is very regular and smooth.  As the
ethmoid bone forms part of the inside, this portion of
the great wing forms part of the outside of the orbit.
and is termed  the orbitary process of the sphenoid
bone.   The horizontal part of each wing terminates
in an acute angle termed spinous process, which pene-
trates between the petrous portion  and  the articula-
ting cavity  of the temporal  bone.  In  this angle is
the foramen for the principal artery of the dura ma-
ter: near the point of the angle  is a small  process, 
40
Os Sphenoides.
  which projects from the basis of the cranium, and is
  called styloid.
    The pterygoid processes  pass  downwards  in  a di-
  rection 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 in-
  accurately 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 thf^same plate is a hook-
 like#process,  round which the tendon of  the last
 named muscle plays, as on a  pulley.  The ossa pa-
 lati, on each side, rest upon these internal  plates;
 and therefore the  pterygoid  processes seem to sup-
 port the whole face.

          Foramina of the Sphenoidal Bone.

 Before these foramina are described, it is necessary to state, that the nerves
  of the  brain are named numerically, 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
 already 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
 lacerum.  It commences largely  at the sella turcica,
 and  extends laterally a  considerable distance, until,
 it is a mere fissure.  The upper  margin of this fora-
 men is formed by the anterior clinoid processes, and
the edges of the smaller wings of the sphenoid bone. 
The Face.
11
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 foramen  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
n erves 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, behind  the  foramen ovale, to transmit the
principal artery of the dura mater, which makes  its
impression upon the parietal bone.
   The sixth  foramen is under the basis of each pte-
rygoid process, and is therefore called the pterygoid,
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 vidian, which, upon its  arrival  in
the cavity of the cranium, enters the temporal bone
by the foramen innominatum.

                   Of the Face.

   The face is the irregular pile of bones composing

     • From its reputed discoverer, Vidius, a professor at Paris-
  Vol. r.                 6 
12
Ossa Maxillaria Superiora.
the front and under part of the head, and is divided
into the upper and lower maxilloe, or jaws.
  The upper jaw consists of six bones on  each side,
of one single bone placed in the middle, and of six-
teen teeth.
  The thirteen bones are, two ossa maxillaria supe-
riora, two ossa nasi, two ossa unguis, two ossa ma-
larum, 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 forepart 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 pose.
  The ossa unguis  are at the internal angles of the
orbits of the  eyes.
  The ossa palati in the back part of the palate, ex-
tending 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 jaw-bones,
may be considered as the basis or foundation of the
face; as they form a large part of the mouth, the
nose, and the orbit of the eye.
  The central part of each bone, which may be con-
sidered as its body, is hollow,  and capable of con-
taining,  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, 
             Ossa Maxillaria Superiora.           43

  In each  upper  maxillary  bone the  following parts
are to be examined.
  The nasal process; the orbitar plate ; the malar pro-
cess ; the alveolar process; the palatine process ;  the an-
terior and posterior surfaces;  the great cavity; the in-
ternal 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  sides support the nasal
bone;  and a cartilage of the  alee 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.
  The orbitar plate, which covers  the great cavity,
and forms the bottom of the orbit, is rather triangu-
lar  in form, and concave.  In  the posterior part is a
groove, which penetrates 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 men-
tioned, 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
anterior  corner of the orbitar  plate;  it supports the
malar bone, and is rough for the purpose of articu-
lating with it.
  The alveolar processes  compose the inferior  and
external  margins  of the  #pper  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 corespond 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. 
44           Ossa Maxillaria Superiora.

  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 pro-
cess; 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 separated,  nor  easily joined  again.
The meeting of the palate plates, by a broad sur-
face ,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 purpose;
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 bone  forms a very small share of the
back part only.  As these thinner bones of the face
have no medulla, they are nourished by their perios-
teum only, and are of course perforated 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 distance below the orbit is the infra-orbi-
tary foramen for  transmitting a branch of the supe-
rior maxillary nerve.   When  these two bones are
ipplied to each other, and the ossa nasi are in their
 *iaces, they form the anterior orifice of  the  nasal 
Ossa Maxillaria Superiora.           4 b
cavity, which has a small resemblance to the inverted
figure of the heart on cards.
  The posterior surface has  been called a process or
tuber.   It  expands 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 anterior to the posterior surface of the bone; it
opens in the cavity of the nose, and is called antrum
maxillare,  or Highmorianum.* There  is but a small
portion of bone between this cavity and the sockets
of the teeth, particularly those of the second molar
tooth.
   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 sup-
porting 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 lachrymal duct, which is on the exter-
nal side of this cavity, netr its anterior opening, 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
 foramen already described.  2d.  The foramen incisi-
 vum or anterior palatine hole, which passes through
 the palatine process, from the nose to the mouth.  In
 the nose  there are  generally two foramina, which
 unite and form but  one in the mouth,  immediately
 behind the middle incisior teeth.  This foramen is
 closed by the soft parts during life,  and transmits a
* Alter an anatomist who described it. 
46
Ossa Nasi.
branch of the spheno-palatine nerve from each side
which runs on the septum narium, and joining at the
lower part of the canal with its  fellow, they unite,
and, according to Mr. Cloquet, form a ganglion. 3d.
The posterior palatine foramen, which is formed by
this bone, and by the os palati, on each side, is situ-
ated in  the suture  which joins them to each other,
and transmits to the palate,  a branch of the upper
maxillary nerve.
  This bone is  united to the frontal, nasal, ungui-
form, ethmoid 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
situation at the root of the nose.   They are each of
an irregular oblong figure, being broadest at their
lower end, narrowest near  the  middle, and larger
again at the top, where tri# edge is rough and thick,
and their connexion with the os frontis is consequent-
ly very  strong.  They are  convex  externally,  and
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, ex-
tending down the middle of the nose, forms a pro-
minent 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 pres-
sure.  [On the  posterior surface  of the os nasi  is a
groove occupied in the recent subject by a branch of
the ophthalmic nerve  called the nasal, which enters 
           Ossa Unguis—Ossa Malar urn.         17

the nose through the foramen orbitare internum antc-
rius.]  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 sep-
tum of the nose.
                   Ossa Unguis.

  The ossa unguis are so named from  their resem-
blance 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 an-
terior, 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 gene-
rally in  contact with the cells of the ethmoid; a small
portion  of the anterior parts is in the general cavity
of the nose.  Each os unguis is joined above to the
frontal bone; behind to the os planum; before  and
below to the maxillary bone.  It sometimes  is ex-
tended 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 concave, for lodging part of the temporal mus-
cles.
  The four angles of each of  these bones have been
reckoned as processes.   The one at the external can- 
48
Ossa Malarum.
 thus 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 near-
 est to a right angle.  The fourth, which is called zy-
gomatic, because it is extended backwards 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 or-
bitar 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 trans-
mission of small nerves or blood vessels from, and
sometimes into, the orbit.  On the internal surface are
the holes for  the 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 ossamallarumisyo*Vzec/,by its superior
and internal orbitar processes, to the os frontis, and
the orbitar process of the sphenoid bone; by the edge
between the internal and inferior orbitar processes, to
the maxillary bone; by the side between the maxil-
lary and inferior orbitar process, again to the maxil- 
Ossa Palati.                49
lary bone; and by the zygomatic process to the os
temporis.

                   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
orbits of the eyes.  Each bone may therefore be di-
vided into four parts, the palate square-bone, the ptery-
goid process, the nasal lamella, and orbitar process.
  The square-bone is irregularly concave, for enlarg-
ing both the mouth and cavity of the nose. The up-
per 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.   Be-
hind, this bone is somewhat in form of a crescent,
and thick,  for the firm connexion of the velum pen-
dulum palati; the internal point being extended back-
wards, to afford  origin to  the palatp-staphylinus or
azygos muscle.   This square bone is  well  distin-
guished from the  pterygoid process by a perpendicu-
lar  fossa, which, applied to such another in the maxil-
lary bone, forms a passage for the palatine branch of
the fifth  pair of nerves; and by another small hole
behind this, through which a twig of the same nerve
passes.
  The pterygoid process is somewhat triangular, hav-
ing a broaa base, and ending smaller above.  The
back part of this process has three fossae formed in
it; the two lateral receive the ends of the two ptery-
goid 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
  Vol. i.              7 
50
Ossa Palati.
 of this pterygoid process is rough and irregular where
 it joins the back part of the  great tuberosity of the
 maxillary bone. Frequently several small holes may
 be observed  in  this triangular process, particularly
 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 external edge of the square bone, and from the
 narrow extremity 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 considerable 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 mid-
 dle of the internal side of this thin  plate, there is  a
 transverse ridge, continued from one which is simi-
 lar to it in the maxillary bone for supporting the back
 part of the os spongiosum  inferius.   Along the out-
 side of this plate, the perpendicular fossa made by
 the palate-nerve is observable.
  At the upper and postesior edge of this  nasal plate
 is a notch, which when applied to the sphenoid bone,
 forms the spheno-palatine  foramen, through which
 a nerve, artery 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 sphe-
 noidal 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 
Ossa Spongiosa.
51
at the posterior part of the lower surface of the or-
bit, and forms a portion of it.   This process of the
os palati is hollow; and its cavity generally commu-
nicates with the contiguous cell of the os ethmoides.
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
pterygoid 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 pro-
cesses of the os sphenoides; by the transverse ridges
of their nasal lamellae to the ossa turbinata inferiora,
and by the spines of the square bones to the vomer.

      The Ossa Spongiosa, or Turbinata Inferiora.

   The ossa spongiosa, or Turbinata Inferiora, are so
named 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 convoluted,  very spongy, and exceed-
ingly  light.  Each of them  is attached  to theos max-
illare  superius, near the transverse ridge, by a hook-
like process, and  covers a part of the  opening of the
maxillary sinus.   One end is turned towards the an-
terior 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 
52
Vomer—Maxilla Inferior.
bone, in being less turbinated 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 sphe-
noides to  the palatine processes of the ossa palati,
separating the posterior 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 nos-
trils.  The upper edge is  firmly united to the base of
the sphenoid bone, and to the nasal plate of the eth-
moid. It is hollow  for  receiving the processus azy-
gos of the sphenoid, and where it  is articulated to
the nasal plate of the ethmoid, it is composed of two
lamina which receive this plate between them. The
anterior edge has a long furrow in it, where  the mid-
dle cartilage of the nose  enters.  The lower edge is
firmly united to the nasal spines of the maxillary and
palate bone.  These edges of the  bone are much
thicker than its middle, which is as thin as paper; in
consequence of which, and of the firm union or con-
nexion this bone has above and  below,  it can very
seldom be separated entire in adults; but in a child
it is much more easily separated entire, and its struc-
ture is more distinctly seen.
  Its situation is not always perpendicular, but often
inclined and  bent  to one side,  as well as the nasal
plate of the ethmoid bone.
  It is united above  to  the os  phenoides  and the
nasal plate of the ethmoid bone; before, to  the mid-
dle cartilage of the nose;  and below, to the ossa
palati and ossa maxillaria superiora.

          Maxilla Inferior, or Lower Jaw.

   The form and situation of this bone are so <*ene- 
Maxilla Inferior.
")3
rally known, that  they  do not require description.
To acquire an accurate idea of the lower jaw, it is,
however, necessary to examine attentively its differ-
ent 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 interior part of the chin, which becomes broad
below so as to form a triangle, and on each side of
this triangular prominence are transverse ridges; from
these eminences the muscles of the lower lip origi-
nate.
   On each side of the jaw, commonly under the se-
cond of the bicuspides, or small  moler teeth, is the
anterior maxillary foramen, through which pass out
the remains of the inferior maxillary nerve and blood
vessels.   This  foramen has a direction upward and
backward.  At a small distance  behind  these  fora-
mina, on each side, is the commencement of a ridge
which continues backward until it forms the edge of
the anterior or coronoid process.   The alveolar pro-
cesses, which form  the upper edge of the jaw, are on
the inside of this ridge; the alveoli or sockets corres-
ponding with the roots of the teeth,  in number  and
form.   The lower edge of the jaw, which is denomi-
nated the base, is round and firm, except at  the an-
gles, 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 perfect,  it is nearly rectangular. The mas-
seter muscle is inserted into the lower jaw, at the an-
gle ; and there are several 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 
 51              Maxilla Inferior.

 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 in-
 tersected each other, would form an angle of more
 than one hundred and forty degrees. The neck of the
 process, or  the part immediately below the condyle,
 is concave on the anterior, and convex on the poste-
 rior surface.
   On the inside of  the jaw, in  the middle  of  the
 chin, is  a small protuberance, sometimes divided by
 a verticle fissure; to this are attached the  fraenum
 lingua1,  and some  muscles of the tongue  and  os
 hyoides.  Further back is a  ridge  which  extends
 backwards and upwards, until, it approaches the al-
 veoli of the last molar teeth, where it  terminates in
 an oblong protuberance. To the anterior part of this
 line the  mylo-hyoidei muscles are attached;  and to
 the posterior extremity, the superior constrictor of the
 pharynx.  The surface of  the bone above this ridge
 is smooth, and covered with the gums and lining mem-
 brane 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 processes, is a. large foramen for transmitting the
third, or inferior  maxillary branch  of the fifth pair
of nerves, and the blood vessels which  accompany
 it; the canal, which commences here, terminates at
the anterior  foramen, already described.  The sur-
face of this canal is perforated by  many foramina,
through which blood vessels and nerves pass to the 
Of the Teeth.
55
different teeth, and to the cancelli of the bone.  On
the anterior side of the  foramen  is a sharp-pointed
process, from which a ligament passes to the tempo-
ral 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 downwards 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  re-
markable  roughness, where the  internal pterygoid
muscle is inserted.
  The lower jaw moves like a hinge, upon its con-
dyles 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 cavities:  if the effort to open
the mouth is continued, the lower jaw is fixed in that
situation,  and the whole head is thrown back, which
separates the upper jaw still further from the  lower.
  The lower jaw can be projected forward without
opening the mouth, by the movement  of both con-
dyles, at the same time, on the tubercles.
  This bone can  also rotate upon one condyle, as a
centre, while the  other moves out of the glenoid ca-
vity, upon the tubercle: but these important motions
can be better understood,  after the muscles, and the
articulation with  the  temporal bone,  in its recent
state, have been described.

                  Of the  Teeth.

  In the adult, when the teeth are perfect, there are
sixteen in each jaw, and those in corresponding situ-
ations, on the opposite sides, resemble each other
exactly.
   They are of four kinds, viz. incisores, or the fore 
56
Of the Teeth.
 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 middle, there are two incisores, one cuspidatus, two
 biscupides, 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 be-
 yond the gums, is covered with enamel,  a substance
 very different from common bone.
  Every tooth in its natural condition has a cavity
 in it, which commences at the extremity of each root,
 and extends 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 fora-
 men near the point of the root, as is evident during
 the growth of the teeth.  These vessels, and the
 nerve, have been traced into the  teeth, although in
 many subjects the foramina appear to be closed up.
  The alveoli or sockets of the teeth, are  formed upon
 the edge of the jaw: the bone, of which they con-
 sist, is less firm than any  other part of the jaws: they
 correspond exactly with the  roots of the teeth; and
 are lined with a vascular 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. 
Of the Teeth.
57
   The  body  of the  incisores  is  broad,  with  two
flat surfaces, one anterior  and the other posterior;
the anterior surface is rather convex, and the poste-
rior concave; they meet in a sharp cutting edge. At
this edge the tooth is thinnest and broadest;  it grad-
ually 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 inci-
sores.
   The cuspidati are longer  than any other teeth, and
are thicker than the incisores.   Their edges are not
broad, as those 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 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 gene-
rally has a longer root.  The bodies are flattened la-
terally, but incline to a roundish form.  On the mid-
dle of the grinding  surface are depressions  which
make the edges prominent.  On the  external edge
there is generally one distinct point in each  of the
bicuspides.  The internal edge is lower than the ex-
ternal in the first bicuspis.  which gives it a  resem-
blance 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 lengthwise, 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  peculiarities.   The body  of the  large
   Vol. i.                 ft 
58
Of the Teeth.
grinders is rather square; the grinding surface  hatf
often five points, and three of these are on the exter-
nal 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  maxillare.   The molares  of the  lower
jaw have but two roots, which are flat, and are 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 call-
ed dens sapientice, from its late appearance.   It is
shorter and smaller than the others;  its body is rath-
er rounder, and its roots are not so regular and dis-
tinct; for they are  sometimes 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 sapientiae take
an irregular direction and shoot against  the adjoin-
ing teeth.
  Infants have a set of deciduous teeth, which differ
in several respects from those of adults.  They are
but twenty in number; the five on each  side  of each
jaw, consist of two  incisores,  one cuspidatus,  and
two molares  or large grinders.  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 inter-
vals.   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
  • The two teeth of a pair do not appear at the same  precise time, but
ferv near to each othpv.                     v        ' uu 
Of the Teeth,
51»
cuspidatus, and finally the last molaris on each side.
There are many deviations from this order of succes-
sion, but it takes place in a majority of cases.
  These deciduous teeth become loose, and are suc-
ceeded by those which are more permanent, nearly
in the same order in which they appeared, but with
a progress much more slow.  The incisores general-
ly become loose between the sixth and seventh year;
the first molares about the ninth; the cuspidati  and
the second molares not until the tenth or twelfth, or
even fourteenth year.  The bicuspides take the places
of the infant molares.
  The three permanent molares appear in the fol-
lowing order:  The first of them protrudes a short
time before the front teeth are shed; it is the first of
the permanent teeth which appears, and is seen be-
tween the sixth and seventh year.  The second mo-
laris 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 gradu-
ally afterwards; during its formation the  root has a
large opening  at the extremity, which  is  gradually
diminished to  the small orifice before described. The
roots, as well  as the body, are formed upon the pulpy
substance,  which gradually diminishes, as they in-
crease.   After the external surface of the body of the
tooth is formed, the enamel begins to appear upon it,
and gradually  increases, until it is completely invest-
ed.  It is probable that the enamel is deposited up* 
♦ »0
Os Ht/o ides.
 on 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 de-
 structible than bone.  Like the substance of bone, it
 is composed of phosphate, with a small proportion of
 the carbonate of lime; but it is destitute of the carti-
 laginous or membranous structure which is  demon-
 strable 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 com-
 menced on the pulps of the incisores. At the time of
 birth, the bodies of the infant teeth are distinctly form-
 ed.  The alveoli, at first, have the  appearance of
 grooves in the jaw, which afterwards 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
 rudiments 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 perceived; 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, support-
 ed between the lower jaw and the larynx,  by mus-
 cles and  ligaments,  which proceed from  the neigh-
 bouring parts in various directions.
  The figure of this bone, as its name imports, re-
 sembles the Greek letter „.   In its natural situation, 
Os Hyoides.
61
the central and convex part is anterior, and the late-
ral portions extend backwards.
   The central part is called the body, and the lateral
portions the cornua.
   The  body is broad, and its  upper edge bent in-
wards;  so that the external surface is convex,  verti-
cally, 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 sternum and scapula be-
low it.
   The internal or posterior surface of the  body is
very concave.
   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 tubercle.
   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;  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 tem-
poral bone, and is sometimes ossified.
   The basis of the tongue is attached to the os hy-
oides, 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 described.
An acquaintance with the individual bones which compose the
 head is principally useful,  as it leads to a perfect understand-
 ing of the whole structure, of 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 font- 
62
Orbit  of the Eye.
        mina subservient to them, which are of so much importance
        in the practice of medicine and surgery, and also in physiolo-
        gy, that the following descriptions are subjoined.
                  Orbit of the Eye.
   The figure of this  cavity is that of a quadrangular
pyramid with  its angles rounded; so that it resem-
bles a cone, the bottom being the apex  and the ori-
fice the base.
   The diameter of the cavity passes obliquely out-
ward from the apex behind.  As the figure is irregu-
lar, 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 enlarged immediately within.  The form of the
orifice is rather oval; as the transverse diameter is
longer than the vertical.  Seven bones are concerned
in the formation of this cavity: the os frontis and a
portion  of the  lesser wing of  the  sphenoid bone
above; the os planum or ethmoid, the os unguis, and
the nasal process of the  upper maxillary bone, and
the os palati below: the os malae, and  orbitar plate
of the sphenoid bone, on the outside.
   On the  upper surface  is  the  depression for the
lachrymal gland; and  at the orifice is the notch or
foramen for the supra-orbitary vessels, &c.  which
have already been mentioned.
   On the inner surface are two longitudinal sutures,
which connect the os planum and the os unguis, to
the os frontis above, and the os maxillare below. In
the upper suture are the  two internal orbitary fora-
mina mentioned in the description  of the os frontis,
the anterior of which transmits a fibre  of the oph-
thalmic 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 
Orbit of the Eye.
63
the ridge of the os  unguis, and the groove for ac-
commodating the lachrymal sac,  which passes into
the canal of the same immediately below.
  On the lower surface is the aforesaid canal, formed
by the nasal and orbitar processes of the upper max-
illary 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 proceeds forwards, and
penetrating into the bone becomes a canal that ter-
minates 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 posterior 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 aper-
tures.  The optic foramen, the  sphenoidal fissure,
 and the spheno-maxillary fissure.
   The optic foramen opens almost at the  bottom of
the orbit on the inside; its direction is forwards and
outwards.
   The  sphenoidal fissure, formed principally by the
lesser and greater  wings of the  sphenoidal bone,
begins at the bottom of the orbit, and extends for-
ward, upward,  and  outward.  It is broad at the com-
 mencement 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, out- 
 64              Cavities of the Nose.

 ward, 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 directly into the zygomatic fossa.   In
 the recent subject it is closed, and only transmits the
 infra-orbitary 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 cribriform plate of the ethmoid and the palatine
 processes of the upper maxillary and palate  bones,
 and between the anterior and posterior nares. They
 are therefore of considerable extent in these direc-
 tions; but the distance from the  septum  to  the op-
 posite side of the nose is so  small, that each cavity
 is very narrow.
   The upper surface of each  cavity consists of that
 portion of the cribriform plate of the ethmoid which
 is between the septum and the cellular portions. An-
 terior to this, each cavity is  bounded  by the internal
surface of  the os  nasi of its respective side; and pos-
 terior to it, by the anterior surface of  the body of the
sphenoid bone.  These anterior and posterior surfaces
form obtuse angles with the upper surface of the nose,
 and are immediately above the openings  called  an-
terior and posterior nares.  The  anterior surface par-
takes of the figure of the os  nasi;  the upper surface
has the perforations of the cribriform  plate; the pos-
terior surface has an opening,  equal in  diameter to a
small quill, that leads into the sphenoidal cell, and it
 is also broader  than the anterior  or  superior  sur-
 face.
   The  internal surface, formed  by the  septum of
 the nose, which is composed of the vomer, the nasal
 plate  of the ethmoid, and  cartilaginous  plate, is 
Cavities of the N'ose.             65
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; by a small
portion of the os unguis; by the upper maxillary bone;
the os turbinatum inferius ;  the os palati; and the inter-
nal pterygoid process 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 32.   It  extends from the
sphenoid  bone, very near 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 posterior ethmoidal cells com-
municate 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 or spheno palatine foramen.  It opens exter-
nally and transmits a nerve and an artery to the nose.
   Below the meatus is the upper spongy bone, which
presents a  convex surface; its lower edge is rolled
up  and not connected with the parts about it. This
spongy bone covers a foramen in the ethmoid bone,
by  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 very
deep, as it  penetrates to the maxillary bone.  The
cells  of the  ethmoid are above it; the inferior turbi-
nated bone  below it; and  the upper spongy bone
projects over it.  In this channel is the opening of the 
66            Cavities of the Nose.
great cavity of the upper maxillary bone.  At the an-
terior extremity of it is a small portion of the os un-
guis, which intervenes between the nasal process of
the upper maxillary bone and the cells of the eth-
moid, and continues down to the 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
meatus of the nose. It is made large by an excavation
of the upper maxillary bone,  particularly at the an-
terior 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 lachrymal duct, which is so situa-
ted that a probe properly curved can be readily pass-
ed 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  pos-
terior ethmoid cells.
  A second in the middle meatus which leads to the
anterior ethmoid cells  and the frontal sinuses.
  A third in the same  meatus which  opens into the
maxillary sinus.
  A fourth in the anterior surface of the body of the
sphenoidal bone,  which opens  into the sphenoidal
sinus.
  To these must be added the opening of the lachry-
mal canal.

   It will be useful to the student of anatomy, after placing three or four
    of the uppermost cervical vertebra: 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,
passing  obliquely  upward  and  forward;  laterally, 
Basis of tlte Cranium.             67
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 inform, rounded above,
flat below, and separated from the other by a thin
partition, the vomer.

             The cavity of the Cranium.
   The upper concave surface of this cavity corres-
ponds with the figure of the cranium.  The ridge in
it for supporting the falciform process of  the  dura
mater, the groove made by the longitudinal  sinus,
the impressions  of the arteries, and the pits made by
the convolutions of the  brain,  are  particularly to be
noticed.
             The Basis of the Cranium.
is much  more  important.  It is divided into three
fossae on each side : tho anterior  of these  are .most
superficial, and  the posterior the deepest.  The bot-
toms of the anterior fossaz are  formed by the orbitar
processes of the os frontis, and consequently are con-
vex ;  between them is the cribriform plate of the eth-
moid, which is commonly sunk below the  adjoining
surface.   The  crista galli is very conspicuous; and
the foramen  caecum can almost always be seen.  The
crista galli is evidently  the beginning of the promi-
nent ridge, which continues on the os frontis,vand
supports the falx of the dura mater.  The  posterior
margins  of  these fossae are  formed by the lesser
wings of the sphenoid bone.
   The middle fossce are  formed by the great wings
of the sphenoidal bone, and by the squamous and
petrous portions of the  temporal  bone.   They are
lower than the anterior,  and higher than the  posterior
fossae.  The projection  of the margin of the anterior
fossae into these cavities, corresponds  with the sepa-
ration between the anterior and middle lobes of the 
68
Basis of the Cranium.
brain.  The suture between the sphenoidal and tem-
poral bones is evident in these fossae.   The  upper
surface of the body of the sphenoid bone, or the sel-
la 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 ascer-
tained, and also,  the anterior foramen  lacerum and
termination of the foramen caroticum,  with the im-
pressions made by the carotid  arteries  on the  sides
of the sella turcica. The petrous portions of the tem-
poral bones are the posterior boundaries of the mid-
dle  fossae.   Their  oblique  direction,  inwards  and
forwards,  is  particularly remarkable; being formed
like 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 attached  to it*
On  the anterior surface, in the  middle fossa, may 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 de-
fined by the edges of the petrous bones above men-
tioned, and by the grooves of the horizontal parts of
the lateral sinuses.  These fossae are nearly separa-
ted from the general cavity by the  tentorium,  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 poste-
rior lobes of the cerebrum; and  under it, in these
fossae, is the cerebellum.
  These fossae may be considered as one great cavi-
ty, which is circular behind,  and somewhat angular
before.  The angular surfaces are formed by the pos-
terior sides of the petrous portions.  Between them, 
Basis of the Crumum.
69
is the oblique surface of the cuneiform process of the
occipital bone, which descends to the great foramen.
On the surface of each petrous bone is the meatus
auditorius internus, and the orifice of the aqueduct of
the vestibule. Behind the petrous portion, the groove
for the lateral sinus is very conspicuous; 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 commonly
a small bony  process, which separates  the  eighth
pair  of nerves from  the internal jugular vein, as they
pass out here.
   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 fora-
men 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
protuberances of the os occipitis, formerly described.
The mastoid processes of the ossa temporum are on
the same transverse line with  the great foramen of
the os occipitis; but the foramen being larger extends
farther forward.  On the inside of the  mastoid pro-
cess, the fissure for the digastric muscle is very con-
spicuous, 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 sur-
faces are particularly striking. The posterior condy-
loid foramina for the cervical veins, and the anterior
for the ninth pair of nerves, are  also in view.  The
position of the cuneiform process of the os occipitis
is by no means horizontal, but extends forwards and 
70
Basis of the Cranium.
 upwards. The petrous or pyramdidalportion of the tem-
 poral bone commences between the mastoid process,
 and the condyle of the lower jaw, and extends  ob-
 liquely forwards and inwards, having the occipital bone
 behind it, and the glenoid  cavity and  the os sphe-
 noides before it. At the commencement, the surface
 of the petrous portion is  not horizontal but oblique,
 sloping into  the  glenoid cavity with a sharp edge
 downwards.   This edge in some cases is curved so
 as to surround the basis of the styloid process, which
 arises  in contact with it, and projects downwards,
 on each side of the vertebrae.  Between the mastoid
 and styloid process, is the foramen stylo-mastoideum.
 On the inside of the styloid process, and rather an-
 terior to it, is the foramen lacerum posterius, for the
 internal jugular vein, the eighth pair of nerves, &c.
 This foramen passes obliquely backwards and up-
 wards, and is bounded behind by the jugular  process
 of the os ocipitis, which  bone seems to contribute
 most to its formation. Very near to this hole 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 posterius, the suture,
 between the cuneiform process of the occipital and
 the petrous portion of the temporal bone, extends to
 the foramen lacerum anterius;  which  is closed  by
 cartilage in the recent subject, but is of an irregular
 and rather triangular form  in the  macerated head;
 this hole is formed by the occipital,  sphenoidal 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 lace-
 rum. The styloid process of the os sphenoides, which
 is seldom more than four lines in length, appears at 
Side of tlxe Head.              71
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 eus-
tachian tube, immediately  anterior  to it;  and at a
small distance on the inside and front of this foramen,
is the foramen ovale, for the inferior maxillary nerve,
or the third branch of the fifth pair.
                Side of  the Head.
  Those portions of the  side of the head which are
formed by 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 ofthe  temporal and malar bones,
which comprises part of the temporal and zygomatic
fossae of some anatomists, is both important and ob-
scure.
   To obtain a view of this, the lower jaw  should be
removed, and the zygoma sawed away, in one pre-
paration; and in another, the upper maxillary  and
palate bones, of one side, should be applied in their
natural position, to the os sphenoides, without any of \
the other bones.
   The upper part of this region, formed by the sphe-
noidal, frontal and malar bones,  is made concave by
the form of the external  angular part of the os fron-
tis and of the os malae;  which projects  backwards
so as to cover  a large portion of it.
   The lower part is formed principally by  the exter-
nal surface of the  pterygoid process of  the sphe-
noid  bone, and by  the posterior surface of the upper
maxillary.   Between the lower end  of the pterygoid
process and the upper maxillary bone, a small por- 
72
Form of the Cranium.
tion 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 the pterygoid process.   This fissure, which
may be called pterygo palatine or pterygo maxillary,
would open into the posterior part  of the cavity of
the nose, if the nasal plate of the os palati  did not
intervene ; this plate forms a partition, which sepa-
rates the nose from this fissure; and the sphenopa-
latine foramen, formed principally by it, transmits  a
nerve and blood vessels 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 se-
cond branch of the fifth pair, or the upper maxillary
nerve, is likewise situated near this place; and when
the upper maxillary,  the sphenoidal, and the palate
bones are in their natural  situation, the distribution
of the branches of this important nerve can be easily
understood: for the same  view presents the course
of its various branches; viz. to the nose, by the sphe-
no palatine foramen;  to the cavity of the cranium,
by the pterygoid foramen; to the orbit, and  the infe-
rior 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 firm of the cranium  is  that of  an irregular
oval.  The greatest length of its cavity is  between 
Form of the Cranium.
73
a part of the os frontis above the crista galli, and of.
the os occipitis above the centre of the crucial ridge
  The greatest breadth is at  about two-thirds of the
distance 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 persons, as their craniums
approach to the oval or round figures.
  The greatest depth of  the cavity is between the
posterior part of the cuneiform process of the occipi-
tal bone, and a part of the cranium which is nearly
over it,  about the middle of the sagittal suture.
  The figure of the cranium is somewhat varied in
different races of men; and it has been much chang-
ed 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 disused this practice;  but one of their
nation, whose head had this form, was in Philadel-
phia about the year 1796.
  At  this time a tribe who inhabit a district of coun-
try 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 surfaces.
  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
  Vol. i.               10 
74
Tlie Head of the Foetus.
these instances that disease ultimately shows itself;
but in other cases,  the preternatural increase of the
cranium finally stops without the occurrence of dis-
ease;  and the disproportion is  lessened by  the in-
crease of the face in the ordinary progress of growth.
   In many cases where men have deviated from the
ordinary stature, the head has preserved the common
size.   It is therefore said to  be small in giants and
large in dwarfs.

              The Head of the Fcetus.
   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 styloid processes.  Instead of a meatus auditorius
externus, there is a bony ring in which the  mem-
brana tympani is fixed.   The squamous and petrous
portions, and  this ring, are originally formed sepa-
rate ;  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 lambdoidal suture to the upper edge of the great
occipital foramen.  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 macera-
tion  into three  pieces.   The  body and the  little
wings  form one  piece.  Each of the great wings, 
The Head of the Falus.            75
with the pterygoid processes 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 deficiencies in it.  Thus the superior an-
terior angles of the parietal bones  being incomplete,
and also the upper  angles of the pieces which com-
pose the os frontis, a vacuity with four sides is occa-
sioned, which is termed the
  Anterior fontanel. This opening may be distinguish-
ed by its form, as well as its greater size,  from an-
other vacuity 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 parie-
tal and the occipital, this vacuity is triangular.
  Besides these,  there are  two other vacuities or fon-
tanels on  each  side,  at the two lower corners of each
parietal bone: these however are much less than those
first described.
  The smaller  fifitanels 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 centre of the base is better calcu-
lated 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 sphe-
noidal 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 
76       >           The Spiiu.
the head, that portion 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 much elevated above
the cavities for  containing the  posterior  teeth: in
consequence, the depth of the face is very small; and
its whole aspect is affected.
   The nose of the foetus differs greatly from  that of
the adult in respect to its  sinuses;  for not only arc
the maxillary cavities  wanting, but those of the fron-
tal and sphenoidal bones also.
   The lower jaw is formed in two pieces, which unite
at the middle; and hence the term symphysis is  used
in describing the chin.  This bone  is not only less
broad in proportion than that of the  adult,  but the
angles are more obtuse,  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.

                    SECTION II.

                  Of the Trunk.

   The Trunk consists of the  Spine, Thorax, and
 Pelvis.

                     The Spine.

   The spine is the long pile of bones extended from
 the condyles of the occiput to the end of the os coc-
 cygis.  It somewhat resembles two unequal  pyra-
 mids  joined in a common base. It is not, however,
 straight; for its upper part  being drawn  backwards
 by strong muscles, it gradually 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 support  the
 viscera of the abdomen.   It afterwards turns  back- 
True Vertebra'.
77
wards, 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
vertcbm:  the former constituting the long upper py-
ramid, which has its base below; while the false ver-
tebrae make the shorter lower pyramid,  whose base
is above.

                  True Vertebra:.

   The true vertebrce 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 Latin verb vertere.
   Each  of these vertebrae  is  composed of its body
 and processes.
   The  body  is the thick spongy forepart, which is
 convex before, concave backwards, horizontal  and
 flat in most of them above and below.  Numerous
 small holes, especially on the fore and back part of
 their surface, give passage to their vessels, and allow
 the ligaments to enter their substance.   The edges
 of the body of each vertebra  are covered, 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 vertebrae  in the
 form of epiphyses. They are of great use in prevent-
 ing the spongy bodies from being broken in the mo-
 tions of the trunk.
    Between the bodies of each two adjoining verte-
 brae, a substance between the nature of ligament and
 cartilage is interposed; which seems  to consist  of
 concentrical curved fibres, when it is cut horizontal-
 ly ; but when it is divided perpendicularly, the fibres
 appear obliqne and decussating.   The outer part of
 these intervertebral ligaments is the most solid and
  hard : and they gradually become softer till they are 
78
The Vertebra}.
 almost in the form of a  glairy liquor in  the centre.
 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 incom-
 pressible, or nearly so.   The  middle point  is there-
 fore 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 what-
 ever direction  our  spines are moved,  as saves the
 body from violent shocks, and their dangerous  con-
 sequences.   This ligamento-cartilaginous substance
 is firmly fixed to the horizontal surfaces of the bodies
 of the vertebrae, to connect them; in which it is as-
 sisted by a strong membranous ligament, which  lines
 all their concave surface, and by a still stronger  liga-
 ment that covers all their anterior convex surface.
   The elastic  substance seems  to be in a  state of
 compression by the exterior ligament and  the bones;
 for, if a section be made through a portion of the ver-
 tebrae and the  intervertebral substance,  this  sub-
 stance will expand, so that its surface will be much
 higher than that of the vertebrae.  It is so elastic, and
 so much confined,  in some subjects, that a sharp
 knife, if plunged into it, will be  gradually  ejected
 when the hand is withdrawn.
   The bodies of the vertebrae are, with some excep-
 tions, 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 dis-
 position, 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 another descends.  The smooth, and ge- 
/
                 The Vertebrce.                 79

nerally  the flattest side of each of these  four  pro-
cesses is covered with a  smooth cartilage; and the
two lower processes of each upper vertebra are fitted
to, and  articulated with, the two upper processes  of
the vertebra below, having their articular ligaments
fixed into the rough line round their edges.   These
processes are termed the oblique or articulating.
   From between the oblique processes of each side,
another process extends  laterally,  which  is  called
the transverse.
   From the back part of the roots of the two oblique
processes, and of the transverse process of each side,
a broad oblique bony plate is extended  backwards:
where these meet, the seventh process of the verte-
brae takes its rise, and stands out backwards.  This
being generally sharp-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
internal surface of the spinal processes, as well as of
the bodies,  particular ligaments connect the bony
bridges  and processes of the contiguous vertebrae to-
gether.
   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 fore-
part, which, joined to the one at the back part of the
bodies,  make 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 spi-
nal marrow.
   In the upper and lower edge of each lateral bridge,
there is a notch. These are so adapted to each other
in the contiguous vertebrae, as to form a round hole
in each side, between each  two vertebrae, through 
80
T/ie Vcrtcbrce.
which the nerves proceed  from the spinal  marrow
and its blood vessels pass.
  The articulations of these true vertabrae are  con-
sequently double; for their  bodies are joined by the
intervening cartilage above described; and their ob-
lique processes, being tipped with cartilages, are so
connected by their ligaments as to allow a small de-
gree of motion on every side.   Hence it is  evident,
that their centre of motion is altered in different po-
sitions of the trunk: for, when we bow forwards, the
weight bears entirely on the bodies of the vertebrae;
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.
  The true vertebrce are divided  into  three classes,
which agree with each other in their general struc-
ture, but are distinguished by several peculiarities.
  These classes are named Cervical, Dorsal, and Lum-
bar.
  The cervical are  the seven  uppermost vertebrae;
which are distinguished from the rest by these marks:
Their bodies 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 vertebrae 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 extend-
ed. Hence the cartilages between these- vertebrae are
firmly connected, and their articulations are  secure.
  These cartilages are thick, especially at their fore-
part; which is one reason why  the  vertebra  project
forward as they descend, and have the larger motion. 
The Vcrtebrce.
81
  Their oblique processes  more justly deserve that
name than those of any other vertebrae.   They are
situated slanting; 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 trans-
verse process rising from between the oblique pro-
cesses 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 circular hole for
the passage of the vertebral artery and  vein, 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
horizontally.   They  are shorter than those  of any
other vertebrae, and  are forked or double at their
ends; they therefore allow a more convenient inser-
tion to muscles.
  The thick cartilages between  the bodies  of these
cervical vertebrae, the obliquity of their oblique pro-
cesses, and the shortness and horizontal  situation of
their  spiral  processes, all conspire  to allow  them
large motion.
  The holes between the bony cross bridges, for the
passage 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  verte-
  Vol. i.                11 
82
The Vertebra:.
brae 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 un-
equal, where the ligaments that  connect this verte-
bra 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 sub-
ject, to receive the tooth-like process  of the second
vertebra.  On each side of it a small  rough sinuosi-
ty may be remarked, where the ligaments going  to
the sides of the tooth-like process of the following
vertebra  are  fastened; and on each side  a  small
rough protuberance and a depression is observable,
where the transverse ligament, which  secures the
tooth-like process in the sinuosity, is fixed, and hin-
ders that process from injuring the medulla  spinalis
in the flexions of the head.
   The atlas has a little spinal process as body; but,
instead of it,  there is a large bony arch, that the mus-
cles 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 depres-
sions, 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 concave surface
which has an internal aspect, and corresponds exact-
ly with the articulating surface on the external side
of each condyle of the os occipitis.   Under the ex-
ternal edge of the posterior part of each of these ca-
vities is the fossa, or deep open  channel, in which
the vertebral arteries make the circular turn, as they 
The Vertebrae.
83
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 processes, extending from within out-
wards and downwards, are large, circular, and slight-
ly concave.   So that this  vertebra,  contrary to the
other six, receives the  bones with which it is articu-
lated, 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 insertion of several muscles;  and there-
fore those muscles which move this vertebra on the
second have a considerable lever to act with, because
of the distance of their insertion from the  axis of re-
volution.
   The hole for the medulla spinalis is larger in the
atlas than in any  other vertebra, not only on account
of the medulla being largest here, but also to pre-
vent its being hurt by the  motions of this vertebra
on the second. This large hole, and the long trans-
verse  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 vertebra; but from the  figure of the bones form-
ing these articulations, it is evident, that  very  little
motion can  here be allowed to either side; and there
must  be  still less  circular motion.
   The second vertebra of the neck is called dentata.
It is somewhat of a  pyramidal figure,  being large,
and extended  downwards,  especially in front, to en-
ter 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 
84'
The Vertebrae.
surface of the anterior arch of the first vertebra plays,
is convex, smooth, and covered with a cartilage; 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 like-
wise 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  occipi-
tal bone;  and another ligament  rises up from near
the point of the process to the os occipitis.
  The  superior oblique processes of the vertebra
dentata are large, circular,  very nearly in  a hori-
zontal  position, and slightly convex, to be adapted
to the inferior oblique processes of the  first vertebra.
The inferior oblique processes of this vertebra an-
swer exactly to the description given of  those com-
mon 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 vertebral arteries pass are reflected  out-
wards  about the middle of each  process; so that the
course of these vessels may be directed towards the
transverse processes of the first vertebra.  Had this
curvature of the arteries been made in a part so move-
able as the neck is, while they were not defended by
a bone and placed in the cavity of that bone, scarce a
motion could have been performed  without  the ut-
most hazard of compression. This is the third in-
stance of similar mechanism in cases of sudden  cur-
vature of  arteries.  The first is the passage of the
carotids 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, 
The Vertebra'.
85
and short,  to give  sufficient origin to  the  musculi
recti majores and obliqui  inferiores, and to  prevent
the contusion of these and other muscles in pulling
the head back.
  The four cervical vertebrae which are next in or-
der, 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 surfaces less  excavated
than the others.  The oblique processes are more
perpendicular;  and the spinal as well as  transverse
processes are without bifurcation.
  After an examination of the condyles of the os oc-
cipitis, and of the whole structure  of the atlas and
vertebra dentata, 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 revolves to a
certain  degree round the processus dentatus of the
second vertebra: the head necessarily moving with it.
  The twelve dorsal maybe distinguished  from the
other vertebral 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 flattened
laterally by the pressure of the ribs, which are insert-
ed into small cavities formed in their sides. This flat-
ness of their sides, which makes the figure  of these
vertebrae almost a  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
behind than any of the other two classes. The upper
and lower surfaces are horizontal.
  The cartilages interposed  between the bodies of 
86
The Vertebral.
these vertebrae are  thinner than in any other of the
true vertebrae; and  contribute to the concavity of the
spine in the thorax, by being thinnest at their fore-
part.
   The oblique processes are placed almost perpen-
dicularly: the upper ones slanting but a  little for-
wards, and the lower ones  slanting as much back-
wards.  The  convexity or  concavity is not so re-
markable 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 depression near the end of
these processes.
   The spinal processes are  long, small-pointed, and
sloping downwards  and backwards.   From their up-
per and back part a ridge  rises, which is received by
a  small channel in the forepart of the spinal pro-
cess 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 chord,
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 con-
nexion of the spinal processes, all contribute  to re-
strain  these  vertebrae from much motion,  which 
The Vertebra.
87
might disturb  the actions of the heart and lungs;
and in consequence of the little motion allowed here,
the intervertebral  cartilages  sooner shrivel, by be-
coming more solid; and therefore the first remarka-
ble 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-shoul-
dered.
   The bodies  of the four uppermost dorsal vertebrae
deviate  from  the rule, and  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 di-
vide at smaller angles.
   The two uppermost vertebrae of the back, instead
of being very  prominent forwards, are flattened by
the action of  the musculi longi colli and recti ma-
jores.
   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 depression 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
vertebra to the seventh or eighth, with their  smooth
surfaces, for the tubercles of the ribs, facing gradual-
ly more downwards; but afterwards, as they descend,
they become shorter, and the smooth surfaces are
directed more upwards.
   The spinous processes of the vertebras of the back
become 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 where- 
88
The Vertcbrce.
in 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 sur-
face 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 sur-
faces of its inferior 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  distinguished  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 surfaces of their bodies
are more concave than in the vertebrae of the back.
2. The cartilages between these vertebrae  are  very
thick, and render the spine convex within the abdo-
men, by their great thickness anteriorly. 3. The ob-
lique processes are strong and deep;  the superior,
which are concave, facing inwards,  and the convex
inferior ones facing outwards; and therefore each of
these vertebrae  receives the one above it, and  is re-
ceived by the one below, which is not so evident in
the other two classes already described.   4. Their
transverse processes are small, long, and almost ho-
rizontal, for allowing large motion to each bone, and
sufficient insertion to muscles, and for supporting 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 in-
 serted. 6. Their spinal processes are strong, straight, 
The Vertebra.               89
and horizontal, 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
upper one furnishes, however, the larger share of each
hole.
  The thick cartilages between these  lumbar verte-
brae, their deep oblique processes, and  their erect
spinal processes, are all fit for allowing large motion:
though it is not so great as what is performed in the
neck;  which  appears  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
oblique processes at a great 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 low-
est; which  consequently make them appear hollow-
er 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 forwards,  than those of any other
lumbar vertebra.
  In consequence of this particular construction, the
spine  is capable of flexion,  principally in  an interior
and lateral  direction, and also of extension. It ought
to be  remarked that during flexion it forms a curve,
  Vol. i.               12 
90                 Os Sacrum.
 and not an  angle; for, in the  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 the difference in the thickness of the  interverte-
 bral substance.  The necessity of fixing  the dorsal
 vertebrae  is  very evident: as  their  motion would
 greatly interfere with the  motion of the ribs in res-
 piration.
   The lumbar vertebrae have more  motion than is
 commonly supposed; for, in addition to a certain de-
 gree 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 their whole pelvis, by a rotation of the lumbar
 vertebrae, to avoid moving the diseased joint.
                  Fake Vertebrce.

   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, be-
 cause the sacrum in young  subjects is composed of
 five distinct bones, each of which has some resem-
 blance to a vertebra; but they are completely united
 in the adult, and form but one bone, which is sup-
posed 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 upwards.  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 ex-
tremities of each of these  lines,  are large round 
Os Sacrum.
91
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.
  The back part of the os sacrum is rough and con-
vex : in the middle there are  commonly  three pro-
cesses similar to the spinous processes of the lumbar
vertebrae,  and a fourth which is much smaller.  Be-
low 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 anterior  surface.   Between the spinous pro-
cesses and the  anterior  part, which  resembles the
bodies of  vertebrae, is the continuation of the verte-
bral cavity which contains the spinal 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
deficient,  and the cavity above mentioned is com-
pletely open behind; but the contained parts are de-
fended by strong membranes.
   The anterior  part  of  each lateral surface is co-
vered 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 in-
serted into it.
   On the  posterior surface of the sacrum, the sides
of the open part of the vertebral canal terminate, so 
92
Os Coccygis.
 as to form a notch, through which passes the twenty-
 ninth pair of nerves.
  The  os sacrum  is very spongy,  and is lighter  in
 proportion to its bulk than any bone in the  body: it
 is defended by the muscles that cover it, and the li-
 gaments which adhere to it.
  It is articulated, above, to the last lumbar vertebra;
 below, to the os coccygis; and on the sides, to the
 ossa ilia.
  That triangular chain of bones depending  from the
 os sacrum, in which each bone becomes smaller as
 it descends, 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 cuckoo's beak, the name
 is derived.
  There are four pieces in people of middle age. In
 children, they are almost wholly cartilaginous.  In
 old subjects, all the bones are united,  and become
 frequently one continued bone  with the os sacrum.
  The highest of the four bones  is the  largest, with
 shoulders 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 shoul-
 ders, a process  often rises up on each side,  to join
 with the os sacrum.  Sometimes these shoulders are
joined to the sides  of the open end of the vertebral
 canal, to form the hole in each side  common to these
 two bones, for the passage of the twenty-ninth pair of
 spinal 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. 
Os Coccygis.
93
  The three lower bones gradually become smaller,
and are spongy, but are strengthened by a strong li-
gament 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 sub-
jects a cartilage is interposed; therefore their articu-
lation is analagous to that of the bodies of the verte-
brae of the neck; for the lower end of the os sacrum,
and of each of the three  superior bones of  the  os
coccygis, has a small depression in the middle; and
the upper part of all the bones of the os coccygis is a
little concave, and consequently the interposed car-
tilages are thickest in the middle, to fill up both ca-
vities; by which they connect the bones more firmly.
Then 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, un-
less when these bones grow together, all of them are
capable of motion; of  which the first and second en-
joy 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
coccygaei muscles, and part of the levatores ani, and
of the glutei maximi,  are fixed.
  The connexions of these bones hinder them from
being moved to either side; and their motion back-
wards  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 moveable; and the right man-
agement of them, in delivering women, is very im-
portant.  The mobility of the os coccygis diminish-
ing as  people  advance in  age, especially when its 
 94        Vertebral Cavity—Thorax—Ribs.

 ligaments and cartilages have not been kept flexible
 by being stretched, is probably one reason why wo-
 men, who are advanced in years before they marry,
 have generally difficult parturition.
  These bones serve to sustain the intestinum rec-
 tum; and, therefore, are curved forwards; by which
 they are preserved, as well as the muscles and teg-
 uments, from any injury when sitting with the body
 reclined back.
 The Vertebral Cavity for containing the Spinal Marrow

  The canal formed by the foramina of the different
vertebrae, when these bones are placed in their natu-
ral 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 different in different places.
  In the cervical vertebrae, it is  largest, and nearly
triangular in form; in the dorsal, it is much smaller
and almost cylindrical;  in  the lumbar,  it is some-
what enlarged, and approaches again to the triangu-
lar figure; in the sacrum, it is broad, but flat, and di-
minishes gradually, so as to assume the form of a
long triangle.
  It has a ligamentous lining, which will be describ-
ed when an  account is given of the fresh bones and
their ligaments.
                  The Thorax.

  The thorax resembles a  flattened cone, cut away
obliquely 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 di-
rection downwards as respects the back bone. Their 
The Ribs.
95
number is generally twelve on each side; though
sometimes eleven or thirteen have been found.
  They are convex externally and concave internal-
ly.  They are made smooth by the action of the con-
tained parts, which, on this account, are in no dan-
ger of being hurt by them.
  The ribs approach towards a round form at their
extremities 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 muscles 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 interrupt
the motion of the vital organs.  The upper edge of
the ribs is more  obtuse and rounder than the  lower,
which is deepened on its internal side by a long fos-
sa, for lodging the intercostal vessels and nerves: on
each side of which there is a ridge, to which the in-
tercostal muscles are fixed.  The fossa is not obser-
vable 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 blood vessels, has origi-
nated 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 hollow surfaces; the lowest of which is gene-
rally the broadest and  deepest.  The two surfaces
are joined to the bodies of two different vertebrae,
and the ridge forces itself into the intervening carti-
lage.  A little way from this head, we find, on the 
\
 96                  The Ribs.

 external surface, a small cavity, where mucilaginous
 glands are lodged; and round the head, the bone
 appears spongy, where the capsular ligament of the
 articulation is fix^ed.  Immediately beyond  this,  a
 flatted tubercle  rises, with a small cavity  at its root,
 which is surrounded  by a roughness, for the articula-
 tion of the rib with the transverse process  of the low-
 est of the two vertebrae, with which the head of the
 rib is joined. Advancing further on this external sur-
 face, another  smaller tubercle may be observed 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
 inserted.   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 car-
 tilage.  In adults, the  cavity at this end of the  ribs
 is generally 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  the sternum, or is
joined to the cartilage of the next rib.  This course,
however, is not in a straight line with the rib: for
the  cartilages generally make  a considerable flex-
 ure,  the concave part of which is upwards; therefore
 at their insertion into the sternum, they make an ob-
 tuse angle  above,  and an  acute one below.   These
 cartilages are of such a length as never to allow the 
The Ribs.
97
ribs to come to a right angle with the spine; but they
keep them situated so obliquely as to make the an-
gle very considerably1 obtuse above, till a  force ex-
ceeding  the  elasticity of the cartilage is applied.
These cartilages, as  all others, are firmer and harder
internally than  they  are on their external surface;
and sometimes, in old people, all their middle sub-
stance becomes bony, while a thin cartilaginous la-
mella appears externally. The ossification, however,
begins frequently at the external surface. The great-
est alternate motions of the cartilages being  made
at their great curvature, that part remains frequent-
ly cartilaginous after all the rest is ossified.
   The ribs then are  articulated at each end, and that
behind is doubly joined to the vertebrae; for the head
is received into the cavities of two bodies  of the ver-
tebrae, and a larger tubercle is received into the  de-
pression in the transverse process of the  lower ver-
tebra.   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
thrusted 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  down-
wards can be but small in any one rib at the articu-
lation itself.  But as the ribs advance forwards,  the
distance from their centre of motion increasing,  the
motion must  be larger; and  it  would  be  very con-
spicuous at their anterior ends, were they  not resist-
ed 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
   Vol. i.               13 
98
The Ribs.
the place near their fore end where they are more
resisted.
  The ribs differ from  each other in the  following
respects:
  The upper rib is the most crooked;  and as they
descend they become  straighten  Their  obliquity,
with respect to the spine, increases as they descend;
so that though  their distances 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 trans-
verse processes of the vertebrae, have their  smooth
surfaces gradually facing more upwards.  The ribs
becoming thus more oblique, while the sternum ad-
vances forwards in its descent,  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 occasions their curvature to be greater.
   The length of their ribs increases  from the first
and uppermost 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 bodies of the vertebrae, gradu-
ally 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. 
The Ribs.
99
Their cartilages are all gradually longer as they de-
scend, and are joined to the breast bone: so that, be-
ing pressed constantly between two bones, they are
flattened at both ends; and are thicker, harder, and
more liable to ossify, than the other cartilages, that
are not subject to so much pressure.   These bones
include the heart and lungs; and therefore are called
true ribs.
  The five  inferior  ribs of each side  are the fake,
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 dia-
phragm is connected.
  The first rib of each side is  so situated, that the
flat sides arc  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 con-
cave surface is opposed to the lungs.   But in conse-
quence of this situation, the channel  for the  inter-
costal 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
vertebra  of the thorax.  Its  cartilage  is frequently
ossified in adults, and is united to the  sternum at
right angles.  This  first rib  frequently has  a  ridge
rising near the middle of its posterior edge, where
one of the heads of the scalenii muscles rises.  Far-
ther forward it is flattened, 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, outwards and upwards, so as to make the
surface of the thorax uniform: and it maybe observed
of all the ribs,  that the aspect of their surfaces is va-
ried upon this principle, according to their situation in
the thorax. 
100
'The Sternum.
  The sixth, seventh, and  eighth  ribs,  have their
cartilages nearly contiguous.  They are frequently
joined to each other by cross cartilages; and frequent-
ly 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
tubercle for jts articulation with  the transverse pro-
cess 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 straightest. Its
head  is only articulated with the last vertebra of the
thorax; and  therefore is not divided  into two  sur-
faces.  This rib is not joined to the transverse pro-
cess of the vertebra, and therefore  has no tubercle,
being  often pulled necessarily inwards  by the  dia-
phragm,  which  an articulation with the transverse
process would not have allowed.  The fossa  is  not
found at  its under edge,  because the vessels run be-
low it.  The forepart of this rib is smaller than its
middle, and has only a very small pointed cartilage
fixed  to it. To its wrhole internal side the diaphragm
is connected.

                   The Sternum
  Is the  broad flat bone, in the front part of the  tho-
rax.  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 peo-
ple, the sternum  is a continued bony substance from
one end to the other; though we still observe  two. 
The Sternum.
101
sometimes three, transverse lines on its surface; 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 thorax: but the convexity on the
external surface is not so conspicuous, because the
sides  are  pressed outwards by the  true ribs; the
round heads of whose  cartilages  are received into
seven smooth pits formed  in each side of the ster-
num, and  are kept firm there by strong ligaments,
which on  the external surface have a particular ra-
diated texture.   The pits  at the  upper part of the
sternum are at  the greatest  distance one from an-
other, and as they descend, are  nearer;  so  that the
two lowest are  contiguous.
  The substance of the breast bone is cellular, with a
very thin  external plate,  especially  on  its internal
surface, where we  may frequently observe a cartila-
ginous crust spread over it.  On both surfaces, how-
ever,  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 move-
able support it has from the cartilages, it  is  suffi-
ciently 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  consi-
derably any violence offered.
  The three pieces which compose this bone are
very different from each other.
  The first piece resembles a triangle with the cor-
ners cut off.  The  upper edge of it is thick, and has
a regular depression in the middle, to accommodate
the trachea.  On each side of this depression is  a
superficial cavity, which on viewing it transversely 
,102
The Sternum.
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 be-
come 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 of this first bone,  the half of the pit for
the second rib on each side is formed.   The upper
part of the surface behind  is covered with a strong
ligament, which secures the clavicles;  and is  after-
wards to be more particularly taken notice 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
one 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 ligamentous membrane or cartilage that fills it, is
described as a h<5le.   When  the cartilage between
this and the first bone is not ossified, a manifest mo-
tion of this upon the first may be observed in  respi-
ration; or in raising the sternum, by pulling  the ribs
upwards; or distending  the lungs with  air,  in a re-
cent subject.
  The third bone 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  ensiformis, than any
other. This third bone is seldom of the same figure, 
Motion of the Ribs, be.           103^
magnitude,  or  situation, in any  two subjects;  for
sometimes it is triangular; with one of the  angles
below, 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, and often, it is bifurca-
ted ; sometimes also, it is unossified in the middle.
In the greatest  number of adults,  it is ossified, and
tipped with a cartilage; in some, one half of it is car-
tilaginous ; 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 articulated with the clavicles.
   It contributes to the formation of the cavity of the
thorax, and supports the mediastinum.  As a move-
able 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 Respi-
                      ration.

   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 horizontal; and  the posterior  extremity of
each rib, which is the centre of this motion, is moved
very little, while the anterior extremity moves much
more.
   At the same  time, the ribs perform a rotation out-
wards, upon their extremities connected with the
spine and sternum;  in consequence of which, the
middle of each rib  is moved outwards  to a consi-
derable  extent.
   It is very obvious, that  by these motions, the tho- 
104
The Pelvis.
rax must be enlarged from side to  side, and from
behind forwards.
  As the ribs are raised from the oblique toward the
horizontal position, the sternum is necessarily moved
forward 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 of the sternum.  The ster-
num, 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 produced by the increase of its verticle diame-
ter, in consequence  of the descent of the diaphragm;
but when the inspirations are very large, and when
the descent of the diaphragm is impeded, as in preg-
nancy, and in ascites, these motions are very consi-
derable.
  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 lower  ribs, hav-
ing no support 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
portions, 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 Pelvis.
105
   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.
   The os ilium is the largest of the three  portions.
 Its external surface has been called its dorsum,  and
 the internal concave surface its costa. The semicir-
 cular edge at  the upper part of the bone, is named
 the spine:  the external oblique muscle of the abdo-
 men is inserted into it, and the internal oblique,  and
 the transversalis arise from it. The ends of the spine
 are  prominent,  and therefore are called processes.
 At a small distance below the anterior spinous  pro-
 cess, is another protuberance, called the inferior an-
 terior spinous  process ; and the edge of the bone be-
 tween these two processes is curved.
   Below the posterior spinal process, another protu-
 berance is also observable, which is applied closely
 to the os sacrum. Under this is a large notch, which,
 with the  ligaments that  pass from the os sacrum to
 the os ischium, forms  a foramen, through which  the
 great sciatic nerve, the  pyriform muscle, and some
 blood vessels pass.
   The external  surface, or dorsum, of the os ilium,
 is greatly 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 acetabulum, is the thickest.
   The internal surface of the os ilium is concave, and
 supports  some of the intestines.   From this concave
 surface a slight concavity is continued obliquely for-
 wards, at the  inside of the  anterior inferior spinal
process,  where part of the  psoas and iliacus muscles,
   Vol. i.               14 
106
Os Ischium.
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
pelvis.   Into this ridge the broad tendon of the psoas
parvus is inserted.
  All the internal surface of the os ilium, behind the
continuance of this ridge, is very unequal:  for the
upper part  is flat, but spongy, where the sacro-lum-
balis and longissimus dorsi rise.  Lower down, there
is a transverse ridge, from which ligaments go out to
the os sacrum.   Immediately 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 manner, 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 thin
cartilaginous skin,  for its immoveable  articulation
with the os sacrum.   From all the circumference of
this large unequal 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
conspicuous, 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, ex-
cept a thin external plate.
   Os Ischium, or hip bone, is of a  middle  size be-
tween the  two other  parts of the os innominatum,
and of a very irregular figure.  Its  extent might be 
Os Ischium,.
107
 marked  by a horizontal line drawn a little below
 the middle of the acetabulum; for the upper bulbous
 part  of this bone forms rather  less than the lower
 half of that great cavity, and the small 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  backwards,  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 posterior cru-
 ral vessels, and the sciatic nerve pass out of the pel-
 vis.  Immediately below this process, is a  depres-
 sion for the tendon of the obturator  internus muscle.
 In a recent subject, this part of the bone, which serves
 as a pully on which the obturator muscle plays with
 a ligamentous  cartilage.
  Below the depression of 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  external, or posterior, sacro-
 sciatic ligament is so fixed,  that between  it, the in-
 ternal ligament, and the sinuosity of the os ischium,
 a passage  is left for the internal obturator muscle.
 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 semitendinosus muscles;  and
the semimembranosus 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 
108
Os Pubis.
we lean upon in sitting, and the external  gives rise
to the largest head of the triceps  adductor femoris.
Between the external margin of the tuberosity, and
the  great hole of the os innominatum,  there is fre-
quently an obtuse ridge extended down from the ace-
tabulum, which gives origin to the quadratus femoris.
As the tuber advances forwards, it becomes smaller,
and is  rough,  for the origin of the musculus trans-
versalis 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  nar-
rower 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 down-
wards to join the end of the small leg of the os is-
chium. 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 continued from it along the os ilium, and
forms the division between the  cavities  of the abdo-
men and pelvis.   This ridge is called crista, and in-
cluding that on the ilium, linea innominata, or ileo-
pectinea.  On the anterior and external edge of this
surface of the pubis, at a small distance  from the car-
tilage, is a prominence or process, called the spine. 
Os Pubis.
109
From this process another ridge,  which is  much
more obtuse, extends to the acetabulum. The upper
surface of the pubis, which is included betwen these
ridges, is concave, for the transmission of the  crural
vessels, and nerve, and the psoas  and iliacus inter-
nus muscles.
  Immediately below the lower ridge, and near the
acetabulum, a winding notch is made, which is com-
prehended in the great contiguous foramen;  but is
formed into a hole in the recent subject, by a sub-
tended ligament, for the passage of the posterior cru-
ral  nerve,  and artery, and  a vein.   The  internal
end of the os pubis is rough and unequal, for the firm-
er 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  thyroi-
deum. The whole of this foramen, except the notch
for the posterior crural nerve, is filled up, in a recent
subject, with a strong ligamentous membrane, that
adheres very firmly to its circumference.  From this
membrane chiefly,  the two external and internal  ob-
turator muscles take their rise. The great design of
this hole, besides rendering the bone lighter, is to al-
low a strong origin to the obturator muscles, and suf-
ficient space for lodging them; that there may be no
danger of disturbing 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- 
no
Ossa Innominata.
 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.
   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 liga-
 mentous 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 anywhere 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 other-
 wise thrust it out. As the margin is extended down-
 wards and forwards, it becomes less;  and at the in-
 ternal lower part is a deficiency 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 greatest part of this sepa-
rate 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 
Male and Female Pelvis.
Ill
to cement these bones together; and strong ligaments
go from the circumference of this unequal surface, to
connect them more firmly.  They are connected to-
gether at their forepart by the ligamentous 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 in-
nominata with the os sacrum, there is great reason
to think, that if the conglutinated  surfaces of these
bones were once separated, (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 aceta-
bulum) for the thighbones 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 per-
formed by the bones  of the spine.
  The form of the cavity of the pelvis, at its  upper
opening, 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 be observed that the dimen-
sions of  this  opening are made less  by the  sacro
sciatic ligaments, than they appear upon an exami-
nation of the  bare bones.
   In consequence of the oblique position of the sa-
crum, sloping downwards and  backwards,  the posi-
tion of the  pelvis is very oblique.   A  line  drawn
through the centre of this cavity, perpendicular  to
the plane of the upper orifice, or brim, would not co- 
112
Trunk of the Fatus.
 incide with the vertical diameter of the cavity of the
 abdomen, but would pass out of that cavity near the
 umbilicus.
   This cavity, and the bones which form it, are dif-
 ferent in the two sexes.
   In women the brim  of the pelvis is wider, and in-
 clines 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
 women,  is derived  particularly from  the following
 circumstances.
   The os sacrum is broader, and sometimes straight-
 er 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 Fcetus.
  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 al-
 most 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 verte-
 bral cavity.  The ends of the longest portions 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 ver-
tebra dentata consists of four  pieces; for in addition
to the three pieces, common to the other vertebrae,
the processus dentatus  is  a distinct portion. 
               Tlie Shoulder.—Clavicle.          113

   The false vertebral, of which the sacrum consists,
 are each formed of three bones as the true vertebrae.
   The bones of the os coccygis are cartilaginous, ex-
 cept the first, which is partly ossified.
   The ribs 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,  sur-
 rounded 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 composed.
   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
 portion which forms the acetabulum, the tuber,  and
 the cms is cartilaginous.
   The upper  part of the os pubis, and that portion
 which forms the s^hysis, are ossified.  The crus-
 like that of the ischium, is cartilaginous.

                    SECTION in.

             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 sca-
pula. It has been supposed by some persons that the
 two last mentioned bones belong properly to the tho-
 rax ; but upon examining the  motions of the Hipper
 extremity it will appear, that they form an essential
 part of it: and it is equally evident that they do not
   Vol. i.               15 
114                The Clavicle.

contribute to the  perfection of the thorax;  they are
therefore considered as a  part of the upper extre-
mity.
  The clavicle is the long crooked bone resembling
the italic/, which is placed almost horizontally be-
tween 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 con-
siderably 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 subject,
the irregular concavities of both are supplied  by a
moveable 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 grows  to the  two bones at both
its internal and external end: itsrobstance at the ex-
ternal end  being  soft, but  very strong, and resem-
bling the intervertebral cartilages.
  From its internal end, the clavicle, for  about two-
filths of  its  length, is  bended obliquely forwards.
On the upper and  front part of this curvature a small
ridge is seen, with  a plane rough surface before it;
whence the sterno-hyoideus  and  sterno-mastoideus
muscles  have in part their origin.  Near the lower
angle, a small plane surface is often to  be remarked,
where the first rib and this bone are contiguous, and
are connected by  a firm ligament.  From this a rough
plane'surface is extended outwards, where the pecto-
ral muscle has part of its origin.  Behind, the bone
is made flat and rough by the insertion of the larger 
The Clavicle.               115
 share of the subclavian muscle. The clavicle is then
 curved backwards, and at first is round;  but it soon
 after becomes  broad and  thin; which shape  it re-
 tains to its external end. Along the external concavi-
 ty a rough sinuosity runs; from which some part of
 the deltoid muscle takes its rise: opposite 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 museums subclavius;
 and towards its back part, a tubercle rises; to which
 and to  a  roughness near it, the strong short  thick
 ligament,  connecting this bone to the coracoid pro-
 cess of  the scapula, is fixed.
   The external end of this bone is oblong horizon-
 tally, smooth, sloping  at the posterior side, and  tip-
 ped in a recent subject with a cartilage, for its arti-
 culation with the acromion scapulae.  Round this  the
 bone is  spongy, for the firmer connexion of the liga-
 ments.
   The surfaces of contact of this bone, and the sca-
 pula, are remarkably small, and flat also.
   The medullary af teries, having their direction  ob-
 liquely outwards, enter the clavicles by one or  more
 small passages 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 fur-
 cula of the sternum, from the posterior prominent  an-
 gle 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 moveable intervening cartilage, the clavicle can
move at this articulation  so  that  the external ex- 
116               The Scapula.
tremity may be elevated  or depressed, and moved
backwards and 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 clavi-
cles, 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 shoulder-blade, 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 anticus 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 se-
cond rib.  The lower side, which is  named the in-
ferior costa, is extended 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. 
The Scapula.
117
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
unequally.  The second process stands out from the
forepart 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
inserted.  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 serratus 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 flattened be-
hind by the origin of the teres major. As the inferior
costa advances forward, 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 appears, where the
longus extensor cubiti has its origin.
  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  scapula blood vessels
and nerves.  Immediately behind this semilunar  ca-
vity, 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 of errrix. 
118
The Scapula.
   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 superior than to the inferior costa. The
 cavity above the spine is  really concave, where the
 supra-spinatus muscle is lodged; while the surface of
 this bone below the spine,  on which the infra-spinatus
 muscle is placed, is convex, except  a fossa that runs
 at the side of the inferior costa.
   The internal or anterior surface of this bone is hol-
 low, except in  the part above the spine, which is
 convex.   The subscapularis muscle is extended over
 this surface, where it forms several  ridges and inter-
 mediate depressions, commonly mistaken  for prints
 of the ribs: they point out the interstices of the bun-
 dles of fibres of which the subscapularis  muscle is
 composed.
   The spine rises small at the base of the scapula,
 and becomes higher and broader as it advances for-
 wards.  On the sides it is unequally hollowed and
 crooked, by the action 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 deltoid fixed to it. The end
 of the spine, called acromion, or top of the shoulder,
 is broad and flat, and is sometimes only joined to the
 spine by a cartilage. The  anterior edge of the acro-
 mion is flat, smooth, and covered with a cartilage,
 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 in-
 clining 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 
Tlie Scapula.
119
three plane surfaces.  Into the  internal, the pecto-
ralis  minor'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, immediate-
ly before the semilunar cavity, a smooth tubercle ap-
pears, where a ligament from the cavicle  is fixed.
From the whole of the external side of this coracoid
apophysis a broad ligament goes out, which becomes
narrower where it is fixed  to the acromion.
  From the cervix scapulae the third process is pro-
duced.  The forepart of this is formed into a glenoid
cavity, which is of the shape of the longitudinal sec-
tion of an cg^, being broad below and narrow above.
Between the margin of this cavity and the  forepart
of the root  of the spine, a'large sinuosity is left  for
the transmission of the supra and  infra spinati  mus-
cles; 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 around, for the  firmer adhe-
sion of the  capsular ligament of the articulation, and
of the cartilage; which is thick  on the margin, but
becomes very thin as it is continued towards the mid-
dle 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 plane sur-
faces, tipped with cartilage; by which neither  bone
is allowed  any considerable motion,  being tightly
tied down by the common capsular ligament, and by 
120
The Scapula.
 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 pos-
 terior 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 clavicle
 and scapula are not  in the  same plane, but stand a
 little transversely, or across each other, and thereby
 preserve this joint from luxations, to which it would
 be subject if either of the bones was to move on the
 other perpendicularly up and down, without any ro-
 tation.  Sometimes a moveable ligamentous carti-
 lage is found in this joint; and sometimes such a car-
 tilage is only interposed at the anterior half of it; and
 in some old subjects  a sesamoid bone has been found
 here.
   The scapula is connected to the head, os hyoides,
 vertebrae,  ribs, and arm bone, by muscles,  that have
 one end fastened to these parts, and the other to the
 scapula, which can move it upwards, downwards,
 backwards, or forwards; by the quick succession of
 these motions, its whole body is caried in a  circle.
 But being also often  moved as upon an axis perpen-
 dicular to its plane, its circumference turns in a circle
 whose centre this axis is.   Whichever of these mo-
 tions  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 oc-
 casions, to allow always to  the  head of the os hu-
 meri a socket to move in properly  situated;  and
 thereby, to assist and to enlarge greatly the motions 
The Arm.
121
of the superior extremity, and to afford the muscles
which rise from  it more advantageous 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 capsular ligament of
the joint is fixed.   Below the forepart of its base,
two tubercles stand out:  the  smallest  one, which  is
situated most to the inside, has the tendon of the sub-
scapularis muscle  inserted into it.  The larger more
external protuberance is  divided, at its  upper part,
into three smooth plane surfaces: into the anterior of
which, the musculus supra-spinatus; into the middle
or largest, the infra-spinatus; and into the one be-
hind, the  teres minor, is  inserted.   Between these
two tubercles, exactly in the forepart of  the bone,
a deep long groove is formed, for lodging the tendin-
ous 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 tendin-
ous sheath extended across  the groove;  in which,
and in the neighbouring  tubercles,  are  several re-
markable  holes, which are penetrated  by the tendin-
ous and ligamentous fibres, and by vessels. On each
  Voi,. i.                16 
122
The Os Humeri.
side of this groove, as it descends in the os humeri, a
rough ridge, gently flattened in the middle, runs from
the roots of the tubercles.  The tendon of the pecto-
ral muscle is fixed into the anterior of these ridges,
and the latissimus dorsi and teres major  are insert-
ed into the internal one.   A little behind the lower
end of this last, another rough ridge may be observ-
ed, where the  coraco-brachialis  is inserted.  From
the back part of the root of the largest tubercle, a
ridge also is continued;  from which the  extensor
brevis cubiti arises.  This bone is flattened on the in-
side, about its  middle, by the belly of the biceps flex-
or cubiti.   In  the middle  of this plane surface, the
entry of the medullary artery is seen slanting oblique-
ly downwards.  At  the foreside of this plane the
bone rises in a sort of ridge, which is rough, and of-
ten 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 bra-
chiaeus internus rises. The exterior of these two flat
surfaces is the largest: behind it a superficial spiral
channel, formed  by the muscular nerve and the ves-
sels that accompany it,  runs from behind  forwards
and downwards.
   The body of the os humeri is flattened behind by
the extensors of the  fore arm.
   Near the lower end of this bone, a large sharp
ridge is extended on its outside; from which the mus-
culus supinator radii  longus, and the longest head of
the extensor carpi radialis, arise.  Opposite to this,
there is another  small ridge to which the aponeuro-
tic tendon, that gives origin to  the  fibres of the in-
ternal and external brachial muscles, is  fixed; and
from a little depression on the foreside of it, the pro-
nator radii teres arises.
   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 cavitvbe- 
The Os Humeri.              123
fore, 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  re-
ceives the coronoid process of the ulna, in the flex-
ions of the fore arm; while the posterior deep trian-
gular 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 transparent in many subjects.   The sides of
the posterior cavity are stretched out  into two pro-
cesses, 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 external condyle, which
has an oblique direction forwards with  respect to  the
internal, when the arm is in the most natural posture,
is equally broad, and has an obtuse smooth head ri-
sing from it forwards.   From the rough part of  the
condyle,  several muscles arise;  and on the  smooth
head the upper end of the radius plays.  The inter-
nal 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 la-
teral 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 forepart of the cavity of this
pulley.  The  external protuberance,  which  is  less
than  the other, has a sharp  edge  behind; but for-
wards, 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 out-
wards, were it not supported by the radius  on that
side.  Between this internal  protuberance and con- 
124
The Os Humeri.
condyle, a sinuosity maybe remarked, where the ulnar
nerve passes.
  The substance and the internal  structure of the os
humeri 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 articulated 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 arti-
culation 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 in the lower part  of the articulation; but,
in the ordinary postures of  the arm, that is, so long
as it is an acute angle with the  trunk of the body,
there cannot be any force applied at this place to oc-
casion a luxation, since the  joint  is protected so well
above.
  The motions which the arm enjoys by this articu-
lation, are to every side; and by the succession of
these different motions,  a circle may be described.
Besides which, the bone performs a  small  rotation
round its  own axis; but when the axis of the bone
is the centre of motion, the  movements are  very dif-
ferent from those which  take place when the axis of
its head is the centre; 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
forwards,  the axis of the head is the centre of mo-
tion; but when the elbow is bent, and the fore arm
forms a right angle with the os humeri, the motion 
The Fore Arm.—Ulna.
125
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
extensive, yet the larger share of them depends on
the motions of the scapula; for the surface of the
glenoid  cavity is directed dpwards or downwards,
and  to a certain  degree backwards or forwards to
support  the head of the os  humeri.  This  is exem-
plified 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; but  serves as a  base, on which
they perform the motions peculiar to themselves; as
will shortly be described.

                  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 the supposed resemblance to the spoke
of a wheel.
  These bones are concerned in very different ope-
rations.   The ulna forms the elbow joint  with the
os humeri: the radius is the moveable 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 gra-
dually diminishes 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 sur-
face, is a semicircular notch.  The end of  the bone
which forms the  posterior part of this notch is deno-
minated olecranon. The anterior part of the notch is
formed by a process called coronoid. This notch ap-
plies to the pulley-like surface on the internal side 
126
Ulna.
 of the lower extremity of the os humeri, to form the
 articulation of the elbow.  In the  middle of the con-
 cave surface 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 outside of
 the coronoid process is a semilunated smooth cavity,
 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 mucilagi-
 nous glands. Below the root of the coronoid process,
 this  bone is scabrous and unequal,  where the  bra-
 chiaeus internus is inserted.  On 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 an-
 gle 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 forepart, the passage of the medullary
 vessels may be seen slanting upwards. The internal
 side  of this bone  is smooth, somewhat convex, and
 the angles at each edge of it are blunted by the  pres-
 sure  of the muscles equally disposed about them.
  As this bone descends, it becomes gradually small-
 er ; 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 pro- 
Radius.
127
cess rises from its inside, to which is fixed a  strong
ligament that is extended to the os  cuneiforme and
pisiforme of the wrist.   At the root of the process,
the end of the bone is smooth, and  covered with  a
cartilage.  Between it and the bones of the wrist, a
doubly concave moveable  cartilage is  interposed;
which is a continuation 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 ca-
vity there; in which mucilaginous glands are lodged.
   The ulna  is principally concerned in the articula-
tion with the os humeri, and forms a hinge-like joint,
which allows extension nearly to a straight line, and
flexion to an acute angle. By the sloping of the pul-
ley-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 to-
wards the head.

                      Radius.
   Before the radius is described, it  is necessary to observe, 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 ex-
tremities are the reverse of those of the ulna in their
proportionate size; and the  body is not  triangular,
although it approaches towards that form. Its upper
end is formed into a cylindrical head, which is hol-
lowed on the top for an articulation with  the tuber-
cle 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 seminulat  d cavity of that  bone. 
128
Radius.
Below the head, the radius is  much smaller;  and
therefore this part is  named its cervix.   At the in-
ternal root of this neck is a flat tubercle, into the in-
ner part of which the biceps flexor cubiti is inserted.
From this a ridge  runs  downwards  and outwards,
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.
  The body of the radius is not straight, but curved
externally, the greater part of its length.  Its exter-
nal surface is rounded; the  anterior  and  posterior
surfaces are flattened; 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 an-
terior surface, at a distance from its head nearly equal
to one-third the length of the bone, is the  orifice  of
the canal for the medullary vessels, which has a di-
rection  obliquely upwards.
  Towards the lower end, the radius becomes broad-
er 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 ex-
ternal 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 forepart of  this end of the 
Radius.                  129
 radius is also depressed, where  the  flexors of the
 fingers and flexor carpi radialis pass,   The  internal
 side is formed into a semilunated 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  insinua-
 ted into the conjunction of the two bones of the wrist
 that are received into the cavity.  The external side
 of this articulation is defended by a remarkable pro-
 cess of the radius, from which a  ligament passes to
 the wrist; and this structure  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 di-
 gitorum 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 articu-
 lation 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 tu-
bercle of the radius plays in a socket of the ulna;
   Vol. i.                17 
130
The Hand.—Carpus.
whilst below, the radius gives the socket, and the ulna
the tubercle.  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 ra-
dius, they must move together.   When  the palm is
turned uppermost, the radius is said to perform supi-
nation: when the back of the hand is above, it is said
to be prone.  But  then  the quickness and large ex-
tent of these two motions are assisted  by the ulna,
which, as was  before observed/can move with a kind
of small  rotation on theysloping 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 ligament  con-
necting 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 concave before, for containing more surely
and conveniently  such bodies as we take hold of.
One half of the hand has an obscure motion in com-
parison of what the other has; it serves as a base to
the moveable  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; meta-car-
pus, or part adjoining the wrist;  and  the fingers,
among which  the thumb is reckoned.

                     Carpus.
    No part of the skeleton is more eomplex than the carpus. The
      following description rill therefore be of little use to a young • 
Curpu*.
131
      student, unless the bones are before him when he is reading it.
      Great advantage will be derived from examining two sets of car-
      pal bones; each set belonging to the same side.  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 o'.her
      set should be accurately cleaned, so that their forms and surfaces
      may be examined.

   The  carpus  is  composed  of eight small bones,
arranged in two rows; one of which rows  is attach-
ed 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, be-
ginning with the row next to the fore arm; and with
the external bone in each row.
   They are, Os Scaphoides, Lunare,  Cuneiforme, Pisi-
forme, Os Trapezium, Trapezoides, Magnum, and Unci-
forme.

                     First Row.

   Os scaphoides" is tiie 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 articulated 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 con-
cavity receives more than half of the round head of
the os magnum.  The internal side of this hollow is
formed  into a semilunar plane to be  articulated with
the following bone.  The external, posterior, and an-
terior edges are rough, for fixing tiie ligaments  that
connect it to the surrounding 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 
132
Carpus.
form of a crescent, and is joined with the scaphoid:
the lower surface is hollow, 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  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 cavity,
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 articulation
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 contiguous to the os unciforme, is oblong,
somewhat spiral, and concave.   Near the middle of
its anterior surface a  circular plane appears,  where
the os pisiforme is sustained.
  Os pisiforme is almost spherical, except one circu-
lar plane, or slightly hollowed surface,  which is co-
vered 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 ligament from the  styloid
process of the ulna, fixed  to its upper part; the trans-
verse ligament of the wrist is connected to its exter-
nal side; liganents extended to the unciforme bone,
and to the os metacarpi of the little finger, are attach-
ed to its lower part;  the abductor minimi digiti has
its origin from its forepart; and,  at the external side 
Carpus.
133
 of it, a small depression is formed, for the passage of
 the ulnar nerve.

                   Second Row.

   Tmpezium 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 semi-
 circular,  for its conjunction with the os scaphoides.
 Its internal side is an oblong concave square, for re-
 ceiving the following  bone.  The inferior surface is
 formed into a pulley; which faces obliquely outwards
 and downwards  when  the  palm presents  forward.
 On this pulley the first bone of the thumb is moved.
   At the internal side of the pulley, a small oblong
 smooth surface is formed by the os metacarpi indicis.
 The forepart 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 ten-
 don of the flexor longus pollicis manus  plays: near
this the bone is scabrous, where the transverse liga-
ment of the wrist is  connected, the abductor and the
 flexor brevis pollicis have their origin, and ligaments
 go out to the first of the thumb.
   Os trapezoides, so  called from the irregular quad-
rangular  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 con-
vex one  externally, where it  is contiguous to the
trapezium; a small internal concavity, for  its con-
junction with the os magnum; and an inferior convex
surface, 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 the carpus, is oblong,  having four quadran- 
134                 Carpus.
 gular sides, with a  round upper end, and a triangu-
 lar plane 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 ca-
 vity for receiving it.  On the outside  a short plane
 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 triangular,  slightly hollowed, and farther
 advanced on the external side than on the internal,
 having  a considerable oblong depression made on
 the advanced outside by  the metacarpal bone of the
 forefinger; 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 hollow for affording passage to the
 tendons of the  flexors of the fingers.  To this  pro-
 cess 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  plane surface is small,
 convex, and joined with the  os lunare :  the external
 side is long, and slightly convex, adapted to the  con-
 tiguous os magnum.  The internal 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 theme-
 tecarpal bone of the little 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 studying the  bones placed together, in their na-
 tural order, in the two rows.
   When thus placed they compose a structure of an
oblong form, whose  greatest  length extends across
the wrist and forms  a  concavity in front, while it is
convex posteriorly. 
Carpus.
135
  Two bones of i.l>e first row, viz. the scaphoides
and  lunare, form an oblong convex  surface, which
has  a  transverse 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 succession ol 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 con-
cavity, which is composed by the  scaphoides, lunare
and cuneiforme,  and receives  a  prominence  of the
second row. It also presents a convex surface, form-
ed by the scaphoides, which is received by  the se-
cond row.
  The upper  surface of the second row, which  is
concerned  in  this articulation, is very irregular;  it
has a head formed  by the magnum and  unciforme,
wuicu  penetrates* deeply into the cavity of she  first
row.  On \ ue outside of this  head the trapezii in and
trapezoides form a surface which  receives the pro-
jecting part of the scaphoides; so that the fiist row
receives, and is received by the second, and the two
surfaces are well calculated  for moving to a  rertain
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 centre; viz.
the trapezoides and the magnum.  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 
J 36              The Metacarpus.
surface for supporting the thumb presents  obliquely
downwards and outwards.
  The trapezoides supports the forefinger, the mag-
num the middle finger.
  The scaphoides and the trapezium are very pro-
minent at the external side of the anterior concave
surface of the corpus;  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 oblong, inclining somewhat to the
wedge-like form, without any considerable head or
cavity, but it is however somewhat hollowed, for the
articulation with the  carpus.  It is   made flat and
smooth on the sides where these bones are contigu-
ous to each other. Their bodies are flattened on their
back part, particularly below the middle, by 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, sepa-
rating 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 forepart of each
side of the root of each  of these heads, one of two
tubercles stand out, for fixing the ligaments that go
from one  metacarpal  bone to another, to preserve
them from being drawn asunder. Around the heads a
rough ring may be remarked, for the capsular liga-
ments of the first joints of the fingers to be fixed to;
and both sides of these heads are flat, by pressing on
each other. 
Metacarpus.
137
   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 forepart of the metacar-
pal 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 supporters for the fingers to
play on.
   Though the ossa metacarpi so far agree, yet they
may be distinguished from each other by the follow-
ing marks.
   The metacarpal bone of the forefinger is generally
the longest.  Its base, which is articulated with the os
trapezoides, 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 trapezium.  The  internal ridge is
also smooth, and flat  on its ulnar side, for its con-
junction with  the os  magnum;  immediately  below
which a semicircular smooth flat surface shows the
articulation  of this  to the second metacarpal bone.
The back part of this base is flattened where the long
head of the extensor  carpi radialis  is inserted, and
its forepart is prominent  where the tendon of the
flexor carpi  radialis 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 general-
ly  the second in length; but often it is as long as the
   Vol. i.               18 
138
Metacarpus.
former: sometimes it is longer; and it frequently ap-
pears 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
plane in the same way as the external side of the for-
mer bone, while its internal side  has two hollow cir-
cular surfaces, for joining the third metacarpal bone;
and between these  surfaces there is a rough fossa,
for the adhesion of a ligament, and lodging mucila-
ginous glands.  The extensor carpi radialis brevior /
is  inserted into the back part  of this base.   The two
sides of this bone are almost equally flattened; but the
ridge  on the forepart of the  body inclines inwards.
The tubercles at the forepart  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 semicir-
cular  and convex, for its conjunction with the os unci-
forme. On its external side are two smooth convexi-
ties, and a middle fossa, adapted to the second meta-
carpal bone. The internal side has a triangular smooth
concave surface to join  it with the fourth one.   The
anterior ridge of its body is situated more to the in-
side than to the outside.  The tubercles  near the
head  are equal.   The motion of this third metacar-
pal 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
 cl.i.pted to the third metacarpal bone.  The internal
  as no smooth  surface, because it is not contiguous 
Thumb.
139
 to any other bone; but it is prominent where the ex-
 tensor carpi ulnaris is inserted.   As this metacarpal
 bone is furnished with a proper moving muscle, has
 the plainest articulation, is most loosely 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 pro-
 minence of the thumb opposite to it.
                Thumb and fingers.

   The thumb and four fingers  are each composed of
 three bones.
   The thumb is situated obliquely in respect to the
 fingers; neither opposite directly to them, nor in the
 same plane with them. All its bones are much thick-
 er and  stronger in proportion to their length, than
 the bones of the fingers  are: which is extremely ne-
 cessary, as the thumb counteracts 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 ap-
 pears convex in  the middle;  but when viewed from
 behind forwards,' it is concave there.  The edge at
 the forepart 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 connexion of the
 ligaments of this joint.  The  body and head of this
 bone are of the same shape as the ossa  metacarpi;
 only that the body is  shorter, the head flatter, and
 tubercles at the forepart of its root larger.
  The articulation of the upper end of this bone is
 remarkable: for, though  it has protuberances and
 depressions adapted to the double pulley of the tra-
 pezium, yet it enjoys a circular motion, as the joints
 do where a round head of the one plays in the orbi-
cular socket of another:  it is however more confined, 
140
Fingers.
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 tu-
bercles may be remarked, for the insertion of liga-
ments. 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 direc-
tions ; yet, on account of the strength  of its lateral
ligaments, the oblong 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 greatest extent is from one side
to the other.   This base is formed into two cavities
and a middle protuberance, to  be adapted to the
pulley of the former bone.  This bone becomes gra-
dually smaller, till near the lower 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 longus
pollicis.
   The motion of this third bone is confined to flexion
and extension.
   The  regular arrangement of the bones of the fin-
gers 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 
Fingers.
141
by the tendons of the extensors, lumbricales, and in-
terossei,  and placed directly backwards, for  their
greater strength; and their flat concave part is for-
wards, 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 an-
gles that are between the convex and concave sides.
   The bones of the  first phalanx of the fingers an-
swer to  the description of the  second bone of the
thumb;  only that the cavity in their base is not so
oblong; nor is their motion on the metacarpal bones
so much confined; for they  can move laterally or
circularly, the forefinger  in particular,  but have no
rotation, or a very small degree of it,  round their
axis.
   The second bone of the fingers has  its base  form-
ed into two lateral cavities, and a middle protuber-
ance : while the lower end has two lateral protuber-
ances and a middle cavity; therefore it is joined  at
both ends in the same  manner; which none of the
bones of the thumb  are.
   The third bone  differs nothing from the descrip-
tion of the third bone of the  thumb, except  in the
general distinguishing marks; and therefore the se-
cond and  third phalanx of the  fingers enjoy only
flexion  and extension.
   All the  difference of the phalanges of the several
fingers consists in their magnitude. The bones of the
middle finger 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  contrivance  for hold-
 ing the largest bodies; because  the longest fingers
 are applied to the middle  largest periphery of such
 substances as are of a spherical figure. 
142
The Inferior Extremities.
                   section IV.

              The Inferior Extremities.

  The inferior extremities consist of the Thigh, Leg,
and Foot.
                   The Thigh.
  Consists of one bone only; the  os femoris, which
is very strong, and larger than any other in the ske-
leton.  It is  nearly cylindrical in  the middle, and
slightly 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 in-
clines 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 inter-
nal part a round rough spongy pit is observable, where
the strong ligament, commonly, but inaccurately call-
ed 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  femo-
ris has a great  many  large holes,  into which  the
fibres of the strong ligament, continued from the cap-
sular, enter, and are thereby firmly united 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. Be-
low this  root, a large unequal  protuberance, called
trochanter major,  stands  out; the  external  convex
part of which is distinguished into three different sur- 
The Inferior Extremities.
143
faces; whereof the one on the upper and front part
is scabrous and rough, for the  insertion of the glu-
taeus minimus; the superior one is smooth, and  has
the glutaeus medius inserted into it; and the one be-
hind is made flat and smooth, by the tendon of the
glutaeus maximus passing.over it.   The upper edge
of this process is sharp and pointed at its back part,
where the glutaeus  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 posterior 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  implanted.  More
internally, a conical process, called trochanter minor,
rises, for the insertion of the musculus psoas and ilia-
cus internus; and the pectineus is  implanted into a
rough hollow below its internal  root.  The  muscles
inserted into these  processes being the principal  in-
iBtruments 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 leaning to  much on the posterior muscles.
  On the posterior concave surface is a broad rough
ridge called linca aspera, which commences near the
great trochanter,  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 smooth,
protuberance may often  be remarked, where the two
heads of the external gastrocnemius  muscle take
their rise; and from the forepart  of the  internal 
144
Os Femoris.
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  protu-
berances, one on  each side, which  are called its
condyles:  between  them  a  considerable cavity  is
found, especially at the back part, in which  the  cru-
ral 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 ob-
liquity to the leg.  These processes are of an oblong
form, and are placed obliquely with respect to each
other; being in contact before and separated to a
considerable distance behind.
  They form in front a smooth pulley-like surface, the
external side of which is highest, on which the patel-
la moves.
  Below, they are  flat; and posteriorly, they are re-
gularly convex.
  Between these  convex portions is a rough cavity,
from which the crucial ligament arises, to be attach*
ed 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 blood ves-
sels pass to the internal substance of the bone.
  The thigh bone  being articulated above  with the
acetabulum of the os innominatum, which affords its
round head a secure and extensive play, can be mov-
ed to every side: but it is restrained  in its motion
outwards, by the  high brims of the cavity, and by
the round ligament;  for otherwise the head of the
bone would have been frequently 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, 
              Os Femoris.—-The Leg.          1^5

from the bone, is such, that the rotary motion  of
the head can only bring the body of the bone for-
wards and backwards.   Nor is the head, as in the
arm, ever capable of being brought to a straight di-
rection 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.  Suf-
ficient space is thereby 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 centre 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 thigh bones,  weak rickety children  become
knock-kneed.

                  " • The Leg

   Is composed of the 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.
   Vol. i.                19 
i
116
                    The Tibia

  Is the long thick triangular bone, situated at the
internal part of the leg, and continued in almost a
straight line from the thigh bone.  The name is de-
rived from its resemblance to the ancient musical in-
strument.
  The upper end of the tibia is large, bulbous,  and
spongy.  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 liga-
ments that compose the great crucial is inserted into
the middle cavity; and the depression  behind re-
ceives the posterior ligament.  The two broad cavi-
ties at the sides of this protuberance are  not equal:
for the internal is oblong and deep, to receive the in-
ternal condyle of the thigh bone; while the external
is more superficial and round,  for the external con-
dyle.  In each of these two cavities of a recent  sub-
ject, 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 carti-
lages 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 cir-
cular hole is left  between each cartilage and the
ligament, in which the most prominent convex  part
of each condyle of the thigh bone moves.   The cir-
cumference of these cavities is rough and unequal,
for the firm connexion of the ligaments of the joint.
Immediately below the edge, at its back  part, two 
Tibia.
147
 rough flattened protuberances stand out; into the in-
 ternal, the tendon of the semimembranosus muscle
 is inserted; and a part of the cross ligament is fixed
 to the external.  On the outside of this last tubercle,
 a smooth slightly-hollowed surface is formed by the
 action of the poplitaeus muscle.
   Before the forepart of the upper end of the tibia,
 a large rough protuberance rises, to wnich 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 aponeurosis of the vastus
 internus, and the tendons of the semitendinosus, gra-
 cilis, 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
 commonly called the spine or shin.  This ridge is not
 straight; but turns first inwards, then outwards, and
 lastly inwards again.  The plane internal  side is
 smooth and equal, being little subjected to the actions
 of muscle; 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
 action of the muscles; the posterior side comprehend-
 ed  between them is not so broad as those  already
 mentioned, but  is more oblique and flattened 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  bone is made
round by the pressure of the musculus solaeus. 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 
118
Fibula.
of this cavity, which is smooth, and in a recent sub-
ject is covered with cartilage, is extended into a con-
siderable  process, commonly named malleolus inter-
nus ; the point of which is divided  by a notch, and
from it ligaments are sent out to the foot.  The exter-
nal 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 de-
pression, the tendons of the musculis tibialis posticus
and flexor digitorum longus are lodged; and in the
external, 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 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 form-
ed on its inside, which, in a recent subject, is covered
with a cartilage; and  it is so closely connected to
the tibia by  ligaments,  as to allow only a very small
motion backwards and forwards.  This head is pro-
tuberant and rough on its outside,  where a  strong
round ligament and the musculus biceps are inserted:
and, below the back part of  its internal side, a tu-
bercle 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 backwards:  which figure  is owing to the actions
of the muscles.   The sharpest angle of the fibula is
forwards;  on each side of which  the bone is consi-
derably, but unequally, depressed by the bellies of
the several  muscles  that rise from or  act  upon it.
The external surface of the fibula is depressed ob-
liquely from above downwards and backwards, by 
Fibula.
149
the two peronaei.  Its  internal  surface is unequally
divided 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  \erf 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 vesalii. The pos-
terior 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 solaeus, and is  hollowed below by
the flexor  pollicis longus.   In the middle of this sur-
face, 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 con-
vex, irregular, 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 intermedi-
ate cartilage and strong ligaments, 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 out-
side of the first  bone of the foot, the  astragalus, to
secure the articulation.  This process, named malle-
olus externus, being  situated farther back than the
internal malleolus, and in an  oblique  direction,
obliges us naturally to turn the forepart of the foot
outwards.  At the lower internal part of this process,
a spongy cavity for mucilaginous glands may be re-
marked ; from its point ligaments are extended to the
bones of the foot, viz. the astragalus, os calcis, and os 
150
The Patella or Rotula.
 naviculare; and from its inside short strong ones go
 out to the astragalus.   On the back part of it a si-
 nuosity is made by the tendons of the  peronaei mus-
 cles.   When the ligament extended over these ten-
 dons  from the one side  of the depression to the other
 is broken, stretdied too much, or made weak by a
 sprain, the tendons frequently start forwards to the
 outside of the fibula.
   The conjunction  of  the upper end of the fibula
 with the tibia is by plane surfaces tipped with carti-
 lage ; and at its lower end the cartilage seems to glue
 the two  bones  together;  not, however,  so firmly in
 young people, but that the motion at the other end is
 very observable.  In old subjects, 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 insertion 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 an-
 kle.  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 tibia-
 lis  anticus immediately adheres to the solaeus  and
 tibialis posticus; but every where else it gives origin
 to muscular fibres.

               The Patella or Rotula

   Is the  small flat bone situated at the forepart 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. 
Patella.
151
Its posterior surface is smooth, covered with carti-
lage, 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 femoris,
on which they are placed in the most ordinary un-
straining postures  of the legs: but when  the leg is
much bent, the patella descends far down on the con-
dyles ;  and when the leg is  fully extended, the pa-
tella rises higher in its upper part thah the pulley  of
the thigh bone.  The plane smooth  surface is sur-
rounded by a rough  prominent edge, to which the
capsular ligament  adheres.  Below, the point of the
bone is scabrous, where the strong tendinous  liga-
ment from the tubercle of the tibia is fixed. The up-
per horizontal part of this bone is flattened and un-
equal, where the tendons of the extensors of the leg
are inserted.
  The substance of the patella is cellular, with very
thin firm external plates; but when 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 notwithstanding this strength, it is
sometimes broken by the  violent  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 backwards. In performing this,
the patella is pulled  down  by  the  tibia.   When the
leg is to be extended, the patella is drawn upwards,
consequently the tibia forwards, by the extensor mus-
cles;  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 consider-
able angle, and act, on that account, with advantage;
but they are restrained  from  pulling  the leg farther 
152
Patella.
than to a straight line with the thigh, by the poste-
rior 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 moveable 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  posterior li-
gament is relaxed; therefore this bone may be moved
a little to either side, or with a small rotation in the
superficial cavities of the tibia; which is done by the
motion of the external cavity backwards and for-
wards, the internal serving as  a sort of axis. Seeing
then, one part of the cross ligament is situated per-
pendicularly, and the posterior part is stretched  ob-
liquely from the internal condyle of the  thigh  out-
wards, that posterior  part of the cross ligament
prevents the leg from being turned much inwards;
but it could not hinder it from turning outwards al-
most round, was not that motion confined by the la-
teral ligaments of this joint, which can yield little.
  This rotation of the leg outwards is of great advan-
tage to us in crossing our legs, and turning  our feet
outwards, on several necessary 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 horizontal, by raising their external side where
the surface of the tibia slants downwards. By these
means the motions  of this joint are more equal and
steady than otherwise they would  have  been.   The
cartilages being capable of changing a little their si-
tuation, contribute to the different motions and pos-
tures  of the  limb,  and likewise  make the  motions
larger  and quicker. 
•
                 The Foot.—Tarsus.             153

                     The Foot.
   The foot is divided into  the tarsus, metatarsus, and
 toes.
   The sole  of the  foot is necessarily described as
 the inferior 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, cunei-
forme externum,  cuneiforme medium, and  cuneiforme in-
 turnum.
   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  in-
 ternal side of the tarsus.  The os cuboides is the most
 external of the row of four bones,  at its  forepart.
 The os cuneiforme externum  is placed  at the inside of
 the cuboid.  The cuneiforme medium  is between the
 external and internal cuneiforme 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 malleolus.   The external  side
 has also such a surface, but larger, for its articula-
tion with the external malleolus.  Round the base of
this head there is a rough fossa; and immediately be-
fore the head, as also below its internal smooth sur-
face, we find a  considerable rough  cavity.
   The lower surface of the  astragalus is divided by
an irregular deep rough  fossa,  which at its internal
end is  narrow,  but gradually widens  as it stretches
obliquely outwards and forwards.  The smooth sur-
face,  covered with cartilage, behind this fossa,  is
   Vol. i.                20 
•
154                  Tarsus,

large, oblong, extended in the same oblique situa-
tion 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 processes, be-
tween 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 planes.   The long one behind, and  the ex-
terior or shortest, are articulated with the heel bone;
while the internal, which is the most convex of tho
three, rests and moves upon a cartilaginous ligament,
that is continued from the os calcis to the os navicu-.
lare, 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
rhe body in leaping, running, &c.
  The forepart of this bone is formed into a  convex
oblong smooth head, which is received by the os na->
viculare, and is placed obliquely; its longest axis in-
clining downwards  and inwards.   Round the root
of this head, especially on the upper surface, a rough
fossa may be remarked.
  The astragalus is articulated above to the tibia
and fibula, which together form one cavity.   In this
articulation, flexion  and extension are the most con-
siderable motions; the other motions being restrain-
ed 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 rota-
tory motion is allowed in this joint; for then the head
of this astragalus is sunk deep between the malleoli, 
Tarsus.
155
 and the ligaments are tense: but when the  foot is
 extended, 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 in-
 tend next to step upon.
  The astragalus is joined below to  the  os  calcis;
 and before 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 insertion 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 ir-
 regular oblong smooth convexity, adapted to the con-
 cavity 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
 forepart 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.
  The external side of this bone is flat, with a super-
 ficial fossa running horizontally, in which the tendon
 Of the musculus  peronaeus longus is  lodged.  The
 internal side of the heel bone is hollowed,  for lodg-
 ing the origin of the massa carnea, and for the safe
passage of tendons, nerves, and arteries.  Under tho
 side of the  internal  smooth concavity,  a particular
 groove is made by the tendon of  the  flexor pollicis
 longus; and from the thin protuberance of this inter-
nal side a cartilaginous ligament that supports  the
astragalus, goes out to the os naviculare;  on whic'- 
156
Os Naviculare.
ligament, and on the edge of this bone to which it is
fixed, the groove is formed for the tendon of the flex-
or digitorum profundus.
  The lower surface of this bone is flat at the back
part, and immediately  before  this plane, there  are
two tubercles, from the internal of which the muscu-
lus  abductor  pollicis flexor digitorum  sublimis, as
also part of the aponeurosis plantaris, and of the ab-
ductor minimi digiti, have their origin; and the other
part of the abductor minimi  digiti and  aponeurosis
plantaris rises from the external.  Before these pro-
tuberances, this bone  is concave,  for  lodging the
flexor muscles; and at its forepart, we may observe
a rough depression, from which, and a tubercle  be-
hind it, the ligament goes out that prevents this bone
from being separated from the os cuboides.
  The forepart 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 cubordes.
  Though  the surfaces by which the astragalus and
os calcis are articulated, seem fit enough for motion;
yet the very strong ligaments,  by which these bones
are connected, prevent much motion, and give firm-
ness to this principal part of our base, which rests on
the ground.
  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 ex-
tremity is  very prominent.   The abductor pollicis
takes in part its origin from it, the tendon of the tibi-
alis posticus is inserted into it, and to it two remark-
able ligaments  are fixed; the first is the strong one,
formerly  mentioned, which supports the astragalus;
the second is stretched  from this bone obliquely 
           Os Cuboides.—Os Cuneiforme.        157

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 naviculare there is a semicircular
smooth  surface, where it is joined to the os cuboides.
The forepart of this bone is covered with cartilage,
and divided into three smooth  planes, 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 mo-
tions  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
forepart of the os calcis.  On its internal side, there
is a small semicircular smooth cavity, to join the os
naviculare.   Immediately  before which, an oblong
smooth  plane is made by the os cuneiforme externum;
below this  the bone is hollow  and rough.  On the
internal side of the lower surface,  a round protube-
rance and fossa are found, where the musculus ad-
ductor pollicis has its origin. On the external side
of this  surface, there is a  broad ridge running for-
wards and inwards, covered with cartilage; imme-
diately before which a smooth fossa may be observed,
in which the tendon of the peronaeus primus runs up-
liquely across the foot.   Before, the surface of the os
cuboides is flat, smooth, and slightly divided into two
planes,  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 concur 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. 
158
Os Cuneiforme.
  The upper surface 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 navi-
v. xulare.  The external side is an oblong square divi-
  ded as it were by a diagonal; the upper half of it is
  smooth, for its conjunction with the os cuboides: the
  other is a  scabrous hollow, with a small smooth im-
  pression made by the os metatarsi of the toe next to
  the little one.  The internal  side of this bone is flat-
  tened 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 cuneiform medium is contigu-
  ous to it.  The  forepart of this bone is triangular,     •
  for sustaining the os metatarsi of the middle toe.
    Os cuneiforme, or 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 exter-
  nal side is  smooth and a little hollowed, where it is
  contiguous to the last described bone.  Behind, this
  bone is triangular, where it is articulated with the os
  naviculare; and  it is also triangular at its forepart,
  where it is contiguous to the os  metatarsi of the toe
  next to the great one.
    The  broad thick part of  the os cuneiforme maxi-
  mum, or internum, is  placed below, and the  small
  thinner edge is above.  The surface of this os cunei-
  forme 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 posterior, that
  runs obliquely forwards and  outwards,  the os cunei-
  forme  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 
Metatarsus.
159
scabrous, with two remarkable tubercles below, from
which the musculus abductor pollicis rises, and the
tibialis anticus is inserted into its upper part.
  The three cuneiforme bones are all so secured by
ligaments, that very little motion is allowed in any
of them.
  These seven bones of the tarsus, when joined, are
convex above, and leave a concavity below, for lodg-
ing 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 notwithstanding the many sur-
faces covered with cartilage,  some of which are of
the form of tho very moveable articulations, no more
motion is here allowed, than is necessary to prevent
too great a shock of the fabric of the body in walk-
ing, 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.
                    Metatarsus.
  The Metatarsus is  composed of five bones, which
agree, in their general characters, with the metacar-
pal 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 proportion 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. 
160
Metatarsus.
   The first or internal metatarsal bone is easily dis-
 tinguished from the rest by its thickness.  The one
 next to it is the longest, and with its sharp edge al-
 most perpendicular.   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 sus-
 tain.  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 pero-
 naeus 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 forepart a middle ridge, and two oblong cavities,
 for the  ossa sesamoidea;  and on the externaf side a
 depression 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 cunei-
 forme  medium,  and the external side produced into
 a process; the end of which  is an oblique smooth
 plane, joined to the os cuneiforme externum.   Near
 the internal edge of the base, this bone has two small
 depressions, made  by the os cuneiforme  maximum,
 between which is a rough  cavity.  Farther forwards
 we may observe a smooth protuberance, which  is
joined to a foregoing bone.  On the  outside  of the
 base are two oblong smooth surfaces for its articula-
 tion with the following bone; the superior smooth sur-
 face  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 ex-
 ternum, is  triangular, but slanting outwards, where 
The Toes.                 161
it ends in a sharp-pointed little process, and the an-
gle below is not completed.
  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 dif-
ferent figure; for the upper one is concave, and be-
ing round behind, turns  smaller  as it advances for-
wards ; and the lower surface is a little smooth, con-
vex, and very near the edge  of the base.
  Os metatarsi of the fourth  toe  is nearly as long as
the former, with a triangular slanting base joined to
the os cuboides, and made round at  its external an-
gle ; having one hollow  smooth surface on the out-
side, 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 tot is the shortest, situat-
ed with its two flat sides above and below, and with
the ridges laterally.  The base of it, part of which
rests on the os cuboides, 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  secundus is in-
serted.  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
  Vol. i.               21 
162
Structure of the Foot.
much stronger, because they are subjected to a great*
er force;  for they sustain the force  with  which our
bodies are pushed forwards by the foot behind at
every stop 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,
compared with those of the fingers, differ from them
in these particulars.  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 se-
cond 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 according to the order of  their posi-
tion ;  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 extremi-
ties of the metatarsal bones and the toes, are  the
abutments.  The heel, or posterior abutment, is  not
so broad as the anterior, and is placed  on the outside
and not in the middle of the extremity 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  paviculare completes it. The arch
thus constructed,  does not appear very firm, and this
apparent want of strength  seems increased by  the
position of the anterior portion of the astragalus, a
part of which is between the os calcis and  os navi-
culare, and not supported by either.  These bones
however are firmly connected by ligaments, and one
winch passes from the os calcis to the os  naviculare,
under the forepart of the astragulus, gives  effectual
support to that bone. 
The Sesamoid Bones.
163
    The outside of the foot, formed  by the os calcis,
 os cuboides, 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 considera-
 ble arch, the foot is to be considered as  possessing a
 double convexity* viz. transversely, as well as longi-
 tudinally.
    The great toe, from  its internal  situation, is the
 principal anterior abuthientof the arch on the inter-
 nal side of the foot; hence its great importance.
    The astragalus, which is the basis of the tibia, and
 of course 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 ac-
 cordingly it has been completely forced  from its po-
 sition, by accidents in Which the leg  has been twisted
 or turned inward, and the foot prevented from turn-
 ing 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 ankle.
   One great object of this peculiar structure is,  that
 the foot may yield  in cases of violent  and  sudden
 pressure,  as. when jre jump  or fall upon the feet.
 The safety of* the  foot, and the facility of its ordina-
 ry movement, are  not the only objects of its peculiar
 structure, but concussion of the whole body, and par-
 ticularly of tho brain, is thereby avoided to a certain
 degree*
   This may be inferred from the fact that many per-
 sons suffer violent concussions, hi consequence of fall-
 ing 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 r\iost
commonly found at tiie second joint of the thumb, and 
164
Extremities of the Faitus.
of the great toe; and are 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 covered with cartilage.
  They are also sometimes found between the heads
of the gastrocnemius 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 Faitus.

  In the upper extremity the clavicle is almost per-
fect at birth; but the acromion and coronoid process-
es of the scapula, as well as the head, are in a carti-
laginous 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.
  There are no bones of the carpus; but in their si-
tuation  is an equal number of cartilages, which re-
semble them exactly.  These cartilages «are separa-
ted 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 af-
terwards become epiphyses.
  The bones of the phalanges are likewise cartila-
ginous at  each  extremity.   The extremities next to
the hand  are epiphyses; but it ,is probable that the
other extremities ossify gradually from their centres.*
  In the  lower extremity,  the  head and neck and
• See Nesbit's Osteogeny, page 126. 
Extremities of the Faitus.
165
two trochanters 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 centre.
  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
cartilaginous, and become epiphyses.
  The astragalus  and os calcis are somewhat ossi-
fied within, and have a large portion of cartilage ex-
teriorly.
  In place of the other bones of the tarsus, there are
cartilages of their precise  shape, which are as dis-
tinct from each other as the future bones are.
  The state  of the metatarsal bones, and the pha-
langes of the toes, resembles that of the  bones of the
hand.*

  * Volehn Koyter, a disciple of Fallopius, has given to the profession one
of the best accounts of Osteogeny, according to Lassus.—Ed. 
SYSTEM  OF ANATOMY.

               PART II.


            MYOLOGY*
                  CHAPTER L

           ♦  of muscles in General.*

  That soft, fibrous, red coloured substance, which
constitutes so large a proportion of the volume of the
more perfect animals, is called Flesh or Muscle.
  By the contraction of this substance, the sponta-
neous motions of animals are produced; and on this
account the fibres which compose it have long beert
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 muscie$i
but they also exist in some of the most  important
viscera, and produce the internal, as well as the ex-
ternal, motions of animals.
  Muscular fibres  are  connected to each other by
cellular membrane. This membrane surrounds  each
muscle; and its various lamina, gradually diminish-
ing in thickness, pass between the different bundles
of fibres, and the different fibres of which each  mus-
cle is composed.
  * Muscles were first named according to their figure arid situation in
1587 by Jacques Dubois, surnamed Sylvius, a member of the Faculty of
Medicine in Paris.—Ei>. 
Structure of Muscular Fibres.
167
  The fibres of muscles, when examined with mag-
nifying glasses, appear to be composed of fibrillae still
smaller; and it has been supposed that this division
of them extended beyond our powers of vision, even
when assisted by microscopes :  but so many errors
have occurred in microscopical observations of very
minute objects,  and so  much difference exists be-
tween  the reports of different observers, that tho
subject at this time does not interest many persons;
and very little attention is paid,  by the anatomists
and physiologists of the present day, to the opinions
of those observers  who supposed  they had ascer-
tained the structure of the ultimato fibrillae.
  These  fibrillae have  been  represented as simple
hollow tubes, as a series of globular vesicles, as con-
tinuations of arteries, as termination  of nerves, cm
structures of rhomboidal bodies, and finally, as cel-
lular.*
  It is supposed by one of the latest observers, who
appears to  be entiled to great attention^  that the
muscular  fibres are not  thus  minutely  divided: that
a single fibre, when separated from the adhering ex-
traneous substances, and viewed  in a  powerful mi-
croscope, is a solid cylindor, formed of a pulpy sub-
stance, irregularly granulated, and covered by a por-
tion of the retioular membrane.
  The connexion of these fibres,  with the blood ves-
sels  and nerves, 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

  • A statement of these descriptions, with reference to the publications
in which they are contained, may be seen in the Elementa Physiolosfisj of
HaUar, v«i. IV.
   JCarlysle, in the Croonian Lecture, London Philosophical Transactions
  5, Part I. 
168         Structure of Muscular Fibres.

Ruysch, that when these arteries are fully injected,
they not  only communicate with the veins, but also
pour out some of their contents in  a dew-lil^e effu-
sion in the muscle.*
  These vessels must terminate, not in the cavities of
the muscular  fibres, but, exterior  to  these  fibres;
otherwise the  dew-like effusion would not be appa-
rent ; and it is probable that the red colour, .which
is so general in muscles, depends 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 disoxygenated
blood occupied all the vessels, while the florid  co-
lour of the muscles continued unchanged;  which
could not  have been the case if the colour  of the
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 completely washed away while the fibrous
structure of the muscle remains unchanged.  From
this also  it may be inferred, that the blood is exterior
to the muscular fibre, and to the vessels likewise.
  It is said by Sabatier that the colour will likewise
be completely removed, by injecting a large quantity
of water  through the arteries; this  does not invali-
date the  inferences 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
appears as if some blood had been  mixed with it; it
contains albumen and  gelatine, with  some  fibrine,
and a peculiar extractive  substance, as well as the
red colouring  matter.
 * See Ruysch's description of the 96th preparation in his Thesaurus
Quartus; and of the 35th preparation in the Thesaurus Decimus. 
Nerves of the Muscles.            169
   The substance of the muscle, when thus  separat-
 ed from the above-mentioned matter by washing, ap-
 pears to be of the same nature with the fibrine of the
 blood:  and after boiling some time  in the water,  it
 seems,  like that substance, to consist of brown inso-
 luble fibres, which are brittle when dry.
   When the great function of muscles is under con-
 sideration, nerves appear of more importance than
 blood vessels.
   The  nerves appropriated to muscles of voluntary
 motion 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  fibrdlae be-
 come soft and transparent, and finally blended with
 the reticular membrane which surrounds the muscu-
 lar fibres.
   It ought to be noted that muscules are indued with
 great sensibility, and that the smallest puncture can-
 not be made in them  without exciting pain.
   Thus arranged, tho fibres of muscles are most ge-
 nerally  attached to tendons, which are inserted into
 the bones these muscles are intended to move.  They
 are also, in some cases, inserted into tendinous mem-
 branes,  and other parts necessary to be moved; but
 in all such  instances  these parts are perfectly pas-
 sive; and the motion in which they are concerned is
 altogether produced by the contraction of the mus-
 cular fibres.
  Notwithstanding the great attention that has been
 paid to  this important operation of muscular fibres,
 the immediate cause is yet unknown.
  Muscular motion takes place under the  following
 different circumstances:—
  1st. When irritation or stimulus is applied directly
to the muscular fibre.
  Vol.  i.                22 
170       Phenomena of Muscular Motion.

  2d. When irritation is applied to a nerve connected
with the muscles.
  3d. When it is induced by volition.
  There are several causes of muscular action which
cannot be arranged under either of these  heads, al-
though  it is probable they are not essentially differ-
ent;  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, di-
vides, lacerates or extends its fibres; by  acrid, and
perhaps other  chemical and peculiar qualities of the
substance applied to  the  muscles;   by  a  sudden
change of temperature;  and by electricity and gal-
vanism.
  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 tremour in it. It be-
comes hard and rigid: its length diminishes, and its
diameter increases.   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 mus-
cle will become hard and rigid notwithstanding.
  It has often been  inquired whether the whole bulk
of a muscle is diminished or increased by its con-
traction.  It now seems  generally agreed that the
bulk is not increased;  and if there is any  real  dimi-
nution 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, ex-
ists in a greater degree in some muscular parts than
others.   It is  suspended by the application of nar- 
Of Muscular Contraction.          1 ? 1
 cotic substances; and it remains, in many  cases, a
 short time after the vital functions have ceased.
   In a majority of cases a general contraction seems
 to 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 overcome
 it.  This condition  of the muscles,  after death, al-
 though very common, is  not universal:  and some
 dead subjects are perfectly relaxed and  flexible from
 the first cessation of the vital  functions.
   The force with which muscles contract  exceeds
 greatly their inanimate power of cohesion.  Thus a
 muscle, deprived  of  life, would  be completely lace-
 rated by a weight suspended from it, which  it could
 readily  raise  by its  contraction  during life.   This
 force of contraction is so great, that the  tendo Achil-
 lis and the patella have been repeatedly  broken by
 the mere power of the muscles inserted  into them.
   The rapidity with  which the successive contrac-
 tions 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 physi-
 ologists.
   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 readily through the intestines, could not oc
carried along any parts of them whose position hap-
pened to be  perpendicular, (as  the colon on the right 
172     Question respecting Animal Motion.

side when we stand,) unless the circular fibres of the
intestine could contract behind it to such a degree as
to close completely the cavity of that tube.
  An interesting question may be  proposed here,-—
Whether the  power of motion, as above described, is
exclusively enjoyed by  muscular  fibres;  whether
these fibres must  be supposed to exist in  all those
parts of the  body which occasionally perform con-
traction ?
  It has often been inferred, that parts were muscu-
lar because they were capable of contraction; but the
question above  ought to be decided affirmatively be-
fore  such inferences can be properly made.
  The sac of the taenia hydatigena appears to be a
membrane 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 protrude 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 con-
sidered as not yet decided affirmatively.
  Muscular fibres  are situated very differently in dif-
ferent parts.  They compose almost the whole sub-
stance of the heart, which is therefore called a hollow
muscle.  They also form one of the coats of the sto-
mach and intestines of the urinary bladder.
  In the muscles on the trunk and limbs,  their  ar-
rangement is very various, being  rectilinear, penni-
form, radiated,  &c.
  There are  a  great many short fibres, with an ob-
lique direction, in  some muscles  of small volume;
which have therefore great power and little motion.

  * See the Croonian  Lecture by Mr. Home; London Philosophical Trans-
actions for 1795, Part 1. page 204. 


*  .* 


4»+~*

 
173
                 CHAPTER II

            OF THE INDIVIDUAL MUSCLES.

      Muscles of the Teguments of the Cranium.

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

                I.  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 la-
teral  sinus; it rises 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 at-
tollens 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 fore-
head 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 com-
pressor  naris  and  levator  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.

              2. Corrugator Supcrcilii,

  Arises fleshy from the internal angular  process of
the os frontis, above the joining of the os nasi, and 
174             Muscles of the Ear.
nasal process 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
orbicularis palbebrarum, 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 forehead, and make it wrinkle, particularly
between  the eyebrows.
                Muscles of the Ear.
                1. Attollens Aurem.
  Arises  thin, broad, and tendinous, from the ten-
don 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
upwards.
               3.  Retrahentes Auris,
  Arise, sometimes by three, but always by.two, dis-
tinct small muscles, from the external and posterior
part of the root of the mastoid process, immediately
above the insertion of the sterno-cleido-mastoid mus-
cle. 
              Muscles of the Eyelids.           175

  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 com-
mon to both, and the upper eyelid one proper to it-
self.

             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, co-
vering 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 ten-
don  which serves to fix the  palpebrae and muscular
fibres arising from it.
  Inserted, by the short round tendon,  into the nasal
process of the superior maxillary bone, covering the
anterior and upper part of the lachrymal sac; which
tendon can be easily felt at the inner canthus of the
eye.
  Use. To shut the eye, by drawing both  lids close
together, the fibres contracting from the outer angle
towards the inner, press the eyeball, squeeze the la-
chrymal  gland,  and convey the  tears towards  the
puncta lachrymalia. 
176
Muscles of the Eye.
   The ciliaris of some authors is only a part of this
 muscle 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 zygomaticus minor, and joins with the levator
 labii superioris alaeque nasi.

           2. Levator Palpebral 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 eyelids up-
 wards ; 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 enters, so that they may be taken out
 adhering to this  nerve; and all having strong fleshy
bellies.
   Inserted at the  forepart of the globe  of the  eye
 into the anterior part of  the tunica sclerotica, and
under the tunica adnata, at opposite sides, which in-
dicates both their names and  Use;  so that they
scarcely require any further description than to name
them singly. 
Muscles of the Eye.             177
                  1. Levator Oculi,
   Arises from the upper part of the foramen opticum
 of the sphenoid  bone,  below the levator palpebral
 superioris,  and runs forwards to be
   Inserted into the superior and  forepart of the tu-
 nica 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 opti-
 cum.
   Inserted opposite to the former.
   Use. To pull the globe of the eye down.
                 3. Adductor Oculi,

   Arises, as the former, between the  obliquus supe-
 rior 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 fora-
 men opticum and  lacerum, being the longest from its
 situation; and  is
   Inserted into the globe opposite to the outer can-
 thus.
   Use. To move the globe outwards.
   The oblique muscles  are two:

         Obliquus Superior, seu Trochlearis,
   Arises, like the  straight  muscles, from the  edge of
 the foramen opticum at the bottom of the orbit, be-
 tween 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 cartila-
ginous trochlea is fixed  to the inside of the internal
   Vol. i.               23 
178            Muscles of the Face.

angular process of the os frontis, through which its
tendon passes, and runs a little downwards and out-
wards, enclosed in a loose membranous sheath.
  Inserted, by a broad thin tendon, into the  tunica
sclerotica,  about half way between the insertion of
the attollens oculi and optic nerve,
  Use. To roll the globe of the eye, and turn the pu-
pil downwards  and outwards, so that the upper side
of the globe is turned inwards, and the inferior part
to the outside of the orbit, and the whole globe drawn
forwards towards their 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 ob-
liquely outwards, is
  Inserted into the sclerotica,  in  the space between
the abductor and optic  nerve, by a broad thin ten-
don.
  Use. To draw the globe of the eye forwards, in-
wards, and  downwards;  and,  contrary to the supe-
rior, to turn the pupil  upwards towards the inner
extremity of the eyebrow; at the same time,  the ex-
ternal  part  of the globe is turned towards the infe-
rior side, and the internal rolls towards the upper
part.

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

                 Compressor Nar is,

  Arises by a narrow  beginning,  from the  root of
the ala nasi externally, where  part of the levator la-
bii superioris alaeque nasi is connected to it; it spreads 
                Muscles of the Face.             179

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 descend-
ing from the occipito-frontalis muscle.
   Use. To compress the ala towards the septum na-
si,  particularly 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 expressing certain passions.

           Muscles of the Mouth and Lips.
  The mouth has nine pair of muscles, which  are
inserted into the lips, and a common one formed by
the termination of these, viz. three above, three below,
three outwards, and  the  common  muscle surrounds
the mouth.
  The three above are,

              1. Levator Antruk Oris.
  Arises, thin and fleshy, from tho hollow of the  su-
perior maxillary bone, between the root of the socket
of the first dens  molaris and the foramen infra orbi-
tarium.
  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
prominent, as in smiling.
      2.  Levator Labii Superioris Alceque Nasi,

  Arises by two distinct origins : the first broad and
fleshy, from the external part of the orbitar process 
180
Muscles of the Face.
 of the superior maxillary bone which forms the lower
 part of the orbit, immediately above the foramen in-
 fra-orbitarium; the second portion arises from the na-
 sal process of the superior maxillary bone, where it
 joins the os frontis at the inner 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 Alceque Nasi,
   Arises, thin and  fleshy,  from  the os  maxillare su-
 perius, 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 la-
 bii superioris alaeque nasi.
   Inserted into the  upper lip and root of the ala nasi.
   Use.  To draw the upper lip and ala nasi down-
 wards 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 connected to that part of the platysma myoi-
des, which runs over the maxilla to the angle of the
mouth, to the depressor 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. 
Muscles of the Face.             181
           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 al-
veoli 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.
  The three outward are,

                   1. Buccinator,

  Arises, tendinous and fleshy, from the lower jaw,
as far back as the last dens molaris and forepart of
the root of the coronoid process; fleshy from  the
upper jaw, between the  last  dens  molaris and ptery-
goid process of the sphenoid bone; from the extre-
mity of which it arises tendinous, being  continued
between both jaws to the constrictor pharyngis supe-
rior, with which it joins; from thence proceeding
with straight  fibres, and adhering close to the mem-
brane that lines the mouth, it is
  Inserted into the  angle  of the mouth within  the
orbicularis oris.
  Use. To draw the angle of the mouth backwards
and outwards, and contract its cavity, by pressing
the cheek inwards, by which the food is thrust  be-
tween the teeth. 
182            Muscles of the Face.
               2.  Zygomaticus Major.

   Arises, fleshy, from the os malae, near the zygo-
 matic 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 prominent, as in laughing.

               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
 outwards, 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
 muscles that move the lips; the fibres of the superior
 descending, those of the inferior ascending, and, de-
 cussating 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 draw-
ing both lips together, and to counteract all the mus-
 cles that assist in forming it.
   There is another small muscle described by Albi-
nus,  which he  calls  Nasalis  labii superioris; but  it
seems to be only some fibres of the former connected
to the septum nasi. 
183
            Muscles of the Lower Jaw.

  The lower jaw has four pair of muscles for its ele-
vation 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 angular 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 radii towards the ju-
gum, 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 dupli-
caturc of which tendon this process is enclosed as in
a sheath, being continued down all  its  forepart to
near the last dens molaris.
   Use, To pull the lower jaw upwards, and press it
against the upper, at the same time drawing it a lit-
tle backwards.
   N. B.  This muscle is covered with a tendinous
membrane, called its aponeurosis, which arises from
the bones that give origin to  the upper and semicir-
cular part of the muscle; 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
origin of a greater  number of fleshy fibres, to fortify
the muscle in its action, and  to serve as a defence
to it.
                   2.  Masseter,

   .Irises, by  strong,  tendinous,  and  fleshy fibres, 
184
Muscles of the Lower Jaw.
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 pro-
cess, filling all the  space  between the two plates;
and from the pterygoid process of the os palati be-
tween these  plates.
  Inserted into the angle of the lower jaw internally.
  Use.  To draw the jaw upwards;  and obliquely to-
wards the opposite  side.
              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 sphe-
noid bone.
  Inserted into a cavity in the neck  of the condyloid
process of the lower jaw; some of its fibres are in-
serted into the ligament that connects the moveable
cartilage and that process to each  other.
  Use.  To pull the lower jaw forwards, and  to the
opposite side; and to pull the ligament from the joint,
that it may  not be pinched during these motions:
when both external pterygoid muscles act,  the  fore
teeth of the  under jaw are  pushed  forwards beyond
those of the upper jaw. 
Muscles of the Neck.            185
 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 inferior part of the masseter muscle and
 parotid glands.
   Use. To assist the depressor anguli oris, in draw-
 ing 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.

            2. Sterno-cleido-Mastoideus,

   Arises by two distinct origins: the anterior, tendi-
nous 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 clavi-
cle ; both unite a little above the anterior articulation
of the clavicle, to form one muscle, which runs ob-
liquely upwards and  outwards, to be
  Inserted, by a thick strong tendon, into the mastoid
process, which it  surrounds ; and, gradually turning
thinner, is inserted as far back as the lambdoid su-
ture.
   Use. To turn the head to one side, and bend it for-
wards.
  Vol. r.               21 
186
Alusclcs between the
    Muscles situated betioeen the Lower Jaw and Os
                     Hyoides.
   There are four layers before, and two muscles at
 the side.
   The four layers are,

                  1.  DigastricuSy
   Arises, by a  fleshy belly,  intermixed  with tendi-
 nous fibres, from the fossa at the root of the mastoid
 process of the temporal bone, and soon becomes ten-
 dinous ; 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 tendi-
 nous  and muscular fibres, runs obliquely  forwards,
 turns fleshy again, and is.
   Inserted, by its anterior belly, into a rough sinuo-
 sity at the inferior and anterior edge of that  part of
 the lower jaw called the chin.
   Use.  To open the mouth, by pulling the lower jaw
 downwards, and backwards; and when the jaws are
 shut, to  raise the os hyoides, and consequently the
 pharynx, upwards, as in deglutition.

                2.  Mylo-Hyoideus,
  Arises, fleshy, from all the inside of the lower jaw,
between the last dens molaris and the middle of the
 chin, where it joins with  its fellow.
  Inserted into the lowTer edge of the basis of the  os
h yoides, 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 in-
side of the chin. 
Lower Jaw and Os Hyoides.         187
  Inserted into the basis of the os hyoides.
  Use. To draw this bone forwards to the chin.

              4.  Genio-HyoGlossus,
  Arises, tendinous, from a rough protuberance in
the  inside 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 con-
cave ; to draw its root and os hyoides  forwards, and
to thrust the tongue out of the mouth.
  The two muscles at the side are,
                  1. Hyo-Glossus,
  Arises, broad and fleshy, from the base, cornu, and
appendix of the os hyoides; the fibres run upwards
and outwards, to be
  Inserted into the side of the tongue, near the stylo-
glossus.
  Use. To  pull the tongue inwards and downwards.

                   2. Lingualis,
  Arises from the root of Vie tongue laterally; runs
forwards 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 museles. 
 188   Muscles between Os Hyoides and Trunk.

                1.  Sterno-HyoideuSf
  Arises, thin and fleshy, from the cartilaginous ex-
tremity 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  notch, and
from the ligament that runs across it; thence ascend-
ing obliquely, it becomes tendinous below the sterno-
cleido-mastoid  muscle;  and, growing fleshy again,
is
  Inserted into  the base of the  os-hyoides, between
its cornu and the insertion of the sterno-hyoideus.
  Use. To pull the os hyoides obliquely downwards.
  The second layer consists  of three  muscles :

               1. Sterno-ThyroideuSf
  Arises, fleshy, from  the whole edge of  the upper-
most bone of the sternum internally,  opposite to the
cartilage  of the first  rib, from which it  receives a
small part of its origin.
  Inserted into the  surface of the rough  line at  the
external part of the inferior edge of the thyroid car-
tilage.
  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. 
Muscles of the Styloid Process.         189
               3. Crico Thyroideus.

  Arises from  the side  and forepart of the  cricoid
cartilage, running obliquely upwards.
  Inserted by two  portions: the first, into  the lower
part of the  thyroid cartilage; the second, into its in-
ferior cornu.
  Use. To  pull forwards and depress  the thyroid, or
to elevate  and draw backwards the cricoid carti-
lage.
Muscles situated between the  Lower Jaw and Os Hyoides
                     laterally.
  They are five in number. They proceed from the
styloid 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 pro-
cess, and from a ligament that connects that process
to the angle 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 lit-
tle upwards.
  N.  B. Its  fleshy belly is generally perforated  by
the tendon  of the digastric muscle, on one or both
sides. There is often another accompanying it, called 
190           Muscles of the Palati.

stylo-hyoideus alter; and has the same origin, insertion
and use.
               3. Stylo-Pharyngeus,

  Anses, fleshy, from the root of the styloid process.
  Inserted into the side of the pharynx  and back part
of the thyroid cartilage.
  Use. To dilate and raise the pharynx  and thyroid
cartilage upwards.
  The two from the pterygoid process are,

          1. CircumftexuSf  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 tendon, which soon spreads into
a broad membrane.
  Inserted into the velum  pendulum palati, and  the
semilunar edge of the os palati, and extends as far
as the suture which  joins the two bones.  Generally
some of its posterior 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 little  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 pen- 
               Muscles of the Fauces.           191

dulum 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.

   Muscles situated about the passage of 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; thence running upwards with-
in the anterior arch, before the amygdala;  it is,
  Inserted into the middle of the velum pendulum pa-
lati, at the root of the uvula anteriorly, being con-
nected with  its fellow, and with the beginning of the
palato-pharyngeus.
   Use. Draws the velum toward  the root of the
tongue, which it raises at the same time, and, with
its  fellow, contracts 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 palati.  The fibres are collected within
the posterior arch behind the amygdalae, and run
backwards to the top and lateral 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 the fibres being lost 
192           Muscles of the Fauces.
between the membrane of the pharynx, and the two
inferior constrictors.
   Use. Draws the uvula and velum downwards and
backwards; and at the same time pulls  the  thyroid
cartilage  and pharynx upwards,  and shortens it;
with the constrictor superior  and tongue, it assists
in shutting the passage into the nostrils; and,  in swal-
lowing, 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 carti-
laginous extremity of the eustachian tube; and are,
   Inserted into the inner part  of the last-mentioned
muscle.
   Use. To assist the former, and to dilate the mouth
of the tube.
   The one in the middle is the
                  Azygos UvulaSf
   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 adhering to the tendons of  the cir-
cumflexi.
   Inserted into the apex of the  uvula.
   Use. Raises the uvula upwards and forwards, and
shortens 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 thyroideus and thyreo-hyoideus 
              Muscles of the Pharynx.           193

muscles; and  from the  cricoid cartilage, near the
crico thyroideus.   This muscle is the largest of the
three;  and is
  Inserted into  the white line, where it joins, with its
fellow; the superior fibres running obliquely upwards,
covering nearly one half of the middle  constrictor,
and terminating in a point; the inferior fibres run
more transversely, and  cover the  beginning of the
oesophagus.
  Use. To compress that part of the pharynx which
it covers, and  to raise it with the larynx a little up-
wards.

          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, cover-
ing a considerable part  of the superior constrictor,
terminate in a point.
  Inserted into the middle of the cuneiform  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 pharynx.  The fibres at the middle part
run more transversely 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 cuneiform 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 sphe-
noid bone; from the upper and under jaw, near the
roots of the last dentes molares;  and between the
jaws, it is continued with the buccinator muscle; and
  Vol.  i.              2/3 
194            Muscles of the Glottis.

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 cover-
ed by the constrictor medius.
  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 mus-
cles, and a single one.

           1. Crico-Arytwnoideus Posticus,
  Arises, fleshy, from the back  part of the cricoid
cartilage, and is
  Inserted into  the posterior part of  the base of the
arytenoid 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-^rytxnoideus Lateralis,
  Arises, fleshy, from the cricoid cartilage, laterally,
where i| is covered by part of the thyroid, and is
  Inserted into the side of the base of the arytenoid
cartilage near the former.
  Use. To open the rima  glottidis, by pulling  the
ligaments from each other.

              3.  Thyreo-Jlrytsenoideus,
  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
farther forwards  than the crico-arytaenoides latera-
lis.
   Lse.  To pull  the  arytenoid  cartilage forwards 
               tMuscles of the Glottis.            195

nearer to the middle of the thyroid, and consequently
to shorten and relax the ligament of the larynx or
glottis vera.
             4. Jlrytxnoideus Obliquus.
   Arises from the base of one arytenoid  cartilage;
and, crossing its fellow, is
   Inserted near the tip of the  other  arytenoid carti-
lage.
   Use. When both act, they pull the arytenoid carti-
lages towards each other.
   N. B. One of these is very often wanting.
   The single muscle is, the

             Jlrytxnoideus 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 ary-
tenoid cartilage.
   Use. To shut the rima glottidis, by bringing these
two  cartilages, with  the ligaments, nearer one an-
other.
   Besides these, there arc a few separate muscular
fibres on each side: which, from  their general direc-
tion, are named,
              1. Thyreo-Epiglottideus,
  .'Irises, 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. virtyxno-Epiglottielcus,
   .irises, by a number  of small  fibres,  from the la- 
196            Muscles of the Neck.
teral and upper part of the arytenoid cartilage; and,
running along the outer side of the external rima, is
  Inserted into the epiglottis along with the former.
  Use. To pull that side of  the  epiglottis  towards
the external 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 Vertebrae.
  These consist of one layer,  formed by four mus-
cles.
                  1.  Longus Colli,
  Arises, tendinous and fleshy, from the bodies of the
three  vertebrae of the  back laterally;  and from the
transverse process of the third, fourth, fifth and sixth
vertebrae of the neck, near their roots.
  Inserted into  the  forepart of the bodies of all the
vertebrae of  the neck,  by  as many small  tendons,
which  are covered with flesh.  i v     ;     '   ' —'
  Use.  To bend the neck gradually forwards, and to
one side.
          2. Rectus Capitis Internus Major.
  Arises, from the anterior points of the  transverse
processes of the third,, fourth, fifth and sixth verte-
brae of the neck, by four distinct beginnings.
  Inserted into the cuneiform process of the os occi-
pitis, a little before the condyloid process.
  Use.  To bend the head forwards.

          3. Rectus Capitis Internus Minor,

  Arises  fleshy, from  the forepart of the body of the
first vertebra of the neck, opposite to the  superior
oblique process.
  Inserted near the  root of the condyloid  process  of
the os  occipitis, under, and a little farther outwairds,
than the  former muscle. 
Muscles of the Thorax.           197
   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 fora-
men 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 oblique muscle of the abdomen; from
almost the whole  length of the sternum; and from
near half of the anterior part of the clavicle: the fi-
bres 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.

                   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 con- 
198           Muscles of the Thorax.
nexion, by ligament, with the coracoid process of the
scapula.
   Use. To  pull  the clavicle  downwards  and for-
wards.

                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  down-
wards, 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
internally, between the insertion of the rhomboid and
the origin of the subscapularis muscle,  being  folded
about the two angles of the scapula.
   Use. To move the scapula  forwards; and, when
the scapula  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.

              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 
              Muscles of the Thorax.           199

their cartilages: from which, to the sternum, there is
only a thin membrane covering the internal intercos-
tals.
  Inserted into the upper obtuse edge of each infe-
rior rib, as far back as the spine, into which the pos-
terior 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 are 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 oblique,  give them a greater power  of
bringing the ribs near each other, than could be per-
formed  by straight ones.  But, by  the obliquity of
the fibres, they 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 ren-
ders it less perceptible;  and, instead of raising the
fibres fixed to the sternum and  spine, would have de-
pressed the ribs.
  .A". B.  The portions of the  external intercostals,
which arise from the transverse processes of the ver-
tebrae 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 costarum longio-
res et breviorcs.
   The portions of the internal that pass over one rib,
and are inserted into the next below it, are by Doug-
kis  called* Coslaruni deprcssores proprii Couperi.
   These portions of both  rows assist in raising the 
200
Abdominal Muscles.
ribs in the same manner as the rest of the intercos-
tals.
  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 to the lower half of the middle bone of the
sternum, from whence its fibres ascend obliquely up-
wards 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 extre-
mities of the ribs; and consequently to assist in con-
tracting the cavity of the thorax.
  This muscle often  varies; and  is sometimes in-
serted into the cartilage of the second rib, sometimes
into the cartilages 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 cartilages: it always intermixes, in a ser-
rated manner, with portions  of the  serratus major
anticus; and generally coheres to the pectoralis ma-
jor, intercostals,  and  latissimus dorsi;  which last
covers the edge of a portion of it extended from the
last rib to the spine of the ilium.
  From these origins the fibres run obliquely down- 
Abdominal Muscles.
201
wards 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 corre-
sponding tendon of the other side, in a line which ex-
tends from the ensiform cartilage to the os pubis.
  This line is called linea alba, from its white appear-
ance, which is owing  to  the  connexion of three
tendons with each other, without the intervention of
muscle, viz. those of the external and  internal ob-
lique, and the transversalis.
  On each side of this line, two long narrow mus-
cles 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 form two bands
more firm and dense than the rest of  the  tendon,
which are called columns: these columns are sepa-
rated from each other; and  the vacuity  between
them is the abdominal ring, or aperture, for the pas-
sage 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
obliquely downwards,  and is inserted  into the os
pubis of the opposite side, near the symphysis, de-
cussating the fibres of the  corresponding column of
that  side.
  The lower edge of the tendon of the  external ob-
lique is attached to  the superior anterior spinous
process of the ilium, and is there blended with the
tendinous fascia, which extends down the thigh.
  Vol. r.               26 
202            Abdominal Muscles.
  From this process the edge of the tendon is ex-
tended, 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 turned inwards is
very small at its commencement, and continues so
for  a great part of its extent; but becomes much
broader  within  an inch of its termination.   This
broad extremity 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  tendinous 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 sup-
ports it for a short distance on the inside of the ab-
dominal ring.
  The edge formed by the fold of the membrane is
called  Pouparfs 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 follow-
ing manner:   The part which is nearest to the spine
of the  ilium is continued into the cellular membrane,
or the 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 cir-
cular opening,  which is  occupied  in  part, but not
completely, by the crural vessels.
   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 
Abdominal Muscles.               203
 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 ex-
 ternal edge, or Poupart's ligament, its  whole extent:
 and there is  also a  fascia which covers  the whole
 tendon  of the external  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 dissection, from
 what it is afterwards; as the division of these con-
 nexions, necessarily made by the dissection, renders
 it much more loose than it could have been while the
 parts were undivided.    This structure has laterally
 been called the crural arch.*
   The  external  oblique muscles compress the abdo-
 men, and therefore contribute to the evacuation of its
 contents;  if the diaphragm is in a passive state they
 force it upwards,  by pressing  the abdominal viscera

   * The fascia which  covers the tendon of the external oblique muscle,
 and descends upon the thigh, can be examined very easily in anarsacous
 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 external
 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 inserted into
 the os pubis.  Then make an incision in the tendon of the external ob-
 lique, about three inches above  Poupart's ligament, parallel to it and
 nearly of the same length; make a second incision from the 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 abdomi-
 nal ring.  Dissect this flap carefully from the internal oblique, until the
 spermatic chord, the cremaster muscle, and the lower origin of the inter-
 nal oblique, are perfectly uncovered.  After examining 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, and its
insertion into the pubis, may also be examined. 
204            Abdominal Muscles.
against it;  and thus assist in producing expiration
and  its various  modifications of  coughing, sneez-
ing, &c.
  They bend the spine forwards,  or approach the
thorax to the pelvis.
  When one acts separately, it  bends the trunk ob-
liquely to the side on which it is situated.

           3.  Obliquus Ascendens Internus.

  Arises from the  spine of the  ilium  the whole
length between the  posterior and  superior  anterior
spinous process; from the os sacrum and the three
undermost lumber vertebrae, by a tendon common to
it, to the serratus posticus inferior muscle, and to the
latissimus dorsi; from Poupart's ligament, at the mid-
dle of which it sends off the beginning of the cremas-
ter muscle; and the spermatic chord in the  male, or
round ligament of the womb in the female, passes
under its thin edge, except a few detached fibres.
  Inserted into the cartilago ensiforms, into  the car-
tilages of the  seventh, and  those of the false  ribs;
but,  at the upper part, it is  extremely thin, resem-
bling a cellular membrane, and only becomes fleshy
at the cartilage of the tenth rib.   Here its tendon
divides into two layers: the anterior 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 joines 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  mus-
cle,  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 be-
fore the rectus muscle; and the whole posterior  layer 
Abdominal Muscles.
205
of the internal oblique, together with the whole ten-
don of the transversalis muscle, excepting at the in-
ferior part, passes behind the rectus, and is inserted
into the linea alba.  At its undermost  part, it is in-
serted into the forepart 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 mus-
cles; by a broad thin tendon, connected to the trans-
verse 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 internally, and from
the tendon of the external oblique muscle where it
intermixes  with some fibres  of the internal oblique.
  Inserted into the cartilago  ensiformis, and  into the
whole length of the linea alba, excepting its lower-
most part.
   Use. To  support  and   compress  the  abdominal
bowels, and it is so particularly well  adapted for the
latter purpose, that it might be called the proper con-
strictor of the abdomen.
  The long muscle in the middle is named,
                 Rectus Abdominis.

  Arises, by two heads, from the ligament of the car-
tdage which joins the two ossa pubis to each other;
runs upwards 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 muscle. 
206             Muscles of the Testes.
   It  is generally  divided by three tendinous  inter-
sections : 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  um-
bilicus. These intersections seldom penetrate through
the whole thickness of the  muscle : they adhere firm-
ly to the anterior part of the sheath, but very slightly
to the posterior layer.*
   Use.  To compress the  forepart, but more  parti-
cularly the lower part of the belly; to  bend the trunk
forwards, or to raise the pelvis.   By its tendinous in-
tersection, it is enabled to  contract at any of the in-
termediate 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 and inner  edge of the  rectus muscle.
   As it is frequently wanting in  both sides without
any inconvenience, its
   Use seems  to be, to assist the  inferior part of  the
rectus.

  * To 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 sepa-
rate the external oblique muscle and tendon from the  internal oblique and
its tendon, as far as the linea semilunaris, and to separate the internal ob-
lique in the same manner from the transversalis ; and then to make an inci-
sion 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 mus-
cle into view.  The structure of the sheath which contains  the rectus can
then be examined. 
Accelerator Urince.
207
     Muscles about the Male Organs of Generation.


   The testicles are said to have a thin muscle com-

mon to both, and one proper to each.

   The common muscle is called the


                         Dartos.


   This consists of muscular fibres  blended with the

cellular membrane lining the scrotum;  and therefore

this portion 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 junction  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 chord.

   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

compress it in the act  of coition.*


  • Mr. J. Cloquet says, that the scattered fasiculi of this muscle are collect-
ed after their distribution on the tunica vaginalis, and run up on the inner
side of the chord, to be inserted into the spine of the pubis.  He makes the
inference from this, that the cremaster is a kind of muscular  loop, drawn
down by the descent of the testicle.  I am satisfied that the muscle, in ro-
bust subjects, frequently exists,  more or less, after the manner in which he
speaks of it; but in the emaciated it is very indistinct, as regards such an in-
sertion.  In the cases where I have  seen this insertion into the spine of the
the pubis, the quantity of muscular fibre has been by no means so great there,
as at its origin. This observation of Mr. Cloquet's is ingenious and interesting,
but it is well worthy of consideration, that Mr. John Hunter's opinion, in his
paper on the descent of the testicle, is opposed to it, and on the following
grounds.  In the young ram, and in several other animals, the cremaster
muscle is formed before the testicle descends from the abdomen into the
scrotum, being  reflected along the gubernaculum testis upwards towards 
208
Accelerator Urinai.
  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 nearly as far up
as the union of these bodies.
  Use. To compress the crura penis, by  which  the
blood is pushed from it into the forepart of the cor-
pora  cavernosa;  and the penis is  by that  means
more completely distended. The erect ores seem like-
wise to keep the penis in its proper  direction.
     2. Accelerator Urinaz, seu Ejaculator Seminis,

  Arises, fleshy, from the sphincter ani  and  mem-
branous 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 com-
pletely enclosed.
  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
transversely inwards, and is

the loins. Mr. Hunter, could not, it is true, verify the same observation on
the human subject, but he is disposed, from analogy, to believe that some-
thing of the kind exists. Ed . 
Accelerator Urince.                209
   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 little outwards and back-
wards.
   There is often a fourth muscle, named
               Transversus Perinei Alter,


   Arises behind the former, runs more obliquely for-
wards, and is
   Inserted into that  part  of the accelerator  urinae
which  covers the anterior  part of the bulb of the
urethra.
   Use.  To assist the former.

  In the Medico-Chirurgical Transactions, James Wilson, Esq.
F. R. S. gives the following account of two small  muscles  of
the membranous part of the urethra, viz.  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 pu-
bis, about one eighth of  an inch above the lower edge of the
cartilaginous arch of pubes, and nearly at the same distance, be-
low 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 ure-
thra, separate from those of the opposite side; spread them-
selves 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 witli similar  fibres of the op-
posite side.
  Its action seems to be  to draw up the membranous  part of
the urethra, and compress it against the inside of the cartila-
ginous arch of the pubes;  and also to contract the circle round
   Vol. r.                27 
210
Muscles of the Anus.
 the membranous portion; 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 surrounds 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 extre-
 mity of the rectum.
   Inserted, before, by a narrow point, into  the peri-
 neum,  acceleratores urinae, and transvcrsi  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 obtu-

  * 1 have frequently dissected for this muscle, and in only two or three
cases have been able to satisfy myself of its having an existence distinct
from that of the Levator Ani.  My friend. Mr. Shaw, who occupies a dis-
 tinguished rank among the cultivators of Anatomy in London, admits of
this muscle, but says there is much difficulty in distinguishing it from the
 ligament of the urethra, meaning I presume its triangular ligament.  Ed. 
Muscles of the Anus.
211
rator internus and coccygeus muscle;  from the spi-
nous process of the os ischium; and  its fibres run
down like rays from a circumference to a centre.
  Inserted into the sphincter ani, acceleratores urinae,
and anterior part of the two last bones of the os coc-
cygis ;  surrounds the extremity of the  rectum, neck
of the bladder, prostate gland, and part of the vesti-
culae 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 eva-
cuation 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 rec-
tum ;  and,  perhaps, by pressing upon  the  veins, to
contribute greatly to the erection of the penis.
     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 back-
wards ; and may serve to  make the body of the cli-
toris more tense, by squeezing the blood into it from
its crus.
  The vagina has one pair.

                 Sphincter Vaginas.

  Arises from the sphincter ani, and from the poste-
rior  side of  the vagina,  near the perineum;  from
thence it runs up the side of the vagina, near its ex-
ternal orifice, opposite to the nymphs and covers
the corpus cavernosum vaginae. 
212            Muscles of the Female
  Inserted into the crus and body % or  union of the
crura clitoridis.
  Use. Contracts the mouth of the vagina, and com-
presses 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 pe-
rineum, between the lower part of the pudendum and
anus.
  Use. To sustain and keep the perineum in its pro-
per place.
  The anus, as in the male', has a single mus.cle, and
one pair.
                  Sphincter Ani.

  Arises, as in the male, from the skin  and  fat sur-
rounding 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 pulling down the perineum, to assist in contract-
ing the mouth of the vagina.

                   Levator Ani.

  Arises, as in the male, within the pelvis,  and des-
cends along the inferior part of the vagina  and rec-
tum.
  Inserted into the perineum, sphincter ani, extremity
of the vagina and rectum.
  Use. To  raise  the  extremity of the rectum up-
wards, to contract the inferior part of the rectum, 
             Organs of Generation, 6ye.          213

and to assist in contracting and supporting the va-
gina; 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 high within the thorax of the skele-
ton as the fourth  rib: it  is commonly divided into
two portions.
   1. The superior, or

         Greater Muscle of the Diaphragm.

  Arises, by distinct fleshy fibres, from the cartilago
ensiformis, 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 obliquely upwards and  backwards;
from  the ninth and tenth, transversely inwards and
upwards; and  from the eleventh  and  twelfth,  ob-
liquely upwards.   From  these  different origins  the
fibres run, like  radii from the circumference to  the
centre of a circle; and are
  Inserted into a cordiform tendon, of a considerable
breadth, which is situated in the middle of the dia-
phragm, and in which, therefore, the fibres from op-
posite sides are interlaced.  Towards the right side
the tendon is perforated, by a triangular hole, for
the passage  of the vena cava  inferior; and to  the
upper convex part  of it the pericardium and medias-
tinum are connected. 
214
Diaphragm.
  2. The inferior, lesser muscle, or

            Appendix of the Diaphragm.

  Arises from  the second, third and fourth lumbar
vertebrae, by eight heads; of which, two in the mid-
dle, commonly called its crura,  are the longest, and
begin tendinous.  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 colums, which  decussate
and leave an oval space  between them for the  pas-
sage of the oesophagus and eighth pair of nerves.
  Inserted, by strong fleshy fibres, into the posterior
part of the middle tendon.
  Use.  The diaphragm  is  the principal agent  in
respiration,  particularly in inspiration: for when it
is in  action, the  fibres, from their different attach-
ments, endeavour to bring themselves into a plain to-
wards 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 muscles, the serrati antici ma-
jores, the serrati  postici superiores, and scaleni mus-
cles, are  brought into action.   And in laborious in-
spiration, 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 
Psoas Muscles, frc.
21 j
 pressure of the abdominal muscles upon the viscera
 of the abdomen; and at the same time that they press
 it upwards, they also,  together with the sterno-cos-
 tales and serrati postici inferiores, pull down the ribs,
 and are  assisted in a  powerful manner by the elas-
 ticity of the cartilages that join the ribs to the ster-
 num ; by which the cavity of the thorax is diminished
 and the  air suddenly pushed out of the lungs: and,
 in laborious expiration, the quadrati lumborum,sacro-
 lumbales, and longissimi dorsi, concur in pulling down
 the ribs.
   The four pair are,

              1. Quadratus 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
 vertebrae of the loins, into the last rib near the spine,
 and by a small tendon  into the side of the last verte-
 bra of the back.
   Use. To move the loins to one side,  pull down the
 last rib, and, when both  act, to bend  the loins for-
 wards.

                2. Psoas Parvus,
   Arises, fleshy, from the sides of the two upper ver-
tebrae 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 trans- 
216
Muscles within the Pelvis.
verse 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  in-
ferior  extremity is fixed, to  assist in bending the
body.

                4. Iliacus Internus,
  Arises, fleshy, from the transverse process of the
last vertebra of the loins, from all the inner lip of
the spine of the os ilium, from the edge of that bone
between its anterior spinous  process and the aceta-
bulum, 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 twTo 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
circumference of the foramen thyroideum, formed by
the os pubis and ischium, and  from the upper part of
the plane of the ischium where it joins the ileum.  Its
inside is covered  by a portion of  the levator ani;
and appears to be divided into a number of fasciculi,
which unite and form a roundish tendon, that passes
out of the pelvis, between the posterior sacro ischi- 
                Muscles of the Back.           217

atic ligament and tuberosity of  the  os ischium;
where it passes over the capsular ligament of the
thigh bone, it is  enclosed as in a sheath, by the ge-
mini 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
prosecuted, until the muscles of the thigh, to which
it belongs, are dissected.

                   2. Coccygeus,
  Arises, tendinous and fleshy, from the spinous pro-
cess of the os ischium, and covers the inside of the
posterior sacro ischiatic ligament: from this narrow
beginning, it gradually increases,  to  form  a  thin
fleshy belly, interspersed 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 for-
wards, 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 sin-
gle  pair.
  The first layer consists of two muscles, which co-
ver  almost the whole posterior part of the trunk.

             Trapezius seu Cucullaris,
  Arises, by a strong round tendon, from the lower
part of the protuberance in the middle of the  os oc-
cipitis 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 mastoid process
of the temporal  bone; runs down along the nape of
the  neck, where it seems to arise from its fellow, and
  Vol. l               28 
218             Muscles of the Back.

covers the spinous processes of the superior verte-
brae of the neck; but 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 length of its origin.
  Inserted, fleshy, into the posterior half of the clavi-
cle;  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 de-
scending fibres draw it obliquely upwards; the mid-
dle transverse straight fibres draw it directly back-
wards ; and the inferior ascending fibres draw it ob-
liquely downwards and backwards.
  N B. Where it is inseparably united  to its fellow
in the nape of  the neck, it is named  Ligamentum
Nuchee 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 tendinous and fleshy, from the extre-
mities of the  three or four  inferior ribs, a little be-
yond 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 collected,  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 
Muscles of the Back.            219
 prosecuted till the muscles of the os humeri, to which
 it belongs, 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.
   Inserted  into the lower edges of  the  four  inferior
 ribs, at a little distance from their cartilages, by as
 many distinct 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
spinous process 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
 directly inwards. —-f0t_
   2. Rhomboideus fQQJfv, arises, tendinous, from the
 spinous processes of the three inferior vertebrae  of
the neck, and from the ligamentum nucha).
   Inserted into the base of the  scapula, opposite to
its spine.
   Use. To assist the  former.
   On the neck:

                   3. Splenitis,
   .hises, tendinous, from the upper superior spinous
processes of the vertebrae of the back: tendinous and
fleshy, from the five inferior of the neck, and adheres 
220            Muscles of the Back

firmly to the ligamentum nuchae. At the third verte-
bra of the neck, the splenii recede  from each other,
so that part of the complexus muscle is seen.
  Inserted, by as many tendons, into the  five supe-
rior transverse processes of the vertebrae of the neck;
and tendinous and fleshy, into the  superior 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  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 spi-
nous  processes  of the neck, and is inserted into the
mastoid process and os occipitis, he calls splenius ca-
pitis;  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
processes of the three last vertebrae of the neck, and
the two uppermost of the back;  •
  Inserted into the second, thiflcH 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 up-
permost vertebrae  of the loins,  and the three inferior
of  the back, by as many tendons.
   Inserted into the spinous processes of the nine up- 
and Neck.
221
permost vertebrae of the back, except the first, by as
many tendons.
   Use. To erect and fix the vertebrae, and  to  assist
in raising the spine.

              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
vertebrae of the  back, chiefly by small double ten-
dons;  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  descendens.

                  3. Sacro-Lumballs.
   .Irises, 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
arc named musculi ad sacro-lumbalem accessorii.
   Use. To pull the  ribs  down, and  assist to  erect
the 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 transverse   processes  of  the vertebrae of the 
222            Muscles of the Back
neck, by three distinct tendons: it is named  ccrvi-
calis descendens; and its use is to turn  the  neck ob-
liquely backwards,  and to one side.
  On the neck are,

                  1.  Complexus.
  Arises from the transverse processes of the seven
superior 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 the os occipitis,
and into a part of the curved line that  runs forwards
from that protuberance.
  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 si-
tuated next the spinous processes,  lies more loose,
and has a roundish tendon in the middle of it: for
which reason Albinus calls it biventer cervicis.

            £ # Trachelo-Mastoideus,
  Arises from the transverse  processes of  the three
uppermost vertebrae of the back,  and from the five
lowermost of the neck, where it is  connected to the
transversalis cervicis, by as many thin tendons, which
unite   into  a  belly,  and run up   under the  sple-
nius.
  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. 
mid Neck.
223
               3. Levator Scapulae.
  Arises, tendinous and fleshy, from the transverse
processes 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 sca-
pula.
  Use. To pull the scapula upwards and a little for-
wards.
  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  se-
venth, 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 ver-
tebrae 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  Spinas,
  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 transverse 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  distinct tendons, which soon grow
fleshy, run in an oblique direction; and are
  Inserted, by distinct tendons, into all the  spinous
processes of the  vertebrae of the loins, of the back,
and of the neck, except the first. 
224            Muscles of the Back.

   Use. When the different portions of this muscle act
on one side, they extend the back obliquely, or move
it laterally;  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 upper-
most six vertebrae of the back, by as many distinct
tendons ascending obliquely under the complexus.
   Inserted into the spinous processes of all the ver-
tebrae 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 up-
permost vertebrae of the back,  by as many tendinous
and fleshy origins;  runs between the trachelo mas-
toideus, 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 backwards, 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 spi-
nous process of the second vertebrae 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 the rectus capitis lateralis, and the insertion of
the obliquus  capitis superior.
   Use. To pull the head backwards, and to assist a
little in its rotation. 
and Neck. •
225
          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 vertebrae of the neck, its outer edge
 being covered by the rectus major.
   Inserted, somewhat broad, into the sides of a dim-
 ple 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 ver-
 tebrae of the neck.
   Inserted, tendinous and fleshy, into the os occi-
 pitis behind the back part of the mastoid portion 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 se-
 cond vertebra of the neck, its whole length; and,
 forming a thick fleshy belly, is
   Inserted into the transverse process of the first ver-
 tebra of the neck.
   Use. To give a rotatory motion to the head.
   On the side of the neck are,

                1. Scalenus Anticus,
   Arises, from the fourth, fifth,  and sixth  transverse
 processes of the first  vertebra of the neck,  by  as
 many tendons.
   Inserted, tendinous and fleshy, into the upper side
of the first rib near its cartilage.
   Vol. i.                29 
226             Muscles on the back
                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 dilate the thorax.
  There are a number of small muscles situated be-
tween the spinous and transverse  processes of con-
tiguous vertebrae; which are accordingly named,

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

             2.  Interfransversales Colli.
  They begin  from the transverse process of the
first vertebra of the back, and fill up the spaces be-
tween the transverse processes of the vertebrae of the 
               and side of the Neck.            227

neck, which are  likewise  bifurcated;  and, conse-
quently, there are six distinct double muscles, which
  Arise from the inferior transverse process of each
vertebra 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.

Interspinales Dorsi  et Lumborum, and the Intertrans-
                  versales Dorsi,

  Are rather smalf tendons than muscles, serving to
connect 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 vertebrae of the loins,  and  serve to draw them
towards each other.
       MUSCLES OF THE SUPERIOR EXTREMITIES.
  These may be divided  into the muscles that are
situated 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
scapula that is above its spine; also from the spine
and superior costa; passes under the acromion, and
adheres to the capsular ligament  of tho os humeri.
   Inserted,  tendinous, into  that part of the large 
228       Muscles situated on the Scapula.

protuberance 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 caspular ligament from between the
bones, that it may not be pinched.

                 2. Infraspinatus,

  Arises, fleshy, from all that part of the base of the
scapula 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 for-
wards, and adheres to the capsular ligament.
  Inserted, by a thick and short tendon, into the up-
per and middle part of the large protuberance on the
head of the os humeri.
   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 ten-
dinous membrane,  from which  a number of their
fleshy fibres arise.   It serves besides to strength-
en 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 in-
ferior costa of the scapula,  and runs forwards along
the inferior edge of the infraspinatus  muscle, and ad-
heres to the ligament.
  Inserted, tendinous, into the back part of the large
protuberance 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
humerus backwards;  and to prevent the ligament
from being pinched between the bones. 
"<
                    Deltoides.                 229

  Along the inferior costa of the scapula is,

                   Teres Meijor,
  Arises, fleshy,  from the inferior angle of the  sca-
pula, and  from all that portion of its inferior costa
that is rough  and thicker  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 tendon of the long head of the biceps, along with
the latissimus dorsi.
   Use. To roll the humerus inwards, and to draw it
backwards 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 op-
posite to the insertion of the cucullaris muscle: from
the origins it runs in  three different directions, i. e.
from  the clavicle outwards and  downwards; from
the spine of the scapula oijtwards,  forwards, and
downwards; and from the acromion, straight  down-
wards ;  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 brachialis  externus.
   Use. To pull  the arm directly outwards and up-
wards, and a little forwards  or backwards, according
to the different directions of its fibres.
                2. Coraco-Brachialis.
  Arises, tendinous and fleshy, from the forepart  of 
230      Coraco-Brachialis.—Subscapularis.

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.
   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 costae,
being composed of a number of tendinous and fleshy
fasciculi,  which make prints on the  bone; they all
join together,  fill up the  hollow of the scapula,  and
pass over the joint, adhering to the capsular  liga-
ment.
  Inserted, tendinous, into the upper part of the in-
ternal 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 irom the upper edge
of the glenoid cavity of the scapula;  passes over the 
           Biceps.—Brachialis Internus.         231

head of the os humeri within  the joint;  and, in its
descent without  the joint, is enclosed in a groove
near the head of the  os  humeri,  by a membranous
ligament that proceeds from the 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 forepart of the os humeri, these heads
unite.
  Inserted, by a strong roundish tendon, into  the  tu-
bercle 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 be-
gins 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, de-
cussate each other. It serves to strengthen the mus-
cles, by keeping them from swelling  too  much  out-
wardly, when in  action; and  a  number of their fleshy
fibres take their  origin from it.

              2. Brachialis Internus,

  Arises, fleshy,  from  the middle of the os  humeri,
at each side of the insertion of the  deltoid  muscle,
covering all the  inferior and forepart  of this bone,
runs over  the joint and  adheres firmly to the liga-
ment.
   Inserted, by a strong short tendon, into the coro-
noid process of  the ulna.
   Use. To bend the  fore arm, and to prevent  the
capsular ligament of  the joint from being pinched. 
 232      Triceps Extensor Cubiti.—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 scapula, near its cervix.   The second head,
 called brevis, arises  by an  acute, tendinous, and
 fleshy beginning,  from the back  part of the  os hu-
 meri, a little below its head, outwardly.  The third,
 called brachialis externus, arises by an acute  begin-
 ning, 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  humerus, from which they receive  addition in
 their descent.
   Inserted into the  upper and external  part of the
 process of the alna, 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
 external  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 below the olecranon,  and  covered with a tendi-
nous membrane.
   Use. To assist in extending the fore arm.

          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. 
    Muscles on the anterior part of the Fore Arm.   233

    3.  Those which act on  the radius so as to roll it back-
      wards and forwards on the ulnaj which are called supi-
      nators 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 ex-
      tensors 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 pro-
gress,  sends off a long  slender tendon.
  Inserted,  into the ligamentum  carpi  annulare,  and
into a tendinous  membrane thai is expanded on the
palm of the hand, named aponeurosis palmaris; which
above, begins at the transverse or annular ligament
of the wrist, and, below, is fixed to the roots of the
fingers.
  Use. To bend the hand, and to  stretch the hiem-
brane  that is expanded on the palm.
  N. B. This muscle  is  sometimes wanting, but the
aponeurosis palmaris is always to be found.


              2  Pronator Radii Teres,

  Arises, fleshy, from the internal condyle of the  os
humeri, and tendinous from the  coronoid process of
the ulna.
  Inserted, thin,  tendinous,  and  fleshy, into the mid-
dle  of the  posterior part  of the radius.
  Vol. i.                30 
234  Muscles on the anterior part of the Fore Arm.

   Use. To roll the radius, together with the hand,
inwards.

              3. Flexor Carpi Radialis,

   Arises, tendinous and fleshy, from the internal con-
dyle 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
ringer, after running through  a fossa in the os trape-
zium.
   Use. To bend the hand, and to assist in its prona-
tion.

              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 condyle of the ulna passes to the fore arm;
and a number of its fleshy fibres arise from the ten-
dinous membrane which covers  the fore  arm.
   Inserted, by a short strong tendon,  into  the os pisi-
forme. At a little distance from its insertion, a small
ligament is sent off to the metacarpal bone that sus-
tains the little finger.
   Use. To assist the former in bending the arm.

           5.  Flexor Sublimis Perforatum,
   Arises, tendinous and fleshy, from the internal con-
dyle 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 tu-
bercle  of the  radius;  and  membranous  and  fleshy
from the middle of the forepart of  the radius, where
the flexor pollicis longus arises. Its fleshy  belly sends 
   Muscles on the anterior part of the Fore Arm.   235

off four round tendons  before  it passes under the
ligament of the wrist.
  Inserted, into the anterior and upper part of the se-
cond bone of each finger, being, near  the extremity
of the first bone, divided for the passage of the per-
forans.
   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 annulare; 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 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 up-
per part of the radius,  immediately below its tuber-
cle, and is continued down for some space  on the
forepart of this bone.  It has likewise generally an-
other origin from the internal condyle of the os hu-
meri, which  forms a distinct  fleshy slip, that termi-
nates near the upper part of the origin from the ra-
dius.
  Inserted into the last joint of the thumb, after hav-
ing passed its  tendon under  the  ligament  of the
wrist.
   Use. To bend the last joint of the thumb.*

 * The thumb has but one flexor muscle on the front of the arm, al-
though it has three extensors on the back part. 
"236           Alusvles on the back part
            8. Pronator Radii Quadratus,
   Arises, broad, tendinous, and fleshy, from the low-
 er and inner part of the ulna; the fibres run trans-
 versely, to be
   Inserted into the lower and anterior part of the ra-
 dius, opposite to its origin.
   Use. To turn the radius, together with the hand,
 inwards.

  Muscles of the External Side and Back of the Arm.

             1. Supinator Radii Longus,
   Arises, by an acute and fleshy origin, from the ex-
 ternal ridge  of the os  humeri, above  the external
 eondyle, 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 consequent-
 ly 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
 eondyle.
  Inserted, by a round tendon, into the  posterior and
 upper part of the metacarpal bone that sustains the
 tore 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. 
Of the Fore Arm.              237
  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 mid-
dle of the ulna, where it passes  over  the  ulna.   Its
round tendon is enclosed 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 begin-
ning,  from  the  external  condyle  of the os  humeri,
where it adheres to the  supinator radii brevis.  Be-
fore 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
forepart of the  metacarpal bones they remit tendi-
nous filaments to  each other.
  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 upper 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. 
238   Muscles on the back part of the Fore Arm,

                   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 mid-
dle  of the radius, and from  the interosseous  liga-
ment.
  Inserted,  generally by  two  tendons,  into the os
trapezium, 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
outwardly.
           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 ob-
liquely outwards.

          10. Extensor Secundi Internodii,
  Arises, by  an acute, tendinous,  and fleshy begin-
ning, from the middle back  part of the  ulna, and
from the interosseous  ligament; its tendon runs
through a small groove at the inner and back part of
the lower end of the radius. 
           Muscles on the Palm of the Hand.       239

   Inserted, into the last bone of the thumb.
   Use. To extend the last  joint of the thumb ob-
 liquely backwards.

           Muscles on the Palm of the Hand.

      To  obtain the 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 sca-
        phoid 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 palmaris, which has been
        described with the palmaris longus muscle.

                  1. Palmaris Brevis,

   Arises  from the ligamentum carpi  annulare, and
 tendinous membrane that  is expanded  on the  palm
 of the hand.
   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.

               •Abductor Pollicis Manus,

   Arises,  by a broad, tendinous, and fleshy beginning,
 from the  ligamentum carpi annulare, and from the os
 trapezium.
   Inserted, tendinous,  into the outer side of the root
 of the  first phalanx 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  liga-
mentum carpi annulare, lying under  the abductor
pollicis. 
240
Muscles on the Palm.
  Inserted, tendinous and fleshy, into the under and
anterior part of the metacarpal bone of the thumb.
  Use. To bring the thumb inwards, opposite to the
other fingers.

          4. Flexor Brevis Pollicis Manus,
  Is divided into two portions by the tendon of the
flexor longus pollicis, and is placed beneath the ab-
ductor, and at the side of the opponens. It is divided
into two heads. The first arises fleshy from the volar
sides  of  the trapezium,  trapezoides, and from the
contiguous part of the internal surface of the annu-
lar ligament. The second head arises from the mag-
num,unciforme, and from the base of the metacarpal
bone of the middle finger.
  Inserted by the first head into the outer sesamoid
bone, and  by the  second into the inner sesamoid
bones.  These  bones acting the parts of patellae, by
having a  tendinous connexion with the first phalanx
of the thumb.
  Use. To bend the first joint of the thumb.

            5.  Abductor Pollicis Manus,
  Arises,  fleshy, from almost the whole length of the
metacarpal bone that sustains the middle finger; from
thence its fibres are collected together.
  Inserted, tendinous, into the inner part of the root
of the first phalanx of the thumb.
  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 
of the Hand.
211
  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 unci-
  forme, 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 unci-
  forme, and from the ligament of the wrist which joins
  with that bone.
    Inserted, by a roundish tendon, into  the inner and
  anterior part of the upper end of the  first bone of
  this finger.
    Use. To bend the little finger, and assist the ad-
  ductor.

          9, Abductor Minimi Digiti Manus,

    Arises, fleshy, from the os pisiforme, and from that
 part of the ligamentum carpmnnulare next it.
    Inserted, tendinous, into the inner side of the  upper
 end of the first bone of the little finger.
    Use. To draw this finger from the rest.

    The spaces between the metacarpal bones are oc-
 cupied by muscles, called, from their situation, inter-
 osseous.  The four following are to be seen on the
 palm of the hand.
   Vol. ..   *             :n 
242      Mitscles on (he 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 tendi-
nous expansion from the extensor digitorum commu-
nis, 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 in-
ner part of the metacarpal bone that  sustains the
fore finger.
   Inserted into the inner side of the tendinous expan-
sion 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 meta-
carpal bone that sustains  the ring finger.
   Inserted, into the outside of the tendinous expansion
of the  extensor digitorum  communis which covers
the ring finger.
   Use. To extend and pull the ring finger towards the
thumb.
            4. Interosseous Auricularis,
   Arises, from the root and  outer side of the meta-
carpal bone of the little finger;  and is
   Inserted into the outside of the tendinous expansion
of the extensor digitorum communis, which covers
the posterior part of the little finger.
   Use. To extend and draw the little finger outwards. 
          Muscles of the Back of the Hand.       243

   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 meta-
 carpal bones that sustain the fore and middle fingers
 externally,  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  expan-
 sion from the extensor digitorum communis, which
 covers the posterior part of the middle finger.
   Use. To extend,  and to draw the middle  finger
 outwards.
                 2. Posterior Medii,
   Arises, by two origins, from the roots of the meta-
 carpal bones, next each other, that sustain the mid-
 dle and ring fingers.
   Inserted into the inside of the tendinous expansion
 from the extensor digitorum  communis, which runs
 along the posterior part of the middle finger.
   Use. To extend and draw the  middle finger in-
 wards.
              3. Posterior Annularis,
   Arises, by two origins, from the roots  of the meta-
 carpal bones that sustain the ring and little fingers,
next each other.
   Inserted into the inside of the tendon on the back
 of the ring finder.
   Use.  To  draw the ring finger inward.
.  The following muscle also appears on the back of
the hand.
             Abductor Indicis Manus,
   • Irises, from the os trapezium, and  from the supe-
rior part and inner  side of the metacarpal bone of
the thumb. 
244          Muscles of the Os Femoris.

  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.
       MUSCLES OF THE INFERIOR EXTREMITIES.
  These may be divided into the muscles situated on
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 behind.
  The layer  before consists of five muscles:
  1. Psoas Magnus.     > gee      215
  2. Iliacus Internus.     )
                   3.  Pectinalis,
  Arises, broad and fleshy, from the upper and ante-
rior part of  the os pubis or pectinis, immediately
above the foramen thyroideum.
   Inserted into the anterior and upper  part of the li-
nea aspera of the os femoris, a little below the tro-
chanter minor, 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.
    Inserted, tendinous,  near the  middle of the  poste-
 rior part  of the linea  aspera, being continued for
 some way down. 
Muscles of tiie Os Femoris.          'lib
            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 inser-
tion 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
aspera; 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 artery 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 directions of their fibres;  and,  in some de-
gree, to roll the thigh outwards.

               5. Obturator Externus,
  Arises, fleshy, from the lower  forepart of the os
pubis,  and forepart 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 collected  like rays towards a centre,
and pass outwards around the root of the back part
of the cervix of the os femoris.
  InsrrleJ by a  strong tendon, into the  cavity at the
inner and back  part of the root of the trochanter ma-
jor, adhering in its course to the capsular ligament of
the thigh bone. 
246          Muscles of the Os Femoris.

   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 exter-
nal side of the os  sacrum, below the posterior spi-
nous process of the os ilium; from the posterior sa-
cro-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 vagince femoris.
  Inserted, by a strong, thick, and broad tendon into
the upper and outer part of the linea aspera, which
is continued from the trochanter  major, for some way
downwards, as far as the origin  of the short head of
the biceps flexor cruris—and  also into the fascia fe-
moris.
   Use. To extend the thigh, by pulling  it  directly
backwards, and a little outwards.
  Second layer,

                  Gluteus Medius,
  Arises, fleshy, from the anterior superior  spinous
process 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. 
             Muscles of the Os Femoris.          247

   Inserted, by a  broad tendon, into the outer and
 upper margin of the trochanter major.
   Use.  To draw the thigh bone outwards, and a lit-
 tle backwards; to roll the thigh bone outwards, es-
 pecially 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 up-
 per 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 gra-
dually  narrower,  it 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 tro-
chanter major.
   Use.  To move the thigh a little upwards, and roll
it outwards. 
248             Muscles of the Leg.
                    3. Gemini,
  Arises, by two distinct origins; the superior from
the spinous process, and the inferior from the tube-
rosity of the os ischium;  also, from  the posterior
sacro-ischiatic ligament.   They are  both united by
a tendinous  fleshy  membrane, and  form  a purse
for the tendon of the obturator 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 os ischium over
which it passes; also, to hinder it  from starting out
of its place, while the muscle is in  action.

               4. Quadratus  Femoris,

  Arises, tendinous and fleshy,  from  the outside of
the tuberosity of the os ischium; and, running trans-
versely, 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.

            Muscles situated on the Thigh.

   These are  called muscles of the leg; and consist
of one, on the outside; two,  on the inside ; four, before;
and four, behinel.  .
   Previous to the description of the muscles that are
situated 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 tendon of the
glutei and adjacent muscles. 
                Muscles on the Thigh.            249

   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 appear-
 ance of  cellular substance,  than a tendinous mem-
 brane.  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 Vaginae Femoris,

   Arises, by a narrow, tendinous, and  fleshy begin-
 ning, 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 outside of the thigh.
   Use. To stretch the membranous fascia, to assist
 in the abduction of the thigh, and somewhat in its
 rotation inwards.
  On the inside are,

                   1. Sartorius,

  Arises, tendinous from the anterior superior spi-
 nous process of the  os ilium, soon grows fleshy, runs
 down for some space upon  the rectus, and going ob-
 liquely 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 ten-
don of the adductor magnus and that of the gracilis
muscles.
  Vol. i.               32 
250            Muscles on the Thigh.

  Inserted, by a broad and thin tendon, into the inner
side of the tibia, near the  inferior  part of its tu-
bercle.
  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 sarto-
rius.
  Use. To assist the sartorius.
  Before are,

                    1. Rectus,

  Arises, fleshy,  from  the inferior  anterior spinous
process of the os ilium, and tendinous from the  dor-
sum 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  out-
wards and inwards, from a tendon in  the middle.
  Inserted, tendinous, into the upper part of the pa-
tella, from which a thin tendon runs down, on the
forepart 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 pulley.

               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 in-
sertion of the gluteus  minimus, the whole length of 
               Muscles on the Thigh.           251

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
patella; and part of it ends in an aponeurosis, which
is continued 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 fore-
part of the os femoris and root of the trochanter mi-
nor, and from almost all the inside of the linea as-
pera,  by fibres running obliquely forwards and down-
wards.
  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.

                   4.  Crura lis,

  .Irises, fleshy, from  between the two trochanters
of the os femoris, but nearer the  minor, and firmly
adhering to most  of the forepart of the os femoris,
and connected to both vasti muscles.
  Inserted, tendinous, into the upper  part of the pa-
tella, behind the rectus.
  lisc. 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. 
252            Muscles on the Thigh.

  Behind are,

                1. Semitendinosus,

  Arises, tendinous and fleshy, in common with the
long head of the biceps, from the posterior  part of
the tuberosity 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 bend the leg backwards and a little in-
wards.

               2.  Semimembranosus,

  Arises,  tendinous, from  the upper and posterior
part of the tuberosity of the os ischium; sends down
a broad flat tendon, which ends in a fleshy belly, and,
in its descent, runs at first on the forepart of the bi-
ceps, and lower, between it and the  semitendinosus.
  Inserted, tendinous, into the inner and back part of
the head of the tibia.
  Use. To bend the leg,  and bring it directly back-
ward.
  N B.  The two last form what is called the inner
hamstring.

              3. Biceps Flexor Cruris,

  Arises,  by two  distinct heads.  The first,  called
longus, arises, in common  with the  semitendinosus,
from the upper  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 is descends to join with
the first head, a little above the  external condyle of
the os femoris. 
                Muscles on the Leg.             253

  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
hamstring;  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 car-
tilage.  As it  runs over the joint, it becomes fleshy,
and the fibres run obliquely inwards,  being covered
with a thin tendinous membrane.
  Inserted, broad, thin, and fleshy, into a ridge at the
upper 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 situated on the Leg.
    These muscles may be arranged in the two general classes
      of flexors and extensors of the foot, and flexors and ex-
      tensors of the toes; but several of them, viz. the tibiales
      and the  peronei, produce effects which  are  different
      from flexion or extension.  For the accommodation of
      the student of anatomy, they may be studied in  the or-
      der of their position as they lie on the front, on the out-
      side, and  on the back of the leg.

           Muscles on the  Front of the Leg.
                 1. Tibialis Anlicus,
   Arises, tendinous  and  fleshy, from  the middle of
that process of the tibia, to which the fibula is con-
nected above: then it runs down fleshy on the outside
of the tibia;  from which, and the upper part of the 
254            Muscles on the Leg.
interosseous ligament, it receives a number of dis-
tinct fleshy fibres; near the extremity of the tibia, it
sends off a strong round tendon, which passes under
part of the  ligamentum tarsi annulare near the mal-
leolus internus.
   Inserted, tendinous, into the inside of the os  cunei-
form 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 begin-
ning, some way below the head and anterior part of
the fibula, along which it runs to near its lower ex-
tremity, connected to it by a number of fleshy  fibres,
which descend obliquely towards a tendon.
   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
outer part of the head of the tibia, and from the head
of the fibula where it joins with the tibia, and from
the interosseous 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 length, where it is inseparable from the
peroncus tertius. It splits into four round tendons, un-
der 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. 
                Muscles on the Leg.            255

   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 forwards to  a tendon, which passes under the
annular ligament, and is
   Inserted into the root of the metatarsal bone that
sustains the little toe.
   Use. To assist in bending the foot.

          Muscles on the outside of the Leg.
                 Peroneus Longus,
   Arises, tendinous and fleshy, from the forepart of
the head of the perone, or fibula, the fibres rupning
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 number 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
sinuosity of the  os calcis, it runs along a groove in
the os cuboides, 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 cuneiform  inter-
num.
   Use. To move the foot outwards, and to extend it
a little.
                2. Peroneus Brevis,
   .Irises, by an acute  fleshy beginning, from above 
256             Muscles on the Leg.

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 run-
ning obliquely outwards towards a tendon on its ex-
ternal 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.
   Use. To assist the former in pulling the  foot out-
wards, 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 fe-
moris.  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  up-
per and back part of the  head of the fibula, continu-
ing to receive many of its fleshy fibres from the pos-
terior  part  of that  bone  for some space  below  its
head.   The  other origin  begins from  the posterior
and upper part of the middle of the tibia;  and runs 
          Muscles on the Back of the Leg.       257

inwards along the inferior edge of the] popliteus to-
wards the inner part of the tibia,  from which it re-
ceives fleshy fibres for some way  down.  The flesh
of this muscle, covered by the  tendon of the gemel-
lus, runs down nearly as far as  the extremity of the
tibia; a little above which the  tendons of both gas-
trocnemii unite, and form a strong round chord, which
is called tendo Achilles.
  Inserted into the wpper and posterior part of the os
calcis, by the projection of which the tendo Achillis
is at a considerable distance from the tibia.
   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 fe-
moris, near  the inferior extremity of that bone, ad-
hering to the ligament that involves the joint in its
descent.   It passes along the second origin of the so-
leus 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 capsu-
lar ligament of the knee from between the bones.
It seems  likewise to assist in rolling the foot in-
wards.

    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 be-
low its head, near the entry of the medullary artery;
which beginning is continued down the inner edge
   Vol. i.               33 
258
Muscles on the Foot.
of this bone by short fleshy fibres, ending in its ten-
don ;  also by tendinous and fleshy fibres, from  the
outer edge of the tibia, and between this double or-
der of fibres, the tibialis posticus muscle lies enclos-
ed.  Having passed under two annular ligaments, it
then passes through a  sinuosity at the inside of the
os calcis; and, about the  middle of the sole of the
foot, divides into four tendons, which  pass  through
the slits of the  perforatus; and, just before its divi-
sion, it receives a  considerable  tendon from that of
the flexor pollicis longus.
  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 pro-
cess which joins it to the fibula; then passing through
a  perforation in the upper part of the interrosseus
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 in-
ternus.
  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 cu-
boides, and to the root of the metatarsal bone that
sustains the middle toe.
   Use. To extend  the  foot, and to turn the  toes in-
wards. 
Micscles on the Foot.
259
         6. Flexor Longus Pollicis Pedis,

  Arises, by  an acute, tendinous, and fleshy begin-
ning, 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 an-
nular 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 mus-
cle, viz.

          Extensor Brevis Digitorum Pedis,

  Arises,  fleshy  and  tendinous,  from  the fore  and
upper part of the  os calcis;  and soon forms a  fleshy
belly, divisible 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 tendi-
nous expansion from the extensor longus which co-
vers the small toes, except the  little one; also into
the tendinous  expansion  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 A/ioneurosis Plantaris, which originates from
     the  tuberosity of the os  calcis, and proceeds forward to
     the  toes, increasing gradually in brearlth.
    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 
260         Muscles on the Sole of the Foot.
  outside which covers the abductor and the flexor of the
  little toe is next in size.  The internal portion, which co-
  vers 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 tho
  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 tendons, nerves, and ar-
  teries pass between them.
Immediately under the middle portion of this aponeurosis
  are the common short flexors of the toes, viz.
 1.  Flexor Brevis Digitorum  Pedis,  Sublimis Per-
                      foratus,

   Arises, by a narrow fleshy beginning, from the in-
ferior and posterior part of a protuberance of the os
calcis, between 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 Carean
                   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 spade  on the  same
bone;  also by a thin  tendinous beginning,  from be-
fore the  tuberosity of the os calcis externally; and,
soon becoming all fleshy, is
   Inserted into the tendon of the flexor  longus, just
it its division into four tendons.
   Use. To assist the  flexor longus. 
          Muscles on the Sole of the Foot.       261

               3. Lumbricales Pedis,
  Arise, by four tendinous and fleshy beginnings, from
the tendon of the flexor profundus, just before its di-
vision, 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 tendinous expansion that is sent from the exten-
sors to cover the upper part of the toes.
   Use. To increase the flexion  of the  toes, and to
draw them inwards.
  On the inside of the foot, and under the common
flexors, are the muscles which are considered as ex-
clusively 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 tuberosity to the sheath of the tendon of
the tibialis posticus muscle, and also from the inter-
nal and inferior side of the os naviculare and cunei-
form  internum.  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 ap-
pear to be connected 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 tendinous.
  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 bones 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. 
262        Muscles on the Sole of the Fool.
           2. Flexor Brevis Pollicis Pedis,
   Arises, tendinous, from the under and  forepart 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 internal  and  external sesamoid
 bones, along with the abductor and adductor pollicis
 and into the root of the first joint of the great toe.
   Use. To bend the first joint.
             3.  Adductor Pollicis Pedis,
   Arises, by a long thin  tendon, from the os calcis,
 from  the os cuboides, from the os cuneiforme exter-
 num, 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
 portion 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 protube-
 rance of the os calcis, and from the root of the meta-
tarsal 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 sul-
cus or furrow for lodging the tendon of the peroneus 
             External Interosseous Muscles.        263

longus;  fleshy from the outside of  the  metatarsal
bone that sustains the little toe, below its protuberant
part.
   Inserted, into the anterior extremity of the metatar-
sal bone, and root of the first joint of this toe.
   Use. To bend this toe.

    Between the metatarsal bones are four external and three in-
      ternal 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 in-
ternum.
   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
metatarsal 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
metatarsal 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. 
264         Internal Interosseous Muscles.
           4. Adductor Tertii Digiti Pedis,
  Arises, tendinous and fleshy, from the roots of the
metatarsal 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.

              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 inter-
nally.
  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
inferior part of the rbot 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 tho
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 ante-
rior extremity of the metatarsal bone of the great toe, 
            Internal Interosseous Muscles.         265

and from the  internal os sesamoideum of the first
joint, adhering 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.
Vol. i.
34 
ALPHABETICAL ARRANGEMENT
MUSCLES.
                         Page
ABDUCTOR   indicis
         manus,           243
       indicis pedis,       264
       minimi digiti ma-
         nus,             241
       minimi digiti pedis, 263
       oculi,              177
       pollicis manus,     239
       pollicis pedis,      262
       medii digiti pedis,  265
       tertii digiti pedis,    ib.
Accelerator urinae,        208
Adductor brevis femoris,  246
       indicis pedis,       264
       longus femorus,     245
       medii digiti pedis,  264
       magnus femoris,    246
       metacarpi minimi
         digiti  manus,     241
       oculi,              177
       pollicis manus,     240
       pollicis pedis,      263
       tertii digiti pedis,   265
Anconeus,                232
Ani sphincter,             213
  levator,                  ib.
Anterior auris,             274
Arytenoideus obliquus,    195
           transversus,     ib.
Arytseno-epiglottideus,      ib.
Attollens aurem,          174
Auris  retrahentes,          ib.
Azygos uvulae,             192
Biceps flexor cubiti,       230
         flexor  cruris,     252
Brachialis internus,       231
Buccinator,               181
Capitis obliquus superior, 226
Capitus obliquus inferior,  ib.
Cervicalis descendens,     222
Circumflexus, or Tensor
  palati,                  190
Clitoridis erector,
Coccygeus,
Colli longus,
       transversalis,
       semispinalis,
       interspinales
Page
 222
 217
 196
 225
 224
 227
       intertransversales,   ib.
Complexus,               222
Compressor naris,         176
Constrictor isthmi   fau-
               cium,     191
            pharyngis,  192-3
Coraco-brachialis,         229
Corrugator supercilii,     173
Cremaster,               207
Crico-arytenoideus late-
         ralis,             194
      arytenoideus pos-
         ticus,            195
       thyroideus,         189
Cruralis,                  251
Cubit, or fore-arm, mus-
       cles of,             234
Cucullaris,                217
Cutaneus,                185
Dartos,                   207
Deltoides,                229
Depressor anguli oris,     180
          labii inferioris,  181
          labii superioris
            alseque nasi,  180
          oculi,           177
Diaphragma,              213
Digastricus,               186
Dorsi interspinales,        228
       latissimus,          219
Dorsi spinalis,            221
Dorsi longissimus,        222
       semispinalis,        224
Erector clitoridis,          211
      penis,               206
Extensor  brevis  digito- 
Alphabetical Arrangement of the Muscles.     267
rum pedis,	260	Flexor parvus minimi di	-
Extensor carpi radialis		giti manus,	241
brevior,	236	profundis perfo«	
carpi radialis Ion-		rans,	235
gior,	ib.	sublimis perfora-	
carpi ulnaris,	237	tus,	234
digitorum com-		Gastrocnemius externus,	256
munis,	ib.	internus,	ib.
longus digitorum		Gemellus,	ib.
pedis,	254	Gemini,	248
ossis metacarpi		Genio-hyo-glossus,	187
pollicis manus,	238	Genio-hyoideus,	186
primi internodii		Gluteus maximus,	246
pollicis manus,	ib	medius,	ib.
proprius pollicis		minimus,	247
pedis,	254	Gracilis,	250
secundi internodii		Humeri os, muscles si-	
pollicis manus,	238	tuated on,	230
Extremities superior,		Hyo-glossus,	187
muscles of,	228	Jaw, lower, muscles of,	183
inferior, mus-		Iliacus internus,	216
cles of,	245	Indicator,	238
Eyeball, muscles of,	176	Infra-spinatus,	228
Eyelids, muscles of,	175	Inter-costales externi,	198
Faucium isthmi constric-		interni,	199
tor,	191	Interosseus auricularis,	242
Flexor accessorius digi*		Interspinales colli,	226
torum pedis,	261	dorsi et lumborum	, 227
brevis digitorum		Intertransversales colli,	226
pedis,	ib.	dorsi,	227
brevis minimi di-		lumborum,	ib.
giti pedis,	263	Isthmi faucium constric-	
brevis pollicis ma-		tor,	181
nus,	240	Labii inferioris depres-	
brevis pollicis pe-		sor,	171
dis,	263	inferioris levator,	ib.
Flexor longus digitorum		superioris alaeque	
pedis,	260	nasi levator,	171
carpi radialis,	234	Latissimus dorsi,	ib.
carpi ulnaris,	I*.	Leg, muscles situated on,	260
longus pollicis ma-		Levator anguli oris,	179
nus,	235	ani, 210-12	
longus pollicis pe-		labii inferioris,	181
dis,	260	labii superioris,	
ossis metacarpi	1	alaeque nasi,	179
pollicis,	239 |	oculi,	17i7
 
268    Alphabetical Arrangement of the Muscles.
palati	190	Palati levator,	190
Levator palpebrae supe-		tensor,	ib.
rioris,	176	Palato-pharyngeus,	191
scapulae,	223	Palmaris brevis,	239
Lingualis,	187	longus,	233
Lips, muscles of,	179	Palpebrae superioris le-	
Longissimus dorsi,	221	vator,	176
Longus colli,	196	Palpebrarum orbicularis,	175
Lumborum intertrans-		Pectinalis,	244
versales,	228	Pectoralis major,	197
Lumborum quadratus,	316	minor,	198
Lumbricales manus,	240	Penis erector,	208
pedis, Masseter,	262	Perinei transversus, 208-12	
	184	Peroneus brevis,	255
Mouth, muscles of,	179	longus,	ib.
Multifidus spinse,	228	tertius,	254
Musculus cutaneus,	185	Pharynx, muscles on the	
Mylo-hyoideus,	180	posterierpart	
Nar is compressor,	178	of it,	193
Nose, muscle of,	ib.	constrictor,	ib.
Obliquus ascendens in-		Plantaris,	258
ternus,	204	Platysma myoides,	185
capitis inferior,	225	Popliteus,	253
capitis superior,	ib.	Posterior annularis,	243
descendens exter-		indicis,	242
nus,	150	medii,	243
inferior oculi,	168	Prior annularis,	242
superior, seu tro-		indicis,	ib.
chlearis,	177	medii,	243
Obturator interims,	216	Pronator radii quadratus,	230
externus,	245	teres,	233
Occipito-frontalis,	173	Psoas magnus,	215
Oculi abductor,	177	parvus,	ib.
adductor,	ib.	Pterygoideus externus,	184
depressor,	ib.	internus,	ib-
levator,	ib.	Pyramidalis,	206
obliquus inferior,	178	Pyriformis,	247
superior,	177	Quadratus femoris	248
Omo-hyoideus,	188	lumborum,	215
Opponens pollicis,	240	Rectus,	250
Orbicularis oris,	182	abdominus,	205
palpebrarum,	175	capitis internus major,	190
Oris anguli depressor,	180	internus minor,	ib.
levator anguli,	179	lateralis,	171
orbicularis,	182	posticus major,	224
Palati circumflexus.	190	posticus minor,	225
 
Alpltabetical Arrangement of the Muscles.    269
Retrahentes auris,        174
Rhomboideus,            219
Salpingo Pharyngeus,     192
Sacro-lumbalis,           221
Sartorius,                249
Scalenus anticus,         225
Scalenus medius,         226
         posticus,         ib.
Scapulae levator,          223
Semimembranosus,       252
Semispinalis colli,        224
            dorsi,        225
Semitendinosus,          252
Seminis ejaculator,       208
Serratus magnus,         198
         posticus inferior, 219
Serratus posticus supe-
         rior,             220
Soleus,                   257
Sphincter ani,         210-12
          vaginae,        211
Spinalis dorsi,           221
Spinae multifidus,         224
Splenius,                211
Splenius, capitis,         227
         colli,              ib.
Sterno-cleido-mastoideus, 185
Sterno-hyoideus,         188
Sterno-thyroideus,         ib.
Stylo-glossus,            189
Stylo-hyoideus,             ib.
Stylo-pharyngeus,        190
Subclavius,              197
Subscapularis,            230
Supercilii corrugator,     173
Supinator radii brevis,    237
Supinator longus,         236
Supra-spinatus,           227
Temporalis,              183
 ! ensor palati,            190
       vaginae femoris,    249
Teres major,              229'
Teres minor,             228
Thigh, muscles  situated
         on,              248
Thyreo-arytenoideus,     194
Thyreo-epiglottideus,     195
Thyreo-hyoideus,         188
Tibialis anticus,           223
         posticus,        259
Trachelo-mastoideus,     222
Transversalis,            205
         colli,            225
         pedis,           265
Trausversus perinei,   208-12
Trapezius,  seu Cucullaris, 218
Triangularis,             200
       or Sterno-costalis,   ib.
Triceps adductor femoris, 244
       extensor cubiti,    232
Vastus externus,          250
        internus,           251
Urinae accelerator,        208
Uvulvae azygos,           192
Zygomaticus major,      180
              minor,      183 
SYSTEM OF ANATOMY*

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

                 CHAPTER I.

            OF LIGAMENTS IN  GENERAL.

  The tendons and the strong membranes connect-
ed 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 ex-
tremely strong, and in general have but little elasti-
city ; their surfaces are smooth and polished; their
colour is whitish and silver-like.
  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. 
              Of Ligaments in general.          271

   In a healthy state,  they are entirely void of sensi-
bility, and can be cut and punctured, or corroded
with caustic applications, without pain.   When in-
flamed,  they are extremely 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 in-
clines to a dull white, and when examined chemical-
ly, they appear to differ in some respects from ten-
dons.
   They agree however with the tendinous parts  as
to their insensibility in a sound  state, and the ex-
treme 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 ani-
mals who seem to suffer no pain from cutting, punc-
turing, 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  instantaneously 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, ap-
pears to have considered them as formed of mem-
brane, while a late writer who has paid great atten-
tion to the subject, and is also of high authority, M.
Bichat,  has satisfied himself  that their structure  is
essentially fibrous. 
272          Of Ligaments in general.
   If a tendon, or 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 converted into a fine membrane, and the fibres
 will disappear to the naked eye.  The same circum-
 stances will occur when a ligament is treated in a
 similar way; but much more force is required.
   Thus constructed,  these parts  are  perfectly pas-
 sive portions 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 in-
 flammations; and hectical 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 ordina-
 ry insensibility.   They are the most common seats of
 gouty painful affections.
  In these cases, pain does not seem to be the simple
 effect of inflammation;  it  often  occurs as the first
 symptom  of the  disease;  it frequently exists with
 great violence for a short time and goes off without
 inflammation, and it is frequently vicarious with af-
 fections 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 circumstances which attend  wounds.
  When thus deprived of life, they retain their usual
 appearance and their texture a long time. The dead
 parts separate from the living in large portions, in a
way which has a considerable analogy with the ex-
foliation of bones. 
              Of Ligaments in General.          273

  The tendons and their expansions, and the various
fasciae,  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 a very long boil-
ing.   The  composition of the part so insoluble in
water, has  not yet been ascertained.
Vol. r
35 
CHAPTER II.
A GENERAL ACCOUNT OF ARTICULATIONS  AND OF BUR9.E
                     MUCOSAE.

                    SECTION I.

                 Of Articulations.

  Those surfaces of bones which form the moveable
articulations  are covered with cartilaginous matter,
which has been already described.*  They are re-
tained in their relative situations by ligaments, such
as have been lately mentioned, which are exterior to
the cavities of the articulations, 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 delicate  membrane,
which in some joints, as those of the hip and shoul-
der, seems to be the internal lamina of a stronger li-
gament 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; adhering firmly to each of the
articulating surfaces, and extending loosely from the
margin of one surface to that of the other.
  In the distribution it  supplies the place of  peri-
chondrium to the  cartilages, and of periosteum to
those surfaces of bone with which it is connected.
  It seems greatly to resemble the membranes which
See page 3. 
             Of Articulations in General.         275

 line the abdomen and thorax, and invests  the parts
 contained in these cavities; and like them it may be
 termed a reflected 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 con-
 sistence 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 vicidity.   It appears 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 perito-
 neum.
   They are generally situated so as to be pressed
 gently, 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 blood vessels
 spread upon them.  Small processes often project from
 their side 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 the membrane.
   The  synovial membrane, like the other  parts of
joints, is insensible in a sound state, but  extremely
painful when  inflamed.  The synovia, which is se-
 creted,  during the inflammation of this membrane,
 has a purulent appearance. 
2*76             Of ButwMitoom
                    SECTION II.

                 Of Bursa; Mucosa;.

  There are  certain  membranous cavities called
bursae 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 now to be
mentioned.
  They are formed of  a thin dense membrane,  and
are attached  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 mucosae 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 Bursar  Mucosae  of
the Human Body, by Alexander Monro; to whom the world is so much
indebted tor the elucidation of many important points in anatomy and
physiology. 
CHAPTER III.
          OF PARTICULAR ARTICULATIONS.

    The connexion of the Hand with the Vertebrae.

  The condyles of the occipital bone, and the cor-
responding cavities  of the atlas, are covered with
cartilage.  The condyle and cavity on each side are
invested  with a synovial ligament, as decribed 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 inserted 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 tooth-like
process of the vertebra dentata, a ligament passes
upwards and  outwards, to be inserted into the  inter-
nal  side of the basis of each condyle of the occipital
bone.
  From  the  anterior margin of the great occipital
foramen, a ligament passes down on the inside  of
the vertebral cavity, over the tooth-like 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
tooth-like process in its anterior cavity.   This liga-
ment adheres above; to the occipital bone,and below
to tiie body of the vertebra dentata.  The  anterior 
278
Particular Articulations.
surface of the tooth-like process plays on the anterior
arch of the atlas; the posterior surface plays on this
ligament.   A synovial  capsule  is  placed on each
surface of the tooth-like 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 effect 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 artic-
      ulation for the tooth-like 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 of the Vertebrae 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 ca-
      nal may be laid open.

  The bodies of all the vertebrae, except the atlas,
are connected to each other by the intervertebral car-
tilaginous matter described in page 77, which unites
them very firmly, at  the same time  that it allows of
some  motion, in consequence of its elasticity and
compressibility.   This connexion is strengthened by
two ligaments, which extend the whole length of the
spine, from the second cervical  vertebra to the sa-
crum.
  The first of these, denominated the anterior verte-
bral ligament, covers a considerable part of the an-
terior surface of the bodies  of the  vertebrae;  it is
thickest in the middle, and varies in its  breadth, in 
           Articulations of the Vertebrte.         279

different parts of the  vertebral  column;  it adheres
very firmly to the intervertebral substance, and not
so firmly to the bodies of the vertebrae.   It has the
shining silver-like appearance of tendon,  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  ver-
tebrae, in the cavity which contains the spinal mar-
row, is the posterior or internal vertebral ligament,
which, like the anterior, extends from the upper part
of the spine to the sacrum.
  In its progress downwards it  is broader where it
is in contact with the  intervertebral matter, and nar-
rower about the  middle of each of the bodies of the
vertebrae.  It appears to consist of longitudinal ten-
dinous fibres, which are similar to those of the ante-
rior ligament.
  The oblique processes of the vertebrae are covered
with cartilage, and  arc invested with a synovial mem-
brane, like the other moveable articulations.  In the
neck and back these membranes are thin and  deli-
cate ; but in the loins they are blended with ligament-
ous 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 attached to the bony plates or arches that ex-
tend from the oblique to  the spinous processes of
each  vertebra.   These plates  form a great portion
of the posterior part of the vertebral  canal; and the
vacant spaces between them are filled up by these
ligaments, which extend from the plates of each up-
per vertebra to those of the next vertebra below.
  They arc situated between the spinal process and
the oblique processes on each side.
  There are, therefore, two distinct ligaments be-
tween the two vertebrae, one on  each side of the
spinal process; and as they extend  only from the 
 280         Articulations of the Vertebral.

 plates or arches of  one vertebra to those of the
 other, they must necessarily be  very  short.  They
 are much more conspicuous on the internal surface
 of the vertebral cavity than they are externally. They
 are thick and substantial, and very elastic; their co-
 lour 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  con-
 nected must  recede from each other, when the spine
 is bent forwards, 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 process to the upper surface of the spi-
 nous process below it.  These  are composed of ten-
 dinous shining fibres,  and are sufficiently loose  to
 permit the  anterior flexure of the vertebral  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
 cervical vertebra to the spinous processes of the os
 sacrum, and adheres to the ends  of the intermediate
 spinous processes.  It is  exterior to  the  tendinous
 origins of the trapezii and latissimi dorsi muscles.
 The upper  portion is  slightly connected to  the tra-
 pezius, the  lower part  adheres more  firmly to the
 latissimus dorsi.
  The ligamentum nuchce, as it  has been denomina-
 ted, 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 seventh cervical vertebra,
 originates from it, or is intimately connected with it; 
             Arttcutatiojt of the Lower Jaw.       281

and a portion of the splenius muscle is also connect-
ed with it.
   From the internal  surface of this ligament, a thin
tendinous  membrane arises, whose  fibres run  ob-
liquely upwards and forwards,  and are  inserted into
the spinous processes of each  of the cervical verte-
bras above the seventh, and  also into the atlas and
the os occipitis.   Attached to  the ligamentum  nu-
chae 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 ob-
     vious that the yelloiu ligaments are among the most important of them;
     in consequence of their position, their strength, and their elasticity.

           Articulation of the Lower Jaw.
   The glenoid cavity of the temporal bone with the
tubercle before it, and the condyle of the lower jaw,
arc covered  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 extended.  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 attached 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 tem-
poral bone, over both synovial capsules and the car-
tilage  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
external  and internal  sides of the articulation, that
they have been called the external and internal  la-
teral ligaments.
   Another ligament is mentioned which arises from
   Vol. i.                36 
282
Articulation of the Shoulder.
the styloid process of the temporal bone, and is  in-
serted into the lower jaw near its angle; but this
seems rather appropriated to the stylo-glossus mus-
cle than to this articulation.
  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  re-
sembles strongly that of the lower jaw and temporal
bone.  A moveable cartilage is placed between the
articulating surfaces, 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 ster-
num.   Exterior to these  capsules and the interve-
ning cartilage, are many  ligamentous fibres, which
are most numerous on the anterior and posterior sur-
faces, but diverge from  each other as they proceed
from the clavicle to the  sternum, and are  therefore
called Radiated Ligaments.
  There is a strong  ligament,  called  the  Interclavi-
cular,  which passes  across the sternum  internally,
from one clavicle to the other,
  And another ligament,  which arises from the in-
ferior rough surface of the clavicle, near the sternum,
which is inserted into the  cartilage of the first rib.
  This is called the Rhomboid,  or Costoclavicular li-
gament.

      Articulation of the Clavicle and Scapula.
  The small  surfaces of the  clavicle and scapula,
which are in contact with each other, are furnish-
ed  with  the  apparatus  of a moveable 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 
             . irtieulalion of the Shoulder.         283

 and acromion arc 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 liga-
 ment are so arranged that they have the appearance
 of an inverted cone: the remaining fibres appear like
 another ligament, and therefore they have been called
 the  Trapezoid and Conoid ligaments.
   By their situation and  strength  they are enabled
 to retain 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 prin-
 cipally concerned 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  the  dried bone when  compared  with the
 head of the os humeri, is enlarged  by the long ten-
 don  of the biceps muscle, which is attached  to the
 upper edge of its  margin, and then divides and pass-
 es 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 per-
fectly regular and uniform.
  The synovial ligament,  in this  articulation, is so
blended with  an  external stronger  ligament,  that it
cannot be separated in the recent subject; but not-
withstanding, it  is applied to the articulating sur- 
284         Articulation of the Shoulder.

faces in the same way that it is applied to the other
joints forming a capsule.  The stronger exterior la-
mina is of course only applied to that part of the sy-
novial capsule which proceeds from the margin of one
cartilaginous articulating surface to the other: it ap-
pears to be most intimately connected with the perios-
teum, and is rendered more firm and thick in particu-
lar parts, by the addition of fibres from the tendons of
the supra  and infra spinatus, and subscapularis mus-
cles  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 articulating surface; and, if dissected
away from the bones, would appear like  a cylindri-
cal bag with both extremities open.
   The  long tendon of the biceps muscle,  in the
groove at the head of the os humeri, appears to pe-
netrate this ligament; but it is not within the cavity
of the  synovial  membrane; 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 covers  it during its
whole  extent, being reflected from the  tendon, at
its upper  termination, to the adjoining surface; so
that the tendon is in fact outside of the synovial cap-
sule, which,  therefore,  confines  the  synovia com-
pletely.
   This 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 disposed in such a manner that,
when the  muscles act, their power is excited to the
same effect.  In  some cases of paralytic affection,
where  the  muscles exert no influence, the weight of
the arm, when it is allowed to hang without support, 
            Articulation of the Elbote.           285

draws the head of the os humeri below the glenoid
cavitv. notwithstanding the capsular ligament.  At
the same time it ought to be observed, that this liga-
ment must be lacerated  in every case of complete
luxation of the os humeri; as it cannot possibly dis-
tend 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 car-
tilage.
  The motion of the ulna and radius on the os hu-
meri is that of the 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 surface  covered with cartilage on each of the
bones, and is reflected from the margin of  this sur-
face, on one bone, to that of the others. As the prin-
cipal motion performed is  hinge-like, the principal
ligaments are on the sides.  There  is also a circular
ligament, which arises from the uljia and invests the
narrow part of the radius immediately below its cy-
lindrical head, like a loop, to  confine the radius in
contact with the ulna, and at the same time permit
its motion.
  This ligament is so blended with the  synovial
membrane that it  sometimes cannot  be  separated
from it.
  The lateral ligaments are denominated from their
origin and insertion, Brarhio-radial, and Brachio-cuhi-
tal, or Internal and External. The ligament which in-
vests the neck of the radius is called Coronary, or
Orbicular. 
286          Articulation of the Wrist.

   There are also some ligamentous bands, which run
upon the front and back parts of the joint to strength-
en it, which  are called Anterior and Posterior acces-
sory ligaments.   Within the synovial  membrane, in
the upper margins of the depressions for the olecra-
non and coronoid processes of the ulna, are the adi-
pose  substance usually formed in joints.

             Articulation of the Wrist.
    The structure of the wrist is particularly complex, be-
      cause it consists of three articulations, which are conti-
      guous 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 uni-
form  that the different bones cannot be distinguish-
ed 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 this head therefore is under
the ulna, but not in contact with that bone: for the
cartilage which lines  the concavity of the radius, is
continued beyond the radius, so as to cover the re-
mainder of the head,  formed by  the  carpal bones.
The lower end of the ulna is in contact with the up-
per surface of this cartilage, and is articulated late-
rally with the semilunar cavity of the radius.  This
semilunar cavity is lined'by a cartilaginous process,
continued from the upper surface of the aforesaid
cartilage; so that the extremity and the side of the
ulna play upon the cartilage continued  from the ra-
dius.  This articulation of the ulna and radius is dis-
tinct from that of the radius and carpus.
   A synovial membrane covers the articulating head
formed by the three bones of the  carpus, and  is re- 
Articulation of the  Wrist.           287
fleeted 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 scaphoides and lunare,
to 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 os  pisiforme.
  Another  ligament,  on  the  external  side,  arises
from the styloid process of the radius, and is inserted
into the scaphoides, some of its fibres being continued
into the aforesaid transverse ligament, and the trape-
zium.
  There are two  broad irregular ligamentous mem-
branes : one of which arises from the anterior mar-
gin of the articulating surface of the radius; and the
other from the posterior margin.   One of them is in-
serted anteriorly, and the other posteriorly, into the
margin of the corresponding  surface of  the  sca-
phoides,  lunare, and cuneiforme.  They adhere to
the synovial  membrane; but in some places this
membrane appears through apertures which are in
them.
  The surfaces, by which the first and second rows
of carpal bones are articulated with each other,  are
very irregular.  The magnum and part of the unci-
forme form a prominent oblong head;  on each side
of which is a much lower surface, formed by the tra-
pezium and trapezoides  externally,  and the remain-
ing portion of the  unciforme internally.*
  The scaphoides, lunare,  and  cuneiforme, form a
cavity  which corresponds with this head, and  also
with the  lower surface  formed  by the  unciforme;
* The palm of the hand is supposed to present forward. 
288  Articulation of the Carpal and Metacarpal JI ones.

while another surface of the scaphoides is articulated
with the trapezium and trapezoides.  These corres-
ponding surfaces,  formed by the two rows of carpal
bones, irregular as they are, compose  but one  arti-
culation, which is  capable  of a limited flexion and
extension.  It has a synovial membrane, with two la-
teral ligaments, and an  anterior and posterior  liga-
ment : these last, however, are short, and can be best
examined from within, by cutting open the articula-
tion.
  The bones of each row move laterally upon each
other.  Their lateral  surfaces,  which are in contact,
are covered with  cartilage; and  the synovial sac
which exists between the first and second row  of
bones, sends off processes  between these  surfaces,
which are disposed like the ordinary synovial mem-
branes 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 mem-
branes, as the most moveable articulations are; but
the ligaments which connect these  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
restrain their motion; and these  bones  accordingly
move less  than the other two metacarpal  bones,
whose surfaces are better adapted for  motion.

            Articulation of the Fingers.
  The first joint of the fingers has  a large  synovial
membrane, wThich  invests the head of the metacarpal
bone and the corresponding cavities of the bones of 
Articulation of the Ribs.           289
 the first phalanx.  On each side is a strong lateral
 ligament, which arises 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, al-
 though 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 posteriorly: and anteriorly, under
 the flexor tendons, there is a soft, but thick ligamen-
 tous substance.  The metacarpal bone of the thumb
 differs greatly from the other metacarpal bones in its
 articulation with the wrist, as  respects its motions.
 The articulating surfaces are calculated  for  lateral
 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 pha-
 langes.

              Articulation of the Ribs.

   The ribs are connected to the bodies of the ver-
 tebrae and the intervertebral cartilages, by one arti-
 culation, and to the transverse processes of the ver-
 tebrae by another: these articulations have the ordi-
 nary 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 In-
ternal and External Transverse Ligaments; and also by
hgamenls which arise  from  the oblique  processes
   Vol. i.               37 
•290
Hip Joint.
These ligaments  permit the motions necessary for
respiration, and restrain all others.
   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 car-
tilages and the sternum; but this fluid is mostly to be
found in the pits,  on the lower extremity of the ster-
num.
                  The Hip Joint.

   The acetabulum is lined with cartilage: and the
brim or margin of it is much enlarged, and the cavi-
ty 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  un-
der part of the  notch  open.  The head of the os fe-
moris is covered  with cartilage, but the  depression
in it is still visible.   From this depression a  strong
ligament arises, which appears to pass into the  de-
pression, near the centre of the acetabulum; but ac-
tually terminates  in the lower edge of the cartilagin-
ous ring or margin, where it crosses over the notch,
and not in the bone.   The thin membrane with which
this ligament is invested extends to the centre of the
acetabulum, and has given rise to the opinion that
the ligament was  inserted in the bottom of the ace-
tabulum. There is therefore  an analogy between  the
termination of this ligament and that of the long ten-
don of the biceps flexor cubiti, at the glenoid cavity of
the scapula.*
  This ligament allows the head of the os femoris to
* See page 284. 
Knee Joint.                291
rise out of the acetabulum, but it is probably torn in
every luxation of the os femoris.
  The capsular ligament, which contains these articu-
lating parts, is the strongest in the  body.   It arises
around the acetabulum, near the basis of the carti-
laginous brim, but it does not adhere to the cartila-
ginous edge; and it is  inserted into the os femoris,
near the roots of the trochanters, 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  ligamen-
tous fibres.   The largest portion of these additional
fibres appears to arise  from the inferior anterior spi-
nous process of the ilium.
  The synovial membrane  forms the internal lamina
of this ligament:  it invests  the articulating  surfaces
in the usual manner, and being reflected from the in-
ternal 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  re-
flected 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 mat-
ter, near the termination of the aforesaid  internal
ligament, which is also exterior to the synovial mem-
brane: some of this can be  pressed out of the aceta-
bulum, at the vacuity in the notch under the cartila-
ginous margin.

             Articulation of the Knee.
  The synovial  membrane  of the knee joint is, in
some  places, without the support of a proper cap-
sular  ligament, or external lamen, so that it is ea-
sier distinguished in this articulation than  in many
others. 
292.
Knee Joint,
  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 sur-
faces.   It arises closely from the edge of the cartila-
ginous surface at the  top of the tibia; but on the an-
terior part of the os femoris, it is continued to some
distance from  the margin  of the pulley-like surface,
and the edges of the condyles.   On each of the por-
tions of the cartilaginous surface of the tibia is a car-
tilage of a  similunar form, so placed, that its convex
edge rests on the margin of the cartilaginous surface,
and its concave  edge  is internal.  These cartilages
are thick at their external, and very thin at  their in-
ternal edges;  so that they form two superficial con-
cavities on the top of the tibia.
  Their extremities are attached by ligaments to the
central protuberance of the tibia, and their anterior
extremities 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 ex-
terior edge, which is connected with the external li-
gaments of the articulation.
  The use of these cartilages, is  evidently to  form
concavities on the top of the tibia, for accommodating
the condyles of  the os femoris: and upon examina-
tion, they will not appear so anomalous as  they are
at first view, for there is a considerable analogy be-
tween them and the cartilaginous edges of the gle-
noid 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  ma- 
Knee Joint.                293
jus; and a process of the membrane, called ligamen-
tum mucosum, passes from  the neighbourhood of the
adipose mass to the os femoris between the condyles.
   These processes retain the adipose substance in
its proper 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 decussate each other partially, on
which account the name crucial is applied to  them.
They are in a state of tension when the  leg  is ex-
tended, 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 fe-
moris 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 a  manner that they
are exterior to it.
   In addition to the crucial  ligaments, this articula-
tion has the following external supports.
   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 admit of that motion.
   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  femo-
ris. and is attached to  the fibula  a little below its
head: and the internal, from the  upper part  and tu-
bercle of the internal condyle, and is  inserted into
the upper and inner part of the tibia.
-   2.  The posterior ligament, whose fibres  run ob-
liquely 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. 
294      Articulation of the Tibia and Fibula*

  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 situation 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 inducted 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  surfaces are nearly horizontal, that of
the tibia looking down, and  that of the fibula looking
up:  they are covered with cartilages and have a sy-
novial  membrane.  This articulation 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, and by
the tendon of  the biceps muscle which is inserted
into the upper  end of the fibula.
  At their 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  contiguous 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 mem-
branous matter, and there is very little  mcftion of the
bones on each other.
  There are very strong external  ligaments, ante-
riorly and posteriorly, which connect  the fibula to
the tibia;  and from the posterior end of the fibula a 
          Articulation of the Ley- and Foot.       290

 small short ligament passes to the nearest part of the
 tibia, which  resembles the margins  of the glenoid
 cavity and acetabulum; for it enlarges the articula-
 tion with the astragalus, while it serves as a ligament
 to 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,
 arc invested with the usual apparatus of articulation.
 The synovial 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 cal-
 cis and naviculare.  Some of the fibres are blended
 with those of the sheath for the tendon of the flexor
 communis; and some  of them have a radiated ar-
 rangement, in consequence of which  this has been
 called the deltoid ligament.
  From the fibula three ligaments arise.  The mid-
 dle ligament, which is strong and thick, passes down-
 wards 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 in- 
296   Articulation of the Os Calcis and Cuboides.

serted 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 appropriated to
it.  The anterior articulation is supplied by an ex-
tension of the membrane which invests  the articu-
lating surfaces of the  astragalus and naviculare.
  The connexion of the astragalus, with  the os cal-
cis, 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 consider-
able motion, as well from the form of the two sur-
faces concerned  in it,  as the perfect state of their ar-
ticulating investments. Their motions are restrained
to a certain degree, by ligaments, which are situated
on the upper and internal surfaces of the  foot.

      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 peroneus longus, as it passes
along the groove in the cuboides. 
CHAPTER IV.
OF PARTICULAR LIGAMENTS, AND OF THE SITUATION OF
           THE INDIVIDUAL BURSiE MUCOSAE.
                    SECTION I.
Enumeration of the most important Ligaments, which have
                 not been decribed.
           Livenncnts proper to the Scapula.
  The triangular ligament arises, broad from the ex-
ternal 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 supra-
spinatus  muscle, and assists in protecting the upper
and inner part of the joint of the humerus.
  The posterior ligament of the scapula is sometimes
double, and is stretched across the semilunar notch
of the scapula, forming that notch into one or two
holes for the passage of the superior posterior sca-
pulary 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 be-
tween  these two bones, and is composed  of small
fasciculi, or fibrous slips,  which run obliquely down-
wards and inwards. Two or three  of these, however,
go in the opposite  direction : and one of them, term-
ed oblique ligament and chorda transversalis  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 passage
of blood  vessels from the fore to the back part of the
bone, and a large opening is found at the upper part
  Vol. i.        •       38 
 298           Ligaments of the Hand.

 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 ivrist is stetch-
 ed across from the projecting points of the pisiform
 and unciform bones, to the  os scaphoides and trape-
 zium, 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 profun-
 dus; forming, at the same  time,  bursae  mucosa?
 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
 fingers.  Upon the body of  the phalanges,  they are
 thick and strong, to bind down the tendons: but over
 the joints they are thin, 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
first and second phalanges of the fingers.  They run
 obliquely forwards within the vaginal ligaments, ter-
 minate in the tendons of  the two flexor muscles of
the fingers,  and   assist in  keeping  them  in  their
places.
   The posterior annular ligament of the wrist is part of
the aponeurosis of the fore arm, extending across
the back of the wrist, from the extremity of the ulna
and os pisiforme  to the extremity of the radius.  It 
Ligaments of the Sternum.          299
 is connected with the small annular ligaments which
 tie down the tendons of the extensores ossis meta-
 carpi et primi internodii pollicis,  and the extensor
 carpi ulnaris.
   The vaginal ligaments adhere to the last mentioned,
 and serve as sheaths  and bursae mucosae to  the ex-
 tensor tendons of the hand and fingers.
   The treinsverse  ligaments,  of the  extensor tendons,
 are aponeurotic slips running between the tendons,
 near the heads of the metacarpal bones, and retain-
 ing 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 differ-
 ent directions, and covering the anterior and  poste-
 rior 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 ensiformis. The ligaments co-
 vering the sternum serve considerably to strengthen
 that  bone.
   There are also thin tcmlinous 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 process of the last vertebra of  the  loins;
tiie inferior to the first transverse process of ^ho os
 sacrum. 
300          Ligaments of the Pelvis.

  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
transverse processes of the os sacrum.
  These with the  two transverse ligaments, assist in
binding the bones  together,  to which  they are con-
nected.
  The two sacro-ischiatic  ligaments are situated in the
under and back part of  the  pelvis.  They  arise  in
common from the transverse processes of the os sa-
crum, and likewise from the under and lateral part of
that bone, and from the upper part of the os coccy-
gis.  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 spin-
ous process of the os ischium.  These  two ligaments
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
connected 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  in breadth.
  The inferior or falciform appendix, situated within
the cavity of the  pelvis, the back part of which is
connected with the middle of the large external liga-
ment, and the rest of it is extended round the curva-
ture of the os ischium.
  These  two  productions assist the large  sacro-is-
chiatic ligament,  in furnishing a more commodious
situation  for,  and insertion  of, part of the gluteus
maximus, and obturator internus muscles.
  Besides the  ilio-sacral, and  sacro-ischiatic liga- 
              Ligaments of the Pelvis.           301

ments, several other slips are observed upon the back
of the os sacrum, which descend in an irregular man-
ner, and strengthen the connexion between that bone
and the os ilium.
  The large holes  upon the back part of the os sa-
crum are also surrounded with various ligamentous
expansions, projecting 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 liga-
ments of the os sacrum, which  spreads over and con-
nects the different pieces of the os coccygis together,
allowing considerable motion, as already mentioned,
in the description of this bone.
  The longitudinal ligaments of the  os coccygis descend
from those upon the dorsum of the os sacrum, to be
fixed to the back part of the os coccygis.  The liga-
ments 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 si-
tuation, 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,
excepting in the state  of pregnancy, when it is fre-
quently 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
throideum, and  fills the whole of that  opening, ex-
cepting the oblique notch  at its upper part for the
passage of the obturator vessels and nerve. It assists
in supporting the contents of the pelvis, and in giving
origin to the obturator muscles.
  The interosseous  ligament of the leg fills  the space
between the tibia and fibula like the interosseous li-
ganrent of the fore arm, and is of a similar structure; 
302            Ligaments of the Foot.

being formed of the 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 con-
tact ; and where vessels and nerves pass to  the fore
part of the leg.
  It serves chiefly for the origin  of part of the mus-
cles 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 su-
perior 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
muscles, behind the ankle is common to both, but di-
vides at the outer part  of the foot and becomes pro-
per  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  calcis, at the  inner side of the heel.  It en-
closes  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 pollicis surrounds this tendon in the hollow of
the  os calcis.
  The vaginal and crucial ligaments of the tendons of
the flexors of the toes enclose these tendons on the
surfaces of the phalanges, and form their bursae mu-
cosae. 
Bursas Mucosa:.
303
  The accessary 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 terminate.
  The transverse ligaments of the extensor tendons run
between them, and preserve them in their places be-
hind the roots of their toes.

                    SECTION II.

    Enumeration of the most important Bursae Mucosae.

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 scaputa
and the capsular ligament of the humerus.
  3. Between the point of the coracoid process and
capsular ligament of the humerus.
  4. Between the tendon of the subscapularis muscle
and  capsular  ligament of the humerus, frequently
communicating with the cavity of that joint.
  5. Between the origin of the coraco-brachialis and
short head of the biceps, muscles and capsular liga-
ment of the humerus.
  6. Between the tendon of the teres  major and the
os humeri, and  upper part of the tendon of the la-
tissimus dorsi.
  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 a peloton  of fat, between  the tendon  of
the biceps and tubercle of the radius. 
 304   Bursae Mucosae of the Upper Extremity.

   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 tri-
 ceps extensor 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 en-
 close the tendons of the flexors upon the fingers.
   3. Four short  bursae on the fore part of the ten-
 dons of the flexor digitorum sublimus in the palm of
 the hand.
   4. A large bursa between the tendon of the flexor
 pollicis longus, the  forepart of the radius, and cap-
 sular ligament of the os trapezium.
   5. A large bursa  between the tendons of the flexor
 digitorum profundus, and the forepart of the end of
 the radius, and capsular ligament of the wrist.
        These two last mentioned bursae are sometimes found
         to communicate with each other.
   7. A bursa between  the tendon of the flexor carpi
 radialis and os trapezium.
   8. Between the tendon of the flexor carpi ulnaris
 and os pisiforme.
   9. Between the tendon of the extensor ossis meta-
 carpi pollicis and radius.
   10. A large bursa common to the extensores carpi
radiales, where they cross behind the extensor ossis
metacarpi pollicis.
   11. Another common to the extensores carpi ra-
diales, where they cross behind the  extensor secundi
internodii pollicis.
   12. A third, at the insertion of the tendon of the
extensor carpi radialis brevior.
   13. A bursa for the tendon of the extensor secundi 
Bursce Mucosae of the Thigh.        305
  internodii pollicis, which communicates with the se-
  cond bursa common to the extensores carpi radiales.
    14. Another bursa between the tendon of the ex-
  tensor 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 ul-
 naris 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 mus-
 cle and the thigh bone.
   3. Between the gluteus medius and trochanter ma-
 jor, and before the  insertion of the  tendon of the
 pyriformis.
   4. Between the tendon of the gluteus minimus and
 trochanter major.
   5. Between the gluteus maximus and vastus ex-
 ternus.
   6. Between the gluteus medius and pyriformis.
   7. Between the obturator internus and os ischium.
   8. An oblong bursa continued a considerable way
 between the obturator internus, gemini, and capsular
 ligament of the thigh bone.
   9. A small bursa at the head of the semimembra-
nosus and biceps flexor cruris.
   10. Between the origin of the  semitendinous and
that of the two former muscles.
   Vol. i.               39 
306    Bursal Mucosce of the Thigh and Knee,

  11. A large bursa between the tendon of the glu-
teus 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 ex-
tensors 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 substance  projects.
  3. Between the tendons of the sartorius, gracilis,
semitendinosus, 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 communi-
cating with the cavity of the knee joint.

             About the Ankle there are,
  1. A bursa between the tendon of the tibialis an-
ticus, 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
longus, and ligament of the ankle.
  4. Common to the tendons of the peronei muscles.
   .0. Proper to the tendon of the peroneus brevis.
   6. Between the tendon  achillis and os calcis, into
the cavity of which upeloton or  mass of fat projects. 
            About the Ankle and the Foot.        307

   7. Between the os calcis and flexor pollicis longus.
   8. Bel ween the  flexor digitorum longus  and the
tibia and os calcis.
   9. A bursa between the tendon of the tibialis pos-
ticus and the tibia and astragalus.

           On the Sole of the Foot are also,

   1. A second bursa for the tendon of the peroneus
longus. with an oblong peloton of  fat  within it.
   2. One common to the tendon of the flexor polli-
cis longus, and that of the flexor digitorum pro-
fundus, 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
muscular action is suspended, as well as the exami-
nation of the artificial skeleton, evinces that this ma-
chine is  not constructed to preserve the erect posi-
tion of itself; but that when unsupported, it bends at
the joints, and invariably falls forward.
   It is retained in the erect position by the action of
muscles:  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 centre of gravity should be  immediately over the
centre 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 centre
of gravity is changed, we must change the  position
of the feet, that  the centre of the basis  may  be di-
rectly under it.
   If this proposition were not almost self-evident, it
might  be illustrated by  several very easy experi-
ments.
   If a person stand 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 for-
ward, he will fall upon his face; there is no power
in his  muscles,  or  in any other part  of the  body, 
         Adjustment of the Centre of Gravity.     309

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 the body.
  When we sit  in such  a position that we cannot
bring the centre 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  a:.gle,  so that the feet are placed
under the body, and we rise with ease.
  When we wish  to stoop forward without advan-
cing 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 consequence of age, bend their lower  limbs,  so
that the pelvis may be projected backwards beyond
the centre of the base of  the body, and  form a coun-
terpoise  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
centre necessarily changes also.   When the feet are
placed one  immediately  before  the other, the cen-
tre 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 centre of the base is be-
tween the heels.
  In these cases, when the situation of the centre  of 
 310     Adjustment of the Centre of Gravity.

 the base is  changed, we  immediately change the
 centre of gravity.   Thus, as we turn the toes out-
 wards, the centre of the base moves backwards: wc
 therefore immediately make the body more erect;
 and by that means keep the centre of gravity over
 the centre of the base.
   We move the centre of gravity laterally, as well as
 backwards and forwards, in conformity to this  prin-
 ciple.
   Thus, when we raise  one foot from the  ground,
 the body inclines so much in the opposite direction,
jthat the  centre of gravity is directly over the other.
 If the spine is diseased in one spot,  and assumes  a
 lateral curvature,  placing  the  centre of gravity on
 one side of the natural centre of the base;  another
 curve is  formed  by muscular action, in a sound part
 of the spine,  to  counteract the first, and keep the
 centre of gravity in its natural position.
   The perception  of a  tendency to fall, when the
 centre of gravity is in a wrong situation, first induces
 us to  make efforts to resist this tendency; we learn
 oy experience what these efforts ought to be: and
 by habit we at length  make them without conscious-
 ness.
  As  the natural tendency of the skeleton, when we
 stand, is  to bend at the articulations, and therefore
 to fall forwards; the muscles which have the  prin-
 cipal  effort in keeping the body erect, must be the
 extensors.
  Thus,  the  muscles on the back of the leg, and
 particularly 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 coun-
 teraction of the antagonist muscles.
  The whole  lower limb is thus made erect by an
 exertion  which begins at the foot, while the foot is 
         Muscles which keep the Body erect.      311

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 os-
sa 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 semi-
tendinosus, 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 longissimus dorsi,  which act from the sacrum
and back  parts of the  pelvis.   The yellow ligaments,
which are ekistic, must also co-operate to this effect:
so that with regard to the spine, there is  an addi-
tional agent distinct from the muscular power.
  Indeed, respecting the  vertebral articulations in
general, it may be observed, that the connexion of
the bodies of the vertebrae, by the intervertebral  car-
tilaginous 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
forward more strongly perceived than in the head.
When we  are awake, and the muscles in a healthy
situation, it  is effectually restrained, and the heacl
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 vertebrae of the neck.
  When we stand on  one foot, some very different
muscles arc called into action;  the  tendency of the
body is to fall sidewise, towards the foot which is
raised from the ground.  To counteract this tendency, 
312    Muscles employed in rising from a Seat.

the two larger peronei 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 femoris.
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 abdominal muscles which draw the spine
to that side, continue the operation: and so do like-
wise the muscles  which act on the same side of the
neck and head.
  In rising from a seat,  the tibialis anticus acts very
powerfully,  to keep the tibia erect, and prevent it
from inclining backwards.  The two vasti, and the
crureus, raise  up the os femoris: while the gluteus
maximus, the semitendinosus, 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 circumstance is merely a matter of accommo-
dation. But there are two essential processes in walk-
ing, 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 ex-
planation ; 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  body forward  or move the  pelvis
on the left thigh,  so that the right side may present
obliquely forward; or lower the right side of the pel-
vis, so that it may be nearer the ground. 
           Motions necessary in Walking.        313

  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 particular-
ly 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 rota-
tion 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, occasion-
ally co-operate with great effect.  By raising the heel,
and thus lengthening the hind limb,  they push the
body forward, and continue its motion in that  direc-
tion 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 round,  presenting
the side obliquely forward; and in  this manner  in-
crease 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 incon-
testibly by the act of walking  on the heel: when the
gastrocnemii and the flexors are so far from acting,
that they are in a state of extension.  In this opera-
tion, 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.
   Notwithstanding these facts, the action of the gas-
trocnemius and soleus is essential whenever we raise
the heel from  the ground, while the weight of the
   Vol. i.                10 
 314       Motions necessary in Jumping,

 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  extra-
 ordinary operation;  but if a man who  lies on the
 ground, with his feet against a wall, makes a muscu-
 lar 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 mo-
 tion is imprest upon the body; which is  projected
 from the wall horizontally, in the same  way that in
jumping, it is projected  from the ground  vertically. 
SYSTEM OF ANATOMY.

               PART IV.
  OF THE  BRAIN AND  SPINAL MARROW :  OF THE EVE
                 AND THE EAR.

                 CHAPTER I.

                 OF THE BRAIN.

  The whole of the soft mass, which fills the cavity
of the cranium, is  called  the  brain.  This mass is
covered  by three  membranes: two of which  were
called meninges or matres, by the ancient anatomists:
who believed that  all the other membranes of the
body originated from them.
  These membranes are denominated the Dura Ma-
ter. Tunica Arachnoidea, and Pia Mater.

                   SECTION I.

  Of the Membranes of the Brain, and Sinuses of the
                 Dura  Mater.

  The Dura Mater encloses the brain and all its ap-
pendages, and lines the  different  parts of the cra-
nium.  It consists  of one  membrane of a very dense
texture, which in several places is composed  of two
or more lamina.   It is the thickest and  strongest
membrane of the body, and is composed of tendinous 
316     Dura Mater.—Tunica Arachnoidea.

fibres, which have a shining appearance, particular-
ly on its inner surface.  In many parts these fibres
run in a variety of directions, and decussate each
other at different angles.
  The dura mater adheres every where to the sur-
face of the cranium, in the same  manner as the pe-
riosteum adheres to the bones in  the  other parts  of
the  body;  but  is  more firmly  connected  at the
sutures and  foramina than elsewhere; and so much
more firmly  in children than in adults, that in sepa-
rating 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  adhesion is sometimes very strong.
  The inner surface of the dura mater, which is re-
markably  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, accord-
ing as it may be affected by the different states  of
respiration.
  The dura mater serves as a defence to the brain,
and supplies the place of a periosteum to the inside
of the cranium ; giving nourishment to it, as  is evi-
dent from the numerous drops of blood which ap-
pear after removing a portion of  it.
  The proper blood  vessels of the dura mater are
not very numerous.   Its arteries are derived partly
from the* external carotids, and  partly from the in-
ternal carotids and  the  vertebral arteries.  Corres-
ponding veins accompany these  arteries;  but the
dura mater  forms also reservoirs, that contain the
venous blood, which is brought from  the substance
of the brain.  These are called sinuses, and are  very
different from common veins. 
fJia Mater.
317
   Nerves have been traced  into the dura mater by
 the French anatomists, derived from the sympathe-
 tic in the neck.   There have been  disputes respect-
 ing its sensibility; but there is reason to believe that
 in a sound state it has very little.
   The  Tunica Arachnoidea is  an  exceedingly thin,
 tender, and transparent membrane, in which no ves-
 sels have been hitherto observed.
   It is spread uniformly over the surface of the brain,
 enclosing  all its  convolutions, without insinuating
 itself between any of them.
   At the upper part of the brain, it adheres so closely
 to the subjacent coat by fine cellular substance, that
 it can scarcely be separated from it; but in different
 parts of the base of the brain, particularly about the
 tuber annulare and medulla oblongata,  it is merely
 in contact  with the  membrane under  it,  and may
 readily be  raised  from it  by the  assistance of the
 blow-pipe.
   The  Pia Mater, named from  its tenderness, is
 somewhat of the nature of the  former covering, but
 is extremely vascular.
  It covers the brain in general, enters double be-
 tween all its convolutions, and lines the different ca-
 vities called ventricles.
  It serves to conduct and support the vessels of the
 brain, and  allows them to divide into such  minute
 parts, as to prevent the blood from  entering the ten-
 der 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 ac-
 company the arteries.
  From the dura  mater certain membranous  pro-
cesses go  off, forming incomplete partitions, which 
318
Falx.—Tentorium.
partially divide  the cavity of the cranium; and  in
the same partial manner separate the parts of the
brain from each other: thus preventing them from
pressing upon each other, and keeping them steady.
   They are formed of the internal  lamina or layer
of the dura mater, like a plait, and therefore each of
them consists of a double membrane.
   The most conspicuous of these is denominated the
falx, which extends from  the anterior to the poste-
rior part of the cranium, and divides the upper part
of the brain into two hemispheres:  but it is not suf-
ficiently deep  to divide the whole of the brain; for
between the under edge of it, and the base of the
cranium, there is a large space occupied by a por-
tion 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 mid-
dle 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
terminates behind, in the middle of the tentorium.
   It runs from before backwards in a straight direc-
tion, 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 centre
of the crucial ridge,  on the internal surface of the
occipital bone, it extends to each side,  and forms a
horizontal partition, which partially divides the low-
er part of the cavity from the upper: but it does not
extend so far forward  as to separate completely the
mass which is  under it, or the cerebellum,  from the
upper part of the brain, or cerebrum.
   This horizontal membrane is  called the  tentorium, 
Sinuses,
319
and  also the transverse septum: it is connected be-
hind 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 bones,
and terminates at the posterior clinoid process of the
sphenoid bone.
  Between the inner edge of the tentorium and the
posterior clinoid process of the sphenoid bone, there
is a large notch, or foramen  ovale, where the brain
and cerebellum  are united, or where the tuber annu-
lare 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 tentorium, adheres to the inferior longitudinal
spine of the os occipitis, and terminates insensibly
at the edge of the foramen magnum of that bone.
  Besides the  process  of  the dura  mater already
described, there are four of inferior consideration :
two of which are  situated  at the sides of the  sella
turcica, and two at the edges of the foramina lacera.
  As these partitions arise like  plaks from the in-
ternal surface of the dura mater,  there must neces-
sarily be a cavity, larger or smaller, between the ex-
ternal layer of the dura  mater,  which lines the in-
ternal surface of the cranium, and the basis of the
partition which arises from it: this cavity must con-
tinue along the whole basis of the partition; 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 tentorium forms two cavities, called the trans-
verse 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 protected from pressure.
   The principal sinuses are,
   1. The  longitudinal sinus,  which  begins  at the
crista galli, and, running along the upper edge of the
falx until it arises at the tentorium, increases gradual-
ly in size, and terminates in the two lateral sinuses.
[In this sinus, and beneath the dura mater near the
top of the head, are many small bodies of various
sizes called glandulae pacchioni. They are of various
dimensions, from a line and less to three or four lines
in diameter.   One  of the largest of these glands on
each side protrudes through the dura mater from the
surface of the brain, and makes a  pit in the os parie-
tale.   Vesalius demonstrated these bodies in 1543.
Pacchioni also demonstrated them fifty years after-
wards ; and, claiming them as a discovery of his own,
succeeded in attaching his name to them.]
   2. The lwo  lateral  sinuses run in depressions of
the occipital and temporal bones, until they terminate
in the internal jugular veins at the foramen lacerum.
   3. The  torcular  Herophili, which receives a large
vein from the interior of the brain, and is situated at
the junction of the falx and tentorium, opening into
the longitudinal  sinus,  where it divides into the la-
teral sinuses.
   These are the largest sinuses of the dura mater;
but, in addition to these,  there  are several small si-
nuses : as, 
Sinuses.
421
  4. The inferior longitudinal sinus, which  is  situ-
ated at the under edge of the falx, and receives blood
from the central parts of the cerebrum; it terminates
in the torcular Herophili, near the beginning.   The
other small sinuses  are situated under the brain, viz.
  5. The circular sinus of Ridley,* which frequently
surrounds the pituitary gland, and carries the blood
from the contiguous parts to the
  6. Cavernous sinuses,  which are placed at the
Bides of the  sella turcica,  surrounding the  carotid
arteries and  the  sixth pair of  nerves, and  receive
blood from the  circular sinuses and several contigu-
ous 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 situ-
ated on the upper edges of the petrous bones.  They
communicate both  with the lateral and the  cavern-
ous sinuses, and receive some small  veins from the
adjacent parts.
  There are also several small sinuses near the great
occipital foramen, which communicate with the la-
teral sinuses, and also with the vertebral veins.  They
are called occipital sinuses.
  The brain, or the whole of the soft substance con-
tained within these membranes, is composed of four
portions, viz. cerebrum, cerebellum, tuber annulare or pons
Varolii, and medulla oblongata.

  * An English anatomist,  who published near the end of the 17th cen-
tury.
  Vol. i.               41 
322
Cerebrum.
                    SECTION II.

                 Of the Cerebrum.

  The cerebrum completely fills the upper part of the
cavity of the cranium.  It has some  resemblance  to
the half of an egg, which has been divided horizon-
tally; 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 cen-
tre of the cerebrum, although it divides it completely
before and behind.   A portion of the central part  of
the  cerebrum, which  is  situated deeper than the
under edge of the falx, is not divided.
  The upper surface of the two hemispheres is con-
vex.  The  under surface is rather irregular: it is di-
vided in each hemisphere into three lobes: the ante-
rior, 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 fis-
sures between these  convolutions do not extend very
deep into the substance of the brain.
  The whole surface of the brain, thus convoluted,
is covered by pia mater; which is connected to every
part of the surface  by an infinite number of small
vessels and processes, that appear when this mem-
brane is peeled off from the surface of the brain. 
Cerebrum.
323
   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 denomi-
nated the medullary.
   The  proportion  of  this medullary part is much
greater than that of the cortical.  The cortical, how-
ever, surrounds it, so as to form the whole of the sur-
face of the cerebrum, that can be strictly said to  be
exterior.
   The colour of the cortical part appears to be de-
rived  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 de-
termination of blood to the head, it is uniformly high
coloured; in pallid and exhausted 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  that carry red
blood; and these points are larger and more nume-
rous in plethoric, than in exhausted  subjects.   It is
rather firmer than the cortical substance.
  These two substances are  most  intimately con-
nected 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 por-
tions of cortical  matter within the  medullary.
  The division of the cerebrum into two hemispheres
extends to a considerable depth from above, and also
to a considerable distance internally, from its anterior
and posterior extremities; of course, the part which
is undivided is in the centre.
  The cortical part covers also the surfaces, which
are in  the great fissure that forms  the  two hemi- 
324
Lateral \ entricles.
spheres,  and is  occupied in a great degree  by the
falciform process of the dura mater.  Towards the
bottom of this fissure, and below the falx, these sur-
faces 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 hemispheres  are separated from each other,  is
medullary; being evidently a union of the medullary
matter of each hemisphere.   This undivided medul-
lary part is equal to about one half of  the length  of
the hemispheres; the fissures at each  extremity ex-
tending inwards, about one-fourth of their length. On
each  side of it, a fissure, equal to it in  length, ex-
tends horizontally into the medullary matter in each
hemisphere, about half an inch; and  the  whole  of
this unconnected surface, the middle of which is di-
rectly at the bottom of the  great  fissure, is termed
corpus ccdlosum.
  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 suture of the corpus callosum.
From the raised lines or bands on each  side of the
raphe, small lines less elevated pass across the cor-
pus callosum, and are lost  in the  medullary matter.
The hemispheres being  thus cut off at the level  of
the corpus callosum, on the cut surface is to be seen
the interior mass of medullary matter,  with the cor-
tical part exterior, its edge exhibiting the convoluted
surface of the brain, and the pia mater following the
convolutions.
   The  medullary surface,  thus exhibited, with the
corpus  callosum in  the centre, is denominated the
centrum ovale. 
Lateral Ventricles.
325
   In the brain there are four cavities called ven-
tricles : three of these are formed in the substance of
the cerebrum; the fourth is situated between the ce-
rebellum, the pons Varolii, and medulla oblongata.
The two largest are called the lateral ventricles, from
their situations; the others are named,from the order
in which they  occur, the third and  the fourth ven-
tricle.
   The lateral ventricles are cavities of an extremely
irregular figure:  they are situated  in each hemi-
sphere a little below the level of the corpus callosum;
and, with the exception of the partition which sepa-
rates them, are directly under it.   They commence
anteriorly, nearly  on a  line with  the termination of
the fissure that  separates the two hemispheres ante-
riorly ;  and continue backwards almost as far as the
commencement of the fissure that separates them
posteriorly: when  they have attained this length pos-
teriorly, they form a considerable curve,  first out-
wards,  then  downwards,  and afterwards forwards;
so that they terminate almost as far forwards as they
commenced; but much deeper.
  At the posterior part of their curve, when they in-
cline outwards, previous to their turn downwards, a
process or continuation of the cavity extends back-
wards, almost as far as the cerebrum  itself.   These
elongations are called the posterior cornua or sinuses,
or the  digital cavities.
   Each ventrical may therefore be divided into three
parts, viz. The portion under the corpus callosum,
the portion  which continues  outwards and  down-
wards  and terminates below  it;  and the  posterior
portion.
   It has been compared to a  ram's horn,  by some
who have contemplated particularly  the upper and
lower portions  of the  cavity; and by others, who
have had the whole extent in  view, it has been call-
ed tricornis. 
326
Fornix.
  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 pro-
ceeds backwards; so that it resembles a portion of a
pear.  It inclines outwards as  well as backwards,
so that the narrow posterior extremities of the two
bodies are further from each other than the anterior
broad extremities.
  The colour of these bodies is  cineritious external-
ly ; but they are striated with medullary matter with-
in, and therefore are called corpora striata.  .
  Between their posterior extremities are two other
eminences, which incline to the oval form, and have
a white  or medullary  colour;  although  their sub-
stance, when cut into,  is  slightly striated: they are
called  the  thalami nervorum opticorum.  These bo-
dies are very near each other; and, being convex in
form, are in contact  at the  centre:  they adhere
slightly to each other; and this  adhesion is called
the soft commissure.
  The corpora striata, and the thalami nervorum op-
ticorum, join each other at the exterior sides of the
thalami:  where they are in contact, there is the ap-
pearance of a narrow medullary band, which conti-
nues during the whole extent of their connexion: it
has  been called,  by  some, tenia semicircularis, from
its form ; by others centrum geminum semicirculare.
  These surfaces constitute the bottom or  floor of
the first portion of the ventricles, which is under the
corpus callosum: upon this floor is laid  a thin la-
mina of the medullary matter, of a triangular  form,
called the Fornix, which covers the thalami nervorum
opticorum, and is attached to them by a membrane;
so that when the ventricles are opened, the bottom
appears to consist of the corpora striata, and the
fornix. 
Plexus Choroidcs.
327
   The upper surface or roof of the ventricles is con-
 cave;  from the middle of it, immediately under the
 raphe  of the corpus callosum, there proceeds down-
 wards a partition of medullary matter, which sepa-
 rates the two  ventricles  from each  other.   This is
 called  septum  lucidum,  from its being nearly trans-
 parent : below, it adheres to the fornix, and anterior-
 ly, it is continued into the medullary matter, between
 the corpora striata.  This septum lucidum is  formed
 of two lamina or plates,  which are separated  from
 each other in the anterior portion of the septum, and
 thus form a small cavity, which has no communica-
 tion with the other cavities of the brain.
   The fornix is not perfectly flat; but, accommoda-
 ted 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 ner-
 vorum opticorum:  and is divided into two small por-
 tions called its crura, which  can be traced some dis-
 tance 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 inter-
position.  At the edges of the fornix, there are many
 blood vessels in this membrane,  arranged close to
 each oth'M\  which are called the plexus choroidcs.
   The posterior side or edg >, of the  triangular for-
 nix terminates in the corpus callosum, or  the medul-
 lary 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 follow-
ing way.
   The surfaces of the inferior portions of the lateral 
328
Commissures of the Brain.
 ventricles are not uniformly concave; but at the bot-
 tom of each, there is a prominent body, which begins
 where this portion of the cavity winds outward and
 forward, and continues its whole extent.   This pro-
 minence has a curved form, and is marked by trans-
 verse  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 hippocampus;  but the terms minor and major
 are applied to distinguish them.
   The posterior angles of the fornix, terminate in the
 large hippocampi; and the margin, or thin  edge of
 the two anterior sides of the fornix, is continued to
 form an edge to the  hippocampus; and is called the
 tcenia hippocampi, or corpus 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 velum interpositum, the thalami  are brought fairly
 into view; and appear like oval bodies placed paral-
 lel to each  other.  They adhere slightly at their up-
 per surfaces, and, when separated, a fissure appears
 between them; which is the third ventricle. At the up-
 per and front part of this third ventricle, near its com-
 mencement, before the anterior crura of the fornix,
 and very near them,  is a white  chord, like a nerve,
which passes across  the ventricle, and can be traced
to some distance on  each side of the medullary mat-
 ter of the brain.
  This chord is  called  the anterior  commissure of
the  brain.  The thalami nerv:  optic: being of an 
Commissures of the Brain.          329
oval form, and touching each other in the middle,
there must  be a vacuity between  them at their ex-
tremities.  This v acuity is behind  the anterior crura
of the fornix,  and has been called Vulva, Iter ad In-
fuudibulum, and Iter ad Terlium Ventriculum.
  It loads of course into the  third ventricle; but a
passage  continues from it  downwards  and rather
forwards, to the infundibulum; which is  a process
somewhat  resembling a funnel that is  composed
principally of cineritious substance, and passes from
the  lower and front part of the third ventricle, to-
wards the  sella turcica;  in which is  situated the
small body called the Pituitary Gland.
  The infundibulum  is hollow  at its commencement,
and  solid at its extremity near  the gland.
  The adhesion of the thalami nerv: optic:  to  each
other, at the upper  part of the third ventricle, has
been denominated the Commissura Mollis.   The re-
cession from each other at their posterior  extremi-
ties, 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
medullary  chord,  called the  posterior  Commissure,
which  appears much like the  anterior commissure;
but does not extend  into the substance of the brain
in the same way.   Under this chord, or posterior
commissure, is a  passage which leads to the fourth
ventricle, called Iter ad Quartum Ventriculum,  or Aque-
duct of Sylvius.
  Behind the third ventricle, and terminating it pos-
teriorly,  are four  convex  bodies, called Tubercula
Quadrigemina,  or  Nates and Testes:  the  nates are
uppermost  and most convex;  the  testes are imme-
diately below,  and  somewhat oval transversely.
  The nates and testes arc situated so far backwards
  Vol. i.                42 
:^30        Communication of the Ventricles.

that they are near the anterior part of the upper sur-
face of the cerebellum, and the anterior edge of the
middle of the tentorium.  The posterior part of the
fornix  is directly over them, but it unites with the
medullary matter  of the cerebrum  above it; there
would  therefore  be a  passage into the lateral ven-
tricles  from behind, between the back of the fornix
which  is above, and the nates and testes which are
below; but the velum interpositum passes in from
behind, and attaches the lower surface of the  fornix
to all the parts on which it lies; and thus closes the
ventricles  at this place.   In  this membrane, imme-
diately over the  posterior end of the fissure  called
the third Ventricle, and in contact with  the nates, is
the  Pineal Gland.  This body is not so large as  a
pea, and formed like a pine apple,  or the cone of a
pine tree.
  When the fornix is raised, by dissecting the mem-
brane,  it may be  elevated with the membrane  and
fornix.
  The nature of this body is not understood: it re-
sembles a small gland  in its appearance, but it is
very soft;  and particles of sand-like matter are often
found in it.
  There is a small chord on each  edge of the third
ventricle, which appears to proceed from the  pineal
gland,  and continues on the edge of the ventricle to
the anterior crura  of the fornix, which it unites to.
These chords join each other under the pineal gland;
they are called the pedunculi, or footstalks of the pi-
neal gland.
  The  membrane connected with the pineal  gland,
it has  been said, is the tela choroidea,  or velum in-
terpositum, in which the ^plexus choroides is placed,
at the  edges of the fornix.   This membrane  is ex-
tended, somewhat thinner and less vascular,  so as
to line the surface of the ventricles.  The plexus 
             i cna Galcni.—Cerebellum.          331
                                             ,-.3
choroidcs 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 pro-
ceeds into the upper portions of the ventricles, and
continuing along the edge of the fornix, passes under
that body at its inferior angle, and meets the plexus
of the opposite side.  Between  this meeting of the
plexus,  and the crura of the fornix, is a vacuity of
an oval figure, which forms a communication between
the  ventricles of the brain.  Under this vacuity or
foramen,  the thalami nerv: optic: recede from each
other, and from the  anterior passage  into the third
ventricle, described at page 329, so that at this place
the three ventricles 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
irom 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
Galcni: which terminates soon after in the torcular
Herophili.
                   SECTION III.

                 Of the Cerebellum.

  The cerebellum is situated in the lower and pos-
terior part of the cavity of the cranium, in contact
with that portion 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 di-
vided below into two lobes, by the falx minor. 
332       Cerebellum.— Valve of the Brain.

  The surface of the cerebellum differs in some re-
spects from that of the cerebrum. Instead of the con-
volutions, 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 cineritious or cortical, and the internal or medul-
lary matter, as is  the case with  the cerebrum: but
the proportions of these substances in the cerebel-
lum, are the reverse of what they are in the cere-
brum.
  If sections be made in the cerebellum, the medul-
lary matter is so arranged that it appears like the
stem or trunk of a plant, with ramifications extend-
ing from it.   This appearance  has been  called the
Arbor vitce.
  On the basis of the brain is a  part called  Tuber
Annulare, or Pons Varolii, which is  formed by pro-
cesses from the cerebrum and cerebellum; and is in
contact with the anterior and inferior portion of the
cerebellum in the middle.  From this part the me-
dulla oblongata proceeds downwards and backwards,
under the cerebellum:  and between the cerebellum,
the medulla oblongata, and the pons Varolii, is the
vacuity, called the fourth ventricle of the brain.
  When the brain is in its natural situation this cavity
is below and behind the nates and testes; and from
the cerebellum there passes up to the testes a lamen
of medullary matter, which  closes it above.  This
lamen is called  the Valve of  Vieussens, or the Valve
of the Brain.   Below, the ventricle is closed by a
membrane, which connects the medulla oblongata to
the cerebellum.
  There is a passage into this cavity from the third 
Olfactory and Optic JVerves.         '3'3'S
ventricle, which passes under the posterior commis-
sure and the nates and  testes,  and enters it below
the testes.

                    SECTION  IV.

Of the Basis of the Brain, and the JVerves which proceed
                     from it.
   When the brain is detached from the basis of the
cranium, and inverted  (which can be readily done,
if the nerves that proceed from it are divided, as it is
inverted,) the  tunica arachnoidea appears more con-
spicuous 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 nerves
and vessles connected with the surface of the brain
are so much involved with these membranes, that
considerable dissection  is  required to expose them
properly.
   The anterior  and middle lobes of the brain are
very conspicuous on the inverted surface.  The an-
terior lobes appear separated from each other by the
extension of the great fissure which  forms the two
hemispheres.  The middle lobes appear at some dis-
tance from  each other in the centre; and the cerebel-
lum forms the posterior and most prominent part of
the surface.
   When the brain has been carefully detached from
the cranium, and the nerves adhering to it are pre-
served, 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 ante-
The nerves are numbered from before. 
334                Pons Varolii.
rior and middle  lobes of the cerebrum, 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
membrane.
  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 op-
tic foramen in the sphenoidal bone.   These nerves
can be traced in the brain to the thalami nerv: optic.
  In the angle  formed by the opic nerves poste-
riorly is a mass of  sottish  cineritious matter; and
also the infundibulum which passes to the sella tur-
cica.
  In this soft cineritious matter are two round white
bodies that resemble  peas;  which are called the
Corpora Albicantia of Willis, or  the Eminentice Mam-
milleires.  Behind these bodies are two large medul
lary processes, ealled the Crura Cerebri, which are
best seen if some of the cortical  part of the adjoin-
ing middle lobes is dissected away. They come from
the medulla of the opposite sides of the  brain, and
gradually approach each  other until they arrive at
the tuber annulare, or pons Varolii.
  The Pons Varolii* is a mass of considerable size,
which has a medullary appearance externally, but is
striated within:  it  is formed by the union of the two
above-mentioned crura cerebri,  and of two similar
processes derived  from the cerebellum,  called also
its Crura.  It  lies over a  part of the body of  the
sphenoid bone, and of the cuneiform process of the
occipital bone, and under a portion of the middle
lobes of the cerebrum and of the cerebellum. There
Named from Varolius, physician to Gregory VIII. in 1573. 
    Medulla Oblongata.—Fourth pair of JSTcrves.  335

is a longitudinal depression on its surface, made by
the basilar artery;  and there are also many  trans-
verse streaks on it.
  The crura of the cerebellum, which runs into this
substance, are evidently continued  from the  arbor
vitae or medulla 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 in-
dented lengthwise, both anteriorly  and  posteriorly,
by fissures which are very evident: it is composed of
medullary matter  externally, and  cineritious matter
within.
  On each side of the anterior fissure,  which is in
view when the brain is inverted, are  two  oblong con-
vex 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 each  other.   They proceed by the cavernous
sinus, and, after penetrating the  dura mater, go out
of the cranium at the foramen lacerum.
   The fourth pair, the smallest nerves of the brain,
resemble sewing thread  in their size  and  appearance.
They come out between the  cerebellum  and pons
Varolii, but can be traced backwards as far as the
testes.  They proceed  forwards by the  sides  of the
pons Varolii, and  after  penetrating the dura mater
near the posterior clinoid  apophysis, pass through 
1
336 Fifth, Sixth, Seventh and Eighth pair of JVerves.

the foramen lacerum  to  the  trochlearis muscles 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 carodid 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 ac-
companies the  carotid  artery through the canal in
the petrous portion of the temporal bone, and, with
a twig from the fifth pair, is the  origin of the inter-
costal nerve.
  The seventh pair appear at the side of the medulla
oblongata, near the pons Varolii.  It is composed on
each side of two chords, called Portio Dura and Por-
tio Mollis, and of one or more small  fibres between
them, called Portio Media.   The portio mollis can
be traced to the fourth ventricle.  The portio dura
seems to arise  from the place of union of the pons
Varolii with  the medulla oblongata and  the crura
cerebelli.   The portio media appears to  originate
in the same 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
olivaria on the side  of  the medulla oblongata. 
               JVinthpair of JVcrves, <S'6,           337

 They are composed on each of one chord called the
 Glosso pharyngeal,  and of a considerable number of
 small filaments, which unite and form another chord
 called the Par Vagum.
   With these nerves is associated a third chord call-
 ed the Spinal Accessory JVerve 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-
 pharyngeal, 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 pha-
 rynx ;  the  par  vagum upon the contents of the  tho-
 rax and abdomen, &c. while the  accessory branch,
 which seems  to have no connexion  with  them,  per-
 forates the sterno-mastoid muscle, and is  distributed
 among the muscles of the shoulder.
   The ninth pair arise from the corpora pyramidalia
 by many filaments, that are united  on each side  into
 three or four  fasciculi, which perforate the dura ma-
 ter separately, and then  unite to pass out of the an-
 terior condyloid foramen of the occipital  bone:  this
 pair is spent  upon the muscles  of the tongue.

  Within the last  three or four years, ti.ere have been many allusions in
 the public papers, to the discoveries of Dr. Gall, iormerlv of Vienna, re-
 specting the brain.  For information concerning these'discoveries 'tiie
reader is referred  to a very learned and judicious Memoir, presented ro
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 18j9. See also Lessons
in Practical Anatomy  by the present editor, part I.
  Galen taught that there were two motions in  the brain, one caused by
the pulsation of the arteries, the  other by  respiration, the air beinff ad-
   V ol. i.                 13 
338              Ninth pair of Nerves, Jyy.
mitted into the ventricles through the ethmoidal and sphenoidal cells.
Vesalius and Fallopius refuted the latter  opinion  and exposed its error.
In 1744, Mr. Schlichting of Amsterdam, announced to the Royal Academy
of Sciences of Paris, that the brain was elevated in expiration and depres-
sed in inspiration. MM. Haller and Lamard repeated his experiments and
found that  the motion of the brain depended on a reflux of blood through
the internal jugulars in cases of laborious respiration, besides the common
motion from the pulsation of the  arteries.—See Discours sur l'Anatomie
par Lassus. Ed. 
CHAPTER 11.
              OF THE SPINAL MARROW.

   The medulla oblongata is continued from the ca-
 vity 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  Spi-
 nal Marrow.
   The dura mater passes with it through the great
 foramen, and encloses the whole of it.  At the com-
 mencement of the spinal canal this membrane is at-
 tached to the surrounding bones,  viz. to the margin
 of the  great occipital foramen, and to the atlas;  but
 below  this  it is loosely connected by a  membrane
 which  sometimes appears to contain a little  adeps.
 The tunica arachnoidea and the pia  mater also in-
 vest the medulla spinalis.  The arachnoidea appears
 unconnected with the dura mater; and it can easily
 be removed from the pia mater.   The pia mater ad-
 heres rather firmly to the substance it encloses.
  The  spinal marrow consists of medullary matter
 externally, and cineritious or cortical matter inter-
 nally.
  The fissures which are observable, anteriorly,  and
posteriorly, in the medulla oblongata, are continued
down the  spinal marrow;  dividing it partially into
two lateral portions: these fissures penetrate to  a
considerable depth.  Each of the  lateral portions is
marked on its external surface, by a more superficial
fissure,  which partially divides it  into  an anterior
and posterior part; so that a transverse section of
the spine has a cruciform appearance.
  The  nerves go off in  fasciculi from the anterior
and posterior surfaces of each  lateral portion of the
spinal marrow; so that each nerve is  formed of two 
 340  Ligamentum Denliculatum.—Cauda Equina.

 fasciculi: one from before, and the other from behind.
 The fasciculi are of different sizes in different parts
 of the spine.  The lowermost of the neck are 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 pro-
 ceed, almost at right angles with the medulla spina-
 lis, to the foramina through which they pass;  those
 which are lower pass off in  a  direction  obliquely
 downwards; and the lowermost  are almost perpen-
 dicular.  Between the anterior and  posterior fasci-
 culi, a fine ligamentous chord passes; which is at-
 tached above to the  dura mater, as it passes through
 the foramen magnum, and continues to the os coccy-
 gis.   It passes between the tunica arachnoidea and
 pia mater, attached to  the  pia mater by cellular
 membrane.  It sends off a small process in a lateral
 direction, to be attached to the dura mater in the in-
 terstices between the places where the fasciculi pass
 through the dura mater, and  nearly in  the middle
 between the upper and lower fasciculi.
  The spinal marrow terminates in a point near the
uppermost lumbar vertebra.  The ligamenta denti-
 culata 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
 medulla and the nerves, as  they originate from it.
  As  the spinal  marrow terminates  at the  upper
lumbar  vertebra,  the lumbar and sacral nerves go
off above: they pass down like a bunch of straight
twigs, and are called Cauda  Equina;  from a fan-
cied resemblance to the tail of the horse. The sheath,
formed by the dura  mater  for the spinal marrow,
 continues of its original size, and encloses  them in
one cavity. 
           .drierics of the Spinal Marrow.        341

   The posterior and anterior  fasciculi pass out se-
parately from the dura mater, after they are out, the-
posterior fasciculus forms a ganglion; from  which
one nerve passes  that joins the anterior  fasciculus,
and thus forms the spinal nerves.
  When the nerves go off, either from the spinal ca-
nal, or the cavity of the cranium, the external lamen
of the dura mater where they pass out, attaches it-
self to the bone  or the periosteum;  while an inter-
nal lamen, together with the pia mater, and perhaps
the tunica arachnoidea, is continued with the nerve.
   This  process  from the dura mater becomes so
much changed, Jhat it has been considered as cellu-
lar 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  down-
wards 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 with-
in the cranium.   This artery  proceeds downwards^
and communicates with those of the neck, and with
the intercostal arteries, by the  intervertebral forami-
na, so that it preserves its size.
  It  terminates  with the  spinal marrow; and the
cauda equina below it is supplied by branches from
the internal iliac, which enter through the foramina
of the sacrum.
  There are generally two arteries on the posterior
surface of the medulla spinalis, which also pass out
from the cranium; arising from the vertebral arteries 
342         Veins of the Spinal Marrow.

or inferior arteries of the  cerebellum; they have a
serpentine arrangement: and communicate with each
other, and with the ramifications of the anterior spinal
artery.
  All of these arteries are  dispersed upon the spinal
marrow and its membrane, and the parts immediate-
ly contiguous.
  The veins correspond with the ramifications of the
arteries;  but they  are  collected  into two  larger
branches called the Stmts 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. 
CHAPTER  III.
                    of the eye.

    It will be very proper to read the description of the orbit
      of the eye in page 62 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 observed
      that processes of the dura mater pass through the fora-
      mina optica and lacera, which line the cavity of the or-
      bit and unite with the periosteum at the margin of it.

   The  eye is an optical instrument of  a  spherical
 form, which  lies  in the  orbit, in a bed of  cellular
 membrane, more or less filled with  adeps  for the
 convenience of its motions.   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 pro-
 minences of the os frontis, called superciliary ridges,
 the adipose membrane is commonly more full than
 it is in the other contiguous  places;  and  the skin
 which covers it is thereby rendered prominent.
   The  supercilia or eyebrows  grow  out  of this pro-
 minent  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 mus- 
34 4                The Eyelids.
cle, and thus express certain passions;  and they are
also moved  by the occipito-frontalis  and orbicularis
palpebrarum.
             The Eyelids or Palpabrse,
  Are formed by a slit or orifice in the skin;  imme-
diately under the skin, surrounding this orifice, is a
portion of the orbicularis muscle, in the  upper eye-
lid : under this portion of the muscle, there is a plate
of cartilage; and  under the  cartilage, a portion of
tunica conjunctiva, or membrane that covers the front
part of the ball of the eye and lines the eyelids.
  The upper eyelid, therefore, is composed of the
skin of some fibres of the orbicularis muscle, of the
cartilaginous plate, and of the  tunica  conjunctiva.
The under eyelid is formed in the same way, with
the exception of the cartilage, which, in it,  is confi-
ned to the margin.
  These cartilages form the margin of each eyelid,
which is called Tarsus. The upper cartilage is broad
in the middle, and narrow at each extremity, and
accommodated to the form of the eyeball and  eye-
lid. The under cartilage* is a narrow flat rim which
does not extend far from the margin of the eyelid.
A thin delicate membrane is extended  from the up-
per and  lower  margins of the  orbit to these  carti-
lages, 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 conveyed towards the nose.
  The use of these cartilages is to keep the eyelids
properly expanded; and to form margins that  apply
accurately to each other.
  These  cartilages  are covered internally by the
tunica conjunctiva. 
Tunica Conjunctiva.            Hl.rj
   The levator palpebrae muscle, which arises from
 the bottom of the orbit, at the upper part of the fora-
 men opticum, and passes over the  superior muscle
 of the eyeball;  is inserted by a broad thin tendon or
 aponeurosis into the cartilage of the upper eyelid ;
 and draws it upwards, within the upper margin of
 the orbit, when the eyelids are opened.
   The tunica conjunctiva, that fines  the eyelids, is
 continued from them, without any interruption of the
 surface, over the anterior part of the ball of the eye;
 in the same manner that the reflected membranes are
 continued from one surface to another.
   Although  this membrane is a continuation  of  the
 skin,  it is essentially different from  its structure;
 being extremely thin, flexible, and sensible,  and also
 transparent.  It abounds with vessels, which do  not
 earry red blood in their natural state,  but receive it
 largely  when they are inflamed or much relaxed.
 It adheres firmly to the cartilage at the edge of  the
 eyelids;  and becomes more loose in its adhesion to
 the lids, as it proceeds backwards.  It  is so reflected
 to the ball of the  eye,  that it covers and  adheres to
 about one-third of it anteriorly.  Where it first joins
 the eye, the adhesion is loose, but this adhesion  be-
 comes firmer as it  advances over the eye; and it
 cannot be separated from the cornea without mace-
 ration, and a slight degree of putrefaction. The part
 immediately connected with *the  cornea is extreme-
 ly thin and delicate.
   This membrane closes the orbit of the eye, and
 completes the  cavity which  contains the  muscles,
 lachrymal gland, &c.  which are  by this means pre-
 cluded from  contact with the external  air.
   On the inside of each eyelid, apparently  between
the tunica conjunctiva and the cartilages, are a num-
ber of lines running inwards from the edge of the lid.
These lines are  of  various lengths, from one-fourth
  Vol. i.               41 
 346    Gland of JUeibomius—Lachrymal Gland.

 to near half an inch; the longest are  in  the middle
 of the upper  lid.   Some of them are straight;  and
 others  are serpentine: their 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 Meibomius.*  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 consequence of their con-
 tact during sleep.                                 ,
   The  eyelashes or cilia are  placed near  the outer
 edge of the lower part of the cartilages of each eye-
 lid. They are always more or less curved, and their
 convexities are opposed to each other.   By this ar-
 rangement the eye is defended  from small external
 objects,  and from light  to a certain degree, without
 closing the lid completely.
   It is necessary, for the perfection  of the eye, that
 the whole surface covered by the tunica conjunctiva,
 viz. the anterior part of tht- eveball 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
 the lachrymal  gland, formerly  called Glandula Innomi-
 nata.
   This body is situated in a depression, in the upper
surface of the orbit, near  its external margin: it is
exterior to,  and above, the tunica conjunctiva. It is

  * Charles Etienne demonstrated  the little sebaceous glands of the
 eyelids, and Casserius caused them to  be drawn and engraved a long
time before Henry Meibomius.  The latter gave his name to them by a
letter printed in  Helmstadt in 1666, in  which they were accurately de-
scribed.—See Lassus. Ed. 
.fears.—Lacti.rymul Sac.           347
 of an irregular oblong form, and  rather flat: but it
 has some thickness.  The under surface is lobulated,
 and forms two principal lobes.
   From the anterior edge of the gland the excretory
 ducts, to the number of six or seven, pass off. They
 terminate at a short distance from  the  gland, near
 the upper end of the cartilage, and near the external
 angle of the eye.  They do not  communicate with
 each other.
   Those ducts are so small 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 eyelid, nearly in the direction of the ducts.
   The fluid secreted by this  gland, (viz. the tears)
 is transparent;  but  it is always salt to the taste.
 When evaporated, by exposure to the air, some cu-
 bic crystals,  and  a small quantity of mucilaginous
 matter, remain. Chemistry has ascertained that these
 crystals contain muriate  of soda  and soda uncom-
 bined; and that phosphate of lime and phosphate of
 soda may be obtained by burning inspissated  tears;
 but the whole of the saline matter does not amount
 to one-hundredth part of the tears in which they are
 dissolved. The tears therefore consist of these salts,
 and of mucus, dissolved in a large proportion of water.
   The tears are carried from the eye by two small
 canals, which commence, one on each eyelid, at the
 internal  extremities of  the cartilages; opposite to
 each other.
   The orifices of these canals, being in small carti-
 lages, (but not in those called the tarsi,) are always
 open,  and are called the Puncta Lachrymalia.
   Each of these canals runs, within the edge of each
eyelid, from the place of its commencement to  the
lachrymal sac; which is a larger  membranous canal
situated  in the  depression formed  by the anterior
portion of the os unguis and the corresponding por- 
348   Caruncula Lachrymalis.— Valvula Semilunaris.

tion  of the upper  maxillary bone;  and extending
thence along the bony canal, which continues from
this depression into the nose, and terminates under
the inferior spongy bone near its anterior extremity.
  These canals are very small  at their commence-
ment  at the  puncta lachrymalia; but this small por-
tion is very short; it forms an angle with the remain-
der of the canal, which is considerably  larger.*
  The canals gradually approach each other as they
proceed towards the lachrymal  sac; into which they
enter, in  contact with  each other,  but by distinct
orifices.
  About one-fourth part of the lachrymal sac is si-
tuated above  the junction of the two  eyelids, or the
tendon of the orbicularis muscle, and the remainder
below. After  it descends 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
schneiderian  membrane in  structure; and are de-
fended with a  similar mucus.  The membrane, of
which they are  composed, 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 termina-
tion of the eyelids, at their junction with each other,
is a small angular  space, which is  occupied  by a
body called the Caruncula Lachrymalis; which is of
a reddish  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.

  * These canals were known to Galen, and are particularly described by
Fallopius in 1584—En. 
    Caruncula Lachrymalis.—Valvula Semilunaris.  349

  Between the  caruncula lachrymalis and the cor-
nea, 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 certain animals, and has been
called the Valvula Semilunaris.
  The muscles of the eye,  described  at  page 177,
&c. are to be ranked among the auxiliary appurte-
nances of that organ.
  [At the internal corner of the eyelids  is a small
muscle  which I had occasion to observe for the first
time in the winter of 1821-2.   It has, I believe, es-
caped the notice of other anatomists till the present
time.   This muscle  is about three lines  broad and
six  lines long, and arises from the posterior flat sur-
face of the os unguis near its junction with the os
sethmoides, and passes forwards and outwards, lying
on the posterior face of the lachrymal ducts.   As it
approaches the junction of the lids, it splits into two
parts, nearly equal, each of which is appropriated to
a duct and inserted along its course almost to the
punctu in lachrymale.
  To get a distinct view of it, the eyelids must be
separated from  the  eye and turned over the nose,
leaving the tendinous attachment of the  orbicularis
and ciliaris muscles. The semilunar valve is brought
into sight by  this process, which must  be dissected
away, and also the fat and cellular membrane beneath
it.  The muscle is now seen, and by passing bristles
through the lachrymal ducts its connexion with them
is rendered evident, at the same time that we get a
good idea of its size, origin and insertion.
   While making this inspection, by turning the mus-
cles a little aside, we shall be convinced  of another
fact of some importance, and which is  equally ne-
glected by most anatomists.   It is, that  behind the
tendon of the orbicularis  muscle a ligamentous mat- 
350            The Ball of (he Eye.
ter passes from the corners of  the eyelids to the
flat part of the os unguis, which ligament would keep
the corner of the eyelids from  being deformed, not-
withstanding  the tendon of the  orbicularis be cut
through in the treatment of fistula lachrymalis. The
lachrymal ducts are included in  this  ligament, and
pass through it into the sac instead of going along
the edges of the eyelids, as is commonly asserted.
   This muscle appears to be intended to keep the
puncta in contact with the ball  of the eye.  Dr. Phy-
sick has suggested, that it will also keep the edgiss of
the eyelids applied to the eyeball  in cases of extreme
emaciation where the eye is much sunk.  While in-
vestigating this subject, my attention  was called by
Dr. Harlan to a motion prevailing in the puncta la-
chrymalia, with which I was before unacquainted.
The puncta project themselves and retract much af-
ter the manner of an earth worm, and it is probable
that the latter motion may be produced in some mea-
sure by this muscle.
   In consideration of some of  the functions of this
muscle, I have ventured to propose that it be called
Tensor Tarsi.]—Ed.#
   The tendons of the four recti muscles, being spread
upon the anterior part of the ball of the eye, consti-
tute a partial  covering, which has been called Tuni-
ca Albuginea.   This tendinous expansion does not
extend to the edge of the cornea, but stops short of
it by several lines.f

                    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;
* For a more full account of this muscle, see Horner's Anatomy.
•j- By line, is meant one-twelfth of an inch. 
The Ball of the Eye.            351
which has an aperture in its anterior part, filled up
with a transparent substance, denominated Cornea,
that closes it perfectly.
  The sclerotica is lined by a thin and delicate mem-
brane, the Choroides, which is in close contact with
it, but does  not extend over the whole internal sur-
face 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  natual 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, anterior part of it, which is covered by
the cornea,  from the  remainder.  This partition is
called Iris; and it has a circular vacuity in the  cen-
tre,  directly opposite  to the middle of the  cornea,
which is denominated  the Pupil. Rays of light, which
penetrate the transparent cornea, pass  through the
pupil into the posterior part of the eye.
   The eye, thus formed, is filled with several trans-
parent substances,  called Humours.   The greatest
part of the cavity, posterior to the iris,  is occupied
by the vitreous humour, which is thus denominated,
from its apparent resemblance to melted glass.
  In front of the  vitreous humour, and  directly be-
hind 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
Humour.
  Several of the parts, above  enumerated, have ex-
quisite delicacy of structure, and require a very mi-
nute description. 
352
Tunica Scleral tea.
              Of the Tunica Sclerotica.

   The  Tunica Sclerotica, or external  coat of the ball
of the  eye,  derives its name from  a Greek word,
which signifies to make  hard.   It is composed of
opaque white fibres, of great firmness; which form a
membrane of very close texture, that supports the
globular figure of the eye.  It is thicker behind than
it is before;  but the expansion of the tendons of the
recti muscles 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 putrefaction; and it is essentially different
from it  in structure.
   The  aperture in it, which is occupied  by the cor-
nea, is not perfectly circular;  but inclines somewhat
to the oval form: the  transverse diameter being ra-
ther longer than the vertical.
   Posteriorly, it is intimately connected with the op-
tic nerve, which enters it, not directly at the extre-
mity of the axis that passes through the centre of the
cornea  and pupil, but on the inside of this spot.
   The optic  nerve has a firm  coat, which invests it
rather loosely: this coat seems to be  continued "into,
or expanded upon, the sclerotica. Within it, the deli-
cate nerve diminishes  considerably before it  perfo-
rates 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 por-
tion, in  some eyes, does not exceed two lines or one-
sixth of an inch.
   The  sclerotica, in  its natural state,  has  few, if
any, vessels, that  carry red blood.   The great vas- 
Tiie Cornea.
353
cularity, which is so evident in ophthalmia, is in the
tunica conjunctiva.

                    The Cornea.

   The transparent membrane, which fills up  the va-
cuity in the anterior part of the sclerotica, is deno-
minated 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 mem-
brane.
   This cellular membrane appears sometimes to con-
tain 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 maceration.   It can also be separated from the
sclerotica after maceration, and a slight degree of pu-
trefaction; especially if the  parts, when in this situa-
tion, are suspended a short time in boiling  water.
   The cornea is lined  internally by a fine membrane,
called the Capsule of the  aqueous humour;   which
will be evident if the coats  of the eye are boiled.  In
this case,  the cornea  hardens;  and the capsule  of
the aqueous humour appears detached from  it, like
the cuticle raised by vesication.
   In a sound  state, the sensibility of the cornea va-
ries considerably.*   The vessels in its structure  do
not carry red blood:  it is  however much changed

  * It is the opinion of Dr. Physick, whose numerous and successful ope-
rations on the eye have afforded him many opportunities of judging, that
the incision of the  cornea  always occasions some  pain ; which is very dif-
ferent, as to its intensity, in ditt'event persons.
   Vol..  i.                 15 
354
The Corned.
 in its structure by inflammation; and it Is said that
 blood has been found between its lamina, in conse-
 quence of violent strokes upon the eye.
   It is the segment of a smaller sphere than the scle-
 rotica ; and therefore is more convex.  The degree
 of convexity is very different in different persons;
 those in whom it is very great are necessarily short-
 sighted.  It is not perfectly circular, but rather oval:
 the transverse diameter being the longest.
  The cornea and sclerotica are connected to each
 other by sloping surfaces. The edge of the sclerotica
 projects over the internal lamen of the cornea; and
 the edge of the  cornea passes  under the external
 surface of the sclerotica.
  The separation above mentioned proves the  cor-
 nea and sclerotica to be  distinct from each other.
 And  although their structure is essentially different
 in the human species, it is much more so in  some
 fishes and in some birds.
  From what has  been already stated,  it  appears
 that  there arc pores in the cornea, through which
 the fluid situated  between its lamina may be pressed.
  It is  probable  that  an exudation  through  these
 pores takes  place  after death;  as  a pellicle  then
 forms on the cornea; which, upon examination, ap-
 pears to originate from  the drying of a fluid effused
 there. This has been considered as a proof of death;
 but there arc few practical physicians who have not
seen a  similar pellicle, during life, in persons who
 were very weak.

                 The Choroid Coat.
  The sclerotica and cornea compose a firm external
 shell for the eye;  upon which its form depends.
  The sclerotica is lined  by a thin, flexible,  very
 vascular membrane, denominated Choroides; which
 is in contact with it nearly throughout its  whole ex-
 tent. 
                 The Choroid Coat.              355

    The choroides has  been supposed to be derived
 from the pia mater;  but this sentiment is  not con-
 firmed by observation: for the pia mater appears to
 be connected with the  interior surface of the sclero-
 tic coat.
   It is so delicate a membrane, and so vascular, that
 it has been considered  by some anatomists as a tex-
 ture composed entirely of vessels and nerves.
   It has three sets of arteries, which are derived from
 the ophthalmic branch  of the internal carotid, viz.
   1st.  The long ciliary  arteries, which are generally
 two in number: they penetrate the sclerotic coat  at
 the posterior part of the eye, and pass, one on each
 side of the external surface of the choroides, dividing
 at the ciliary circle, each into two  branches, which
 inosculate with each other around the great circum-
 ference of the iris.
   2nd. The short ciliary  arteries,  which are  very
 numerous: 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.
   3d.   The  anterior  ciliary arteries,  which  are not
 very numerous;  and penetrate tho sclerotic coat no
 great way behind the cornea.  These arc distributed
 among the branches of  the long  ciliary arteries on
 the iris.
  The  veins  of  the choroides are  very peculiar: be-
 sides  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 
  356  Blood vessels—Nerves—Pigmentum Nigrum.

  this arrangement  of their  branches they arc called
  the Vasa Vorticosa.
    The nerves which appear on the choroides, come
  from the ophthalmic ganglion: they pass very ob-
  liquely through the sclerotica,  and  run  forwards;
  having a very flat appearance 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 an-
  terior part of it, and thinner 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 retc
  mucosum of negroes, when that is softened by putre-
*  faction.  It is asserted that the colour of this pigment
  has never been changed by the ordinary chemical
  agents, or by moderate  heat.  When it is washed
  away, the internal surface of the choroides appears
  to be villous.
    There  is also a portion of this substance  on the
  external surface  of the  choroides.  It  is said that
  in very recent subjects, this matter appears to be in-
  herent in the structure of the internal  surface, and
  does not  come off when it is rubbed gently; or even
  when immersed in  water; but it  is certain, that a
  considerable quantity of it sometimes appears on the
  exterior surface of the  choroides, in eyes that are
  not very  recent.
    The celebrated Ruysch,  and many anatomists af-
  ter him, have considered the  choroides as composed
  of two lamina;  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  vessels.
    In the white rabbit, and  some other  animals, the
  pigmentum nigrum is entirely deficient:  and the pu- 
Ciliary Ligament.              357
 pil of the eye appears of a red colour, owing to the
 blood vessels of the choroides.
   The general connexion between the choroides and
 sclerotica is very slight;  depending upon a fine cel-
 lular substance, and very small  blood vessels  and
 nerves.
   But immediately around the margin of the cornea,
 the choroides and sclerotica are firmly connected to
 each other,  by the intervention of a portion of cellular
 substance,  which, although  soft,  is dense and  com-
 pact, and of some thickness. As this substance extends
 round the circumference of the cornea, it necessarily
 forms a  ring; which is between one and  two lines
 broad.   This substance, thus placed, constitutes the
 Ciliary ligament:  which has, to the  great perplexity
 of students, been called by many different names; as
 Orbiculas Ciliaris, Aunulus gangliformis, 8rc*
   It is very distinguishable  from the choroides, the
 sclerotica, and the iris; and appears generally of a
 gray colour; but contains the ciliary nerves  and arte-
 ries, in great numbers, as they pass to the iris.
   In this circular band is a small canal, discovered
 by the Abbe Fontana, which is moistened by a pellu-
 cid fluid; but its use is not known.f        i
  All the choroides, which is posterior to the ciliarv
 ligament, is in close contact with the internal surface
 of the sclerotica; but the choroides continues anterior
 to the ligament: and this anterior  portion takes  a
 different  position.  It no longer lines the internal sur-
 face 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.

  * Discovered by Fallopius, in 1584.
  + See Fontana on the poison of the viper, vol.  2, page 310: and also
Atlolph Murray, No\ a Acta Upsal, vol. J. 
358
The Iris.
   The choroides begins to take this reflection in-
 wards, at the place where it is  connected with  the
 ciliary ligament.  Immediately anterior  to the liga-
 ment, the cornea is  continued from the sclerotica;
 and being more convex than the scletorica, it pro-
 jects externally and  anteriorly.   As the  ciliary li-
 gament is situated between-the  sclerotica  and cho-
 roides, very near to  the  place where the  sclerotica
 unites to  the cornea,  and where  the choroides is re-
 flected internally to form  the ciliary processes, the
 edge of the ciliary ligament must lie  in the angle
 formed by the cornea, which is anterior and external,
 and the reflection of the choroides, which is internal.
 To this edge of the ciliary ligament is fixed the cir-
 cumference of the circular membrane, called Iris,
 which is now to be described.

                     The Iris

   Is a flat membrane, which does not partake of the
 spherical  figure of the  sclerotica and cornea, or of
 the choroides; but extends across a  portion of the
 cavity of the eye,  and forms a septum.   As it is cir-
 cumscribed  by the ciliary ligament, it is necessarily
 circular.   It has a round foramen near its centre,
 which is called the Pupil; which, in the healthy sub-
ject, varies continually in  size,  according to the de-
 gree 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 con-
 tact with the circumference of the cornea: it is actu-
 ally in contact with the anterior edge of the ciliary
 ligament,  and with the  anterior surface of that part
 of the tunica choroides, which is reflected inwards
 and forms the ciliary processes.
   As the  iris is flat or plane,  and the cornea is the
segment of  a sphere,  there must be a considerable
vacuity between them.  This vacuity constitutes the
anterior chamber of the eve. 
The Iris.                 359
   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 scle-
 rotica.
   The anterior, or external surface of this mem-
 brane, is very remarkable for its colour: in persons
 of a light complexion it is generally of a light blue
 intermixed with white: or of a gray, or light  hazel,
 &c.  In those whose  complexions are dark, it is al-
 most invariably dark also.   These colours  are so
 arranged, that frequently there  is an appearance of
 lines,  sometimes  nearly radiated,  more frequently
 curved in various directions, but tending from the cir-
 cumference towards the pupil or centre; and when
 the general colour of the iris is blue, these lines are
 often whitish.
   When this surface is examined  in water  with a
 magnifying glass, it appears to be covered with very
 fine villi;  which probably have the effect  of increas-
 ing its lustre.
   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  un-
 fortunately 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 determining 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 
360
The Ins.
probable that light blue is much influenced by the
black pigment.
  The iris is capable of dilatation and contraction to
a very considerable degree;  by which the pupil, or
central vacuity, is enlarged or diminished.  By this
means it regulates the quantity of light admitted into
the eye.   Upon the first exposure to strong light, the
pupil of every healthy person is observed to be  di-
minished ;  and, upon the diminution of light to be en-
larged.
  It has  been ascertained by experiment, that this
motion of the iris is not excited by the action of light
immediately upon it,  but  on the interior  surface of
the eye;  and this circumstance has  occasioned the
greatest attention to the structure of this extraordi-
nary and important membrane.
  Anatomists of the greatest respectability hold opi-
nions  extremely  different  indeed,  respecting the
structure  of  the  iris.  They agree  that there are
many radiated fibres  on the posterior surface,  com-
mencing at its circumference, which can  be readily
seen when the black pigment is washed away; but
while many respectable anatomists declare that they
have not been able  to see any circular fibres, Dr.
Monroe describes them minutely; and has published
a plate of them.  He considers them as  forming a
circle immediately round  the pupil; which  circle
makes about one-fifth part of the breadth of the iris*
  In the  human subject, the iris does not  appear to
be divisible into lamina.  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 pu-
pil, upon  exposure to light, and dilating it,   when

  *  See his publication, entitled Three Treatises: On the Brain, the
Eye, and the Ear. 
The Iris.
361
 light is diminished or withdrawn, have been explainedv
 very differently by persons who have different senti-
 ments respecting its structure.  Some of those per-
 sons, who do not believe in the existence of muscu-
 lar fibres in the iris, suppose its  motions  to depend
 upon the sudden turgescence or depletion of  its
 blood vessels: while others  impute it to a peculiar
 quality, exclusively  enjoyed by this membrane.
   Dr. Monro, who refers the contraction of the pu-
 pil to the action of the circular  fibres,  which is ex-
 cited by the stimulus of light applied  to the retina,
 considers this operation 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 ex-
 cited by substances  applied  to  the  glottis, which
 would have produced no irritation if they had been
 applied to the muscles themselves.
   The dilatation of the pupil appears, in the human
 species, if not in other animals, to depend upon a
 different cause. It seems to be a passive state of the
 eye, which takes place when the  stimulus is with-
 drawn, and the consequent action ceases.   There is
 some elasticity in the iris;  and a great many, per-
 haps all, of its natural or healthy motions in the human
species, may be explained by the contraction of the
 circular fibres, induced by irritation : and by the con-
 traction of the rest of the membrane in consequence
of its elasticity;  which always  exhibits its effects
 when the muscular  action ceases.
  The elastic power in this  case may have  some
analogy to the elasticity of the arteries, which cer-
tainly produces  some of the  contraction of those
vessels; but there is  another principle of contrac-
tion superadded to this, which produces effects dif-
ferent from those of mere elasticity.
  In the foetus, prior to the seventh month after con-
  Vol.  i.              46 
362            The Ciliary Processes.

ception, the pupil is closed by a delicate vascular
membrane,  called the Membrana Pupillaris;  which,
after this period, completely disappears.*
  The iris was formerly supposed to be a continua-
tion of  the choroid  coat;   but it is now generally
agreed  that it is a distinct membrane;  for when the
eye is very  slightly  affected by putrefaction, it can
be pulled off and the choroides left entire.
  The choroides, on the contrary, cannot be sepa-
from the ciliary processes  without  laceration; and
when the pigment is washed away from its internal
surface, it is very obvious  that these processes  arc
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 a circle,
which has the ciliary ligament before described, near
its circumference, and anterior to it.
  It is so disposed, that the whole of its internal or
posterior surface appears to be formed  into radiated
plaits, which extend from the  circumference  to  the
central  vacuity, where they terminate.
  The  whole of  this structure,  or the membrane
thus plaited, is called the ciliary body, while the plaits
are called the ciliary processes.
  In a  natural state of the eye, the ciliary body is
covered with a large portion of the pigmentum ni-
grum.   It may be seen very well by placing the eye
on the  cornea and  removing the  posterior  part of
all the coats, without deranging the humours. When
thus viewed from  behind, it  has a black surface,
and  appears like a ring formed of radiated  lines;

  * The discovery of the Membrana Pupillaris is claimed by Wacheridorf,
Prof, of Botany in the University of Utrecht; by John Hunter ; by Haller ;
and by Albinu;?. 
                The Ciliary Processes.           363

it has been  compared  to a flower with  radiated
petals.
   When the  black paint is washed off, and the hu-
mours of the eye removed with proper caution, the
plaited structure of these radiated processes will be
very apparent;  it then will appear that the mem-
brane of the  choroides is so arranged as to form ra-
diated plates, 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 look-
ing 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 strive, which
soon unite and  form it.   The process  or plait, thus
formed is rather larger at its  central extremity than
at any other  part: and their central extremities are
not of equal lengths,  but alternately longer  and
shorter.
   The ciliary processes do not extend to the  centre
of the circle of which they are radii, but stop short
of it; and  thus  include a circular vacuity or aper-
ture, which is larger than the pupil of the iris, and
situated a Kittle way within or behind it.  This aper-
ture is occupied by the crystalline lens (to be here-
after described;) but the  central extremities or ter-
minations of the ciliary processes  do not adhere to
the lens,  for  they are loose and moveable;  but they
arc in contact with its anterior surface, near the mar-
gin.
   It is however  to be observed that the ciliary pro-
cesses  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 humour.
   The ciliary body, (or the radiated ring formed by 
364                'Tim Retina
all the processes) is about two lines broad in the hu-
man subject: but the part next to the nose is rather
narrower than the rest of it.
  The black pigment is spread over the whole of the
posterior, or internal surface, of the  ciliary body;
but it is much more abundant towards the circumfe-
rence  than towards  the  centre.   It  is also more
abundant in the furrows between  the ciliary pro-
cesses than it is in the processes themselves : 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
surfaces of the processes;  on all that part which is
loose, and not in contact  with the posterior surface
of the iris,
  When  the pigment is  completely washed  away,
the colour of the ciliary body appears grayish;  but
if the eye has been successfully injected, it will ap-
pear to be composed almost entirely of vessels; end
to have a villous surface.

                   The Retina.
  Within the tunica  choroides, and in contact with
its internal surface, is a third.coat  of the  eye: the
Retina.  This coat is evidently derived from the op-
tic  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 pene-
trates its coats; and when the nerve  perforates the
tunica sclerotica, as described in page 352, this ar-
tery 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.
365
  The retina has the appearance of mucus,  and the
semi-transparency of a surface of ground glass;  but
when immersed in water, it floats like a membrane.
  By particular management, when the retina floats
in water, a considerable quantity  of the soft  sub-
stance may be removed; and a delicate,  soft, trans-
parent membranous substance,  with the vessels, will
remain.
  The retina, therefore, seems to consist of a  deli-
cate, vascular, membranous web, with a medullary
pulpy matter spread upon it, and supported by it.
  Thus constituted, the retina extends from its ori-
gin,  at the optic nerve, to the commencement of the
ciliary processes.
  It  lines the choroid  coat, and is therefore in  con-
tact  with the pigmentum nigrum, on its internal sur-
face  ; but it is simply in  contact with it, and is not
tinged by it.  No  vessels pass  from it to the  cho-
roides ; and when a posterior section of  the  eye is
made,  it slips from it without any appearance of ad-
hesion; being attached only to the optic  nerve.
  Most anatomists agree respecting these circum-
stances; but there is the greatest difference of opinion
respecting the extent of the retina.   Several  distin-
guished 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 opposite. Monro is con-
vinced that it extends, under the ciliary processes, to
the  crystalline lens: and Soemmering asserts posi-
tively, that it terminates at the commencement ofthe
ciliary processes.   Some of the* anatomists of Lon-
don incline to the  opinion embraced  by Soemmering:
and the late ingenious  Bichat  adopted the opinion
embraced by Monro.

  * See the new Cyclopedia, by Dr. Kccs and others; article Eye. 
366
The Retina.
   Both parties confide in their own observations, and
refer to the eye.   An object which appears so very
different to different persons, who  have good sight,
cannot be very distinct. The pulpy  substance of the
retina  appears  to terminate at the commencement of
the ciliary processes; but a membrane, of a very dif-
ferent  texture,  seems continued from it to the crys-
talline lens.
   Although the eye and the  retina  have long been
objects of anatomical attention, professor Soemmer-
ing 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 entrance  of the optic
nerve,  there is  a spot of a  circular or oval figure,
about  one line, or rather more, in diameter, of a yel-
lowish or saffron colour, which is  brightest about the
centre.
   In the centre of this spot is a round hole, equal,
in diameter, to one-fourth  of the spot.  There  are
generally several small plaits of the retina about this
place:  one of these, which is very constant, extends
from the optic nerve to this spot.
   The colour of  this spot is pale in  children, bright
in young persons of mature age, and pale at an  ad-
vanced period of life.
   The foramen is to be found in the foetus, but not
the yellow spot.  The colour of the spot diminishes
when vision 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 ascer-
tained, most decisively, that the extremity of the op-
tic nerve, from  which the retina originates, is insen-
sible to the rays of light.
   [Within three or four years a membrane has been
discovered  by Mr. Jacobs, Demonstrator of Anatomy 
The Retina.
367
in Trinity  College, Dublin, which is situated be-
tween the retina and the tunica choroidea. Its tenuity
and delicacy are extreme.  It is diaphanous arid is
thought by its discoverer to be a serous membrane.
It extends from the optic nerve  as far forwards as
the retina goes,  and adheres by a delicate filamen-
tous structure to both the retina and the choroid coat,
but much more  firmly to the former.  Mr. Jacobs
asserts that this  filamentous structure, by which it
adheres to  the other two coats,  is  vascular: as this
assertion however is founded on a process of reason-
ing, and not on absolute demonstration,  our assent
may very properly be  withheld from it till an injec-
tion is brought forward to prove the fact. This mem-
brane is well marked  also in the sheep, ox, horse,
dog, and other domestic animals, indeed in all the
mammalia which he has had the opportunity of ex-
amining.  It exists also in birds and  fishes, and is
said to be particularly strong in the latter.  Mr. Cu-
vier has described it in fish as one of  the lamina of
the retina,  but its sensible properties are asserted by
Mr. Jacobs to be very dissimilar from those of the
retina.
  As this  membrane  may possibly be  confounded
by the student with one of the lamina  of the human
retina, it should  be borne in mind that  the latter con-
sists of two parts, a pulpy or nervous expansion and
a reticulated vascular structure on which the pulp is
laid, the pulpy part  being exernal.
  The reticulated structure is called by some the tu-
nica vasculosa retinae.  Most anatomists have known
and  admitted these two membranes  as  composing
the retina, yet but few have had  the  expertness to
separate them from each other, and to leave at the
same time the membranous structure  visible.   Albi-
nus had the success to accomplish this separation, and 
366
Humours of the Eye.
I am informed, on the authority of Dr. Physick, that
Mr. Hunter also succeeded in it.
  When the common dissection of the retina is made
and fixed in clear water, this membrane will be seen
floating around it in delicate flocculi; but if a more
careful dissection be made, by fixing the  eye to the
bottom of a basin of water, by its cornea, through the
aid of shoemaker's wax, and the sclerotica and cho-
roidea be removed from behind, this membrane may
be turned down  entire from the retina, with the end
of the handle of a scalpel.]  Ed.

                   SECTION III.

            Of the Humours of the Eye.
  The three humours of the  eye, viz.  the Aqueous,
the  Crystalline, and the  Vitreous, are separately in-
vested with a membranous capsule;  which is very de-
licate, and perfectly transparent.

               The Vitreous Humour
  Occupies almost all the cavity of the eye which is
posterior to the iris.  It of course possesses a sphe-
rical form.   It has a depression in the centre of its
anterior surface, in which  the  posterior  surface  of
the crystalline lens is received.  It is covered by the
retina as far as the retina extends.
  The peculiar consistence of this body,  which re-
sembles that of melted glass, is owing to its mem-
brane ;  which is a  spherical sac, divided by many
septa, or partitions, that form small irregular cavi-
ties, in which a fluid  is contained.  This  membra-
nous  sac  is  most  perfectly transparent, and  very
flexible; it has,  however, some strength; as it will
support the weight of all the fluid it contains; and
may be suspended from a hook or forceps.   The
fluid  may  be  separated  from  the membranes,  by 
Tunica Hyaloidca.              369
 beating the vitreous humour in a cup with a spoon;
 or  by suspending the vitreous humour,  and then
 puncturing it.   In either case the fluid escapes; but
 the internal arrangement of the membranes  is not
 visible.
   It is said that when  this body is frozen, the por-
 tions of fluid in the different cavities, have sometimes
 been  distinguishable  from  each other,  as distinct
 pieces of ice;  and that their form is that of small
 wedges; with their edges directed to the crystalline
 lens as a centre, and their bases to the circumference
 of the vitreous humour.   It is  also said, that if this
 body be immersed in a solution of potash, the mem-
 branes will become opaque, while the fluid continues
 transparent: and that  the  appearance of the cells,
 thus exhibited, agrees with the form of the pieces of
 ice  above mentioned.
   This membrane is now  generally called the Tu-
 nica Hyaloidea, 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 artery,) sends a branch through  the vi-
 treous humour  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 ap-
 pears to  consist of but one lamen; but at the front
 part, near the  ciliary processes,  there are two  lami-
 na.  The internal, or posterior, seems to be a por-
 tion  of the proper tunica hyaloidea,  and passes be-
 hind the  crystalline lens.  The external, or anterior,
 passes over and before the lens; or at least is attached
to the anterior part of the capsule, in which the lens

             * Discovered by Fallopius in 1584.
   Vol. i.               47 
370
Fluid in the Tunica Hyaloidea.
is  contained.  It is  supposed by some anatomists,
that this membrane is continued completely over the
crystalline lens; but it has not been separated.
  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 im-
pressed with radiated plates by the ciliary processes,
and some of the pigmentum nigrum of these processes
adheres to it.
  As these lamina of the tunica hyaloidea  are sepa-
rated by the crystalline lens,  there  is a vacuity be-
tween them, around the margin of the lens: and this
vacuity must necessarily be circular in its course.
  It is not probable that any considerable quantity
of fluid is  contained  in  this vacuity; for the two  la-
mina concerned in its formation, appear in contact
with each other.  It can be readily  demonstrated by
puncturing the external lamen, and blowing into it
through a small pipe.   When thus  distended,  there
appear to be incomplete partitions  in the canal; or
partial adhesions of the lamina forming  it, which
have the effect  of 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  cele-
brated Petit who discovered it.
  The anterior lamen of the tunica hyaloidea, which
forms part of this canal, seems to adhere to  the coats
of the  ciliary processes; for if a section is made be-
hind the ciliary ligament of all the  coats of the eye,
the vitreous humour will be  found  adhering to the
anterior portion of the section, when it is lifted up.
   When the fluid  contained in the tunica hyaloidea
is discharged  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 
Crystalline Lens.
371
 called the Aqueous Humour.    This  circumstance
 proves that the particular consistence of the vitreous
 humour is derived from the arrangement of its inter-
 nal membranes.
   The fluid, thus obtained, consists of water slightly
 impregnated;  1st, with  albumen, 2d, with gelatine,
 and 3d, with muriate of soda.
   The vitreous humour appears necessary, to give
 the ball of the eye  the  necessary  size, for the per-
 formance of its optical functions: to keep the retina
 properly distended: and to retain the crystalline lens
 at the proper  focal distance from the retina.

                The Crystalline Lens
   Is a solid body;  although it is considered as one
 of the humours of the eye. It is of a softish consist-
 ence: and has been compared to gum half dissolved;
 but is more firm  in the centre than about  the cir-
 cumference.
   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 convex-
 ity of the different surfaces, is different.  The ante-
 rior surface, which is the  least convex, is  the seg-
 ment  of a sphere, whose diameter varies from six
 to nine lines.   The posterior surface, which is most
 convex, is the  segment of a sphere, whose diameter
 varies from four  lines and a half,.to five lines and a
 half. This lens is most convex in young subjects.
   It is invested with  a  tunic of the same lenticular
form with itself; which has some firmness; but in a
healthy state,  is  also perfectly transparent.   The
lens either does not adhere at  all to this tunic, or  so
slightly, that  it projects from, it  with  very slight
pressure, as in the operation of extracting the ca-
taract.
   The posterior surface of this tunic adheres firmly 
372
Crystalline Lens.
 to the tunica hyaloidea, with which it is in contact:
 and this last membrane, is generally ruptured in the
 attempt to separate them, although the  separation
 can sometimes be effected without rupture.
   The anterior surface is  so  intimately  connected
 with that lamen of the hyaloid tunic which passes
 before it from the canal of Petit, that it is not separa-
 ble 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 exte-
 rior portion of the lens, there  is  reason to  believe
 that it has a peculiar organization; for if it  be im-
 mersed 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 con-
 centric  lamellae, which resemble  those of the bul-
 bous 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 es-
 capes whenever the capsule is punctured. This fluid
 is supposed to be most abundant on the anterior sur-
 face, and is called Liquor Morgagni.
   The lens is said by chemists to be composed  of
 albumen and gelatine^ with some  phosphate of lime;
  * See Dr. Young's Memoir  in  the Philosophical Transactions  for
: 1793. 
Aqueous Humour.              373
and  it is asserted that the proportion of gelatine is
much smaller in the centre than in the exterior parts.
   No blood vessels are to  be seen in any of the hu-
mours of the eye, or their capsules, excepting those
of the foetus.   In the foetus a branch can be traced
from the central artery of the retina, through the vi-
treous humour, to the posterior surface of the  crys-
talline capsule, on which it ramifies. In similar sub-
jects vessels have been seen passing from the ciliary
processes to the anterior surface of the capsule; and
it is also asserted by very respectable anatomists that
they have seen vessels passing from the capsule into
the substance of the lens.
   The use of the crystalline lens is to  concentrate the
rays of light,  so as to form a distinct  image at the
bottom of the eye.
               The Aqueous Humour

  Occupies the space which is between the crystal-
line  lens and  central extremities of the ciliary pro-
cesses and the cornea.  This space  is divided by
the iris into two chambers, very dissimilar in figure,
which  communicate with each other by means of
the pupil.   The posterior chamber is much small-
er 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 hu-
mour in a state of congelation.
  The aqueous humour, in  a natural   state, is  per-
fectly transparent: but in the  foetus, and for a short
time after birth, it is reddish and turbid.  It consists
of water impregnated with albumen,  gelatine, and
muriate of soda;  and of  course resembles the  fluid
of the vitreous humour.
  It is probable  that this  fluid has also a capsule
appropriated  to it; for, after boiling an eye, a  defi-
nite membrane  can be found lining the internal sur- 
37 4              Dissection of the Eye.
  face of the cornea,  and extending  from it over the
  anterior  surface  of the  iris.   It has not yet  been
  traced  as far as the pupil, but it is probable that it
  extends through  the  pupil,  and  lines the posterior
  chamber also.*
    The aqueous humour is quickly renewed after it
  has escaped in consequence of wounds or operations,
  and blood  accidentally effused into its cavity is  of-
  ten absorbed.t
    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 easi-
  ly obtained.  They resemble the human eye  in many respects:
  and the circumstances in  which they differ may be readily as-
  certained by  the diligent student j especially if he dissects the
  human eye afterwards.
   For this purpose it will  be requisite to  have forceps,  finely
  pointed; with knives and scissors that are equally delicate in
  structure ; and also a pair  of strong scissors, bent  like those in
  the cases of pocket instruments.
   When removing the exterior parts, it will be useful to pre-
 serve a portion of the optic nerve, to lake  hold of.
   The  dissection of the coats of the eye can behest performed
  when the eye is placed in  a vessel of water; which should be
  shallow or deep, according to the different stages of dissection.

   * This capsule was discovered by Messrs. Demours  and Descomet, win
 disputed each others claim in 1767.   It is thought to  be useful in prevent-
 ing the cornea from being penetrated by the aqueous humours,  and the
 pigmentum nigrum from being washed off' the iris, and making this humour
 turbid.  Mr. J. Cloquet says that he has traced it in the posterior chamber
 of the eye.  From his account it appears that there is one capsule in early
 fetal life for the anterior chamber, and another for the posterior chamber,
 and that the Membrana Pupillaris is formed by these capsules being stretch-
ed across the pupil, back to back.  En.
   j- The aqueous humour, according to Mr- Hunter, can be coagulated
 with Goulard's Extract.  En. 
Dissection of the Eye.                3/D
  In some dissections it will be serviceable to form a  bed of
jelly, to support the eye, as^sroposed by Mr. C. Bell.
  As the first process in this  operation, the sclerotic 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 cnoroides.
  The choroides, by a careful process, may then be separated
from the retina,  which it leaves surrounding the vitreous  hu-
mour.   Trie ciliary processes, being a part of 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-
mours and the retina.  The retina, originating  from the op-
tic 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 humours ; and the pigmentum nigrum, which of-
ten adheres to  that part of the  vitreous humour which was
connected with the  ciliary processes,  may be washed  away
with a piece of  soft sponge.  By this washing  the  radiated
grooves in the vitreous humour, which were connected with
the ciliary processes,  will be very apparent.
  lo examine the iris in its natural situation, an aperture may
be made in the cornea of a fresh eye near its  circumference,
and the cornea cut out with the strong scissors. This exposes
the anterior surface of the iris.
  The  iris may then be  easily removed, and  the  crystalline
lens, \yith  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 process will appear very distinctly,  seen through a por-
tion of the vitreous humour.   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 humour
should  be cut away with the scissors and forceps, so as to less-
en the quantity without deranging the parts under it.
  Several  methods  have  been  proposed for  rendering  the
structure of the vitreous humour, and the  processes of the tu-
nica hyaloidea, more distinct.   None of them have been very
successful: but if the vitreous humour be suspended in water
by means ot a thread passed  through  that part which sur-
rounds the crystalline lens, and some large incision be made 
376              Dissection of the Eye.

jnto the most depending part of it, after some days of suspen-
sion, 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 ve'ry apparent', and by
various degrees of exposure to light, may have its colour va-
ried 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
applications it could only be  said, that the pulpy substance of
the retina appeared to terminate at  the commencement of the
ciliary processes, while a membrane of a different texture seem-
ed continued from it to the crystalline lens. 
CHAPTER IV.
                   OF THE EAR.

   The organ of hearing is composed of three dis-
 tinct parts, viz.  1. The exterior portion, which, al-
 though merely auxiliary, is denominated the Exter-
 nal Ear.   2. A chamber, situated  in  the  petrous
 portion of the temporal bone, which is called the
 Cavity of the Tympanum   3.  A deeper seated
 cavity in the same bone, which, from its complicated
 form, is denominated the Labyrinth,

                    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 tym-
 panum, called Meatus Auditorius Externus.
   The form of the Ear is so familiar to every one
 that it is not necessary to describe  it.  The  upper-
 most 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 euticle 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 sub-
jacent cartilage by a dense cellular membrane, which,
 in most places, is  free from adeps.
   The cellular membrane of the lobus contains adeps
 very delicately arranged.
   Vol. i,               48 
378
The External Ear.
  The circumference of the ear is formed by a fold
of the margin of the cartilage:  and this folded edge
is denominated Helix, from its winding direction.  It
commences in the cavity called Concha,  to be  pre-
sently described:  and after proceeding forwards and
upwards,  it turns round backwards and downwards.
  Within this prominent  margin is a second  promi-
nence, called the  Antihelix,  which  appears to be
formed by a convexity of the surface of the cartilage,
but is found in every ear.   It is nearly semicircular,
with its concavity towards  the meatus; and it forms
the margin of the cavity called Concha, above men-
tioned. The upper portion of the antihelix consists
of two superficial ridges which  unite after forming
between them a shallow depression, the  Fossa Na-
vicularis,  or Scapha.
  The helix and antihelix form therefore three ca-
vities or depressions, viz.  1. A sulcus, occasioned by
the fold of the helix, which is sometimes called Fos-
sa 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 Antitra-
gus, formed also by this cartilage.   The  Tragus is
anterior to the meatus auditorius, and covered by a
continuation  of the  skin of the  face.  It projects
backwards, so as partly to cover the meatus.   On the
inside of it there is commonly a tuft  of  hair, from
which its  name is derived.
  The Antitragus  is opposite to the  tragus,  on the
posterior  margin of the concha.
  On the  posterior  surface of  the ear the convexity
of the concha is very conspicuous.
  When the skin and cellular  membrane is careful-
ly removed,  and  the cartilaginous  skeleton  of this
structure  is  examined, its  form will  not appear so 
The External Ear,           379
regular as that of the undissected ear; for there are
several deficiences or vacuities in it;  the most re-
markable  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 mem-
branes, which connect it to the zygomatic and the
mastoid processes 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, de-
scribed at page 175, there are a few muscular fibres,
which, in some subjects, may be discerned on parti-
cular parts of the cartilage, and therefore are consi-
dered as muscles proper to these portions of the ear.
   There are five of these portions of fibres :  two on
the helix, one on the tragus, one near the antitragus,
and the fifth on the other side of the ear.
   The  Major Helicis is on  the anterior and  most
prominent part of the helix above the tragus.   The
Minor Helicis is  lower  down  on the  helix,  in the
concha.
   The  Tragicus lies on the tragus, and the Antitra-
gicus behind the  antitragus, while the T?*ansversus
Auris is on the other side of the ear, on the  promi-
nence 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 ma-
jority of mankind, cannot be  perceived to produce
any effect at all.
   There are difficulties in explaining the form of the
cartilage; for, notwithstanding the well known opin-
ion of  the Geometrician said to have been employed
by Boerhaave,  that the line of reverberation is di-
rected to the meatus auditorius externus from every 
380     fad Meatus Auditorius Externus.

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 rever-
berated into the meatus.
   It may be questioned whether the backward posi-
tion  of the ear, which is commonly observed at  the
present day, is altogether natural; as a  more promi-
nent position seems much better calculated for  the
reverberation of sound ; but this position of the car-
tilage is observable in many infants at birth.
   It is asserted by some comparative anatomists that
the cartilage is stronger and more elastic in propor-
tion  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, ex-
tending from the concha to the membrana tympani;
the external extremity of which is principally com-
posed of cartilage, and the  internal of bone.  The
cartilage in the external portion of the tube is a con-
tinuation of the  substance of the  concha.  It does
not solely form a complete tube,  for when the mea-
tus is opened longitudinally and spread out, this  car-
tilage  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 Incisure ; and the fibrous structure which
closes that which is transverse,  has been called by
Santorini,  who  described  it, Musculus  Incisurx
Majoris.
   The cartilage is attached  to the bony portion of
the meatus at  the lower part of its margin, and forms
about one half of the length of the meatus.
   The  skin covering the external ear is continued
into the meatus, and lines it throughout: extending
over the incisure, and also over the membrana tym- 
The Meatus Auditorius Externus.     381
pani.  It adheres more firmly to the periosteum of
the bony part of the meatus than to any other portion
of  the canal.   Some fine hair is  often observable
growing out of it at the external extremity.   As the
skin advances deeper  in the meatus it becomes more
and more  delicate and sensible.  The extreme pain
excited by the 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 surrounds it, are many small glands*  of a yel-
lowish colour, whose ducts open upon the surface of
the meatus, and  pour upon it the substance called ce-
rumen or ear wax.  These glands are most numerous
about the  middle of the meatus, and at those  places
in which the eartilage is deficient.  The cerumen  is
fluid at first, and gradually thickens.  In some dis-
eases of the meatus it has the appearance of pus.—
The use of this  secretion is probably to exclude in-
sects, 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 for-
wards : 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 fig-
ure.  In the foetus the  bony part of this duct is not
formed, and the  meatus  consists entirely of cartilage.
• Discovered by Stenon, in 1662—Ed. 
382      The Cavity of the Tympanum,


                    SECTION II.

        Of the Cavity of the Tympanum,

  The meatus auditorius externus is terminated ab-
ruptly by the membrana tympani, which forms a sep-
tum that closes it completely.
  On the inner side of this septum is the Cavity of
the Tympanum, which may be regarded  as the con-
tinuation of the bony meatus.
  It differs however from the form of this canal, for
its diameter is greater, and it is not so regularly cy-
lindrical.
  It is not deep, as the distance from the membrana
tympani, which constitutes the external side,  to the
opposite internal side, is seldom more than  three or
four lines.
  The breadth of the cavity of  the tympanum  is
therefore greater than its depth.
  It is situated immediately between the membrana
tvmpani, 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 cellular structure of the mastoid  process.
  There are also two deficiencies in  the bony plate,
which separates it from the labyrinth, called the Fo-
ramen Ovale, and Foramen Rotundum ; but in the
natural state of the parts these deficiencies are closed,
and there is no direct communication of the tympa-
num either with the labyrinth or the meatus audito-
rius externus.  The only direct communications be-
ing those above mentioned,  with the  fauces  and the
mastoid cells.
  That deficiency in the bone between the tympa- 
The Cavity of the Tympanum.      383
num and the labyrinth, which is  called Foramen
Ovale, is closed by one of the small "bones of the ear,
called the Stapes.  The other deficiency, called Fo-
ramen Rotundum, is covered by the membrane which
lines the tympanum.
  In the cavity  of the  tympanum are  four of the
smallest bones of the body, which are articulated
with each other so as to  form  one flexible piece.—
This piece  is attached by one end to the membrana
tympani, and the other to  the Foramen Ovale; and
it is moved by small muscles connected with it.
  The cavity of the  tympanum is  lined by a mem-
brane which has been considered as similar to  the
periosteum: but it is asserted by  Bichat that this
membrane,  when inflamed, resembles  the mucous
membranes; and that in its natural state it secretes a
mucus which passes  into the  fauces by the Eusta-
chian  tube.
  This lining membrane is continued over the inter-
nal  surface of the membrana tympani, and was sup-
posed 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
60und state, and  therefore is very different from pe-
riosteum, which it was supposed to  resemble.

            The Membrana Tympani,

Appears to be fixed  in  a  bony ring  in the meatus
auditorius,  and is nearly circular in form.   It is not
perpendicular to the  meatus, but has an oblique posi-
tion in it; the inferior margin projecting further in-
wards than the superior.
  The external surface forms a conical concavity, 
 384         The Membrana Tympani.

 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 mem-
 brane may be separated into four lamina, viz. 1. The
 Cuticle;  and 2.  The  Cutis; which are continued
 from the skin o£ the meatus externus.  3. The pro-
 per  Membrana  Tympani;  and  4.  The Lining
 Membrana of the Tympanum; which is extended
 over the internal  surface  of the membrana tympani.
 Notwithstanding  these lamina, it is  almost transpa-
 rent in  the living subject, when in a healthy state,
 and appears highly  polished on its external surface,
 when light is thrown upon it.  It has been injected
 so as to appear vascular  in every part; and one or
 two vessels are sometimes seen even in common  in-
 jected 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,  than an aperture,  occasioned by
 accident or disease, is sometimes perceived in per-
 sons who enjoy the faculty of hearing to a consider-
 able degree.  Some persons, thus circumstanced, are
 accustomed to force tobacco smoke from the mouth
 through the ears.
   It is asserted by a respectable anatomist * that the
 membrana  tympani,  when viewed in a microscope,
 which will  magnify twenty-three times, appears to
 be supplied with muscular fibres arranged in a radi-
 ated manner.  These fibres are on the internal side
 of the membrane.   He thinks that under favourable
 circumstances they can be seen with the naked eye,

 * See Mr. Home's Memoir on the structure and uses of the membrana
Tympani. in the Philosophical Transactions for 1800. 
The Mastoid Cells.
3&3
              The Eustachian  Tube.
   The  communication between the cavity  of  the
tympanum  and the fauces is formed by the Eusta-
chian Tube, a canal which  consists of bone at one
extremity, and of cartilage at the other.   It commen-
ces in the upper and  anterior part of the cavity of
the tympanum, and continues forwards  and inwards
through a part of the petrous portion of the temporal
bone, above the fissure in the cavity for receiving the
condyle of  the lower  jaw.   The  bony canal termi-
nates in a very rough  and irregular orifice, which is
united to a tube composed of cartilage and of mem-
brane, that terminates by a large orifice behind the
inferior turbinated bone  of the nose, and on a line
with it.
  This  tube is lined by a continuation of the mem-
brane of the posterior nares, which becomes more thin
as it proceeds towards the cavity of  the tympanum.
  Above the  Eustachian  Tube, and  separated from
it by a thin plate of bone, is a small canal which is
nearly parallel to it, and  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
tympanum, nearly opposite to the  orifice of the Eus-
tachian 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 apparently similar.  Their
size is proportioned to that of the mastoid process,
and consequently they do  not exist in the foetus.

Foramina  and Protuberances of the Tympanum.

  That part of the surface of the cavity of the tym-
panum which is opposite to  the  membrana tympani.
  Vol.  i.             49 
386
The Bones of the Ear.
is very irregular, but it contributes to the formation
of  several parts  which are very  important in the
structure of the ear.
  When the lining membrane is removed, the aper-
ture 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 Labyrinth ; but it is closed by the
base of the stapes.
  Above the foramen ovale  is a prominence of the
surface, in which passes the canal for the 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 mem-
brane which lines the tympanum.
  Behind the  foramen ovale is a protuberance with
a perforation 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 tympa-
num 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 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 
The Bones of the Ear.
387
from the upper end of the handle.  The handle of
the Malleus forms an angle with its body, the salient
side of the angle presenting outwards: the space from
this angle  to the termination of the manubrium, or in
other words the whole manubrium is connected with
the membrana tympani.
  The Incus resembles a molar tooth, with two roots,
widely separated from each other.   On the body is
a depression which is connected with the head of the
malleus.   One of the  roots or crura is much longer
than the other.
  The Os 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  com-
mon stirrup.   The upper part is called its Iiead, the
lower part its beise, and  the  two  lateral portions its
crura.   One of the crura is longer than the other.
A groove is also observed on  the inner side of its
crura, when they are examined with a microscope.
The base is applied to the Foramen Ovale.
  The situation of these bones is such, that the head
of the malleus and the body of the incus are in the
upper and anterior part of the cavity of the tympa-
num, which extends above the membrana  tympani.
The malleus is  the most anterior of the two bones :
its manubrium  projects  downwards, and is included
between the  internal lamen of the membrana tym-
pani and the membrane  itself.  Its long process ex-
tends 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 short-
est leg projects backwards horizontally, and is attach-
ed by a ligament to a point in the opening  into the 
S88   The Muscles oj the Bones of the far.

mastoid  cells.   While  the long leg  projects down-
wards like the handle of the malleus,  but behind it,
and at a small  distance inwards from the  membrana
tympani.
   The situation of the stapes is almost at right angles
with  the long  leg of the incus, projecting  inwards.
Between the head of the stapes and the long leg of
the incus, the  os orbiculare intervenes.
   When these bones are viewed in their natural po-
sition, the short leg of the incus projects horizontally
backwards, the long process of the malleus  horizon-
tally forwards; the handle of the malleus, and the long
leg of the incus, directly downwards, one connected
with  the membrana  tympani, and the other  with the
foramen ovale, by the intervention of the os orbicu-
lare and stapes.*

       The Muscles of the Bones of the Ear.
   The aforesaid bones  appear to  be  regularly arti-
culated for motion with  each other, and they are fur-
nished with several  muscles.
   One of these muscles  runs in the bony canal above
the Eustachian tube, and is  inserted  into the poste-
rior side of the handle of the malleus, below the root
of the long  process.   Its effect is to draw in the mal-
leus and membrana tympani.   It  is  therefore called
 Tensor  Tympani, or Iternus Auris.
   Another muscle, as it is supposed to be, runs in

  * Lassus ia bis excellent discourse on Anatomy informs  us that Fallo-
pius and Eustachius described nearly the whole interior of the Ear. The
most ancient authors  had remarked the thin and transparent meinbraDe
which closes the extremity of the meatus externus.   Fallopius described
particularly the tympanum; of the four bones within it, the malleus, incus,
os orbiculare and stapes. Berenger de Carpi described the two first; In-
grasias, Eustacbius, Columbus, and Louis Collada, a Spanish physician, dis-
puted the discovery of the fourth with each other; and Vesling assures us
that Francis de la Boe, a Dutch  physician, discovered the third which is
the smallest - 1'- 
The  Chorda Tympani.         389
the fissure on  the  outside of the Eustachian tube,
and is inserted into the long process of the malleus.
  This  is supposed to draw the malleus obliquely
forward, and of course to  relax the tympanum.  It is
therefore called  Laxator Tympani,  or Externus
Mallie ; but there  are  the strongest doubts respect-
ing the muscularity of this organ.
  Morgagni,  Haller,  Lieutaud,  and Meckel, could
not satisfy themselves that it was  muscular ; and Sa-
batier also 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  mar-
gin 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 pyra-
mid.  Its  tendon passes through the foramen in that
protuberance, and is inserted into the posterior part
of the head of the stapes.  It pulls the head of the
stapes upwards and backwards.

             The  Chorda  Tympani.

  In the upper and posterior part of the cavity of the
tympanum 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 cavity for  the  head of the lower
jaw.  In this course it crosses the long leg of the in-
cus, and the manubrium of  the malleus,  and passes
between them, being in contact with the manubrium. 
390
The Chorda Tympani.
   This nerve comes off from the portio dura imme-
diately before  it  emerges from the  foramen stylo-
mastoideum,  and  after  passing  a  short   distance
through a small canal,  enters the cavity of  the tym-
panum 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 spheno palatine nerve,  which entering
the os petrosum  by the Vidian Foramen joins the
portio dura; and after  passing with 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 per-
      sons in whom the membrana  tympani has  been des-
      troyed, should  enjoy the sense of hearing  in a very
      considerable 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 maybe duly performed.
    This is evinced by the deafness which results from the
      obstruction of ths  Eustachian tube, and the cure of
      this deafness by relieving that obstruction j as well as
      by the  salutary effects of opening the membrana tym-
      pani ;t and even of instituting a communication through

  * I have followed Mr.  H. in  this dissection and  have no doubt of hrs
opinion being correct.—Ed.
  f See Dr. Sim's paper on  this  subject in the first volume" of Memoirs of
the Medical Society of London ; and Astley Cooper's in the London Pbi-
v-so^hical Transaction 
The Labyrinth
391
  the mastoid cells, in cases where the obstruction of
  the Eustachian could not be removed.
It has beeu supposed that the Eustachian tube has the
  effect of transmitting sound to the ear, and particu-
  larly 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 orifice 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, however, to be remembered,
  during the investigation of this subject, that persons
  who hear with difficulty are almost invariably in the
  habit of opening their mouths when they listen.
section in.
                 Of the Labyrinth.


  Those parts of the organ of hearing which have
been already described, seem calculated for  concen-
trating the vibrations of air; and for communicating,
with some modification, 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 beeu
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 circle.  These tubes communicate with the ves-
tibule  by each  extremity ;  but they form only five
orifices, because two of their extremities are united 
392
The  Vestibule.
 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 Labyrinth, thus complicated  in its form, is
 situated on the inner side  of the cavity of the tym-
 panum.   Its position is such that the Vestibule and
 the Cochlea are opposite to the Membrana Tympani,
 and the Semicircular Canals are posterior to it.  The
 apex of the cochlea is on  the  side of the  labyrinth
 which  is next to the tympanum, the basis of the
 cochlea is next to the brain.
   The texture of the  bone which immediately sur-
 rounds 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 sur-
 rounds  these cavities, corresponding exactly to their
 form.
   The  Labyrinth, when thus prepared, may be con-
 sidered as a solid body which has been enveloped in
 a softer substance, and is brought into view by de-
 taching the soft substance,  which surrounded it.
   In the foetus it is nearly  as large as in the adult,
 so that  the structure of the ear can be investigated
 with great advantage in such subjects.

                  The  Vestibule
   Is situated within the Foramen Ovale.  There are
 two remarkable depressions of  its internal surface;
one, which is in the superior part, is  called Semi El-
 liptical; 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 
The Cochlea.
393
 Ovale, already mentioned. A round aperture, by which
 it communicates  with one  of the cavities of the
 cochlea, and the five openings of the semicircular ca-
 nals. Besides these, there are several small perfora-
 tions from the Meatus Auditorius Internus for the trans-
 mission of nerves.

                   , The Cochlea.
   Commences at the anterior  part of the vestibule.
 It is a conical tube, so convoluted that it has the form
 of the shell of a  snail,  making two circuits and a
 half round a centre.
   It may be considered  as wound  in a spiral direc-
 tion 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 dimi-
 nishes in  diameter as it proceeds  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 broader, and thus
 forms a  second cone inverted.   This last  portion
 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 Cu-
pola.
   The tube thus wound  round the modiolus, or the
 cochlea,  is divided from the beginning to the end by
 a partition.
   The cavities are called Scalce,  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
 cartilaginous.
   Vol. i.                ;j() 
394  Lamina Spiralis and Scala of the Cochlea.

   3d. A cellular portion, which appears to contain
a pellucid fluid.
   4th. A thin membranous strip, which completes the
septum or partition.
   These parts may be distinguished from each other,
when magnifying  glasses of sufficient  power  are
used.
   The bony plate is  composed of two  lamina  with
small cancelli between them, in which are canals for
the transmission of the fibres of nerves.   These ca-
nals are extended into the cartilaginous part.
   The membranous part which completes the sep-
tum is continued into the lining membrane  on the
surface of the cochlea.
   The bony portion of the scala does not extend to-
wards the apex of the cochlea  so far as the cartila-
ginous and membranous portions; and none of them
continue to the apex, for  the lamina  spiralis termi-
nates in the infundibulum 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
cochlea, the two scala? necessarily communicate with
each other at the apex.
   These different bands or strips which compose the
lamina spiralis, are called its Zones, and are termed
Zona Ossea, Zona Coriacea, Zona Vesicularis, and Zona
Membranacea.
   From what has been stated  it follows that there
are two cavities in the cochlea, each of which  con-
tinues throughout its whole  extent.  One begins at
the  vestibule;  the other at the tympanum.   But
a membrane extended over the foramen rotundum
separates this last from the  tympanum.   They com-
municate  with each  other at their terminations.
From their origins they are denominated Scala Ves-
fibuli and Scala Tympani. 
            The three Semicircular Canals.        395

   As both the cochlea  and the vestibule are filled
with a fluid, it is evident  that a vibration produced
on the membrane of the foramen rotundum may be
communicated  through the two scalae to the vesti-
bule.

           The three Semicircular Canals

   Are placed obliquely behind the vestibule.  Their
position is such that one is  Superior, another Poste-
rior, and the third Exterior.  The superior and  pos-
terior are so placed that one extremity of each may
be  considered  as internal  and  the other  external.
They unite at their internal extremities, which there-
fore 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 diame-
ter, viz. rather more than  two lines*
   At one of their extremities each of them has  an
enlargement, which is called Ampulla;  and there is
no other variation of their diameters.
   The cavity of the labyrinth, thus complicated, is
perforated by many small foramina, through which
various nerves are transmitted.
   These foramina communicate with the large canal
on the posterior side of the petrous bone called Mea-
tus Auditorius Internus; which continues very near to
the basis of the cochlea, and transmits  the  seventh
pair of nerves.
   The bottom of this cavity is divided by a ridge
into two unequal fossae; the uppermost of which is
the leant.
   In the  Upper fossa are two foramina:  the anterior,
which is the largest,  serves to transmit the  Poriio
dura, a part of the seventh pair, to be hereafter des- 
396          Contents of the Labyrinth.

cribed, which passes through the petrous bone to the
face.  The posterior foramen forms a pit with a cri-
briform bottom, which admits nervous fibrillae to the
vestibule.
  The anterior part of the Inferior Fossa is also cri-
briform ; its perforations lead to the cochlea; one of
them, which passes through the modiolus to the in-
fundibulum, 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 of bone.
  In the cavity of the Vestibule are two sacs distinct
from each other, and also from the lining membrane.
  One of these,  denominated Sacculus  Sphericus, or
Sacculus Vestibuli, is situated partly in the Hemispherical
Cavity of the vestibule, and has no direct communi-
cation 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 membranous semicircular canals, which
are soon to be described, communicate with it by
each of their extremities: it has been called Alveus
Communis by Scarpa, and  Utriculus by Soemmering.
  In the bony  canals already  described,  are three 
                The Auditory Nerve.            397

Membranous 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
longer.

                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  appen-
dage, the Portio Media, composes the seventh pair of
nerves of the brain.
  It is called Portio Mollis, and is very distinct from
the Portio Dura, although they pass  together along
the Meatus Auditorius Liternus.
  Corresponding to the foramina and the cribriform
structure  of the bottom of the Meatus Auditorius In-
ternus, the Auditory Nerve, passes into the Labyrinth
in branches, or fibrillae,  of various sizes.  One por-
tion of them enters the Vestibule, and has been traced
upon the Alveus or Utriculus, and its internal surface;
and also upon the  Semicircular membranous  tubes.
Another portion seems exclusively appropriated to  a
part of these tubes. And a third is spent upon the
Sacculus  Sphericus.
  These nervous fibres seem to terminate in a pulpy
expansion on the  internal surface of the aforesaid
sacs and  canals, in a way which has some analogy
with the termination of the optic nerve.
  A large bundle of these fibrillse enters  the Cochlea
at its base; and the largest of them passes through  a
foramen, mentioned before, along the centre of the
Modiolus to the Infundibulum. 
398
The Aqueducts.
  These fibrillae divide most minutely,  and passing
between the plates of the Lamina Spiralis, as well as
the other parts of the bony structure of the Cochlea,
at length form a  plexus, which has  the appearance
of a pulpy membrane, that is extended over the whole
of the Lamina Spiralis. 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  Semicircular 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 anato-
mist who first suggested their use,  the Aqueelucts 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 Aque-
duct of the Cochlea.
   The other  originates  in the vestibule,  under the
common orifice of the two canals; and terminates on
the posterior surface of the petrous bone,  by a small
orifice, which  is situated at some distance  behind the
Meatus Auditorius  Internus.  It is called the Aque-
duct of the Vestibule.
   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 Mea-
f See Sandifort's Thesaurus Dissertationum, &c. vol. 3. 
The Portio Dura.
399
tus Auditorius Internus, proceeds in a canal which is
called the  Aqueduct of Fallopius, through the bone,
to the  Foramen  Stylo Mastoideum, on  its inferior
surface; where it emerges, and  is distributed  to the
face.  It is  therefore called the Fascial 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 ofTthe Chorda Tym-
pani, immediately before it  passes out at the Fora-
men Stylo Mastoideum.  It also sends off small fibrils
to the muscles of the bones of the ear.
   It has not been ascertained  whether  the  Portio
Dura, the 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 comparative
      anatomy, is very interesting; but for want of more ac-
      quaintance with the state of this function in the different
      animals, no very decisive inferences have been drawn
      from it.
    The Vestibule and Semicircular Canals occur much more
      frequently than the Cochlea, which  is to be  found in
      few animals, if any, besides those of the classes of Mam-
      malia and of Birds.  It is therefore supposed necessary
      to that perfect state of hearing which  the animals of
      these classes enjoy.  But there remains a considerable
      difficulty on this  subject; the  Cochlea is not by any
      means so perfect in birds as in quadrupeds ; yet many
      birds appear to have clear perceptions of musical sounds,
      and some birds imitate  articulate sounds with conside-
      able  accuracy.
    That the impression which  produces hearing is made on 
400   Functions of the different parts of the Labyrinth.

       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 consider-
       able diminution of the size of the Auditory Nerve: while
       all the other  parts of the organ were in a perfectly na-
       tural  state.

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

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

                 CHAPTER I.

          OF THE CELLULAR MEMBRANE.

  That substance  which is situated between the
skin and the muscles, which is insinuated between the
different muscles, and between the fibres which com-
pose them;  which also connects  the  different  parts
of the body to each  other, is denominated the Cel-
lular Membrane, or Tela Cellulosa.
  As it extends  over the whole of the  body, and is
most intimately connected with the  skin, it is  consi-
dered 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 lamina,
exquisitely fine and delicate in their structure, which
are so  connected to each other that they compose
cells or  cavities of various forms and sizes.
  When these cavities are empty, this  arrangement
of the cellular membrane  is not apparent; but when
they are distended by water or air it is very evident.
  The lamina  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 considera-
  Vol, I,              51 
402          The Cellular Membrane,
ble length, and between the coats of the eye they are
very short.
  In  some places these  lamina are  compressed to-
gether, and form a dense  membrane somewhat re-
sembling tendon; but whenever they are separated
from each other they appear pellucid,  and extreme-
ly 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 cellular 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 con-
sidered by some very respectable physiologists as in-
organie; 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, co-
vered by an  emollient cataplasm, or a soft plaster,
a  complete  change of  colour 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 gran-
ulations will form on its surface.
   These vessels must have existed previously in the
sound state of the membrane, and conveyed a trans-
parent fluid;  although no structure of this kind was
visible.  This single fact therefore proves complete-
ly its organization.
   In some parts of the body, this cellular membrane
appears to be moistened  by a small quantity of fluid,
or halitus, 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 h 
The Cellular Membrane.         403
contained in cavities which are somewhat different
from the ordinary cavities of the cellular membrane.
  The cells or cavities which contain the moisture
er halitus  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 diffused over the whole body;
and produce the disease called emphysema.   In a pa-
tient who is affected with that species 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 after he
has been in an erect position for some time, the  fluid
will be accumulated in  the legs and feet, or most de-
pending  parts of the  body, in consequence of its
gravity.
  It is well known in dissecting rooms, that the ef-
fused water may be completely discharged from ana-
sarcas subjects, by making incisions in the feet, and
placing the subject erect.
  Blood  effused  in  the cellular membrane  is some-
times dispersed in the same way;  an ecchymosis of-
ten appears in the eye-lids in  consequence of a con-
tusion on the upper part of the head; and similar ap-
pearances 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
manner:  wherever it is first effused, it remains; un-
influenced by gravity, or the ordinary pressure.
  Fat is  not observed in every part of the  body; it
is never  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 ac-
cumulation of fat in these places is very obvious: and
it is equally certain that the cellular  membrane, in 
404   The Reticular and Adipose Membranes.

them, must be different from that in which fat is pro-
duced.
   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, su-
peradded to the cellular membrane; and some ana-
tomists, with  a view to  precision,  have called the
part containing fat, Adipose Membrane, and the other
part Reticular Membrane*  They state that in drop-
sical subjects, who are much emaciated, the mem-
brane, which  in a healthy state contained adeps,  is
more ligamentous than  the ordinary cellular, mem-
brane.
   It seems  to  be proved,  by reasoning, that there
must be a considerable difference between these dif-
ferent parts of the cellular  membrane; but it ought
to be observed that those  parts  of the  omentum
which are especially appropriated to the production
of adeps, do not exhibit any peculiarity of structure.
   This adipose substance is  distributed in unequal
proportions in  different  parts of the body.   In cor-
pulent persons there is a considerable quantity of it,
immediately under  the skin, and  especially under
the skin of  the abdomen.
   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 birth, it appears to be confined to the
parts immediately  under  the skin, but it  soon be-
comes more diffused.
   It is observed  by dissectors that there are no sub-
jects,  however emaciated, which  are  entirely free
from fat; except those which have been affected with
anasarca.
  * See remarks ou the cellular membrane, &c. by Dr. W. Hunter, in the
London Medical 0^=CT-->;itions and Inquiries vol. II. 
Connexion of the Cellular Membrane and Skin. 405

  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, ori-
ginate from  the cellular membrane in those parts.
  Whether this proposition be true or not, to the ex-
tent above  stated, it is a  fact that granulations, in
some instances,  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
cedematou6 swelling of  the limb, which increased sud-
denly to a great degree.   While  this was going on,
the granulations on the surface of the wound tumifi-
ed with the limb; and upon  examination, appeared
somewhat pellucid with an  effused fluid indenting by
pressure, precisely as the skin was indented.
  The cellular membrane appears to have a most in-
timate connexion with  the skin;  and cannot be com-
pletely separated from it  by dissection.  It is said
that in certain  cases of disease,  where it is reduced
to a slough, while the texture of the  skin remains
unchanged,  as in some  species of anthrax or carbun-
cle, 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 natural condition. 
CHAPTER II.
                  OF THE SKIN.

  The skin is composed of three dissimilar lamina, which
    are denominated the  Cutis Vera, the Bete Mucosum,
    and the Cuticula.

                    SECTION I.

                Of the Cutis Vera.

  The innermost of the above mentioned lamina is
much more substantial  than the others,  and there-
fore is called Cutis Vera.
  It is  an elastic,  dense,  and  strong  membrane;
which contains in its  texture a  large proportion of
fibres that appear to be tendinous, and  are woven
together in an intricate mauner.
  Blended with these fibres is an immense number
of vessels which enter into  the texture of the skin :
these vessels 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  ru-
befacients during life ; and  by fine injections, in the
dead subject.   Their existence is also demonstrated
in the vigorous infant, at birth, by the universal red-
ness 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 extend to every part.
   It is highly probable that the  processes of absorp-
tion and  exhalation are effected  by  small vessels 
Cutis Vera.
407
which originate 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.  al-
though its texture changes immediately upon its re-
flexion.
   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 leg, where op-
posite 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 distention, and returning to its usual size;
as in pregnancy,  dropsy, &c. but' it is particularly
demonstrated  in some eases  of parturition, when the
skin of the  perinaeum stretches immensely,  and, af-
ter labour, very quickly recovers size.
   The external surface of the skin is very generally
divided  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 ar-
ticulations, 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.
   On the external surface of the true skin, when the
two exterior lamina are removed ;  many papilla are
to be seen.  They differ in  size in different parts of
the body: they are vascular, and, on the ends of the 
 408      Pores, fyc. of the Otitis Vera.

 fingers, appear like villi, when examined by a mag-
 nifying 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 pro-
 bably are the exhaling or absorbing pores, but their
 connexion with  the  vessels which  perform  these
 functions has not yet been demonstrated.
   The internal surface of  the skin,  when carefully
 dissected from the subjacent cellular membrane,  in
 a subject of ordinary corpulency,  appears to have
 some adipose substance in  its texture; but, as has
 been already mentioned, when the cellular membrane
 is destroyed, these portions of adipose matter disap-
 pear, and the surface of the skin appears pitted.  It
 is probable that this connexion of the cellular mem-
 brane and skin may occasion that delicacy of skin
 which appears some in hydropic patients.
   In some places on  the  under surface of the skin
 are  small glands called miliary, from  their resem-
 blance to  the millet seed ; these  glands are supposed
 to secrete a sebaceous matter,  but they are  not  so
 general as has been supposed.
   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  accidently adheres to the
surface  of the  matter, and  forms  very 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 
  Vessels on the External Surface of the Skin, 409

 in the ducts in such quantities that it forms small tu-
 mours in the skin.
   Muscular fibres have been  supposed by some per-
 sons to exist in the skin,  but such fibres have never
 been demonstrated  in it.   The skin of the scrotum
 is often much  contracted, but the fibres which pro-
 duce this effect are very visible in the cellular mem-
 brane, and have a muscular appearance.
  Although the skin is not muscular,  it sometimes
 changes 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 consi-
 derable degree, the skin will  contract very sensibly;
 and at the same time a great  number of conical pa-
 pillae will project from its surface.   This constitutes
 the Cutis Anserina ; and is  supposed to be produ-
 ced by a sudden contraction  of the vessels in the skin,
 which forces out their contents, and of course dimi-
 nishes its bulk ; while the papillae do not contract  in
 the same degree, and therefore are somewhat  pro-
jected.
  When the skin is free  from disease, the two ex-
 terior lamina may be separated from it completely,
 after  maceration or putrefaction, and the surface will
 appear smooth ; but in an inflamed skin, a net-work
 of vessels has been  injected; which is considered by
 Mr. Cruikshank*  as an  additional  lamen.  In this
 lamen the  pustules of small pox originate.   When
 the skin is injected they  appear to be formed at first
 by very small vessels, arranged in a radiated man-
 ner, with a white uninjected substance in the centre,
 which is supposed to be a slough,  occasioned by the
 irritation of the variolous matter.   Mr. Cruikshank
after  removing this  lamella was able, by continued

 * Sec Experiments on Insensible Perspiration, &c. by W. Cruikshard:,
  Vol. :r,                :>3 
410           Of the Rete Mucosum.
 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 in spirits,
 and was  macerated in putrid water a week during
 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 inter-
 mediate colours.
   The variety of colours in the  human species de-
 pends upon the  lamella  next  to the cutis, which is
 now to be described.

                    SECTION II.

              Of the  Rete Mucosum,

   Immediately in contact with the external surface
 of the cutis vera  is a thin stratum, of a  pulpy or mu-
 cilaginous consistence, which  appears to be spread
 uniformly 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  ease  it  appears  like a  pulpy
 substance, spread  upon a  membrane of a soft and
 delicate texture.   This is the Rete, or Corpus Mu-
 cosum.
   In this pulpy  substance  resides the  pigmentum,
 or colouring matter, which gives the peculiar com-
 plexion  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 ne-
 gro ; copper coloured, yellow, or tawny, in many of

  * It has been asserted that the rete mucosum of the scrotum, can some-
-times be exhibited in a separate state. 
   Vessels between the Rete Mucosum and Cutis. 411

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 des-
cendants.
   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 de-
scribed, 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 anato-
mical pursuits in London, made a preparation which
excited the attention of the British anatomists, on ac-
count of its particular relation to this subject.
   He injected one of the lower cxtromities,  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 lamina,   he  macerated it  in cold water
for some days.  Upon separating  the  cuticle,  after
this treatment, he discovered a texture of  vessels 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 regreted  that  Dr.   Baynham, who is
particularly  qualified to decide,  has  not  published
his opinion  on the  subject.   Mr. Cruikshank, to
whom he afforded the most  satisfactory opportunity
of examining his preparation, believes that the afore-
said 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 sepa-
rated from the cutis,) while this texture remained on
the surface of the cutis.  He considers these vessels 
412      Change of Colour in Negroes.

as belonging to the additional  lamellae already men-
tioned, of which he says Dr. Baynham is the discov-
erer.
   There  is therefore every reason  to  believe that
there is a texture of vessels, either in the rete muco-
sum, or between the cutis vera and  the rete muco-
sum.
   After putrefaction, or maceration  for a long time,
the 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  putrefaction, the rete mucosum can  be
washed  away,  like  the  pigmentum  nigrum of  the
eye ;  leaving the cutis white,  and the cuticle nearly
transparent.
   In the negroes the black colour of the rete muco-
sum 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 cicatrices ;  but  those of
long standing are often dark coloured, although  not
so black as the  original skin.  The pits of the small
pox 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  cli-
mates ; and recovers it again in summer.
   The rete  mucosum sometimes  undergoes very  im-
portant changes; there have been several instances
in the United  States, where large  portions of  the
skin of  the African  have changed  from black to 
          Change of Colour in Negroes.      413

white; owing probably to an absorption of the black
pigment from the rete mucosum ;  or perhaps to an
absorption of the rete mucosum 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 colour
began 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
proportion of her face is  also white, and the remain-
der of it much  lighter  than it was originally.  At
this>J;ime,  some  part of her face has  an  unnatural
whiteness ; but the skin of her fore-arms appears like
that of a  European  in a  perfectly  healthy state.
This change  of colour is  attended with no  unusual
sensation ; so that if she  did not  see the alteration,
she would  not  suspect that her  skin  was any way
different now from what it had originally been.  She
does not appear sensible  that the white parts  arc
more susceptible 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 dimi-
nution of the dark colour ;  this change goes on gra-
dually, and then small spots appear, which are per-
fectly white.  They gradually 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 origi-
nal  blackness.
  These circumstances in negroes have been  consi- 
414 Changes of the Rete Mucosum in White Persons,

dered as great deviations  from the ordinary course
of nature,  but a process very analogous to it some-
times goes on in persons  who are white.   Thus,
there are some  in  whom   the skin becomes much
browner than natural in some parts of the body, par-
ticularly 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
colouring 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 deposition of whiter  matter
in it.
   The colour of the rete mucosum sometimes under-
goes 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 oc-
curs, the skin becomes very susceptible of irritatipn
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 conti-
nues 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 pf day.  They are generally desig-
nated by the epithet of Albinoes.
   The texture which exists between the cutis  vera
and the epidermis is probably the principal seat of 
             The  Cuticula or Epidermis.         415

several important cutaneous diseases; as the Scarla-
tina Pemphigus, &c* and from what  has been sta-
ted, there is good reason to believe  that the  small-
pox, also commences in it.  It is therefore much to be
wished that  its structure was more  precisely ascer-
tained.

                      SECTION III.
             The  Cuticula or Epidermis,

   Has been examined with the greatest care by se-
veral of the most successful anatomists; but notwith-
standing their labours, the structure of this substance
is  by no means understood.
   It appears to have some resemblance to  the mat-
ter  of  the nails,  and of horn; but is rather  more
flexible,  even  after allowing  for  the  difference of
thickness.
   In those parts where it is thinnest it is semitrans-
parent.
   It is insensible, and no vessels can be seen  in  it.f
   It extends over the whole external  surface of  the
body, except the parts covered by the nails, and is
accommodated to the surface of the skin, by forming
ridges or  furrows, corresponding to it.
   It adheres most closely to  the cutis; and  when

  * 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 altered in these
cases, and the cuticle is also unchanged, the cause of this separation must
exist in the intervening structure which connects them.
  f 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
injected with mercury.  Ruysh declared the thing impossible, and invited
him to an investigation of the subject.  This invitation was not accepted,
and the affair has been generally considered as a mistake  or an imposi-
tion. 
 416           Pares of the Cuticle,

 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 cuticle, to and from  the skin.  This sen-
 timent appears very reasonable, but no vessels that
 pass in this way can be injected.
   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  extre-
 mities.
   There  are also many processes which contain a se-
 baceous substance that may be pressed out of them
 in the form of worms:  these  are the ducts of seba-
 ceous glands.
   Besides these, there is an immense number of whi-
 tish  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  supposed  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

     ff See tiie Lsa'iou Medical Observations and IuquLie^ Vol.  II. 
Questionrespecting the Outlets of Perspiration. 417

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 said 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. Grew* and by Mr. Cruikshank.f  Small specks
of fluid can be seen with the naked eye, in the same
situations, in warm weather, or when the ends of the
fingers are made turgid by a ligature.  It is 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 fur-
rows; and it is probable that similar pores are distri-
buted over the surface of the body.
   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 professor Meckel  of  Berlin, who was one
of this number, was induced to believe that the mat-
ter of exhalation, and of absorption, soaked through
the  cuticle, as  the vapour  of  warm water   passes
through leather4
   In support  of this doctrine he states,  that perspi-
ration goes on through the cuticle on the palm 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

  • In the Philosophical Transactions, vol. III. Lowthrop's Abridgment
  t See his Experiments on Insensible Perspiration.
  t See Memoirs of the Royal Academy of Sciences of Berlin, vol. XIH-
for 1757.
   Vol. i.               53 
4lS   Peculiar Permeability of the Cuticle.

weight of the body, in persons who walk; and those
in the hands would experience the same fate, in la-
bourers, who work with heavy hammers, &c.
   On  the  other hand, Mr. Cruikshank, who could
likewise find no pores in the separated cuticle, con-
tends strenuously 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 although it has been punctu
red 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 perforated it, no
foramina have appeared in it.
   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 ob-
liquely.
   That the cuticle is  pervious, is proved incontesta-
bly 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 process, if the cuticle is not
lacerated, it will confine the effused fluid for  a con-
siderable time, without any appearance of its escape
through these pores.
   This fact,  which is strongly opposed to the hypo-
thesis of Meckel, is  explained by Cruikshank upon
the supposition that  the pores of the skin are lined
by processes of the cuticle, and that when the cuti-
cle is  separated from  the  cutis, these processes  go
with it, and act like valves in confining the fluid.
   Bichat supposes the oblique vessels to produce the 
         Causes which produce J\sicaiion.     419

6ame effect upon analogous principles; and compares
their situation to that of the ureters, which pass ob-
liquely between the coats of the bladder.
  This peculiar quality of the cuticle, in  admitting
of perspiration and sweat, and also absorption, while
it prevents evaporation from  the  parts which it en-
closes, is of immense  importance.
  If a portion of skin be deprived of cuticle a short
time before death, by a blister for example, this por-
tion will in a  few days become  perfectly dry and
hard, like horn; while the other parts of the skin of
the subject, covered by the cuticle, retain their mois-
ture and flexibility.
  It may therefore be admitted, that the use of the
cuticle is to keep the skin  soft and flexible,  by con-
fining its moisture 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 re-
sisting the action of chemical  agents, it is surprising
that epispastics and rubefacients should act through
it, upon  the skin, with so much certainty as we find
they do; and that cantharides should produce vesica-
tions, 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 its 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 por-
tions of  cuticle may be separated into distinct la-
mina.
   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 
420        Separation of the Cuticle.

in that situation; and also by those parts of the skin
to which poultices have been applied.
   Notwithstanding the uniform adhesion of the cuti-
cle to the cutis, it is observed, in  the living subject
to be separated, and formed into vesicles, by a variety
of causes, viz.
   1.  Pinching of the skin, or violent mechanical irri-
tation; such as labouring with hard instruments.
   2.  By the application of cantharides, and certain
other substances which  produce vesications.   Some-
times these substances  appear to inflame  the  skin;
but on  other  occasions the vesication is  produced
while the skin appears unchanged  in colour, and free
from  inflammation.  The process appears different
from that of simple inflammation; for certain  rube-
facients often inflame  the skin considerably,  with-
out vesicating or blistering it.
   3.  The  boiling heat will  very  generally produce
vesication.
   4.  Certain diseased processes seem to occasion ve-
sication in a manner which  is not well understood,
viz. erysipelas, zona or shingles, pemphigus, and
some other eruptions which have no name.  In erysi-
pelas there 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 ten-
dency to gangrene.
   6. They  also occur  in  some cases of simple frac-
ture, 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. 
        Chemical Qualities of the Cuticle,     421

  The cuticle appears to be least deranged when it
is separated 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 se-
baceous glands, are particularly obvious.
  The external surface of the cuticle varies in dif-
ferent places, according  to the  surface of the skin.
In some places it  appears scaly at times,  and  has
therefore been  supposed to  consist entirely of scales;
but in other parts, when examined attentively, it ap-
pears like a half transparent concreted 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 secre-
tion  deposited on the skin, and  of a portion of the
external surface of  the cuticle.  The same substance
appears upon the first washing of the skin, after that
process has been discontinued for any length  of time.
  Many speculations have arisen respecting the man-
ner in which the cuticle is originally formed, and re-
produced ; but none of these are perfectly  satisfac-
tory.
  It is also a question whether the cuticle is endued
with vitality, or is  merely an inanimate  unorganized
concrete.   No decisive arguments have been addu-
ced in favour of its vitality; and it has already been
stated, that neither nerves, nor vessels,  can be  de-
monstrated 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 sulphuric and muriatic acids:
although the nitric  acid acts upon it. 
422
The Nails.
  It resists for a short time,  but is at length dissol-
ved, by the pure fixed alkalies, and by lime.
  It is supposed by the chemists to consist of albu-
men, 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; 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 papillae 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 be-
tween the nails and cutis ;  but this opinion is proba-
bly 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 well as their insensibility, and
their resemblance to the horny excrescences o£ the cu-
ticle, they are considered as appendages of it.
  The root is opaque, 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 cutis  depends upon the state of the
circulation ; and  becomes livid when the  blood is dis-
oxygenated, 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 composed  of lamellae :  and these  lamellae, of
fibres.   They grow rapidly,  and when they are not
pared or worn away,  they sometimes acquire an im-
mense size. 
The Hair.
423
  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 a half in length.
  The growth seems to take place altogether at the
roots.
  The nails, when chemically examined,  appear to
consist of a modification  of  albumen ;  and thus re-
semble cuticle and horn, in their  composition.

                    The Hairs

  Originate from bulbs which are situated  at the bot-
tom 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 membrane.  In some cases, where
the cuticle is separated after putrefaction, it seems
that these lining processes of the cuticle come away
eompletely, 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 consis-
tence 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
blood vessels nor nerves  have been  traced  to these
bulbs, although it  is probable they extend there: for
the operation  of extracting hair by the roots is gene-
rally  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, enclosed  in a membrane which  often
is imperfect at the extremity;  in consequence  of 
424     Vicarious connexion of the Skin.

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  structure,  as in the advance of life
the hair is so generally without it, while its structure
continues unchanged ; although  it becomes less flexi-
ble.
   The colour of the hair appears to have some con-
nexion 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 relates an instance which came under his ob-
servation, in  which the hair became perfectly white
in one night, in consequence 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  in-
      sensible 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 respi-
      ration are so much regarded as symptoms of the same
      disease, that the term hives is used as  the name for
      each of  them. 
ALPHABETICAL INDEX TO VOLUME I.
	I'age		Page
Arm, bones of	121	Attolens aurem	174
Abductor indicis manus	243	Auris retrahentes	ib.
indicis pedis,	264	Azygos uvulae	192
minimi digiti		Ancle Joint 295	, 302
manus	241	Auditory nerve	397
minimi digiti		Aqueducts of the Ear	398
pedis	263		
oculi	177	Bones, structure of	1
pollicis manus	239	formation of	7
pollicis pedis	262	terms used in '	9
medii digiti pe-		Biceps flexor cubiti	230
dis	265	flexor cruris	252
tertii digiti pe-		Brachialis internus	231
dis	ib.	Buccinator	181
Accelerator urinae	208	Bursae Mucosae 276	303
Adductor brevis femoris	246	Brain	315
indicis pedis	264	membranes of	ib.
longus femoris	245	sinuses of	319
medii digiti pe-		Basis of Brain	333
dis	264		
magnus femoris	246	Cartilages, structure of	6
metacarpi mini-		Cranium, cavity of	67
mi digiti manus	241	basis of	ib.
oculi	177	form of	72
policis manus	240	Clavicle	114
pollicis pedis	263	Carpus	130
tertii digiti pe-		Clavicle and Scapula, ar-	
dis	265	ticulations of	282
Anconeus,	332	Capitis obliquus superior	226
Ani sphincter,	213	Capitis obliquus inferior	226
levator	ib.	Cervicalis descendens	222
Anterior auris	274	Circumflexus, or Tensor	
Arytenoideus obliquus	195	Paliti	190
transversus	ib.	Clitoridis erector	222
Arytaeno-epiglottideus	ib.	Coccygeus,	217
Vol. i.	5	4	
 
426
INDEX.
Colli longus
      transversalis
      semispinalis,
      interspinales
      intertransveYsales
Complexus
Compressor naris,
Constrictor isthmi fau-
      cium
Constrictor Pharyngis
Coraco-brachialis
Corrugator supercilii
Cremaster
Crico-arytenoideus late-
      ralis
Crico-arytenoideus posti-
       cus,
Crico-thyroideus,
Cruralis
Cubit, or fore-arm, mus-
       cles of
Cucullaris
Cutaneus
Cerebrum
Commissures^of brain
Cerebellum
Corpora albicantia
Cornea
 Choroid coat
 Ciliary ligament
 Ciliary body
Chorda Tympani
 Cochlea
 Cellular membrane
 Cutis vera
 Cuticle

 Dartos
 Deltoides
 Depressor anguli oris
       labii inferioris
       labii   superioris
          alaeque nasi
        oculi
 Diaphragma
 1961
 225
 224
 227
   ib
 222
 176

 191
192-3
 229
 173
 207
Digastricus              lnt>
Dorsi interspinales        228
      latissimus          219
Dorsi spinalis            221
Dorsi longissimus        222
      semispinalis.       224
    Eye, orbit of
    Extremities, superior
           bones of
    Extremities, inferior do
    Erector clitoridis
           penis
    Extensor brevis digitorum
194        pedis
           carpi radialis
195          brevior,
189        carpi radialis lon-
251          gior,
           carpi ulnaris,
234        digitorum  com-
217          munis
185        longus digitorum.
322          pedis,
328        ossis metacarpi"
331          pollicis manus,
334        primi  internodii
353          pollicis manus,
354        proprius pollicis
357          pedis
362        secundi internodii
389          pollicis manus
;193  Extremities, superior mus
401        cles of
406  Extremities, inferior mus.
415        cles of,
     Eyeball, muscles of,
207  Eyelids, muscles of,
229  Elbow joint
 180  Eye
 181  Eye, auxiliary parts of
     Eyelids
 180  Eyeball
 177  Eye, humours of
 213  Eye, manner of dissecting 374
 62

113
142
211
206

260

236

 ib.
237

 ib.

254

238

 ib

 254

 238

 228

 245
 176
 175
 285
 343
  ib.
 344
 350
 368 
	INDEX.		4J7
Ear	377	Gastrocnemius externus,	256
Ear, bones of	386	internus,	ib.
Eustachian tube	385	Gemellus,	ib.
		Gemini,	248
Frontis os	20	Genio-hyo-glossus,	187
Face, bones of	41	Genio hyoideus,	186
Foetus, head of	74	Gluteus maximus,	246
Foetus, trunk of	112	medius,	ib.
Fingers	139	minimus,	247
Femoris os	142	Gracilis,	250
Fibula	148		
Foot	153	Head, bones of	12
Foetus, extremities of	164	Hyoides os	60
Faucium isthmi constric-		Humeri os	121
tor,	191	Hand, bones of	130
Flexor accessorius digi-		Hip joint	
torum pedis,	261	Humeri os, muscles si-	
brevis digitorum		tuated on,	230
pedis,	ib.	Hyo-glossus,	187
brevis minimi digit	i	Hip joint	290
pedis	263	Hairs	423
brevis pollicis ma-			
nus	240	Ischium os	106
brevis pollicis pe-		Ilium os	105
dis	263	Iliacus internus,	216
longus digitorum		Indicator,	238
pedis	260	Infra-spinatus,	228
carpi radialis	234	Intercostales externi,	198
carpi ulnaris	ib.	interni,	199
longus pollicis ma-		Interosseus auricularis*,	242
nus	235	Interspinales .colli,	226
longus pollicis pe-		dorsi et lumborum,	227
dis	260	Intertransversales colli,	226
ossis metacarpi		dorsi,	227
pollicis	239	lumborum,	ib.
parvus minimi di-		Isthmi faucium constric-	
giti manus	214	tor	181
profundus perfo-		Jaw, lower, muscles of,	183
rans	235	articulation of	281
sublimis perfora-		Iris	358
tus	234		
Finger joints	288	Knee joint	291
Foot, articulations of	295		
Fornix	VG	Labii inferioris depressor	171
 
42 N	INDEX. «		
Labii inferioris levator	171	Nose, cavities of,	64
superioris alaeque		Naris compressor,	178
nasi levator,	171	Nerves, origins of	0 n 0
Latissimus dorsi,	ib.	Nails	422
Leg, muscles situated on,	260		
Levator anguli oris,	179	Osteology	1
ani, 210-12		Occipitis os	28
labii inferioris,	181	CEthmoidesos	31
labii superioris,		Obliquus ascendens inter-	
alaeque nasi,	179	nus,	204
oculi,	177	capitis inferior,	225
palati,	190	capitis superior,	ib.
palpebrae superio-		descendens exter-	
ris,	176	nus,	150
scapulae,	223	inferior oculi,	163
Lingualis,	187	superior, seu tro-	
Lips, muscles of,	179	chlearis,	177
Longissimus dorsi,	221	Obturator internus,	216
Longus colli,	196	externus,	245
Lumborum intertransver-		Occipito-frontalis,	173
sales,	228	Oculi abductor,	177
Lumborum quadratus,	316	adductor, -	ib.
Lumbricales manus,	240	depresser,	ib.
pedis,	262	levator,	ib.
Ligaments	271	obliquus inferior	178
of scapula	296	superior,	177
interosseous of> fore arm 3	ib.	Omo-hyoideus,	188
		Opponens pollicis,	240
Lachrymal gland	346	Orbicularis oris,	182
sac	347	palpebrarum,	175
Labyrinth	391	Oris anguli depressor,	180
		levator anguli,	179
Maxillare sup. os	42	orbicularis,	182
Malarum ossa	47		
Metatarsus	159	Parietale os	23
Masse ter,	184	Palati os	49
Mouth, muscles of,	179	Pelvis	104
Multifidus spinae,	228	Pubis os	108
Musculus cutaneus,	185	Patella	150
Mylo-hyoideus,	186	Palati circumflexus.	190
Motions of skeleton,	308	levator,	ib.
Medulla oblongata	33 5	tensor,	ib.
Mastoid cells	385	Palato-pharyngcus.	191
		Palmaris brevis,	239
Nasi os	46	longus,	233
 
	INDEX.		4-jy
Palpebrae superioris le-		Rectus internus minor	190
vator,	176	lateralis,	171
Palpebrarum orbicularis,	175	posticus major,	224
Pectinalis,	244	posticus minor,	225
Pectoralis major,	197	Retrahentes auris,	174
minor,	198	Rhomboideus,	219
Penis erector,	208	Ribs, articulations of	289
Perinei transversus, 208-12		Retina	364
Peroneus brevis,	255	Rete mucosum	410
longus,	ib.		
tertius,	254	Skeleton	12
Pharynx, muscles on the		Sutures	15
posterior part of it,	193	Sphenoides os	35
Pharynx constrictor,	ib.	Spine	76
Plantaris,	258	Sacrum os	90
Platysma myoides,	185	Sternum	100
Popliteus	253	Scapula	116
Posterior annularis	243	Sesamoidea ossa	163
indicis	242	Spinal marrow	339
medii	243	Salpingo Pharyngeus,	192
Prior annularis,	242	Sacro-lumbalis,	221
indicis,	ib.	Sartorius,	249
medii,	243	Scalenus anticus,	225
Pronator radii quadratus,	235	medius,	226
teres,	233	posticus,	ib.
Psoas magnus,	215	Scapulas levator,	223
parvus,	ib.	Semimembranosus,	252
Pterygoideus externus,	184	Semispinalis colli,	224
internus,	ib.	dorsi,	225
Pyramidalis,	206	Semitendinosus,	252
Pyriformis,	247	Seminis ejaculator,	208
Pelvis, ligaments of	299	Serratus magnus,	198
Plexus choroides	327	posticus inferior,	219
Pons varolii	334	Serratus postrcus superior	,220
Portio dura	399	Soleus,	257
		Sphincter ani, 21	0-12
Quadratus femoris,	248	vaginae,	211
lumborum.	215	Spinalis dorsi,	221
		Spinae multifidus,	224
Ribs	94	Splenius,	219
Radius	127	Splenius, capitis.	220
Reclus,	250	colli,	ib.
abdominis.	205	Sterno-eleido-mastoideus,	18.1
capitis interims ma-		Sterno-hyoideus,	188
jor,	190	Sterno-thyroideus,	ib.
 
430                   INDEX.
Stylo-glossus,	189	Transversus perinei 208-12	
Stylo-hyoideus,	ib.	Trapezius, seu Cucullaris,	218
Stylo-pharyngeus,	190	Triangularis,	200
Subclavius,	197	Triangularis or Sterno-cos-	
Subscapularis,	230	talis	ib.
Supercilii corrugator,	173	Triceps adductor femoris,	244
Supinator radii brevis,	237	Triceps extensor cubiti,	232
longus	236	Tensor Tarsi	S49
Supra-spinatus	227	Tibia and Fibula, articula-	
Shoulder joint	283	tion of	294
		Thorax, ligaments of	299
Temporum os	25	Tunica conjunctiva	345
Turbinatum os	51	sclerotica	352
Teeth,	55	Tympanum	382
Trunk, bones of	76	Unguis os	47
Thorax, bones of	94	Ulna	125
Tibia	146	Urinae accelerator,	208
Tarsus	153	Uvulae azygos,	192
Toes, bones of	161		
Temporalis	183	Vomer	52
Tensor palati	190	Vertebrae true	77
vaginae femoris	249	cervical	80
Teres major,	229	dorsal	85
Teres minor,	228	lumbar	88
Thigh, mnsclessituatedor	1,248	articulations of	278
Thyreo-arytenoideus,	194	Vastus externus	250
Thyreo-epiglottideus,	195	internus,	251
Thyreo-hyoideus,	188	Ventricles lateral	324
Tibialis anticus,	253	Vena galeni	331
posticus,	259	Vestibule	392
Trachelo-mastoideus,	222		
Transversalis,	205	Wrist joint 288-98	
colli,	225		
pedis,	265	Zygomaticus major,	182
		minor,	ib.
 
 
 
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