(^i-iojf'

FROM THE LIBRARY

OF

Dr. CHARLES VOSE BEMIS,

MEDFORD, MASS.

THE GIFT OF

Dr. NORMAN FITCH CHANDLER,

TO THE

BOSTON MEDICAL LIBRARY,
1907.

Digitized by the Internet Arcinive

in 2011 witii funding from

Open Knowledge Commons and Harvard Medical School

http://www.archive.org/details/courseofmedicals01burd

COURSE

OF

MEDICAL STUDIES:

CONTAINING

A COMPARATIVE VIEW

OF

THE ANATOMICAL STRUCTURE

OF MAN AND OF ANIMALS ;
A HISTORY OF DISEASES ;

AND

AJJ ACCOUNT OF THE KNOWLEDGE HITHERTO ACaiTISED WiTSJ

REGARD TO THE REGULAR ACTION OF THE

DIFFERENT ORGANS.

A WORK CHIEFLY DESIGNED FOR TEE USE OF
MEDICAL STUDENTS.

BY J. BURDIN, M.D.

TRANSLATED FROM THE FRENCH.

IN THREE VOLUMES,
VOL. I.

LONDON:

PRINTED rOE CUTHELJ, AND MARTIN, MIDDLE-ROW*

HOLBORKJ

BY H. WilXS, CHANCERY.LWfE,

1803.

^ ' ■?*, ? \ 5

J\J^

PRELIMINARY DISCOURSE,

In this work I have endeavoured to exhibit a general
view of the knowledge acquired in regard-to the organi-
zation of man.

My principal obje£l In undertaking this labour was to
unite different branches of fcience, defigned to illuftrate
each other, in fuch a manner as to enable every intel-
ligent perfon to become acquainted with fubje6ls, which,
confidering their importance, ought to be mojre gene-
rally cultivated. It is indeed aftonifhing, at a period
when attempts are made to comprehend in public in-
ftruiStion all the ufeful fcie^ces, that we do not find
among them one which gives to man a knowledge of
his organic fl:ru£\ure ; which makes known to him the
phsenomena exhibited by the regular adtion of his dif-
ferent parts ; and which points out to him the general
caufes and natural progrefs of his numerous derange-
ments.

A methodical ftudy of the phainomena of the organi-
zation is alone capable of enabling man to avoid what
may be hurtful to him, and to acquire thofe habits
which are moft conducive to his prefervation. For want
of this knowledge fome abandon themfelves with fecu-
rity to irregularities, the dangerous confequences of
which they cannot fprefee ; others, with a view to ame-
liorate or to preferve their health, fubje^l themfelves to
an auftere regimen ; deprive themfelves of thofe varied
and agreeable enjoyments which are necelTary to com-

YOL. I. a plete

11 PRELIMINARY DISCOURSE.

plete life ; and at length, by rniftaken care, weaken
that good conlthution which they are defirous to main-
tain. Thofe who remain ignorant in regard to the
nature of their orp:;ani£ation expofe themfelves alfo,
when it experiences any derangements^ to the mercy of
every thing ai : un^ them; and it is not uncommon to
find perf ns of great talents, who in fuch cafes believe
in the greatefr abfurdines, and thus give importance to
the rncit d2.,geroiis errors.

To this may be adced, that the only means of banifh-
ing quackery, againft which mankind declaim fo much,
is to propagate the knowledge acquired in regard to the
phyfical nature of man. Thofe, indeed, who have cor-
real: ideas of the phsenomena of their organization will
not readily become dupes to advice dictated by ignorant
zeal or by forward felfifhnefs ; whereas the rich and the
ill-informed are always more expofed to deception, as the
honeft and enlightened phyfician has too little influence
to be able to convince them of their danger, and to pro-
tect them againft the ignorance and effrontery of thofe
who endeavour to miflead them.

If the ftudy of the organization, notwithftanding fo
many motives of intereft, is not fo generally cultivated
as it ought to be, and if it has not yet been made a
part of the ufual courfe of education, this deficiency
mud be afcribed to the detached manner in which the
different branches it embraces have been treated ; as
they have not yet been united into a proper fyftem,
worthy of being claffed among works- on the exacl
fciences.

But other caufes alfo have contributed to retard the '
progrefs of this ufeful fcience. It may be obferved, in
the firft place, that a ftudy which is fo difficult, and

which,

PRELIMINARY DISCOURSE. Ill

which, befides great talents, requires a mind entirely
divefted of prejudice, could not make a confpicuous figure
among the objects of human knowledge, till at a very
advanced period of its improvement. It may be re-
marked, alfo, that few cultivate this fcience merely with
a view of fearching for new dlfcoverles ; and this, per-
haps, is owing to the difgufi: which mufl be overcome
before people can acquire fufficlent refolution to extend
the field of their obfervation to the fick and the dying.
It Is well known, alfo, that young men, who devote
themfelves to the ftudy of medicine, are in general
obliged to apply too foon to pradlice ; which does not
allow them fufficient leifure for difficult refearches and
profound meditations.

In the laft place, thofe who have divided among them-
felves the different branches which relate to the phyfical
nature of man, do not fufficiently comm.unlcate to each
other the refult of their experience and of their obfer-
vatlons.

A phyfician who begins pra6lice with a certain degree,
of knowledge, is always (truck with the confufion exhi-
bited to him by the fcience of medicine. At firfl:, he
afcribes it to the difficulty of the fludy; but if he con-
tinues to be a calm obferver, and to believe nothing
implicitly, he foOn perceives that thofe who cultivate
the different branches of which it is compofed have fo
little intercourfe, that, though very ex.tenfive knowledge
has been obtained, the refult of their individual labours
is, for the moft part, loft to the fcience in general ;
and that a great number even, without knowing it, are
divided in their opinions in regard to the p: Incipal points
on which it is founded. Hence it happens, that the
difllnifl; fludy of the different parts of the hiftory of the

a 2 organi-

IV PRELIMINARY DISCOURSE.

organization, inftead of promoting, ferves rather to re-
tard its progrefsj becaufe thofc by whom it is cuhivated
do not fet out from common and fundamental princi-
ples, to which all their particular obfervations might be
referred.

When a phyfician, therefore, begins to praflife, he
is neceflarily flruck with the . number of popular errors
which he every where finds among perfons who are
always defirous to explain, in their own manner, the
different ph«nomena of health and difeafe ; which indi-
cates, at leaft, how anxious they are to obtain informa-
tion refpe£ling every thing that relates to the organiza-
tion. Unfortunately, moft phyficians feem, at firft, to
participate in thefe falfe notions, that they may not too
openly attack received opinions : by thefe means they
gradually become familiarized with them ; and at length
adopt them entirely as inconteftable truths. Thus, men
who in confequence of their fituation ought to contribute
moft towards the difFufion of ufeful knowledge, only
give importance to fatal errors, which being eftablifhed
by time and the force of habit, muft be difficult to be era-
dicated, and can be deftroyed only by their united eftorts.

Before I enter into any detail in regard to the plan of
the work, the motives of which I have here explained,
it will be proper to make a few general obfervations on
organized bodies.

Organized bodies have been diyid.ed into vegetables
and animals ; but they are far from being all naturally
fufceptible of arrangement under thefe two divifions.
There is a very numerous ferles of beings evidently or-
ganized, with the intimate ftruAure of which we are ab-
folutely unacquainted, either on account of their ex-
treme-

PRELIMINARY DISCOURSB, Y

treme mlnutenefs, or becaufe their tranfparency deprives
us of the means of obferving their organs, by making
them appear to us under the form of a homogeneous
vifcofity.

When thefe beings develop themfelves without
changing their place, or by exhibiting a fort of ramifi-
cation, they are clafled among vegetables : of this kind
are the byfli, lichens, fuci, ulvjc, confervse, and- tre-
mellas. On the other hand, when they move, or feem
to have a diftincl alimentary canal, like the volvox, mo-
nades, fponges, lithophites, alcyons, &c., they form a
part of the clafs of animals. There are alfo feveral
fpecies which are placed alternately in thefe two clafles,
according to the ' different obfervations which have been
made.

It appears, that it is among thefe beings, fo little
known, that the divifion between animals and vege-
tables takes its origin, or where the two clafies are
confounded.

The numerous clafs of animals exhibit a natural divi-
fion by the exiftence or non-exiftence of the vertebral
column. The difference between vertebral and in-ver-
tebral animals is fo great, that Daubenton was of opi-
nion that the former ought not to retain the name of
animals, if it be given to the latter.

Vertebral aairnals comprehend fifties, reptiles, birds,
and the order of the mammalia, at the head of which
man is placed.

The knowledge acquired in regard to the organiza-
tipn of man, which I have endeavoured to unite in this
work, comprehends : — ift. Anatomical refearches ; 2d.
A hiftory of difeafes ; 3d. An examination of the vital

a 3 fun£lion$.

Vi PRELIMINARY DISCOURSE.

funftions. Thefe three branches of knowledge, which
compofe the, philofophy of man, naturally divide the
Work into three parts.

Firjl Tart. The anatomical defcription of man, as
well as that of a great number of animals, which forms
the fubje£l of the firft part, has been given with great
minutenefs, and fcrupulous exa£lnefs, by celebrated ana-
tomifts : but as a complete and connected view of the
different fyftems of organs in man, compared with the
fame fyftems of organs in other animals, is not to be
found in any work, the refuk was, that only one part
of the pi£lui*e was exhibited j and therefore it was im-
poffible to form a proper idea of the whole. The lec-
tures of Cuvier, from which I have endeavoured to de-
rive as much advantage as poffible, and which were col-
lected and in part publifhed by Dumeril, will form in
this new line a complete work, the conclufion of which
is looked for with Impatience.

The firft difHculty which occurs, in defcriblng the
fyftems of organs, arifes from the choice of the order
proper to be adopted. As all the fyftems of organs
difcharge their • fun6lions almoft fimultaneoufly, a fuc-
ceflive defcription of them is always attended with this
difadvantage, that it feparates cbjeCIs which ought to
remain united. It was therefore neceffliry that the order
adopted ihould, as far as poffible, remedy this inconve-
nience.

The whole of the parts of the body is compofed of
fix principal fyftems:

I ft. The fyftem of the bones and mufples.

2d, The cerebral and nervous fyftem.
- 3d. The fyftem of the fenfes.

4th,

PRELIMINARY DISCOURSE. Vir

4th. The fyftem of digeftion.

5th. The fyftem of circulation and refpiratlon.
. 6th. The fyftem of generation.

The defcription of each of thefe fyftems, in man,
is preceded by= a curfory view of the correfponding or-
gans in the different clailes of animals.

In the fyfleni of the bones :will be feen the variety
of forms exhibfted by the flseleton.^ from that confifting
of one ieries of fimilar vertebras, of which the head
feems to be only one more complex, to that which is
compofed of a vertebral column, a head, a thorax^ and
limbs,"

. The.t di^pofition of the mufcles varies according to
the parts to whicli they are attached.

The defcription of tne bones, and of the mufcles. Is
followed by tables, the arrangement of which is fuch,
that, while they prefcnt a nomenclature of tiie different
parts, they exhibit their pofu'ion and their ufe.

The fyftem of the bones, and that of the mufcles,
conftitute the fouadation of the human body. They
comprehe.id tte greater pajt of its material fubftance ;
and the other organs exhibit a difpohtion which is ne-
cefldtily fubordinate to them,.

The cerebral fyftem is compofed; id. Of the ence-
phalic organ, united to iis rachidian prolongation. 2d.
Of the ganglions of fhe trifplanclmic. T'hefe two
principal organs, analogous ones to v/hich are found in
all vertebral animals, give rife to the nerves that diftri-
bute the principle of motion and fenfation to the differ-
ent parts. It is obferveu, that the nerves proceeding
from the trifplanchnic are diftributed, in particular, to
the vefTels which form the different tiffoes, and to the
organs not fubje£l to the empire of the will j and that

a 4 they

Viii PRELIMINARY DISCOURSE.

they thus maintain that animal life only which each
poiiit of the organization enjoys ; while thofe which
proceed from the encephalon and its prolongation furnifli
to the principal fyftems of organs fecondary nerves,
which communicate to them relative life, by caufing
them to perform the fundlion for which they are proper.
It is to be remarked, that in all animals the organs dif-
tributed to the organs of the fenfes, and to fome other
determinate parts, are always furnilhed by analogous
pairs.

The defcription of the cerebral and nervous fyftems in
man is followed by a fynoptic table of the nerves, and
an analytical view of the cerebral organ, v/ith a reca-
pitulation of the various parts which compofe it, and
of which the ufe is unknown.

The organs of the fenfes are merely particular termi-
nations of fome nerves, difpofed in fuch a manner as to
perceive the fligbteft. impreflions, and to vary the forms
of touching. An examination of thefe organs in the
different clafles of animals, beginning at the fimpleft,
and proceeding to the moft complex, affords the only
mean of difcovering the ufe of the different parts which
-enter into their compofition. Thus, it is feen that
among the numerous pieces of which the ear is formed,
the one moft important and indifpenfably neceflary for
that organ is the membranous capfule, containing a
vifcous fluid, amidfl which the auditory nerve expands j
becaufe this capfule is found in all animals, and in fome
it exifts alone.

In the defcription of the digeftive fyftem, either In
animals in general, or in man in particular, the pro-
grefs of the aliments has been followed. It is curious
to examine the gallric fyftem in different animals, from

thofe

PRELIMINARY DISCOURSE. IX

thofe In which it confiils of a fmgle bag with one
aperture, to thofe in which it is compofed of a mouth
armed with teeth, with a tongue, with falivary glands*
&c. J of an cefophagus, which leads to one, two, three,
and even four ftomachs ; of inteftines of different
lengths and fizes, provided with ccecal appendices,
more or lefs numerous, and receiving fluids from a
liver and a pancreas.

The refult of digeftion is the chyle : this fluid, ab-
forbed by particular veffels, proceeds into the veins;
which affords a natural tranfition from digeftion to cir-
culation.

la the fyftem of circulation, the courfe of the blood
has been followed, by giving a fucceflive defcription of
the organs which it traverfes. This fyftem, in animals,
exhibits a ftill more aftonilhing variety of forms than
the digeftive fyftem. How many particular arrange-
ments are obferved between the mammalia, whofe
blood is warm and red, and the worm, which feems
to have only one dorfal velTel, with branches ramified
to every part of the organization, and a few external
apertures which afford an entrance to the atmofpheric
air ! ,

In man, the arterial blood, which Is of a bright red
colour, and which has the temperature of 40 degrees
of the centigrade thermometer (104^ Fahr.), when it
proceeds from the aorta is diftributed by an order of
velTels (the arteries) to every part of the organization.
During its progrefs, it is continually freeing itfelf from
the excefs of its heat by the excretion of the cutaneous
organ ; and from its excefs of aqueous, faline, &c, parts,
by urinary fecretion. The blood, after fupplying every
part with the materials of nutrition, returns by two

ordert

X PRELIMINARY DISCOURSE.

orders of veffels (the veins and the lymphatics), and tra-
verfes organs which tend to make it refume the quahties
of arterial blood. For the lymph, thel'e organs are : the
numerous lymphatic glands i and for a part of the venous
blood, the hepatic fyftem.

The lymph mixes with the ■'■enous blood, and the
veins unite into two large trunics, v\hich pour the blood
into the right fide of the heart ; whence the whole of it
pafles into the pulmonary organ : it is difLributed to
every part of that organ, and auring the acl of refpira-
tion refumes its former qualities of arterial blood : it
then proceeds to the left fide of the heart, whence it
pafles int'o the aorta, to ferve for a new circulation.

In the defcription of the different parts of the fyftem
of circulation, by thus following the pro2,refs of the
fluids, the reader is bettei enabled to comprehend the
organic phsenomena, and in fome meafure to divine the
lavi's by which life is maintained.

Having defcribed the organs which the blood tra-
verfeSj and fhown the refults of the chemical analyfis
of that fluid, an accurate defcription is given of the
difbribudSn of the arterie?, followed by a fynoptical table
of thefe vefl^els. This article is terminated by the veins
and lymphaticc-j and in explainins; them the progrefs of
the fluids is frill followed, as far as poflible, by taking the
veflels at their capillary origin, and tracing out their
union into ramufculi, rami, branches, and trunks.

In explaining the lymphatics, the glands are defcribed
in the order in which thefe veflels proceed thither. This
method feems to be the moft convenient.

In the laft place, this firft part is terminated by a de-
fcription of the fyftem of generation, with a curious de-.
tail of the parts of which it is compofed indifferent animals.

7 It

PRELIMINARY DISCOURSE. XI

It is there feen that if all organized beings are conneded
by feme relations, it is in particular by the organs of ge-
neration ; for an analogous ftrudlure of pans is found
in all thofe the generating organs of which are known.

This firft divifion concludes with a curfory examina-
tion of the general ftruclure of the tiffaes, of which the
different fyllems of organs are compofed. It is ob-
ferved that all thefe fyflems (anatomical fyllems of or-
gans) confifl of a certain number of fimilar parts. It is
of very great importance to examine carefully their gene-
ral difpofition, as thefe parts perform analogous func-
tions, and as they experience derangements of the fame
nature. This laft circumftance tends to throw great
light on the hiftory of difeafes, which is treated of in the
fecond part.

In defcribing the different derangements to which the
higher orders of fociety are at prefent fubjeft, it appears
on the firft viev/ impoffible to clafs, in a proper manner,
all thefe diforders fo exceedingly various : however, by
the help of a few general confiderations, refpe£lin;g the
whole of their mod important phcenomena, it will foon
be found that they may all be arranged under a few prin-
cipal heads, from which the particular cafes may be na-
turally deduced.

Difeafes confifl in an alteration of the parts, or in a
derangement of their regular action. Th^fe which ex-
hibit a manifeft alteration in the intimate flrudlure of the
organs compofe i\iQ phleg?naji<s : thofe which confifh in a
general or particular derangement in the exercifc of the
fun£lions, without any effential alteration of the parts,
eftablilh the feries of fevers^ or the different orders of
fiffeB'wns^ wliich in fome meafure are merely nervous.
Any irritation whatever, excited in a part, produces

a new

XU FRELIMlNARt D'lSCOURSE.

a new mode of aftIon^ the refult of which is a ferles of
phsenomena that may vary, according to the ftruflure
and ufes of the affe6led part. Thus, phlegmafiae exhibit
peculiar charafters, according to the parts where they
are developed. All thefe difeafes of the fame order,
when confidered in fucceffion in the different anatomi-
cal fyiiems of organsj furnifli very natural marks of fe-
paration. This dillin£lion, for which we are indebted
to the moderns, but which has not yet received all the
extent of which it is fufceptible, has thrown great light
on the phasnomena of thefe afFeftlons. Thus, in the
hiitory of phlegmafise, thefe affe6lions are diftinguifhed
into the following claffes : I ft, Thofe of the cellular and
parenchymatous tilTue ; 2d, Thofe of the ferous mem-
branes J 3d, Thofe of the mucous membranes ; 4th,
Thofe of the white fibrous parts j 5th, Thofe of the
bones ; 6th, Some fpecial organic affeftions j 7th, Phleg-
mafiae of the fkin.

The phlegmafise comprehended in each of thefe fec-
tlons exhibit very important differences, according as
their progrefs is rapid or flow (acute or chronic phleg-
mafise), and under various other points of view.

It is to be obferved that in thefe orders of phlegmafiae
almoft all the difeafes called chirurglcal or exiemal are
united and confounded, with a great part of thofe called
internal. A comparifon of thefe derangements, of the
fame nature, which reciprocally illuftrate each other, is
fufficient to (how how abfurd it was to keep them always
feparate.

In the hiflory of phlegmafia; it is feen that thofe of the
cellular tiflue and mucous membranes have given rife to
the popular errors ia regard to humours. In thefe dif-
eafes, the regular action of the cellukr tiiTue, or of the

mucous

PRELIMINART DISCOURSE. XiU

mucous membranes, is deranged ; and thefe parts, in-
ftead of furnifliing the liquid by which they are habi-
tually lubricated, fecrete a more abundant humour oftea
highly irritating, which has been confidered as the caufe
of the difeafe, while it is merely the efFeft. It was there-
fore imagined that this humoral caufe might exift in all
other cafes of difeafe, though not apparent. This un-
founded fuppofition produced, in the courfe of time,
a very feducing theory, which by the concurrence of
a thoufand particular circumftances was afterwards
adopted.

When phlegmafise have a rapid progrefs, the local al-
teration is fometimes fo great as to produce in the whole
of the different functions that general derangement which
confiitutes j^i;^r.

Phlegmaliae then naturally lead to the hiftory oi feven^
by an account of thofe called eruptive. In thefe fevers,
the febrile derangement, inftead of being produced by a
local afFe£lion, as in phiegmafi^, gives rife to an eruption
of the fkin, which appears about the third or fourth
day of the difeafe. In defcribing the eruptive fevers, I
have dwelt more particularly on the natural or inocu-
lated fmall-pox, and on the vaccine : this article will
enable the reader to appreciate eafily what has been faid
for or againft this difcovery.

The chapter of fevers has always been one of the mod
obfcure in all works on nofology, becaufe the nature of
the derangement which conftitutes this order of difeafes
has never been confidered under its real point of view.
There Is only one fort of derangement, charatlerized by
a general perturbation of the fundions, which conftitutes
FEVER ; but this difeafe afterwards aflumes a thoufand
particular forms, according to the caufes which produce

it.

XlV PRELIMINARY DISCOURSE.

it, and the dlfpofition of the individuals : it conducts
back to heakh or terminates in death, by a feries of phsS-
riotliena which fucceed each other with a fort of regu-
larity".

Of fevers fome have a continued progrefs, with flrik-
ing exacerbations ; others come on regularly by par-
oxyfms, which leave between them a remijfiorij more or
lefs complete, and which in this manner feem to be fo
many diftindi difeafes. This circumftance, of fo much
importance in the progrefs of the difeafe, and which ren-
ders fo great a difference neceffary in the treatment, fur-
nifhes the firft divifion of fevers into intermhtetit and re-
mittent. There are no fufEcient reafons for uniting af-
feftions which exhibit charadlers fo effential and fo di-
itina.

Continued fever exhibits forms highly varied, from the
flight paroxyfm, which terminates fpontaneoufly at the
end of twenty-four hours, to the form which continues
for a longer or (horter time, with a fuccefiion of phaeno-
mena more or lefs violent, and which, for the moll part,
proves fatal*

In this long feries of affe£lions it is obferved that fome
of them have a regular progrefs, which brings back health
at the end of a limited period (finiple fever )\ and that
others, exceedingly fevere and frequently fatal, are fuf-
ceptible of becoming epidemic, and even contagious.
(^Pemidous fever.)

Pernicious fever is charadlerized by a flate of ex-
treme proftration {_ad\n3m'ic or putrid f eve) \ fometimes
it exhil)Ics in its fymptoras abrupt changes and different
anomalies {malignant or ataxic fever) : in a word, this
pernicious form prefents very remarkable varieties in the
hofpital or jail fever, the yellow fever and the plague,

which

PRELIMINARY DISCOURSE. XY

which are only the fame dife'afe with comparative degrees
of intenfiry.

Iniennittefit like continued fever exhibits a Jlmple and
Vk pernicious form. The fimple form varies according to
the time which elapfes between two acceffions, and fur-
niflies the tertian^ quartan-, quotidian^ &c. types.

The pernicious form may take place under the diffe-
rent types above mentioned : it is charaflerized by the
exacerbation of any fymptom, v/hich frequently brings on
death at the end of the third or fourth acceffion. It
often exhibits the epidemic chara6ler.

This fimple and natural arrangement of febrile difeafes,
while it renders the ftudy of them eafier, tends to throw
fome light on the nature of the phaenomena which con-
ftitute them, and to furnifh hints for the mode of treat-
ment v^hich ought to be employed.

The difeafes not clafTed among the phlegmafiae and fe-
vers are all thofe which arife from particular derange-
ments in the exercife of fome of the organs, whether the
nervous aftion of their parts be diminiflied, increafed, or
deranged. Thefe numerous affections may be naturally
Claffed under the four following heads : comaioje^ ajihe-
nic, fpafmodic^ and vefanic aifedlions.

Comatofe afFeO;Ions, charaifler'zed by a fufpenfion of
the principal external figns of life, comprehend : apoplexy., '
the various kinds of afphyxia^ cataktfj.^ ■s.xid^fyncope.

Aflhenic and fpafmodic afreflions are taken into con-
fideration fuccefhvely, according as they are obferved in
the different fyflems of organs.

The vefanlc affedtions, which exhibit a derangement
more or lefs flriking of the intellectual functions, are :
h)JIeric5, nymphomania^ Jatyrinfis-^ hypcchaidriajis^ melan-
(holy.y and 'mama.

In

acvi PRELIMINARY DISCOURSE.

In the long recapitulation by which the hiflory of dif-
eafes is terminated, an attempt is made to prove that
man is not fubjefl to more difcafes than animals ; and to
fhow in what manner the different affe£lions to which
he is expofed may have beeh developed at different
periods of civilization, and under different circum-
flances of climate, food, habits, &c. It is there fecn
that animals, coUecled into herds and flocks, are fub-
jecl, under analogous circumflances, to afFeclions of the
like kind.

The treatment moft proper for the different difeafes is
deduced from general confiderations on the nature of
their development, on the general progrefs of their fym-
ptoms, and the regular a(3:ion of the vital phsenomena.
The effects daily produced by a blind adherence to the
common medical routine furnifli alfo a feries of proofs,
which has not been neglected.

When medicine was a fcience merely hypothetical, it
proved of great utility in the hands of the phyfician who
formed the bed conje6lures -, but at prefent, when ana-
tomical knowledge has been carried to the higheft degi:ec
of perfc6t;ion, when the hiiiory of difeafes is complete,
and phyfiological refearches begin to be very extenfive,
it can no longer be faid that the medical art is deftitute
of a proper foundation.

When anatomy v/as little cultivated, in confequencc
of the fludy of it being fettered by religious prejudices,
furgery alfo was often an art merely conje£lural, the
precepts of which were mixed with the grofleft errors :
but for half a century pail, during which anatomy was
more generally cultivated, furgery in France made a ra-
pid progrefs, and has now attained f o a degree of fupe-
riority which makes it to be held in high eftimation.
Men, indeed, who have a thorough knowledge of the ar-
rangement

preliminahy discourse. xvu

rangement of the parts, and of the diforders which al-
terations In them produce, ought to be the moft proper
for applying the necelTary remedies. For the. fame rea-
fon, thofe who with a correal knowledge of anatomy
have ca/efully obferved ihe regular adiion of the different
organs, and the natural progrefs of the derangements to
which this a£lion is liable, mail alone, be capable of giv-
ing falutary advice in regard to thofe difeafes which effen-
■ tially belong to the province of medicine.

The knowledge acquired in regard to the comparative
ftru6lure of man, which forms the fubjeft of the ^r/?
parf^ and the numerous difeafes, the hiftory of which is
given in thtfecond, furnith a fund oF information, by the
help of which the regular adiion of, the difrerent vital
functions 13 examined in the thi"d.

In examining x\\t funBlons of tlie difTrrent fyftems of
organs, the order adopted in the dfcrlfticn of thefe f)^-
ftems has been followed ; bs^^inning, however, with the
action of the nervous and cerebral fyftem, without Vvhich
there can be no life.

The cerebral fyftem is rirH: confulered as an organ of
fecretion. The large quantity of blood which the heart
fends to the brain by a very fnort pafTi^gc; the peculiar
difpofition of the ar-teries, which diitribute it to the fur-
face of that organ; the Rate of extreme divi!;bility which
It foon alfumes by penetrating Into its Interior parts ;
the flow and tortuous progrefs which it affects in its re-,
turn, all announce that this com.mon principle of nutri-
tion ferves for a very important fecretion, and the cerei-
bral organ feems to affimiiate a fluid of great tenuiry,
which is diftributed by meaiu of the nerves to all the
parts of the body, where it maintains, by its prefence,
the atSlion peculiar to them.

VOL. I. b It

sx Preliminary discourse.

is, in the Erd place, obferved that ftrong and unufual
impreffionp, capable of diRurbing the regular action of
the organs, produce a change of ftate, which conftitutes
the ftnfatlon of vneafinejs ; anr!, on the other hand, that
thofe which contribute to complete life by maintaining
the natural motion of the funilions, produce another
change of flate, which is the fenjatmi of eafe. In the
lait place, it is to be obferved that every living being is
irrefiftibly excited to acl^ in order to withdraw itfelf from
the caufes of deilructtion, and to place itfelf under clr-
cumilances farourable to its prefervation.

The habit of thus receiving alternately painful and
agreeable fenfations, foon renders living beings capable
of appr,eci?.ting vei^ flight changes of ftate, in fome
meafure indifferent to the organic cider, and which con-
flitute {-\n\'^\t fenfations.

The faculty of perceiving fimple fenfations becomes an
organic function, which, like all the reft, is improved by
proper exercife, and by the force of habit. It refults
from this difpofition, that the fimpie fenfations already
experienced may be com.pletcly renewed without the
prefence of the objefts by which they were firft commu-
nicated \ but merely by circumilances which have a
greater or lefs relation with them.

The faculty which man has of experiencing recalled
fenfations^ in coiifcquence of new direlyt fe-'fitions^ and the
neceiTity of aB'tng to avoid pain, to fatisfy his wants,
and to obtain cafe, makes it necefTary for him to com-
bine thefe different fenfations, and to adt agreeably to the
refait of that combination.

The faculty of combining fenfations gradually in-
creafes with the fiow prrgrefs of civilization; 2,\\^x this
fuiiclion; which at niTt fccined lo be a blind kind of in-

illna,

PRELIMINARY DISCOURSE. XXI

fiincl:, gives rife to the nobled operations of the human
mind.

Thefe Ideas on the development of fenfations, and the
origin of the intelietiual faculties, which are deduced
from the knowledge acquired in regard to the ilrufture
of the organs and the phcenomena they produce in the
different circumftances of health and difeafe, may give to
metaphyfics that folid bafe which has hitherto been
wanting.

An exanaination of the vital action In the bones gives
rife to Tome important confiderations.

The funtSlion of the gailric fyftem exhibits a feries of
very remarkable phienomena. It is oblerved, that the
digePcive power does not belong exclufively to the gaftric
apparatus, but that it is peculiar to all the organs. Hence
foreign fubftances, brought Into contact with parts of the
body, either in the aerian palTages, in th.e interior or ac
the furface of all the tiilues, and even of the (l:in, may
be digefled. The nutritive parts fufceptible of entering
into the compofition of the animal fluids are ral:cn up by
the abforbing vefTels, and the refiduum Is thrown out.

Digeftion, properly fo called, that which is effected in
the flomach and inteftines, is the refult of the whole in-
fluence of the vital power. The aliments of whatever
kind are transformed into a chymous pulp, which always
contains chyle of the fame nature ; this affimilation is
produced by the ailion of the digeftive juices, favoured
by .the prelTure of the fides of the inteftines on the ali-
mentary fubftances, but in particular by their long ftay
in a living organ, where that affimilating power, which
is obferved only within the fphere of the a61:ivity of or-
ganized bodies, is exercifed in its full extent.

In the fundlion of the gaftric fyftiem ?.re dlftinguiflicd :
b 3 the

^

Xxii PRELIMINARY DISCOURSft.

the digeftive a£lion of the organs on the alimentary fub-
flances j the flimulating allien of the aliments on thefc
organs, and the refults of this reciprocal influence.

This article is terminated by pretty extenfive confider-
ations on the general mode of aftion of medicines.

In the fyftem of circulation, after confidering the
force by which the blood is propelled from the heart,
and that which continues to make it circulate in the
velTels;, the changes which this fluid undergoes in tra-
verfing different organs is examined.

The continual lofs which the blood experiences, in
confequence of the different excretions, is repaired by
the produ£ls of digeftion and of refpiration. In this
uninterrupted aflimilatlon, it is of great importance to
obferve, that the fubflances which iffiic from the body
exhibit altogether more denfity than thofe which enter
it, the refult of which muil neceflarily be an habitual
elevation of temperature.

The excefs of the heat of the blood i$ carried off by
the evaporation of the fv/eat, which even produces that
excefs of heat ; and the habitual temperature remains
nearly at 40 degrees of the centigrade thermometer,
(i04*of Fahren.)

In arterial circulation, the blood, by means of the
kidneys, is flill freed from its excefs of aqueous parts,
and from different faline fubflances.

The arteries, in diftributing themfelves to all parts,
are fubdivided indefinitely, and reduce the arterial
blood to a (late of rarefaction proper for effecSling the
different changes which take place in every part of the
organization.. This repairing fluid afterwards returns
by the veins and the lymphatics, the degree of the ca-
pillary minutenefs of which is equal to that of the arte-
ries.

s

PRELIMINAIlY DISCOUBSE. XXiU

ries. During its return, the venous blood undergoes
different afTimilations, which tend to make it refume its
qualities of arterial blood. The lymph and the chyle
acquire new charafters cf ainmaliz-.ition, in paffmg
through the numerous lymphatic glands. The venous
blood, in its partial pafTage through the liver, frees It-
felf from oily and albuminous fubftances j but it is in
the pulmonary organ, in particular, that this fluid ex-
periences the mofl important changes, and completely
refumes the qualities of arterial blood : it there frees it-
felf from the materials of carbonic acid gas, as It aban-
doned in the liver the conflltuent principles of the bile.
Neither carbonic acid gas, however, nor bile are found
ready formed in the blood ; they are the refult of
a fpecial fecretion ; and fome have been inclined to
believe that in the a61: of refpiratlon the carbonic acid
does not arife from a particular combination of the oxy-
gen of the air with the carbon of the blood, fince ani-
mals expofed in azotic and hydrogen gas throw out
carbonic acid gas, as they do in atmofpheric air.

The air in IfTuing from the lungs, with more or lefs
force, can difcharge another important fundllon : the
moveable cartilage which covers the aperture of the
glottis, like the mouth of a vi'ind inftrument, caufes the
air to vibrate in Its pafTage, and gives rife to the produc-
tion of found. Thu':, every thing in the organization
is fitted for being ufeful ; the expired air ferves for the
production of melody and cf fpeech,as the excretion of
the bile becomes one of the powerful inftruments of dU
geflion.

Generation, confidered in regard to the general re-

produflion of organized beings, exhibits a remarkable

uniformity. All living beings j)roduce, in fome of their

b 4 partsj

XXIV PRELIMINARY DISCOURSE.

part?, fiTir.il bodies; wliich, Ly their further Increafe,
form beings fimi'ar tc thcfe from v/hich they arife. In
fome clailes iiicU bein^i in miniature (<?>« \r, gcms^ &c.)
require only, for their expanfion, to be feparated from
their mother, and to be placed under certain favour-
able clrcuradances [JJiti). In others, thefe fmall bodies
(feeds^ova^ germs) are not completely developed until fome
fpecific irritant has imprefTcd on them, by its conta6l,
the firft movement of Individual life. Reprodu£lion,
confidercd in tnis general manner, becomes a phjenome-
non which can be reconciled m.uch better with the prin-
ciples of philofophy, than that of the transformation of
the aliments into a cnymous pulp.

The lad pait concludes with a view of the knowledge
acquired in regard to the vital i"an6lions. In this part,
particul.T attention is paid to the development of the
infelle£lual faculties. By obferving the ilov/ progrefs of
this faculty, during the fa-ft years of life, and at the
different periods of civilization, the fuccefiive connection
of thefe different phaenomena can be followed. But if
we negle6l to examine the earliefb exertioi^s of this func-
tion ; if we attempt to account for the phsenomena ex-
hibited by the human mind when it has attained to the
hi^heil degree of inteliecSlual vigour, without having
previoufly obferved, with care and attention, the deve-
lopment of ti\Q different fenfations, and the origin of
the racionai faculties, we {hall find nothing but an im-
menfe abyfs, into which it will appear impoiTible to pene-
trate,-and man will feera condemned to remain a flranger
to the nature of that facult)' v.^hich he daily employs for
making new discoveries.

When it is conGdered that mtn who had no knowledge
of the organic ilru£lure were the nrfl who attempted

to

PRELIMINARY DISCOURSE. XXV

to explain the phcenomena of tlie mod aftonifhlng func^
tion of the organizatioiij the capital errors which occur
in their works will not excite fo much furprife as the
great difcoveries which they made.

It may readily be conceived that the only proper me-
thou to be piirfiKd in order to explain, in a fatisfa£lory
manner, the fun£lion which gives rife to the intelietS^ual
■ faculties, is to acquire a thorough knowledge of the or«
ganic flimSlure, and of the natural progrefs of the func-
tions under the different circumftances of health and of
difeafe.

If in the fearch after truth vye (Dught to proceed from
thin . known to thofe which are unknown, it will be
neceflary to iludy the phyjical nature of man before we
attempt to make refearches in regard to ^cvhat is beyond
the province of natural philofophy, and which forms
the. obje£l of metaphy/ics.

CONTENTS

CONTENTS

OP

THE FIRST VOLUME.

System of the bones ' . ...

Page 1;

Of the trunk , . .

. ib.

Vertebral column in animals . ,

2

Vertebral column in mai^ . . . .

5

Ribs and sternum in animals ....

10

Hibs and sternum in man ....

12

Of the head ......

14

Cranium in animals ......

. ib.

Cranium in man

. 16

ii'ace in animals ..... o

. 20

Face in man . . . ...

: 23

Articulation of the head in animals

. . 29

Articulation of the head in man

. 30

Of the limbs in a-nimaes ....

33

Thoracic limbs of animals ....

. ib.

Shoulder in animals ......

. 33

Shoulder in man ,,.....

34

Tlie arm ...,..,

35

The fore arm

• 37

The carpuS;, metacarpus, and phalanges in animals

. 39

The hand of man . ..'.,.

. 42

General disposition of the thoracic limbs

. 45

Of the pelvian limbs in animals

. . 47

Of the hip bone in animals . .

. ib.

Of the hip bone in man .....

, 43

Of the thigh .......

. 51

Of the leg

. 52

Last

CONTENTS OF THE FIRST VOLUME.

XXV

Xast part of llie pelvian limb in animals . - Page 55

Of die Jbot in man , , , . , . . * 56

General disposition of the skeletori . . . , GO

Differences exhibited by the female skeleton - ' . 65

Development^ physical stiuctui-e_, and cliemical analysis

of the boues ' . . , . ' . 6S

Table of the bones . , . . ^2

MUSCULAR SYSTEM . . . . 7^

General disposition of the muscles in animals . . 76

Muscles in man . . . • , ib.

Mtiscles which produce motion in tlie vertebral column 77
Muscles which give motion to the breast in animals . 79
Muscles which give motion to the breast in man . 80

Muscles which move the head In animals . .83

Muscles ^^'hich move the head in man . . 84,

Muscles which move the face . . .87

Muscles of the limbs in animals . . Q2

Muscles \yhich move the shoulder on the breast . §4

Muscles which move the arm on the shoulder . q6

Muscles which move the fore arm on the arm . Qg

Muscles which make the radius turn on the os cubitus . 101
Muscles which move tlie wrist on I he fore arm . 103

Muscles which produce motion in the fingers . , 107

Muscles which move the tliigh on the pelvis . .113

Muscles which move the leg on the thigh . .118

Muscles which move the foot on the leg . .132

Muscles which give motion to the toes . .127

Physical structure and chemical analysis of tlie muscles 132
Table of the muscles .... 134

CEREBRAL AND NERVOUS SYSTEM . .141

In animals without vertebrae '. . . . ib.

In vertebral animals . , , , .142

Of the encephalon and encephalic nerves' . .143

Cei'ebral and rachidian prolongation with its nerves . 149

The ^

STV^ilt - CONTENTS OF

The trisplanchnic

Page 150

Cerebral and nervous system in

man

. ib.

Encephalon .

. ib.

Meninx and uieningine

. 153

Cerebellum

. 164

Encephalic nervas

. 167

First pair

. ib.

Second pair .

. l68

Third pair

. 169

Fourth pair

. ib.

Fifth pair

. 170

Sixth pair

. 177

Seventh pair .

. 178

Eighth pair

. ISO

Nintli pair

. ]Si

Tenth pair

. 182

Eleventh pair

, 1S4

Twelfth pair .

. 1S5

Vertebral nerves

. ib.

The cervical pairs

. 186

Trachelo-cutaneous plexus

. 187

Diaphragmatic nerve

. 189

Brachial plexus

. ib.

Nerves of the thoracic limb

. IfiO

Dorsal pairs

. 196

I ambar pairs

. , 198

Sacral paii's

/ 200

Hypogastric plexus

. ib.

Crural plexus

. 201

NeiTcs of the pelvian limb

. ib.

Lumbar plexus ^ • .

. ib.

Sacral plexiis

. 203

Trisplanchnic '

. 208

CcHliac ganglion

.211

Cueliac plexus

. 212

Physical structiii'e and chemical

analysis of the

nei-ves . 213
Table

THE FIRST VOLUME.

XXIS

Table of thf cerebral system
Table of the nerves

SYSTEM OF THE SENSES

. 233

Of vision

. ib.

Cornea

. 234

Aqueous hnmonr

. ib.

Ciystalline humour*

. ib.

Vitreous humour

.' 235

H}'aIoid membrane

. ib.

The retina ■ . , .

^ . . 236

Sclerotica

. ■ . . ib.

The choroid membrane

. 237

The orbits

. 240

Muscles of the eye

. 241,

Eye-lids

. ib.

-Eyes in man .

.244

Of hearing

. 252

Organs of hearing in animals

. ib.

Organs of hearing in man

. 257

Membranous labyrinth

. ib.

Cochlea

. 258

Semi-circular canals

. ib.

Vestibulum

. 259

Osseous labyrinth

. ib.

Tympanic cavity

. ib.

Small bones of the ear^ and mu

3cles attached to them . 2Sl

Membrana tympani

. 262

The concha . . -

. 203

.Ligaments and muscles of the e

ar ,. . . 264

Of smelling ,

.266

Olfactory organs in animals

. ib.

Olfactory organs in man

. 271

Ethmoidal nerve

, ib.

Nasal fossae

. 272

Superior and middle tm-binated

bones , . 2/3

-

Inferior

Page 216
, 221

SXX CONTENTS OP

inferior turbinated bone . : . Page 274

Cartilages of the nose^ and mtiscles attached to them . ib^
Sinuses . , ^ . i . ib.

Etlimoidal cells . „ , i . TJS

SYSTEM OF DIGESTION ... 270

System of digestion in animals i . • ib.

Jaws , ... . .277

Teeth , , * . i i 279*

The tongue ^ • . . * • 284

The stomach , i i i ' i i 285

Ventriculus or paunch .... 288

Honeycomb^ bonnet^ or king's hood . . . 289

Omasum or manyplies . , . , ib.

Abomasum . ^ : . . . 29O

Kumination , , l i. i i29i

System of digestion in man . . . • 297

The teeth ..,.♦. ib.

Inside of the mouth . . . . • 300

The tongue . 0 . . « • 301

0& hyoides . . . . . • 302

Muscles which move the tongue and the jaw i . 303

Velum palati . i , . ^ » 305

Salivaiy glands . ... • 307

The pharynx ...."• 307

Glottis and epiglottis . . . • 308

CEsophagus . . , . . • 309

The stomach . . . " . .310

Intestines . • . • - .311

Small intestines . . ' . . .312

Muscles of the anus . . . . .313

The liver . . : . • .314

The bile . . . . •. -310

Chemical analysis of it . * » .317

Bilious concretions . . . • .318

The spleen . . . , . . ib.

The

THE FIRST VOLUME.

XXXI

The pancreas . . . ,

s Page 319

''The peritonaeum . . ^

. ib.

SYSTEM OF CIRCULATION ' .

^ 321

Circulation in plants and zoophites

. ib.

In crustaceous animals, &C,

. 32a

In fishes . , '. .

. 323

In reptiles . . • .

. 324

In the mammalia and birds

. 325

Urinaey systsm . . .

. 327

Hepatic system

; 323

ReSI'IRATION .

. 330

Tracheae ....

. ib.

Branchiae . , « .

. 331

Lungs ....

. 332

Apparatus of circulation in man

. 33s

Stracture and disposition of the arteries

. 337

The skin . . .• .

. .239

Dermis ....

. ib.

Mucous tissue

. ib.

Epidermis . .

. 340

Super-renal glands . . .

. 341

Kidneys ....

. a>.

Ureters \, . •

, 342

The bladder • - . .

. 343

Urine ....

. 344

Chemical analysis of it

s . 345

Urinar}^ calculi

. S48

The veins ....

. 351

Lymphatic vessels

. 352

The liver ....

. 355

Sinus of the venae cavse

. 359

Pulmonaiy ventricle

. 3(50

The lungs . . . ,

. 361

The larynx ....

. 362

-Muscles of the larynx

. :j63

Trachea

XXXVl

CONTENTS OF THE FIRST VOLUME.

Trachea
Bronchiae - .
Sinus of the pulmonary veuia
Aortic ventricle
The pleura . '
The tJiymus .
The pericardiiuii •
The blood
The lymph .
Chemical analysis of the blood
Distribution of tiie arteries
The aorta . .

Cardiac arteries
Cephalic artery
Anterior cerebral artery
Brachial artery
Axillary artery
Humeral artery
Radial artery-
Cubital artery
Thoracic aorta
Abdominal aorta
Gastric artery
Hepatic ariery
Splenic artery
Pelvian artery
Crural artery
Taele of the heart and arteries

Page 365
366
367

ib.
308
36^

ib,
370
371

ib..
373

ib.

ib.

ib.
379
383
387
389
391
393
395
39
39s

ib.

399

405
408

4lS

A COURSE

OF

MEDICAL STUDIES.

SYSTEM OF THE BONES,

OF THE TRUNK.

I, The organs of fmall animals are not fupport-
cd by olleous parts ; bones in general are found
only in the large animals ; and the fkeleton which
they afford feems always to have been formed ac-
cording to an uniform plan.

The Ikeleton determines the general form of the
animal ; it contains fome organs, and fupports
others ; it affords points to which a great many are
attached, and ferves for various kinds of motion.

Animals which have a fkeleton are called ver-
ielral animals \ becaufe in the Ikeleton the verte-
bral column is a conflant and central part^ little
fubjedl to variation,

yoL. lo , B The

a ' ORGANIC STRUCTtTRE.

The Ikeleton of fome animals Confifts only of
the vertebral column and the head ; but in the
greater number thei'e are alfo limbs.

2,. Vertebral column in animals. The
vertebral column, rachisj or fpine, is conftituted
of a feries of longer or fhorter bones^ variable in
extent, called vertehrce*

The number of the vertebrae varies between i6
or 20 to more than 2,00 in fifhes, and in fome
ferpents it exceeds 300.

The vertebra are each compofed of one efiential
part^ which is thehody of the bone ; the vertebra
are placed one above the other, and in this manner
form a column, which ferves to fupport the trunk,
and as a ftay to the head.

Vertebrae, of the limpleft kind, confift IbmC'
times merely of the body. The more complex
have alfo a groove or an arch, and protuber-
ances on four faces. Each vertebra therefore has
tv/o faces for joining to the two contiguous ver-
tebrae ; the reft of its furface, whatever be its
formj always prefents four faces: a fpinal face,
fpna dorfi ; a praefpinal or antifpinal \ and two
lateral ones.

The fpinal face has fometimes a notch like that
in the fpine of olTeous iifl:es ; but for the moil
part it is furnifbed with a cavity which forms a
hole.

The

SYSTEM OF THE BONES, 3

The jundlion of the notches produces a groove,
that of the cavities a canal.

The fpinal face exhibits alfo, in general, a pro-
'tuberance caUed the fpinal apophyfts : it is placed
above the cavity ; ancrwhen there is a groove the
latter is cut out on the apophyfis.

The fpinal apophylis of the vertebrae varies both
in its form and its dire61ion ; it is more or lets
elongated, round or flattened ; terminates in a
point or edge, and ftands at right angles, or pro-
ceeds in an oblique dire(5lion.

The prse fpinal face is feldom furnidied with
apophyfes ; they are obferved however in the ver-
tebra of the rattle-fnake, and in the tails of
fifhes.

The lateral faces fometimes have only apophyfes,,
called tranfverfe, which fupport the ribs, as is the
cafe in fiflies ; but other animals have two other
articular or lateral apophyfes^ one above, the other
below the tranfverfe apophyfis, and articulated
with the adjacent vertebrae correfponding to
them.

On the (ides of the vertebral canal there are
holes ox foramina, which penetrate to its cavity.

Striking differences are obferved in the verte-
brae in regard to their conne(?l:ion. In fifhes they
join only by their fubftance ; in other animals they
are articulated not only by their fubflance, but by
their articular apophyfes.

B 2 The

4 ORGANIC STRUCTURE.

The articular faces of the bodies of the verte-
brae have fometimes conical cavities, as in fifhes :
the jun61ion then takes place by the edges of
thefe cones ; and the rachis or fpine forms a
ferics of elliptical cavities, filled with a white firm
and elaftic or cartilaginous fubftance ; but for the
moft part the vertebrag are articulated by their
plain furfaces. The furfaces of the articular
apophyfcs exhibit the fame difpofition.

The difpolition of the articular faces of the ver-
tebrae, and that of their apophyfcs, always deter-
mine the quantity of motion they can perform by
the means of mufcles J this motion may be ex-
ceedingly free when the vertebrae are articulated
only by their bodies, and when their apophyfcs
do not mutually confine each other, as is the cafe
in iifhes : by a contrary difpolition they may be
reduced to perfc6l immobility.

The rachis or fpine of fome fifhes con fi (Is of a
long feries of vertebrse, which exhibit no diffe-
rence ; in ferpents, a great part of the vertebrae
are joined to ribs, but thofe towards the tail are
not : the former are called dorfal, the latter cau-
dal vertebra.

The greater part of fifhes have alfo vertebrae
united to ribs, and which are called dorfal ; but the
caudal vertebrae, towards the belly, are ail fur-
niQied with apophyfcs : fifhes have fome like-
wife without ribs, and which exhibit no ventral

apophyfcs :

SYSTEM OF THE BONES. 5

apophyfes : thefe vertebrse, when they are above
thofe of the tail, are called lumbar^ and when im-
mediately below the head, cervical.

In animals provided with limbs a part of the
vertebrae receive the ribs ; another part are fuf-
tained by the pelvis, and the reft remain free above
and below the //^or^^ and the pelvis : this difpoii-
tion allows us to diftinguifh the vertebrse into cer-
vical, dorjal, lumbar, pehian, and caudal.

The cervical vertebrse are between the head and
the thorax ; the dorfal fuflain the ribs ; the lum"
har lie between the thorax and the pelvis ; the
pelvian are affixed to the pelvis, and the caudal
come after the pelvis.

The cervical vertebrae, in the mammalia *, are
in number always feven : in the other claffes they
vary.

3. Vertebral column in man. Man has
feven cervical vertebrae, twelve dorfal, five lum-
bar, five pelvian united and forming a bone
called the os Jacrum, and three or four caudal
alfo united, and forming a fmall bone called the
coccyx,

4. Vertehra. In general, each vertebra pre-
fents a body, on the fpinal face of which is a ring ;

* Except the three-toed floth, which has nine.

B 3 the

6 ORGANIC STRUCTURE.

the whole of thefe rings forms the vertehrdl canal.
Before the fplnal arch of each ring is a fp'inal afO"
fhyfis % on each fide of the body or ring of the
vertebras is a tranfverje apophjjis, and above and
below this apophyfis there is another articular one.

The articular apophyfes unite with the corre-
fponding ones of the neighbouring vertebras. In
the cervical and dorfal vertebra the facets of the
fuperior articular apophyfes are turned backwards ;
thofe of the inferior forwards ; while in the lumbar
vertebrce the fuperior facets are turned inwards_,
and the inferior ones outwards.

Between the articular apophyfes of one vertebra
and that adjoining to it is a hole which communi-
cates with the vertebral canal (24 -vertebral fora-
mina).

In the cervical region the upper part of the
bodies of the v^ertebrae is indented and inclined
forwards: in the reft this part is plane and hori-
zontal.

The firft cervical vertebra, called the atlas, is a
fimple ring, v/hich on its upper part and both fides
prefents two facets for its articulation with the
head, and two others below unite it with the
fecond. The internal part of the arch of this
firft vertebra exhibits alfo an articular facet, which
fupports a round and elongated tubercle (procejfus
odontoides) which rifes above the body of the fe-
cond

SYSTEM OF THE BONES. J

cond vertebra. The latter is diftlnguifhed by the
-name of ^A'o/V/^i".

The free motion of the head on the neck arlfes
from the peculiar difpofition of thefe firll: two
vertebra?.

The cervical vertebrae are the fmalleft : their
bifid or forked fpinal apophyfes are turned a little
downwards, and their tranfverfe apophyfes are
perforated.

In the dorfal vertebra the fpinal apophyfes,
which are longer^ are turned downwards ; the
tranfverfe apophyfes, inclined backwards, exhibit
demi-facetSj which when united form complete fa-
cets deflined to receive the ends of the ribs ; the
ift, theiith, and the 12th, exhibit a complete
facet. Thefe facets are turned downwards in the
upper vertebrae, and upwards in the lower.

T^e lumbar vertebrze are the largeft ; their fpi-
nal apophyfes are exceedingly llrong, and turned
backwards.

The different regions of the fpinal and pracfpfnal
face of the rachis or fpine are alfo dillinguithed
by peculiar names.

Thus the region of the neck behind is called
the cervical, and before the trachelian ; that of the
back behind, \\\c dorfal, and before, the prcedorfal\
that of the loins behind, the lumhari and before,
the prcsJumhar.

The five pelvian vertebras united into oiie piece
B 4 form

S ORGANIC STRUCTURE.

form the os facrum j this bone is flat, triangular,
and concave before ; its broad and thick fummit
is united by its body and articular apophyfes to
the laft vertebras of the back ; it is articulated on
the tides with the bone of the pelvis, and on the
lower part it receives the coccyx.

The OS facrum exhibits on the fore part the bo-
dies of the vertebrae of which it is formed, and
behind and on the fides confufed tubercles, which
correfpond to the fpinal, tranfverfe and articular
apophyfes. This bone contains alfo the vertebral
canal ; the foramina which terminate there are
placed before and behind.

The laft three or four vertebrae, united into one,
form a fmall bone called the coccyx^ which termi-
nates in a point, and is articulated with the os
facrum, on which it can be bent backwards. In
this bone the form of the vertebras which compofe
it can fcarcely be diftinguifhed.

Between the articular furfaces of thebodies of the
vertebrae is found a white, thick, firm and elaftic
fubftance, the conliftence of which decreafcs from
the circumference to the centre ; this fubftance,
which is of a fibrous ftru(?l:ure, adheres ftrongly to
the two contiguous vertebrae, and is called the I'l'
gamentO' cartilaginous.

The bodies of the vertebrae are covered, both
before and behind, with a tiffiie of white compact
fibres, exceedingly folid, which proceeds along the

whole

SYSTEM OF THE BONES. ^

whole rachisor fpine, and which iscaJled the com^
mon vertebral ligament, pqfterior and anterior.

On the poilerior part of the fpinal canal, and
between the articular apophyfes, there are exceed-
ingly ftrong ligaments called the infermeJIar (yd-
low ligaments).

The vertebrae are faftened alfo behind by a liga-
ment (the Juferffinal), which proceeds along
the fpinal apophyfes, and by ligaments (inier^
fpinal) which extend from one fpinal apophy (is to
the other. Each articular apophylis has alio a
ftrong capjular ligament^ which is united to the
neighbouring vertebra*.

The means by which the lail: lumbar vertebra
is united to the os facrum are the fame as thole
by which the vertebra are united \ and the coccyx
is fixed to the os facrum by an articular capfule
and ligaments placed before and behind.

The vertebral column is flightly bent, in fuch a
manner that the region of the neck before is con-
vex, that of the back concave, the region of
the loins convex, and that of the os facrum
concave.

Though each vertebra can perform on the other

* All the articular furfaces of thcfe bones, which form
moveable articulations, are covered with a ftrong, Imootb, and
mpift cartilage, and the portions of the bone articulated arc
always wrapped up in a fort of membrane which furrounds the
articulated furfaces in the form of a capfule, and keeps them
firm. This arrangement being always the fame, we (hall diitin-
gulih it In future by the name of the ariuular ea^uh.

only

30 ORGANIC STRUCTURE.

only very confined movements, the whole ofthefe
movements is complete in the whole of the fjJine;
find it is well known how far thofe who exhibit
feats of tumbling can carry the pliability of this part.
It is by means of the lumbar vertebrae in particu-
lar, that the greatefi: movements of the trunk arc
performed, becaufe they are not impeded in their
motion, like that of the back, by being united to ribs.
The body of the vertebras confifts of a fpongy
fubftance ; that of the apophyfes is of a more com-
pact texture.

5. The ribs and sternum in animals. In
almofi: all animals the ribs are fuftained by a
greater or lefs number of vertebra. Thefe bones,
however, are wanting in many cartilaginous fifhes ;
in fome of the ofleous, and in frogs.

The number of the ribs, which varies from 12,
to 23 on each fide in the mammalia^ is conliderably
increafed in ferpents and fome fidies, which have
almofl: as many as they have vertebrae.

In the falamander, and feveral genera of fiOies,
the ribs are very fhort ; in fome of the mammalia
they are exceedingly long. In the herring they
are as fmall as needles ; and in the two toed ant-
eater (myrmecophaga d'ldaByla) fo long that they
cover each other like tiles.

In general they are fingle ; in feveral fiOies
however they are forked, fo that two proceed
fometimes from the fame vertebra.

The

SYSTEM OP THE EONES. H

The ribs arefeldom flraight, being for the mod
part bent almofl in a femicirciilar form j in the
mammalia their configuration determines the form
of the thorax, and in iiflies and ferpents that of
the belly and abdomen.

One of the extremities of the ribs always rells
on the vertebra ; the other either remains ful^
pended in the foft parts, or is united with a carti^
lage, or refts on a bone called the fiernum*.

The name o^ Jlernal vertebras is given to thofe
which on one fide adhere to the vertebrae, and on
the other to the fternum ; and that of ajicrnal to
thofe which do not reach the fternum.

In mammalia the ribs which end at the fternum
are towards the head : birds, in general, exhibit
a contrary difpofition ; fometimes, however, they
have afternal ribs towards the head, and towards
the pelvis. In animals which have no ribsf the
fternum is wanting; ferpents and almoU all fillies
have ribs, without having a Iternum.

In mammalia the fternum is long, of confidera-
ble thicknefs, broader or narrov/er, ofl^ous, fome-
times cartilaginous, and, for the moft part, confifts
of feveral pieces. In birds it is exceedingly broad
as well as thin, and prcfents a very falicnt ridge,
particularly in thofe of a rapid flight. In fome
reptiles it afiiimes very Angular forms, is extremely
fmall, and in fifties is always wanting.

* In the crocodile the ventral ribs reft on the as puhh,
■\ Frogs excepted.

6. Ribs

■I
12 ORGANIC STRUCTURE.

6. Ribs in man. In man the ribs are In num-*
ber 1 2 on each fide ; thefe bones are long, bent
irregularly in a femicircular form ; are flat, and,
as it were, tvvifted backwards.

At the pofterior extremity they prefent a double
facet, feparated by a falient line ; this facet is
articulated between the lateral parts of two verte-
brae. At the diftance of an inch from this extre-
mity, the ribs have behind another facet, which
is applied to the tranfverfe apophylis of the lowed
vertebra. Thefe two articular facets are feparated
by a narrow part or ftri6lure called the neck of
the rib.

The ribs then proceed backwards and outwards,
after which they feem to bend in order to proceed
forwards, and exhibit there a falient line nearer
the vertebrae in the upper ribs : angle of the ribs.

The anterior extremity is terminated by a car-
tilage which unites with the flernum ; the flrft
feven ribs (Jiernal ribs) proceed in this manner to
the fterrium, by means of an Intermediate carti-
lage ; but the cartilages which terminate the lad
five (ajiernal ribs), reft one' upon the other, and
are fupported by the cartilage of the feventh rib.

The firft rib, which is fhortcr as well as broader,
has its external face turned upwards ; the follow-
ing ones become longer, and their external faces
are directed forwards : in the laft place, the lower
ones become fhorter, and obferve the fame di-
redion.

The

SYSTEM OP THE BONES. Ig

The articulation of the ribs with the bodies of
the vertebrae is fecured by an articular capfule, an
anterior ligament, a cojio-tranfverfe ligament, and
an interior ligament. The tuberotities of the firll
ten ribs are faftencd to the tranfverfe apophyfes
of the correfponding vertebrse, by a capfule and a
tranfverfe ligament,

7. The fiernum. The llernum in man is a
flat bone, broad at the top, and terminating at the
bottom in a thin cartilage of greater or lefs extent.
This bone often confifts of two pieces, which in
the courfe of time coalefce and adhere together ;
on the fides it has facets proper for receiving the
cartilages, which terminate the ribs ; thefe carti-
lages are retained on the fides of the fternum by
an articular capfule, an anterior and 2^ poflerior
ligament.

The fternum is exceedingly fpongy ; it is co-
vered both without and within by a very ftrong
feriofteum.

The fternum, the ribs, and the dorfal vertebras,
form the capacity of the thorax.

The thorax has the form of a very irregular
cone, with its bafe truncated downwards and its
fummit upwards ; it is flat before, broad and
rounded on the fides ; flat and concave behind.

OF

OF THE HEAD.

The bead, with refpe^l to its form^ is that part of
animals moft liable to variation. It confifts of
the cranium and face.

8. Cranium of animals. The cranium, or
cephalic cavity, contains the brain.

The differences obferved in the form of the
head of various animals confift chiefly in the
greater or lefs contraction of the fize ef the cra-
nium, and the greater or lefs elongation of the
face.

The extent of the cranium, in regard to the
elongation of the face, may be determined on
the furface pre fen ted by a vertical fe6lion of the
head : it is obferved, in the different clalies of the
Hiamraalia, that the cranium occupies on this fur-
face an extent either greater or fmaller than or
equal to that of the face, without including the
lower jaw. Among the Europeans the extent of
the cranium is nearly quadruple that of the face;
in the Negro, the extent of the cranium remaining
the fame, that of the face is increaled by a fifth,
6 In

tSYSTEM OF THE BONES. 1^

In the different fpecies of apes, the area of the face
goes on increaling ; in the mandril (fima maimon),
and the greater part of carnivorous animals, it is
nearly equal to that of the fkull ; in various fpe-
cies of graminivorous animals it continues to in-
creafe to fuch a degree, that in the horfe it is
aimofl four times as large as that of the cranium.

The cranium aife(5ts different forms ; but for
the moil part the fammit of it is oval or rounded,
and its bafe an irregular plane.

The bones of the cranium do not feem io be
numerous in fifhes ; in thefe animals they are
united by plane fur faces, coal efce at an early period,
and leave fev^ traces of their jun6lion. In birds
thefe bones, vi^hich are fitted into each other by
futures, coalefce alfo at an early period, and the
traces of their articulations difappear vi^ith age.
But in the greater part of the mammalia, and in
man, thefe ofleous pieces are very difi:in6l, and at
moft are eight in number, viz. before, the frontal
bone ; on the fummit and at the fides, the two
parietal bones ; lov/er, and on the fides, the two
temporal bones ; behind, the occipital ; and at the
bafe, the fphenoid, and the ethmoid. Of thefe
bones the frontal, fphenoid, and ethmoid, are com-
mon to the cranium and face.

Thefe bones, in the various genera of animals,
differ both in regard to their form and relative
iize; and it may thence be eafily conceived in

how

\

i6 ORGANIC STRUCTURE*

how many ways the configuration of the craniUM
may be varied.

The cavity of the cranium in the mammalia 19
filled with the brain ; but in reptiles and fifhes
this organ occupies only a very fmall part of it*

9. Cranium in Man. In man the craniunni
is round, well expanded, and prefents a cephalic
cavity comparatively larger than that of other ani-
tnals : it confifts of eight bones.

10. The fpbenoij, osJpbenoiJes. The fphenoid
is a bone of a very lingular form ; it is long, and
pafles through the middle of the bafe of the era*
nium and the breadth of the face ; it exhibits a
great number of prolongations, by means of which
it is articulated with all the bones of the craniumj
and a great part of thofe of the face**

On account of its poiition and numerous con-
nexions, it has been confidered as the key of the

* This bone has on each of its fides two unequal prolonga-
tions, called the greater and kfs ala, or wings j at the bottom
two apophyfes, called the pt. rygoides, which form behind ^fojfa^
called the pfery^i^y id. The m ddle of this bone is the body of it,
the upper part of which, traniverlally deprefled, is known under
the name of the fella tuc'ica, and is furrounded by the anterior
and pqjierior dmoid apophyfes. This bone is perforated with
holes, which afford a palfage to the velfels and nerves j viz. the
optic foramina, the fphenoidal fiffures or rima, the upper and
lower maxillary foramina, and tvvo fpinous foramina. In the
thicknefs of the body the fphenoid tiffurcs are contained.

8 bones

SYSTEM OP THE BONtS, If

bones of the head. This bone is feen atthebafe
and on the (ides of the cranium ; it concurs to
form the cavities of the eyes (brhits) and thofe of
the noftrils.

i I. Frontal Ip&ne^ Os frontis. The interior part
of the cranium, or the forehead, is formed by the
OS fro7itis. This bone forms alfo the upper part
of the face; it is curved and rounded at the fum-
rriit, and before and on the fides it is furnifhed
with two procefles called the frontal, and in the
middle, lOwer down, with two other procefles
called the nafal. The lower part of it is bent
back in a horizontal direction: it is indented in
the middle to receive the os ethmoides, and its
fides are arched to form the upper part of the
cavities that contain the eyes.

This bone is articulated below with a part of
the bones of the face ; behind and at the bottom
with the OS fphenoides, and behind and at the top
with the two following bones.

12. Parietal hones. The fummit and fides of
the cranium are formed by the junction of the
two parietal bones. Thefe bones are convex o\\
the outfide, quadrilateral and ferrated at the
edges; they articulate with each other above,
with the frontal bone before, with the occipital
behind, and at the bottom with the temporal bones
and the fphenoid.

13. Occipital bone^ Os hajilare. The back of the
VOL. I. c head

18 ORGANIC STRUCTURE.

head and a part of the bale of the cranium are
formed by the occipital bone. This bone is con-
vex on the outfide, and is (haped fomewhat like a
lozenge ; two of its edges arc fitted by a future
into thofe of the parietal bones ; it prefents on
the outfide behind a protuberance called the oar-
pi/al; on the (ides two falient lines called the
occipital arch, and within two grooves, corre-
fponding to thefe two lines. Below is the large
6ccij)ilal foramen, which forms a continuation with
the vertebral canal; on the fides and within this
hole there are two tuherofities, with which the
head is articulated on the vertebral column : in
the lad place, that part of the bone before this hole
is called the fuh-occipital.

This bone has feveral holes sJfo for the pafllige
of the nerves and veilels : it is articulated before
with the fpbenofd ; at the bottom with the rachis or
Ipine, and on the lides with the following bones.

14. Temporal hones, Ojja temporaTm. Below
and on the fides the cranium is formed by the two
ieu'cporal hones. Thefe bones are of a very irregu-
lar figure ; they prefent on thj| outfide a flat,
rounded, and very thin part, which may be com-
})ared to the fhell of an oyfter. This part gives-
birth on tlie outfide to an apophyfis^ called the
zygomatic : it is long and thin ; proceeds forwards,,
receding from the bone, and unites with the apo-
phyfis of another bone to form an arch.

5 Below

SYSTEM OP tHE BONES, \g

Below the root of this apophyfis Is the glenoid
cavity, which receives the condyle of the jaw-
bone J beyond this cavity is the external orifice
of the meatus auditorius ; and ftill further back
is a large tiiberofity called the apophyfis maf-
toideiis. Below the auricular foramen is the
apophyfis Jiyloides, behind which is obferved the
jugular foffa.

The temporal bone prefents, in the infidc, a
thick part, very unequal and exceedingly hard,
called the petreous (petrea). It is in the thickncfs
of this part that the organs of hearing are con-
tained. The temporal bone exhibits a great num-
ber of holes, the principal of which are : below,
\k\Q Jiylo-maftoid \ the carotid canal, and the gut-
tural conduit of the ear ; in the infide, the interior
auditory foramen.

This bone is articulated before with the fphe-
noid ; at the top with the parietal bones, and be-
hind with the occipital.

15. All thefe bones of the cranium are fitted
into each other by futures, or are united by fmooth
furfaces. Their edges are generally cut obliquely
in different dire(?tions : the fame bone, therefore,
has a part of its edge cut into a bevel on its ex-
ternal face, while in another part it is cut into a
bevel on the internal face. This peculiar difpofi-
tion exhibits a method of articulation as flrong as
it is wonderful. > ^^

c 3 Thofe

10 . ORGANIC STRUCTURE,

Thofe ferrated marks produced by the jiincllonr
of the bones of the cranium, and which are called
futures, become effaced fometimes with age.

The bones of the cranium exhibit, on the out-
ilde, particularly behind and on the fides, depref-
fions or afperities, that indicate theinfertion of the
nnifcles by which thefe parts were covered.

In different points of the bone of the cranium
there are holes of greater or lefs fize, which pene-
trate to the iBtide of it^ and which afford a paffagc
to the veflels and nerves.

The upper part of the cavity of the cranium-
exhibits furrows of greater or lefs depth, which
extend in a ramrfied form. : thefe furrows corre-
fpond to veffels which reited directly againft the
lides of this cavity.

The bafe of the cranium prefents, in the infide,
eminences and excavations very diftindl: the ca-
vities fcrve to lod_Q;e portions of the cerebral organ.

The lower part of the cephalic cavity, the bafe
of the cranium and the fides of the head contain
holes, iiffures, and indentations, which afFord a
paffagc to the nerves., arteries, and veins'^.,

The

* The inferior fide of the cavity of the cranium, proceeding
from the fore part backward', prefents the foramen civcwn, the
holes with which the cribriform plate of the os ethmoides is per-
forated, the optic foramina, the fphenoid fiflures, the up.per
maxiilas-y or large round foiamina, the lower or oval maxillary

forajr.ine.

SYSTEM OP THE BONES. 21

The bones of the cranium are covered through-
out their whole extent, both internally and exter-
nally, by a membrane which firongly adheres to
them, and is called the pericranium.

i6. The pace in animals. It is of import-
ance to examine the face in the different clafles
of animals, in regard to its greater or lefs elon-
gation.

The form and elongation of the face are always
determined by the gre>ater or lefs prolongation of
the jav/-bones.

It is obferved, in general, that the perfedlibility
of the oriranization of animals is in the inverfe

foramina, the fpinous or fmall round foramina, the internal
orifice of the carotid canal, the polterior foramina laqcra, titie
anterior foramina lacera, the interior auditory foramina, the pof-
terior foramina lacera, the anterior condyloid foramina, (ihe
pofterior condyloid, and the maftoid foramina when they exift,)
the grand occipital foramen.

The bafe of the cranium prefenlsj the anterior palatine fora-
mina, the pofterior palatine foramina, the pollerior aperture of
the nafal foffas, the potterior aperture of the palatine and
pterygoid cbnduits, the anterior foramina lacera, the carotid
canal, the pofterior fora-mina lacera, the anterior and pofterior
condyloid foramina, and the grand occipital foramen.

The lateral parts of the head prefent: the external orifice of
the auricular conduit, the ftylo-maftoid foramina, the fpinous
foramen, the foramen ovale or lower max'.lhry foramen, and tie
zygomatic fofla, in which are found : the fpheno-maxillary rirr,a
or fiffure, the orifice of the fub-orbitar, palatine, pterygoid,
fpheno-palatine, and pterygo-palatine conduits.

c 3 ratio

22 ORGANIC STRUCTURE,

ratio of the fmall fize of the cranium, and of the
great elongation of the jaw-bones.

Man, of all animals, has the largeft cranium
and the fhorteft face.

To determine the iize of the facial angle, Cam-
per raifes above the plane of the bafe of the cra-
nium a line, which, proceeding from the bottom
of the upper incifive teeth, is continued in an in-
clined diredlion to the moft prominent- part of the
forehead. The plane of the bafe of the cranium
pafles through the anterior edge of the upper
part of the noftrils, and through the auditory
foramina. The facial angle, therefore, in Euro-
pean heads, in general, is equal to eighty degrees ;
in thofe of the Moguls to feventy-five ; in thofe
of the negroes to feventy ; in the orang-outang to
fixty-five ; and in carnivorous and graminivorous
animals it decreafes fo much, that in the horfe it
does not exceed twenty-three degrees.

This meafurement, however, can be applied
with any degree of exa6lnefs only to the human
fpecies and the quadrumana* . Other animals ofteq
prefent fuch fingular configurations of the head,
and fuch projedlions of the forehead, that it is not
poffible to meafure their facial angle : befidcs, it
is of little importance to obfervc the fize of the

* Quadrumana — anltnjtls with four bands ; a name given to
the fecond order of the mavimalia in Blumenbach's Handhucb dex
Naturgefchichte, The fpecies included under this denomination
are : Simia, Papio, Cercopithecus, Lemur. In the older works
Ihis order were called Pitted. Trans.

headi

System of the bones, 23

head, except in regard to the volume of brain it is
fappofed to contain : in reptiles and fifhes the
brain occapies oply a fmall portion of the cavity
of the head.

The Greeks feem to have been fentible that the
beauty of the head confifts, in an eflential manner,
in a ftraight dirediori of the face. In the ftatues
of the gods or heroes whom they were defirous of
ranking among their deities, it is feen that they
increafed beyond the hmits of nature this angle,
which they fometimes carried to nearly a hundred
degrees, as if they wifhed by thefe means to give
them a form of countenance as far diftant as poi""-
iible from that of the common race of men.

It is obferved, indeed, that the ftraight form of
the face generally pleafes even in animals ; and,
on the other hand, that elongation of the muzzle
and depreffion of the cranium give them always a
ftupid and ferocious air.

17. Face tn man. In man the face has fuch
fi diredlion that the eyes and mouth look diredtly
forwards : the bones which compofe it ^vc in
number fifteen, befides the thirty-two |:eeth.

18. Bones op the nqse. The bones of the
nofe are fmall, obloftg, and quadrilateral ; they
coalefce, and thus form the upper part of the nofe;
they reft laterally on two prolongations of the
upper jaw-bone ; at the top they are indented

c 4 into

'14 ORGANIC STRUCTURE. ■

into the frontal bone and the os ethnoidesx their
lower edges being iKt(t are united with the carti-
lage of the nofe.

19. Lachrymal bones. On the interior fides qf
the orbits there are two fmall thin bones, called
the lachrymal bones. Their exterior face exhibits
a portion of ihe fo/fa lachrymaUs, which has a com-
munication with the noftrils.

Thefe bones are articulated : at the top, with
the frontal bone; before and below wiih the
upper jaw-bone, and behind with the os ethmoides
and the lower cornets.

20. Zygomatic hones. On the external and
lower fide of the orbits there are two fmail
bones, called Zygomatic hones, of a very irreg'ular
form, flat, and fomewhat convex on the outfid.e.
Their circumference cpnfifts of four indented
fides, terminated by pretty long angles, called
apophyjes.

Thefe bones are articulated : by the upper
apopbyfis, with the os frontis and os fphenoides ;
before and at the bottom with the upper jaw-
bone. The pofterior apophyfis, being longer, is
united with that which, as already faid, rifcs
above the temporal bone, and forms with it an
arch., called \}i\& zv somatic.

21. Super-maxillary hones. At the middle and
anterior part of the face are the two bones of the
upper jaw, or iho, fuper-maxillary bones: thefe
bones are each very irregular, and prefent, in thejr

thicknefs.

SYSTEM OF THE BONES. 25

thicknefs, a cavity called the fmus maxillaris,
which has a communication with the noftrils.

The fuper-maxillary bone is connedled with all
the bones of the face, and with a part of thofe of
the cranium. It is articulated : in the inlide and
at the bottom with its fellow, and two other bones ;
before and at the top it has an afcending apophy-
lis, called the orbito-frontal, which refis on the
frontal, the lachrymal and the ethmoid bone, and
which fupports the bones of the nofe : at the bot-
tom and on the 'outfide of this apophyfis is the an-
terior orifice of the fub-orbitai conduit : on the
outfide it is united to the zygoma and the os fphe-
noides : before and below it receives the teeth.

Thefe bones conftitute a great part of the face
and palate ; they contribute to form the arch of
the nofe, the fides of the noftrils and thofe of the
orbits ; they receive the upper teeth, and ferve
for raaftication.

22. Bones of the palate. Behind the fuper-
maxillary bones, and at the bottom of the noftrils,
are the palatine bones, which extend as far as the
orbits, Thefo bones are of a very fingular form,
which is necefiary that they may adapt themfelve?,
in a great part, to the flill more lingular form of
the 05 fpbenoides.

Thcfe two bones unite behind the fuper-maxil-
lary bones : they are articulated with the os fphe-
no'ideSy the os ethmoides, and the lower cornets
(turbinated bones j), and with an ofl^eous plate,

23. The

'26 ORGANIC STRUCTURE.

23. The OS ethmoldes. In the infide, and at
the fummit of the noflrils, under the indentation
of the frontal bone, is the os ethno'ides, of a cubic
and elongated form, exceedingly light, and con-
flfling in the inlide of very thin plates^ pierced
with holes, which affume different directions, and
form a great many cells communicating with each
other.

The upper face of this bone, wJiich is of a more
compa(5l nature than its interior plates, is pierced
with about forty holes : it correfponds on the in-
iide to the bafis of the cranium, and in the middle
prefents a ridge. Its compact lateral faces concur
to form the internal fides of the orbits. The
other faces of this bone are open, and correfpond
to the fummit of the noftrils.

This bone is articulated : at the top with the
frontal bone ; before, with thofe of the nofe, the
fuper-maxillary bones and the lachrymal ; behind,
with the OS fphenoides^ z.nd. the palatine bones; at
the bottom and in the middle with an olieous
plate.

24. Lower cornets. TurVinated hones. Be-
neath, and on the fides of the os eihmoides, are
two bones, formed of plates twifted into the form
of cornets : thefe bones feem to be an appendix of
the OS ethmoides, and are united to it. Thele cor-
nets are articulated alfo with the fuper- maxillary
bones, the lachrymals, and the palatine bones.

2^, The vomer. Between thefe two cornets,

below

SYSTEM OF THE BONES. ^27

below the os ethmoides, and in the middle of it, is
an ofleous plate, which divides the nafal fofTse into
two noftrilsj and is called the vomer. This thin
and long bone receives in a groove, on its anterior
and fuperior edge, a cartilage, which completes
with it the partition of the noftrils. It refts at
the bottom, between the two fuper-maxillary and
the palatine bones, and is joined at the upper
part, in the bottom of the noftrils, to the middle
of the OS JphenoideSy by a large farrow.

2.6. Jaw-bone. The lower jaw-bone, oj- ;;w.v/7-
lare, is formed of a bone turned round on its plane
face, in the form of'a horfe fhoe : the upper edge
of the arc contains fixteen cavities for receiving
the teeth ; the lower edge has a projection to-
wards the chin.

Behind and in the middle of this bone is a fmall
ridge, called the genian ; on the (ides of which
are two falient lines, known by the name of the
mylean, which terminate at the orifice of the
dental canal.

The extremities of the maxillary bone are bent
up and backwards, fo as to make an angle of forty-
iive degrees, and terminate in a flattened trans^
vcrfe tuberofity, called the condyle, which is re-
ceived in the articular cavities of the temporal
bones. Before this tuberofity is a large apophyfis,
called the coronoid, feparated from the condyle by
^ deep indentation.

The

28 ORGANIC STRUCTURE.

The articulation of this bone with the temporal
isfecuredbya lateral external ligament, a lateral
internal, a tylo-maxillary ligament, and an articu-
lar capful e.

Mammalia, iifhes, and many reptiles, have jaw-
bones armed with teeth. {See that part of the
article on Digejiion.'j
J*

27. The bones of the face, as well as thofe of
the cranium, arc conne6led by means of fmootb
furfaces or indentations, and exhibit the fame pe-
culiarities. Thefe bones have alfo depreffions or
afpcrities in thofe places to which the mufcles
were attached, and holes through which the vef-
fels and nerves were conveyed to the interior
parts.

The aggregate of the bones of the face, toge-
ther with thofe of the cranium, feem fitted in a
fpecial manner, by the formation of the cavities
of the ear, the orbital foflae, the nafal foffe, and
thofe of the mouth, for receiving the organs of
hearing, of fmell, and oftafle.

The aggregate of the bones of the cranium
and face exhibit alfo externally fome remarkable
parts, to which it is of importance that particular
names fhopld be ailigned, in order that they may
be diftinguiOied Vv-ith greater facility. Thqs the
cranium has on each tide a large depreflion called
the temporal fojja, the lower end of which termi-
nates near the zygomatic arch : below this arch is

another

SYSTEM OP TI-iE BONES, 2g'

another cavity of lefs breadth, but much deeper,
known by the name of the zygomatic fojf a *.

28. Articulatioi<3" of the head. The
head, in diff^^rent animals, is articulated on the
.vertebral column by one or two condyles.

In birds, it is articulated behind by a tingle
condyle, which allows it to perform fuch extenfive
motion, that thefe animals can turn their beaks
diredly behind them : it is well known that they
often fleep with their heads refting in this manner
between their wings. A part of the oviparous
quadrupeds have only one occipital condyle. Ser-
pents have a condyle with three facets, difpofed in
the form of a trefoil leaf, which admits of few
movements. Moil fifhes have only one condyle>

'* If the face be examined from the top downwards, we ob-
ferve the holes of the eye-brows and the orbital foITse. In the
orbital foffae are found the ocular holes, the fphenoidal and
fpheno-maxillary fiffures, the internal orbital foramina, and the
orifice of the nafal canal. Below and between the orbital foflae
the face prefents the aperture of the nafal foflae. In thefe foffae
are feen the holes ©f the cribriform plate of the os ethmoides, the
apertures of the fphenoidal finuses and of the pofterior ethmoidal
cellules ; the aperture common to the anterior ethmoidal cellules
and the frontal finuses j thofe of the maxillary finuses 5 the
fpheno-palatine foramina; the orifices of the anterior palatine
conduit. On the fides of the nofe, the face exhibits alfo a fofla
called the canine., in which is feen the fub-orbital foramen ; and
below, the face exhibits the dental arches and the orifices of the-,
dtntal canals.

articulated

3d ORGAlSriC STRUCTUE.Ec

articulated by means of cartilages, and which pof-
feOes very little mobility. The ray and fhark
have two condyles, the movements of which- are
very confined. In the lafi: place, the mammalia
are furnifhed with two condyles, more or lefs
moveable.

In man, the head is articulated on the vertebral
column, by means of two tubercles or condyles,
placed on the fides of the large occipital foramen.
Thefe condyles are fitted into two articular cavi-
ties fituated on the interior fides of the arch of the
iirfi: vertebra.

This difpofition of the articular faces permits
the head to perform, with eafe, every motion of
flexion and extenfion, backwards and forwards;
and eafy movements of flexion and rotation on
the fides.

But the movements of rotation performed by
the head are owing, in a great meafure, to thofe
performed in the fame diredion by the firfi ver-
tebra on the fecond ; and the different motions
which the vertebrae perform on each other contri-
bute greatly alfo to thofe of the head.

The articulation of the head is fecured by an
anterhr liganmit ^ a fojier'ior ligammt, and an articit'
lar capjide.

The peculiar articulation of the fecond vertebra
on the lirfi-^ by means of the odontoid apophyfis of
the latter on the anterior arch of the former, is

fecureti

SYSTEM OF THE BONES. 31

fecLired by a tranfuerfe ligament, two lateral Tiga"
merits, an accejjory ligament^ and a capfide.

The middle of the head is not placed exadily
on the vertebral column, and Camper has obferved
that the part which is before the large occipital
foramen is to that behind in the ratio of eisrht to

o

(even ; fo that the head, when not kept back, has a
flight tendency to fall forwards.

In the vertical pofition of the head, man alone
has the mouth and eyes looking diredlly forwards.

We have already feen that the trunk and head
confift of bones, fome of v/hich have always their
fellow, while others are conftantly fingle. The
fingle bones are always fymmetric, that is to fay,
can be divided into two iimilar parts : thefe are
necefTarily placed in the centre. Bones which
have, fellows are always placed one on the right
and the other on the left, and never have a fym*
metric form ; fo that in the ikeleton one fide Jias
a perfed refemblance to the other.

OF

32

OF THE LIMBS.

29* Limbs in animals. The fkeleton of fer-
peots and fifhes confifts of the trunk and the
head only ; but that of oviparous quadrupeds,
birds, and the mammaJia, is provided with four
limbs, which feem always to be formed according
to an uniform plan.

The fins of fifhes, properly fo called, are parts'
which fupply the place of limbs; but they catinot
be confidered as fuch, becaufe their ftru6lure has
nothing in common with that of limbs.

Cetaceous animals, which are not fifhes but
amphibious mammalia, have no fins : their place
is fupplied by limbs, which difcharge the fame
functions.

The limbs of all animals are conftantly fixed,
fome to the breafi: or thorax, and others to the
pel-vis; on which account they are diilinguifhed
into thoracic and pelvian.

Thoracic Limbs,

30. Thoracic limbs of animals. The
thoracic limbs of animals are thefhoulder, the arm,
the fore-arm and the hand j the pelvian are the
haunch, the thigh, the leg, and the foot.

Th^

SYSTEM OP THE BONES. 33

The other limbs vary in the different orders of
animals, with refpet^t to their form, their length,
their covering, and in particular their termination.
This variety determines the ufe for which they are
proper.

31. Shoulder in animals. The fhoiilder
confifts fometimes of one bone called the fcapula
{omopJata), as is the cafe in the mammalia with folid
hoofs. It is often formed of two bones, ih^ fcapula
and the clavicle ; as in the qnadrumana, fome car-
nivorous animals, and the greater part of oviparous
quadrupeds. In birds it confifts of three bones,
viz. the fcapula, the clavicle, and the tbrk.

The fhoulder has always a cavity which receives
the head of the bone of the arm. This cavity,
for the moft part, is contained in the fcapula;
fometimes it is formed both in the fcapula and
clavicle i and in birds the three bones of the fhoul-
der concur towards its formation.

The fcapula is generally a broad, flat bone,
iituated at the dorfal part of the ribs ; but its figure
greatly varies in different animals : in the mole it
is exceedingly long; in the frog and the toad it
confifls of two pieces.

The clavicle, for the moft part, is a long thick
bone, refting on one fide on the top of the fler-
num, and on the other againft the fcapula, which it

VOL. I. D fixes

34 ORGANIC STRUCTUEE.'

fixes and keeps back. All animals provided vvitfe
this bone can extend their thoracic limbs forwards,
with more or lefs facility to perform great motions.

Animals which have no clavicle employ their
thoracic limbs only for walking. Some carnivo-
rous animals, fuch as dogs and cats, &c. have the
clavicular bones fufpended in the flefh, and alto-
gether ufelefs.

The forked bone in birds has the form of the
letter V ; it ferves, together with the clavicle, to
keep the fcapula firm, and to prevent it from ad-
vancing too far forwards: birds v^hich have this
bone exceedingly flrong fly^ in general, with great
rapidity.

The fhouldcr of the tortcife confifts of three
bones, analogous to thofe of birds : thefe bones
coalefce, and form only one offeous piece.

The (houlder, in man, confifts of the fcapula
and the clavicle.

32. The fcapula. The fcapula is a flat, thin,
triangular bone, placed at the lop of the back be-
hind, having one of its angles elongated and di-
rected downwards.

Its external face has, at the upper part, a pro-
jecting apophytis, running acrofs it, which is pro-
longed outwards by a large tuberofity flattened
from the top downwards, and on the fide of which
the clavicle refl;s. This apophyfis is called the

acromion :

SYSTEM OP THE BONES. 35

Acromion: its upper edge is dlftinguifhed by the
name o( fdper-acro??itan, and the lower by that of
fub-acromlan.

The external angle of the fcapula, which is
truncated and fwelled up, prefents a facet, to re-
ceive the head of the bone of the arm : above and
within this facet is a very ftrong apophyiis bent
forwards, and known by the name of the coracoid.

The fcapula is fecured by mufcles.

33. The clavicle is a long, round bone, bent
into the form of an J: it is articulated on one
part into the top and fides of the fternum, and on
the other with the fide of the acromion apophyfis.
The acromian extremity is united to the acro-
mion by an articular capfule, and two Tigammis
(the rhomboid and conoid) which proceed from the
coracoid apophyfis.

The fternal extremity is fixed to the fternum
and the cartilage of the firfl rib, by an articular
capfule, a cojlo- clavicular and a flrong inter-clavi^
cular ligament. This articulation has alfo an
inter-articular ligament.

It is feen by this difpofition that the fhoulder is
articulated with the trunk only by the extremity of
the clavicle, which is united to the fternum ; and
that the fcapnla can perform great movements by
gliding on the thorax.

34. The arm. The arm, in all animals_, con-

n z fills

3d ORGANIC STRUCTUHE*

fifrs of only one bone, called the humerus^ thb
bone varies with relped to its proportion ; it is ex-
ceedingly fliort in cetaceous animals, and verj
long in bats.

35. The HUMES.US. The iiumeras of maa
has at its upper extremity a fmooth hemirphere,
turned inwards and upwards *, by means of which
it is articulated with the fcapula.

Around this hemifphere is a flight depreffion^
which forms its neck ; and on the back part of it
there are two tuh'ei'ofjks, one larger than the other ;
the largeft is dillinguifhed by the name of the im"
chitery and the fmaller by that of the t7-oc]mi-: they
are feparated by a groove. The articular facet of
the fcapula, which is narrow and almoU plane, is
incrufled in a thick cartilage turned up at the
edges, fo as to form a cavity proper for receiving
the hemifpheric facet of the humerus : thefe bones
are maintained in their proper portions by an ar-
ticular eapfule, which embraces the neck of the
humerus, from the ofleous and cartilaginous edge
of the cavity of the fcapula.

The arm can perform on the (houlder very free:
movements, in every dirediioii.

* In defcribing the bones of the thoracic Kmbs of man, it i»
fuppofed, in regard to the refpedlive pofition of the different
parts, that the limbs are extended along the body with the palm
of the hand turned forwards.

The

SYSTEM OF THE BONES. QJ

The humerus becomes broader at the lower
part : it is plane behind, convex before, and turned
a little outwa4-ds : it is terminated on the fides by
two tuberofities : the interior, which is larger and
does not defcend fo low, is called the epitjochlea ;
the other is known by the flame of the eplcmdyJe,
At the extremity of the bone there are two fmooth
round furfaces, flightly hollowed into two grooves,
Separated from each other by a projecting line :
the interior moves around the bone, from the fore-
part backwards, in the form of a pulley, trochlea ;
and is terminated before and behind by a cavity i
the exterior is placed at the lower part before, and
is called the condyle.

36. The pore-arm. The fore-arm in fome
animals, fuch as the bat, confifts of only one bone ;
in ruminating animals it appears to be formed of
two bones which have coalefced : in the greater
part of aflimals, and in man, it confifts of two di-
ftin^l bones, called the cubitus or uhia and the
radius.

37. Cuhitiis. The bone of the elbow, which is
flender and of a triangular fhape, becomes larger
at the upper part, where it has a deep articular
indentation of a femi- circular form, turned for-
wards and inwards, called the Jygmoid cavity. The
humeral extremity of this bone has on the back
part an eminence^ which forms the elbow or ole^

D 3 cranon:

3S ORGANIC STBl'CTURE.

cranon.' before, it has a larger one called the coro-'
noid, and within a fmall articular y^<:^^ called the
{m^WJygmoid cavity : this articulation is fecured by
an miterior ligament, a fojierior ligament, two la-
teral one^, and a capfule.

The bone of the elbow is terminated below by
a fmall plane articular facet, on the interior tide of
which is an apophyfis called Xhejlyloid.

38. The radius. The radius at the upper end
has a fmall articular facet, fomewhat concave, the
fmooth internal edge of which is articulated with
the fmall fygmoid cavity of the cubitus. Below
the head it is much fmaller, fo that this part forms
its neck. This bone becomes broader towards
the lower end, and is terminated by an articular
facet, lengthened in a crofs dire(51:ion, and fome-
what concave. On the exterior fide of this bone
is a Jlyloid apophyfis^ and on the interior a fmall
articular facet, vvhich correfponds with that of the
cuVitus. *

The fore-arm is articulated on the arm by its
two bones, which are articulated alio with each
other above and below.

The fygmoid cavity of the cubitus embraces
the articular facet of the humerus, which is fhaped
like a pulley, and gliding on it caufes the fore-arm
to execute great movements on the arm as if by
a hinge. The olecranon placing itfelf in the ca-
vity which is behind the pulley of the humerus,

limits

SYSTEM OF THE BONES. 3Q

limits the motion of extenfion ; and the coronoid
eminence by refti^ng againfi: the cavity, which is
tefbre this pulley^ fixes the movements of flexion.

The articular facet of the radius reds againfi
the rounded furface on the exterior fide of tlie
pulley of the humerus, and glides on that furface,
accompanying the cubitus in its motions.

In its articulation with the humerus, the radius
can turn on itfelf. This rotary motion takes place
at the top againfi: th^ external edge of the cubitus,
and at the inferior end around that bone.

The bones which form the articulation of the
cubitus are fecured by an articular capfulc, and
two lateral ligaments.

The interfiiice between the two bones of the
fore-arm is filled up by a very flrong interojfeous
ligament. The two bones of the fore-arm are
kept together alfo above by an annular ligament,
and below by a capfule or triangular ligament.

39. The laH part of the thoracic limb has re-
ceived different names*, according to its par-
ticular difpofition; but in all anim.als it confifis of
the ^-^r^z^j-, the metacarpus^ and ihe phalanges.

40. Carpus. The carpus is compofed of
fmall fhort bones of an irregular figure, the num-
ber of which is variable. In birds it is formed of two
bones in a row. The number of the bones of the

* It has been called hand, paw, hoof, paficrn, biftard wing,
fin, &c.

p 4 carpus

40 ORGANIC STRUCTURE.

carpus varies in the mammalia from 5 to 10, which
are always difpofed in two rows.

In oviparous quadrupeds, moft of the batrachians
have the carpus formed of eight bones in three rows.

41. Metacarpus. The metacarpus conlifts
of longifh bones, the number of which varies from
I to 5 ; but in general it is equal to that of the
fingers.

In ruminating animals and the foIij)eda the meta-
carpus confifts of a very long bone, which conlli-
tutes the cannon bone. This bone feems to add to
the Hmbs of thefe animals one part more, which
in them is generally taken for the fore-leg.

The metacarpus of birds is formed of a bone
with two branches united. In cetaceous animals
the bones of the metacarpus are united and flat-
tened.

42. The phalanges. The phalanges are
tliofe longifh bones which form the fingers.
Sometimes they have the appearance only of
imperfe6t rudiments ; the perfect phalanges form
fingers, which remain concealed under the fkin^
or are covered by lax membranes, or are en-
veloped in a .carneous matter, or form externally
Separate and diftincSt fingers.

Animals have nevef more than five fingers,
each of which confifts, at moft, of three phalanges;
and the thumb has never more than two. The
folipeda have only one perfe(£l finger, which is
known by the name of the paftern, coronet or

coffin-

SYSTEM OF THE BONES. 41-

coffin-bone. Ruminating animals have two fin-
gers, fupported by the bone of their metacarpus
which forms the cannon bone. The three-toed
lloth has three fingers. Several animals with
folid hoofs have four fingers, as the fwine, the tapir,
and the hippopotamos. In the laft place, five fin-
gers are obferved in mofl carnivorous animals, in
apes, and in man.

In bats, the extremity of the laft phalanges, which
are very long, terminates in points without claws*:
it is fometimes enveloped in a corneous fubftance,
as in ruminating animals and the folipeda : it ter-
minates mfxed claws in dogs, and retra£lile claws
in cats: in apes and in man it is enveloped by the
fkin, and covered with a fiat nail.

Birds have a large finger with two phalanges,
and a pointed bone which fupplies the place of a
thumb : thefe two fingers, as well as the bone of
the metacarpus which fupports them, ferve for
^?earing feathers f .

The thumb is formed of one or two phalanges;
compared with the other fingers it is generally
ihorter : in carnivorous animals it is of the fame
length, and in the phocae longer : in apes, and
in man, the tliumb is free, and can be oppofed to

* Except the thumb, which remains fhort and nail-like.

-|- The thumb bears the baftard feathers, and the large finger
ai well as the metacarpus bears the primary feathers.

the

42 ORGANIC STRUCTURE.

the other fingers ; this difpolition forms the cha»
radier of the hand.

^ Thefe different conftitutions of the extremity of
the thoracic limb enable animals to employ it
differently ; and their habits^ in this refpedi, are
always the refult of the peculiarities obferved in
the organization of this part.

43. The hand of man. In man the hand is
compofed of the carpus^ the metacarpus, and the
fingers.

44. The Carpus. The carpus of man is form-
ed of eight bones'^, difpofed in two rows : the
two of the firll row towards the thumb are re-
ceived in the articular facet of the bone of the ra-
dius ; the third is united to the bone of the cubi-
tus; and the fourth rolls on the interior fide of
the third. The bones of the fecond row are ar-
ticulated above with thofe of the firf}-, viz. the
two towards the thumb with that which is above ;
the third with the fecond and third ; and the
fourth with the third : all the bones of the carpus
are articulated alfo with each other on the fides.

The bones of the carpus being articulated on

* Each of thefe bones Is uiftinguidied by ^ particular name.
Thofe of the tiirt row counting from the thumb are; ift, os
fcaphoidee ; zd^ os femi lunave ; 3d, os cuneiforme; 4th, os
pififorme. Thofe of the fecond row, taken in the fame direc-
tion, are ; ift, OS trapezium; 2d, os trapezoides j 36, os mag-
num j 4thj OS unciforme.

thofe

SYSTEM OF THE BONES. 43

thofe of the fore-arm, muft follow the movements
which the latter perfonn on each other. Thus
the bone of the radius is articulated above with
the humerus, and can turn on itfelf by gliding on
the fide of the i}'gmoid cavity: below, this bone of
the radius is articulated on the exterior fide of the
fraall head of the os cubitus, around which it
turns- by moving forwards, and the radius crofles
before the bone of the cubitus, in the form of a
laltire, defcribing below an arc, the fize of which.
is determined by the breadth of the bone in that
place.

In this motion of the radius the carpus, which
on the one fide is articulated with it by its firft
two bones, and which on the other is united to
the bone of the cubitus by its third, is carried
forwards and inwards by the radius ; and in this
movement it turns on the extremity of the os
cubitus as on a pivot. It is thus that the move-
ments o^ pronation and fupinaf ion are performed.

The articulation of the three bones of the car-
pus with the two bones o( the fore-arm is enve-
loped by an articular capfule ; this articulation
contains a triangular cartilage, and is fixed by an
anterior ligament, a fojierior 3lU(\. two lateral I^ga^
ments.

The fecond row of bones of the carpus is alfb
fixed to thofe of the fecond by an articular cap-
fule ; and the bones of the carpus are conneded

44 ORGANIC STRUCTURE,

by ligamentous fibres exceeding!}! varied^ wbicb
extend from the one to the other.

45, Metacarpus. The five bones of the me-
tacarpus in inan are long, and fomewhat convex
behind; on the upper extremity they have a facet
for their articulation with the bones of the carpus j
and on the fides there are other fmall facets for
uniting them to each other : their inferior extre-
mity is terminated by a round head^ which is re-
ceived by the phalanges.

The three firft bones of the metacarpus are ar-
ticulated with the three hril of the fecond row of
the carpus ; the laft two are articulated with the
fourth.

The articulation of the bones of the metacar-
pus with the bones of the carpus is fecured by an
articular capfule ; and by ligaments which proceed-
ing from the fecond row of the bones of the carpus
are fixed at the bafe of the bones of the metacarpus:
thefe ligaments are numerous, exceedingly varied,
and placed before, behind, and on the fides.

46. Fingers. The five' fingers of man are each
formed of three phalanges, except the thumb^
which has only two.

The firft phalanges are longer, and at the upper
end have articular facets which receive the heads
of the bones of the metacarpus ; and at the lower
end round procefles which are received by the
facets of the following phalanges (phahng'mes). In

the

SYSTEM OF THE BONES. 4$

the laft place, thofe which terminate the fingers
(hhaJangettes) are very fmall ; they have alfo at
the fuperior end articular facets, which receive the
heads of the phalangines, and are terminated by a
tubercle which fupports the nail.

The metacarpal articulation of the thumb has
always, towards its palmary face, two fmall round
bones called ojfa fefijnoidea. Others are fome-
times found towards the articulations of the other
phalanges. The articulation of each phalanx is
lecured by an articular capfule and lateral liga-
ments.

Independently of the movements which the
hand is fufceptible of performing by following
thofe of the radius, it can alfo bend forward's,
backwards, and towards the tides. The bones of
the carpus, as well as thofe of the metacarpus,
perform on each other only very light and gentle
movements; but the aggregate of thefe move-
ments produces a very ftriking effe61:, and greatly ^
contributes to give the hand pliability and mobi-
lity. The four fingers, being feparated and free,
can perform feparate movements of flexion, in ths
articulation of the phalanges, and lateral move-
ments on the bones of the metacarpus.

The two phalanges of the thumb, and tlie cor-
refponding bone of the metacarpus, form a fepa-
rate finger, v/hich -is articulated diredlly on the

carpus ;

40, ORGANIC STRUCTURE.

carpus ; moves freely in every direclion^ and cnti
be oppofed to the other fingers.

The thumb of man is freer, and proportionally
larger, than that of apes; its metacarpal bones are
alfo lefs concave than thofe ofthefe animals; fo that
man, v»'ith rerpe6l to the bones of the hand, exhi-
bits an arrangement more advantageous than any
other animal. ,

47. The thoracic limbs are inferior in flrength
to the pelvian ; they are alfo fhorter : their great
mobility on the fhoulder and with the fhoulder 1
their eafy flexibility in the articulation of the cu-
bituSj but in particular that variety and pliability
of motion of which the fore-arm and the hand are
fufceptiblcj form one of the great advantages
which man enjoys over oth<^r animals.

Some relation feems to have been remarked
between theincreafe of the thoracic limbs and the
expanfion of the bones of the cranium. It has
been obferved that children, in whom the bones
of the cranium do not afTume their ufual develop-
ment, becaufe the brain is in part wanting face-
phali), have their arms exceedingly long, while
thofe in whom the bones of the cranium, in con-
fequence of water collected in the iniide of itj
afliime a great expanfion, (hydrocc^halij) have the
arms very fhort.

It may be remarked alfo that, of all the jnanima-

SYSTEM OF THE BONES, 47

//i7, man has the largeft head and the fhorteft
limbs. This ilrudure would be very unfavour-
able for walking on all four.

Of the Pelvlan Lirnbs.

48. Pelvian limbs op animal?. All animals
which have thoracic limbs are furnifhed alfo with
pelvian limbs : we muft however except cetaceous
animalsj in which thefe parts are wanting.

The pelvian limbs, in general, have a flruc-
tyre analogous to that of the thoracic limbs : thus
a bone has a cavity proper for receiving the bone
of the thigh, as the fcapula receives the humerus :
the thigh is formed of only one bone, in the fame
manner as the arm ; the leg like the fore- arm
confifts of two bones ; and the foot, in the fame
manner as the hand, is formed of three analo-
gous bones. Nctv^ithilanding this great limila-
rity between the thoracic and the pelvian limbs,
each of their parts exhibits differences {o (Irik-?
ing, that it is hardly poflible to confound them ;
and therefore it is of importance that they fhould
be examined feparately.

49. The hip. The upper part of the pel-
vian limb is formed of a broad bone placed at
the bottom, and on the fide of the vertebral co-
lumn : it is called the coxal bone, and forms the
hip.

The hip bones are direded in- the portion of

a curve

4a ORGANIC STRUCTURE.

a curve towards the belly, and unite at a certam
diilance from the vertebral column.

The excavation formed by the two coxal boneSj
and that part of the vertebral column to which
they are attached, has bee ndiftinguifhed by the
appellation ot pelvis.

The hip bones are generally articulated with-
out motion on the vertebral column : in tortoifeSj
however, they are moveable. In birds the lum-
bar vertebras, the os facrum, and the coxal bones
form only one.

Animals with pouches, fuch as the didelphk^
have before the pelvis (pubis), two articulated and
moveable bones, called tha marjup'ial hones : to
thefe bones are attached particular mufcles, which
fupport a bag or pouch containing the teats.

The coxal bones vary much in their form iii
different animals; which gives to the pelvis various
configurations^ and produces ftriking changes in
the mode in which the thigh is articulated on
thefe bones.

50. The hip in man. The hip bon^ in man,
which is very irregular, forms chiefly the haunch :
it is iDroad behind, and at the top ; but becomes
narrower, excavated, and indented at the bottom
and before.

At an early age this bone confifls of three

parts, which have been diflingulGied by names

accoi'ding to their polition. The broad portion,

5 which

SYSTEM OF THE BO^-ES. 4g

which is behind and on the fides, is called the
ilium ; that part below the firft is named the if-
chium', and that entirely before is \hQ pubis.

The iliac portion of the coxal bone exhibits be-
hind and within a large articular furface, with
which this bone is united to the facriim ; it then
advances by a large plane portion which juts out
at the top and on the fides ; the upper edge of
this bone is broad and rounded ; it defcends be-
hindj and at the end has a large tuberofity : be-
fore, this edge terminates in a right angle, at the
bottom of which is a tuberofity.

The ijchlal portion is below and before the
ilial ; in the middle and on the exterior fide it
has a deep cavity called the cotyloid^ which receives
the head of the thigh-bone ; this cavity, which
turns outwards, downwards and a little forwards, is
not completely formed by this part of the hip
bone: the other two contribute alfo to its forma-
tion. At the bottom of this cavity is a fmall fofi[a,
and on its interior edge a deep indentation.

The ifchial portion has behind two notches fe-
parated by a tubercle ; it is terminated below by
a large tuberofity, on which the human fig-ure
refls when it fits ; in the infide and before it has
a notch, which being united to another belonging
to the pubis forms the /uh-fuhia?i hole, which in
the male is oval, and in the female triangular.

The pubic portion of the hip bone is entirely

VOL. I. E before i

50 ORGANIC. STRUCTURE.

before ; it is terminated by a narrow edge farnidied
with a cartilage, by means of which this bone is
applied to the cartilage of the correfponding part.

This articulation is called the JymphyfiS of the
piVis. Above their junction, thefe portions of
bone have a prominence, aiid below an arch (of
Xht pubis) ^

The fpace circumfcribed by the broad hollaw
part of the ihum conftitutes the large pelvis ; the
other fortned below by the ifehium., the pubis, the
OS faqrum, and the coccyxj and which is nar-
rower, conftitutes the lejfer pelvis: the name of
ufper Jlralt has been given to the fomewhat nar-
row edge which feparates thefe two cavities, and
that of lo%vei:Jk^i4iJjQ_^Q fpace comprehended be-
iweenytfre •uiberblitiesjtj\he ifchium, the arch of
the cfu^is and the coccyx^

'hefe^EHiisl'behk/d haye notches filled up in
part W exceedii3^l3L-ftr0r)wligaments, which ferve
ta fix tnbfeJboft^s th-fe^s facrum, and to the lafl
of the lumbar vertebras : they are called the ileo^
lumbar^ the large awd fniall facro-fciatic\\ga.m&n\^j
and ihefacro-iliac ligaments.

The articular portions of the hip bones, which
form the f}'mphylis of the pubis, are covered be-
fore with a cartilage of greater or Icfs thickncfs;

They are kept together before by a bunch of
ligamentous fibres, and below by a triangular li-
gament.

SYSTEM OF THE BONES. 51

In confequence of the vertical pofition of man,
the pelvian cavity is turned upwards ; and it can
receive and fupport a part of his abdominal vifcera:
this advantageous difpolition cannot take place in
animals, and particularly quadrupeds, the aper-
ture of whofe pelvis is turned dire6lly forwards ;
but the region of the pubis, which in thefe is
very narrow and forwards, is lower, and often
very broad in man, and fupports a part of the
vifcera.

51. The thigh. The thigh always conlifts
of one bone, named the fe?nur ; which, in gene-
ral, has nearly the fame fhape, but varies a great
deal in its proportion. In ruminating animals
and the folipedait is fo fhort, that the limb which
it forms, being in part concealed by the fiefh, is
not commonly taken for the thigh : this bone is
ftill fhorter in the phoc£e.

52. Femur. In man, the thigh, the length of
which determines that of the limb, is nearly
cylindrical : it has, however, behind a rough line
called the femoral, which indicates the place where
the mufcles are attached, and is continued along
two thirds of the bone at the upper part.

This bone has at its fummit an articular head,
which is turned inwaids, and a little upwards^
and which is fupported by a neck: this head has
a fmall depreffion in the middle. The femiK-
direcflly above, is terminated by a large tuberolity,
E 2 - which

52 ORGANIC STRUCTURE*

which projects a little outwards, and which is di-
ftinguiflned by the name o{ trochanter. On its in-
terior fide behind it has a cavity. Behind thefe
parts, but lower down, and a little within, is an-
other fmaller tubcrofity, called the trocbant'in.

The femur is terminated below by two large
articular facets, rounded from the tore part back-
wards in the form of the portion of a wheel, and
called condyles: of thefe condyles the exterior is
fmaller, anil does not defcend fo low as the inte-
rior : they are feparated by a groove, which ter-
minates behind at a dcpreffion called the fojfa
^o^l'itea : from behind the condyles proceed two
lines, which afcend obliquely, and unite at the fe-
moral line : before thefe condyles the rotula is
placed.

The femur is articulated by its Bead with the
cotyloid cavity of the hip bone, and can perform
On it motions in every direclion. Thefe bones
are retained in their pofition by a fi:rong articular
capfule, and an inter-articular {round') ligament.

53. Leg. The leg fometimes is formed of
only one bone, called the tibia, as in ruminating
animals. In others, fuch as the dog, rat, fwine,
and birds, it is compofed of the tibia and another
bone or portion of a bone, which coalefces with it
for a greater or lefs extent. In a great many of
the mammalia the leg is formed of two diftindl
and feparate bones, viz. the tibia, and another

much

SYSTEM OP THE EONES. 5g

much flenderer called the perone or find a : thefe
two bones are articulated below with thofe of the
foot ; above, the tibia only is joined to the bone of
the thigh, and the perone remains united on the
fide of the tibia. In the laft place, in the greater
part of oviparous quadrupeds, the two bones of
the leg are articulated at the top with the bone of
the thigh, and below wirh thofe of the foot.

Before the articulation of the thigh with the leg,
there is generally a fmall 'flat bone called the rotula.

In man, the thigh is formed of the tibia and a
dx^xm& perone, which is articulated above only with
the tibia : the knee is furniOied alfo with a rotula.

54. Tibia. The tibia, throughout almoft its
whole length, afFeds a triangular form : the an-
terior edge (pratibial) is very falient ; it is termi-
nated at the top by a tubercle, to which a ftrong
ligament is attached. This portion of the tibia be-
comes much larger in that part, and is diftin-
guifhed by the name of the head : below this head
is a plane furface, on which there are two articu-
lar faces, flightly excavated, which receive the con-
dyles of the femur, and are feparated from before
backwards by a double elongated tubercle. The
lides of the head of the tibia are difiinguiflied by
the name of condyles. A little behind the head of
the tibia, under the exterior condyle, is a fmall
ftrticujar facet, which receives ihe perone,

E 3 The

54 ORGANIC STRUCTURE.

The tibia is fmaller below, and terminates in b
concave articular furface of greater extent in a
crofs dire6lion, and which refts on a bone of the
foot. On the interior fide of this furface is a
large tuberofity, prolonged below, and which
forms the interior malleolus : its exterior fide,
flightly notched, has an articular facet, which re-
".eives the perone. The poflerior face of the tibia
J difiinguifhed by the name of the pophtean.

^^, Perofte. The perone, which is very flender,,
is fituated at the exterior fide of the tibia, and a
little behind it. At the upper extremity it has a
head, on the fide of which is an articular facet
refling agalnfi that bone. At the lower end the
perone defcends below the tibia: it makes a pro-
je(9ion outwards, which forms the exterior malleo-
lus, and on the infide has an articular facet for its
jun6lion with the tibia, and the bone of the foot
which receives it,

^6. Rohda. The rotula is a fmall flat round
bone, having behind it a double facet, which cor-
refponds before the femur.

The articulation of the knee is fecured by an
articular caffuU and two later al\\^2im^Vi\'&\ before
by a firong ligament, which belongs to the rotula,
and behind by two crofs ligaments: this articula-
tion has alfo two inter-articular cartilages of 2ifemi~
lunar form.

The

SYSTEM OP THE BONES. 55

The perone is fixed to the tibia by an articular
capfule, and an anterior and pofterior ligament.

The fpace left between the two bones of the
leg, which is larger above, is filled by a ligament
attached on the edges of thefe bones.

The leg can perform only very extenfive move-
ments of ilexion backwards.

57. Last part of the pelvian limb.
The lafl: part of the pelvian limb, like that of the
thoracic limb, has received different names ac-
cording to its mode of termination ; but it is
alwavs formed of a tarfus^ a inetatarfus, and toes.

The bones of the tarfus vary very much both
with refpe61: to their form and number. The tar-
fus in birds confifts of only one bone ; in the
three-toed floth it confifts of three; in ruminating
animals, of from five to fix, and very often of feven.
The bones of the tarfus are in general thick and
(hort : in fome animals, however, they are very long.

The bones of the leg are articulated, in general,
with only one bone of the tarfus ; but in reptiles
they reft on two bones of that part *.

The bones of the metatarfus, in animals, have
the fame o-eneral arrangement as thofe of the meta-
carpus ; and the toes, which are articulated to one
or the other of thefe parts, exhibit alfo the fame
mode of termination.

* The tibia refts on the aftragalus, and the perone on the cal-
caneum.

£ 4 The

56 ORGANIC STRUCTURE.

The pelvian limb has only five toes * ; each toe
confifts at moll of four phalanges j-, and the large
toe has only two ;|:, The folipeda have only one toe
on the hind-foot, and one finger to the fore- foot.
Ruminating animals have two on each foot, articu*
lated on their cannon bone. Some animals, fuch
as the tapir and the rhinoceros, have three toes,
and the fwine has four. The greater part have
five. The frog has fix. The toes are often pa-
rallel, as in carnivorous animals: in the quadru-
mana and pedimana the great toe is a thumbs
which can be*Oppofed to the other toes. In birds
which have three toes they are parallel : thofe fiir-
nifbed with four have one or two turned back-
wards, or all the four turned forwards. The
number of the phalanges in thefe animals is in-
creafed by one for each toe, proceeding from the
great toe. The large toe is fhorter than the reft
in the quadrumana and pedimana, all the toes of
which are very long : in fome of the carnivorous
animals it is nearly equal to the refi : in man it is
the largcfl of all the toes,

58. Foot of man. The foot of man is formed
of the tarfus, the metatarfus, and the toes.

Tarfus. The tarfus of man confifis of {QVtn.
bones. That on whiph the two bones of the leg

* The frog has fix.

•f" In the toe before the lafli of the lizard there are five,

J In that of the chameleon there are three.

SYSTEM OP THE BONES, 57

Sfe articulated is called the afiragahis \ it is placed
on another larger bone which forms the heel, and
which is called the calcaneiun z a third, fituated
before the afiragahs, is diftinguilhed by the name
of the fcaphoid bone (cs fcaphouies) ox navicular
bone (os naviculai-e). The other four, placed in
a row, receive the bones of the mctatarfus : the
firft three, counting from the great toe. arc knowa
by the name of the cuneiform bones, and ihe fourth
by that of the cuboid.

59. j4firagalus. The aflragalus has at the top
an articular facet, rounded from before backwards,
in the form of the portion of a pulley ; it is re-
ceived by the articular cavity of the tibia. On
the fides of this facet, the afiragalus receives with-
out, the extremity of the pcrone, which forms
the exterior malleolus, and within the tuberoiity
of the tibia, which produces the interior mal-
leolus. The aftra2;alus has alfo articular facets
for its union below with the calcaneum, and
before with the fcaphoid and even the cuboid
bones.

60. Calcaneum. The calcaneum, which is larger
than the preceding bone, is lengthened from the
fore part backv.'ards ; and has above and before a
deep indentation or notch which receives the af-
tragalus, and diredly before another facet for its
junclion with the cuboid bone. This bone is
lengthened behind by a large tuberofity, which

forius

58 ORGANIC STUUCTURE. -

forms the projedion of the heel, and below it
there are two tubercles.

6i. Scaphoid hone. The fcaphoid bone is arti-
culated behind with the aftragalus ; on the out-
lide with the cuboid bone, and before with the
three cuneiform bones.

62. Cuhoid bone. The cuboid is united behind
to the calcaneum and the afiragalus; in the in-
lide to the fcaphoid bone and the third cuneiform
bone; before it is articulated with the two 1 aft
bones of the metatarfus.

63. Cuneiform hones. The three cuneiform
bones are articulated behind with the fcaphoid
bone ; on the outfide with the cuboid, and before
with the four firft of the metatarfus ; fo that the
firft cuneiform bone touches the two iirfl; bones of
the metatarfus ; the fecond touches only the fe-
cond J the third touches the fecond, the third, and
the fourth. Thefe bones are articulated with each
other on the fides. It is to be obferved that the
three cuneiform bones have really the form of a
wedge ; that their difpofition with the other bones
of the tarfus is fuch, that this part forms a move-
able arch marked by the inftep, and that, in pro-
greffion, all the bones of the tarfus do not reft on
the ground.

64. The articulation of the \tg with the foot is
Secured by a capfule, an interior lateral ligament,
and three exterior lateral ligaments,.

The

SYSTEM OP THE BONES. 5Q

The five bones of the metatarfLis, which are
nearJy of the fame length, have behind articular
facets for their union with the mhoidRnd the three
cuneiform bones; and before fmall heads, which are
received bv the excavated facets of the firft pha-
langes : thefe bones are articulated alfo with each
other on the fides by their pofterior extremity.

The articabtion of the bones of the tarfus with
thofe of the metatarfus, and that of all thefe bones
with each other, is fecured by ligaments analogous
to thofe which fix the bones of the carpus and
metacarpus i except the firft bone of the metatar-
fi.is, which is not feparated like the firft of the me-
tacarpus.

The phalanges of the toes have the fame mode of
articulation and the fame means of junction as thofe
of the fingers, and are equal to them in number.

The five toes are parallel ; and the ' large toe is
longer than the reft, which go on decreafing in
fizc to the laft.

6^. The ftrucfture and arrangement of the bones
of the foot are fuch, that they conftitute an
arch more elevated and more extenfive in the in-
fide than without: the foot refts behind on the ex-
tremity of the calcaneum, which is dire6led a little
outwards; it refts before on the anterior extremity
of the bones of the metatarfus, and on the toes ;
and in the middle of its exterior edge the foot refts

on

go ORGA^^IC STRUCTURE.

on the pofterior head of the laft bone of the meta-
tarfus. It Is to be remarked, that the aftragalus
forms in the infide the fummit of the arch, and
that the leg, fupported by this bone, correfponds
with this arch in the place where the bones by
which it is formed do not touch the ground.

66. Befides the bones already mentioned, there
are always two fmall round bones below the meta-
tarfian articulation of the large toe : there are
fmall bones alfo fometimes at the articulations of
the phalanges : thefe bones are called ihQfefamoid
(ojjli fefamoidea).

67. The bones of the limbs have alfo fome pe-
culiarities common to the bones of the trunk and
the head : thus, for example, they are all covered
with a periofteum ; frequent afperities, which mark
the places where the mufcles adhered, are alfo ob-
ferved in them, and they have holes by which they
are pierced throughout their whole thicknefs. The
long bones have alfo in the infide a cavity, larger
in the middle, which goes on increafing to the ex-
tremities, where it terminates in offeous fibres that?
crofs each other in different dire6lions, and form a
kind of tiet-ivork.

The cavities of the long bones are lined alfo
with an interior periofteum.

68. The flvcleton, examined in general, e^^

6 . hibits

SYSl'F.M OF THE BONES. 6l

hiblts an aflemblage of pieces equally pliable and
ilrong.

The vertebral column confifls of 24 very fliort
bones, light, exceedingly ftrong, articulated in fe-
veral points, and their articular furfaces are covered
with a thick cartilage highly elallic^ and fufcepti-
ble of yielding to every purpofe. All thefe bones
are retained in their portion by ligaments fiiffi-
ciently ftrong and numerous to give that column
the requifite degree of tlrength. The aggregate
of the vertebrae afFedis different curves, which can
be increafed or diminifhed according to circum-
llances.

The head refts on the vertebral column almofl
by its centre ; and the two firfi: vertebrse have a pe-
culiar difpofition, which allows the greateft move-
ments.

The difpofition of the bones of the cranium, in
the form of an arch, is exceedingly well calculated
to (ecu re the brain from the a61ion of all external
bodies ; and the vertebral canal protedls the pro-
longation of the brain which it receives.

The vertebral column fcrves alfo to fupport the
ribs, the aggregate of which, together with the
flernum, forms a conical cavity ftrong and exceed-
ingly flexible, which envelops the heart and the
lungs.

The vertebral column rcfts on the os facrum :
this bone with the two hip bones forms a cavity,

the

52- OUSANIC STRUCTURg*

the different pieces of which, united ftrongly by
cartilages * and ligaments, are however fufceptible,
when neceflary, of very linking movements.

The cotyloid cavity is fituated in an oblique
diredlion on the exterior fide of the hip bones :
the femur is bent forwards j its head and neck have
an oblique dire(5lion, and its interior condyle is
longer : the knee is flightly inclined inwards, and
the thigh is always ready to bend upon the leg :
the tibia is fomewhat curved, and the foot inclined
outwards, and forms an arch.

This general conflru6tion, which every where
exhibits curves, angles, and folding levers, unites
agility to ftrength, and feems to be well adapted
for performing, without any fhock, thofe move-
ments communicated to the trunk by fiamping
the feet againft the ground.

69. When a man walks fail, flamps with his
foot, or falls in an upright pofiure, there is pro-
duced, in this adlion, a quantity of motion which
mufi: neceflanly be employed, and produce an
effect ; and if by habit this efFecl occaiions no dif-
order, the motion muft be diftributed by a peculiar
difpofition to every part, without producing any
fliock.

When the foot indeed flrikes the ground, the

* Thefe cartilages fwell up during the laft months of preg-
nancy; which gives more amplitude to the pelvis, and difpofes the
bones of which it is formed to move with greater facility.

7 motioiv

SYSTEM OF THE BONES. ^ 53

motion produced is communicated to the places
which begin to bear : thus the heel, the anterior
extremity of the bones of the metatarfas, and the
exterior edge of the foot, receive the firfl impref-
lion. The arch formed by the foot on the interior
iide gradually links down ; the inter-articular car-
tilages yield, and the motion then propagated
along the tibia immediately increafes its curva-
ture.

The motion, when it reaches the knee, is not
communicated in a ftraight line to the thigh : it
divides itfelf on the fides, pafles from the condyles
of the tibia to thofe of the femur, and the femilu-
nar cartilages, interpofed between thefe parts, im-
mediately yield : on the other hand, the direc-
tion of the knee inwards and fomewhat forwards
dilpofes it to give way, and it then bends.

The motion being then continued along the
femur immediately increafes its curvature, and
when it reaches its neck forces it to bend. The
bead of the femur does not bear diredlly under
the pelvis, but reds obliquely in the cotyloid ca-
vity; fo that it acls upwards and backwards on
the edge of that cavity, compreffing the articular
cartilages ; and at that moment the pelvis bends
on the thigh as the thigh bent on the leg.

It is to be obfervcd, tltat, in this aiiion of the
parts, the articular capfules, the ligaments and the

mufcles.

64 ORGANIC STRUCTURE;.

mufcleSj which farround the articulations, eafily
give way, and recover their former ftate.

The motion communicated to the bottom of
the cotyloid cavities tends to carry the hip bones
upwards and inwards. To obey this impreiiion,
the curvature of thefe bones decreafes momen-
taneoufly ; they move before in the articulation of
the f}^mphyfis, and behind they glide on the fa-
crum. This bone, fliaped like a wedge, pene-
trates between the hip bones, tends to feparate
them, and oppofes the firft impulfe that tended to
bring them together : in this adtion the inter-arti-
cular cartilages and the ligaments yield more or
lefs.

In the laft place, if any motion remains, it is
communicated obliquely to the vertebral column
by the top of the facrum, and continuing along
that part it increafes its different curvatures; de-
pretles its inter-articular cartilages ; and caufes
the vertebrce to glide on their different furfaces.
The motion, when it reaches the cervical region,
communicates itfelf to the head, which is there
fufpended, and as it were in equilibrium ; and as
it has a tendency to fall forwards it bends on the
neck.

From this arrangement, it may be feen that the
fum of the'motion communicated to the feet mufl
be very great before there can reach the vertebral

column

SYSTEM OF THE BONES. 65

eolamn and the head a quantity capable of pro-
ducing derangement in the parts it contains;
which indeed happens Very rarely,

70. Female Jkeleton. The female Ikeleton is in
general fhorter than the male ; but the trunk is
comparatively lengthened, fo that the half of the
body, which in man correfponds to the pubis, is
above that part in the female. The bones which
compofe the female Ikeleton are flenderer, weaker,
fmoother, rounder and whiter : the eminences,
afperities, cavities, and holes_, are neither fo ftrong
nor fo ftriking.

The female fkeleton, compared to that of the
male, exhibits alfo very apparent local differences.

The vertebral column is comparatively longer,
find the capacity of the breaft fhorter i fo that the
lumbar region is the moll extenfiVe. The greater
elongation of the trunk feems to be connected
with* a greater thicknefs of the bodies of the lum-
bar vertebrae, and particularly of their inter-articu-
lar cartilages.

The alternate curvatures of the vertebral column
feem a little lefs ftriking in the female ; but the
whole trunk affedls a fort of obliquity ; the facral
region is thrown backwards ; the bread is carried
more forwards, and the head requires to be kept
more ere6l. This difpofitlon, which is owing to
the greater capacity of the pelvis, and the more

VOL. I, F forward

66 ORGANIC STRUCTURE.

forward pofition of the cotyloid cavities, is ftili
increafed in the fiat'e of pregnancy, when the
projeclion of the abdomen forces the breafl and.
head to be thrown backwards, in order that the
equihbrium may be preferved.

The tranfverfe apophyfes of the dorfal vertebrae
are thrown more backwards; the pofterior arch
of the ribs is more convex, and the vertebral
grooves are more excavated.

The ribs are flenderer as well as fmoother ;
their convexity behind is much greater, and the
cartilages of the falfe ribs are more elongated.

Of the two pieces which compofe the fternmn,
the fuperior is generally thicker and longer.
The inferior is much fhorter in the female,
but in fuch a proportion that the whole fternum
is fhorter : the point of it is thrown a little
forwards, while in man it is turned direclly down-
wards.

In confeqaence of the peculiar ftruclure of the
dorfal vertebrae, of the ribs and the fternum, the
thorax, in the female, has lefs tranfverfe breadth ;
is lefs flattened before, and is more convex be-
hind ; it is alfo wider below, and more rounded in
its circumference.

The clavicle, in the female, is longer, and al-
moft ftraight, fo that the flTOulders are thrown
more backwards, and project lefs on the fides of
the thorax. To this peculiar difpofition of the

fcapula^

SYSTEM OF THE BONES, Qy)

fcapula, thrown farther back, is afcrlbed the dif- ;'
ficulty which women experience in 'performing i
great movements with the arms, and in projedl-
ing bodies, which they cannot do with the fame '-
force and eafe as men.

The head, in the fctnale, is fmoother and more '
rounded; and the face i'^.fhorter.

The pelvis', in general, is broader and (halloxver
in the female ;- the iliac portions of the hip bones
are thrown more back; the pubis is tranfverfely
broader, arid has lefs height : the pubian arch is
wider, and the fab pubian hole is tri.mgular. The '
aperture of the pelvis is turned more upwards j the
diftance of the tuberofities of the ifchium is great- *
er, and the curvature of the os facrum is more ap-
parent.

The cotyloid cavities are more forward^ lefs
oblique, and of lefs depth.

The neck of the femur has a more horizontal
dire6lion ; the interior condyle of that bone is :
larger, more convex, and dcfcends louver.

It follows from the peculiar conformation of the
pelvis, and that of the femur in women, that the
haunches are broader; that the facral region pro-
jecSts more pofteriorly ; which determines the in-
clination of the trunk, an'd the projection forwards
of the thorax. The cotyloid cavities are at a ,
greater diftance, and the knees are larger, and ap- -
F 2 preach

08 ORGANIC STRUCTURE.

proach each other more j which forces the feet i(3
turn outwards.

This peculiar difpofition determinev'3 the grand
lateral movements of the pelvis^ which women
perform in walking to tranfport alternately the
weight of the body to the two femora, and thus
prcferve the centre of gravity.

Dupuytren has obfervcd, that till the age ol*
puberty the female pelvis diifers very little from
that of the male; that both have the fame trian-
gular form, and the antero-pofterior diameters
nearly equal : but at that period the female pelvis
acquires a rapid expanfion ; it becomes oval ; its
tranfverfe diameter has lefs extent, and it foon
aflumes all its diilinguifhing chara6ters.

The general difpofition of the bread and pelvis,
in the male and female, is fuch, that if two paral-
lel lines be continued upwards and downwards,
from the fides of the thorax, it is obferved in the
male that a part of the fhoulders is cut. by thefe
lines ; while in the female thefe lines interfedl a
part of the bones of the pelvis. The breaft in the
male is in fome meafure fquare ; in the female it
is conical.

71. During the firft: days of conception, the
germ is a gelatino-albuminous fluid, in the mid-
dle of which fibres or filaments gradually appear.

This

SYSTEM OF THE BONES. 'g'^

This ftkte continues till the 20th day, at which
period there is developed in different points of the
embryo a concrete, white, elaftic fubflance, called
cartilage ; and towards the 30th or 40th day the
foetus begins to fexhibit in various parts of the carti-
lages fome fpecks of more confidence, which are the
firft development of the bones. :

It is remarked that orie cartilage only is formed
for the whole of the bones that are to rfem^in
united ; fuch as the cranium, the vertebral co-
lumn, and the pelvis; and that a partidiilar one is
formed for each of the bones which are to remain
fepafate alnd moveable. Thfe part which at that
period forms the cavity of the cranium is a fort of
membrane.

The bones continue to expand during the t?m6
of geftation : the firft points of offification' appear
in the bones of the fhoulder and thofe of the cra-
nium ; they next appear in the ribs, the bones of
the arm and fore-arm; then in the vertebrae and
the pelvis : in the laft place, they are fecn in the
bones of the thigh and leg, in thofe of the meta^
carpus, the metatarfus, the fingers and the toes.

The bones of the carpus, thofe of the tarfus,
the calcaneum excepted, and the rotula, remain
cartilaginous till after birth.

The long bones explmd by three points of ofll-.
fication ; one for the centre, and two for the ex-
tremities : the large flat bones have their point of
F 3 offificatioa

70 .-.-QRCANIC STRUCTURE.

oflification in lh,e cenlre, : This poinf furnifhes
longi.tudinal or radiated; fibres, which advance,
raeel, and crofs each other to form one iblid

piece. _ , ■;; ; ' . ,

,. . At th;^ period of Wrth the fl^eleton of the foetus
jexh.ibits- my rernarkable ■ pece1iaritit;s • the/ whole
of it is fti!!, in a grca,^jn:veafu;r?, cartilaginons.'

.Tlie ver^earal 0011101 n is quite ftraight, and; its
p,ppphyr<?s: fcarcdy;] appear,

- .Thc^brGaff is very fmaii, and the bead is com-
paratively, ycry large,;; ; , ^ .^ ■ '

, ..The bones of the face are not much expanded,
and the,jflice_ itfclf is exceedingly,- fhort.^^ for the
\yapt pf teeth exhibits a facial angle very large.
The finuses of the head, as well as its different pro-
ini]^finces,5,9rp,<carcely marked; while the cavities
of the eyes,, and particularly the auditory canals,
feem at that^period; to have acq-uired their full ex-
panlion.

The thoracic }i,n:ib.s are comparatively very long.
The pelvis is very fma'l, and its axis is almoil: di-
re6i:cd ftraight upwards.

The thighs and the legs are alfo very {lender
and (liort ; fo that in the feet js, at that period^ the
half of the body correlponds nearly to the navel.

' The boneSj which are flexible and flender in in-
fancy, increafe by degrees, and their complete ex-
panfion makes the fkeleton aliume the form vvhich
it is observed to have lo adults. When the body

has

SYSTEM OP THE BONES. " 7I

has attained to its full growth, the bones are firmed
as well as more elaftic, and affume a grayifh co-
lour ; but with age they become dried and more
brittle/ and their colour is a dirty yellow.

72. In old a^^e all the prominences, cavities, af-
perities and holes are more apparent ; the curva-
tures of the bones are greater ; the articulations
are lefs moveable in confequence of the ofTification
of a part of the cartilages, ligaments, tendons,
capfules, &c. by which the articulations are fur-
rounded.

The face becomes fhortened by the lofs of the
teeth; the chin ftands more forward, and the
alveolar edges become fharper.

73. The various parts of the bones exhibit
ftriking differences in regard to their denlity ;
fome are formed of a clofer and more compact
tilTue, and have a white and fmooth appearance ;
others exhibit a cellular, polyedral tiffue, lax, and
as it were fpongy ; they are lighter, and not to
white ; fome of thefe bones exhibit only a ity:s!
fibres, which crofs each other, and form an open
Q>x reticular \A^K\^ \ in a' word, they compo(e fblid*
bodies more or lefs elafiic, which feem to conlifl
of laminae laid above each other.

74. If a bone be placed in an acid, fuch as the
muriatic, diluted with water, it becomes foft, and

F 4 lofes

'^'l OaGANIC STRUCTURE.

Jofes about the half of its weight. Carbonic aci4
gas is difengaged from the liquor, and there is
depoiited at the bottom a fediment, the weight of
which is equal to that lotl: by the bone : this de-
poiit is muriate and phofphate of lime : what re-
mains of the bone exhibits a fibrous, vafcular and
gelatinous charadler.

If a bone be placed in a folution of cauilic al-s
kali (potafh or foda), it lofes half its weight in the
fame manner; it remains folid, but becomes brit-
tle and friable: the refiduum is found to be a
fort of foapj and the earthy part is phofphate and
carbonate of lime.

In the laft place, if a bone be calcined in an operi
fire, it flill lofes half its weight, and what remains
is phofphate and carbonate of lime.

If it be required to afcertain, by a morp accu-
rate analyfis, the quantity of folid matters which
enter into the compoiition of bones, the following
method may be employed : calcine the bones till
they are white, and, having pulverized them, fuh-
je6l them to the adtion of the nitric acid. This
acid will diflblve the lime and the phofphate of
lime : then pour ammonia into the folution, and
the phofphate of lime will be precipitated : fepa-
rate this fait by filtration, and weigh it after it
has been thoroughly dried. The filtrated liquor
ilill contains lime, which muft be precipitated by
«3ommon potaOi : this lime is united tq carbonic
6 acidj

TABLE OF THE BONES WHICH FORM THE SKELETON.

(

1st. OF THE TRUNK,

wAicA comprehends^

2d. or THE HEAD,

ivhicA comprehends.

5d. OF THE LIMBS

1st. THE VERTEBRAL
COLUMN,

formed by

2d. THE THORAX,

foryntd by

1st. THE CRANIUM,

formed by

2d. THE FACE, t

formed by ^

■•{

1st. THE THORACIC,
formed by

2d. THE PELVIAN,

formed by

VOL. I. — To front page 72.

24 VERTEBRA, VIZ. 7 ccrvical (the 1st Atloid, the 2d Axoid), 12 dorsal, 5 lumbar, the sacrum and the
coccyx.

12 RIBS on each side (7 sternal, 5 asternal), the sternum and the 12 dorsal vertebras.

The sphenoid, the frotital, the parietals, the occipital, the temporals, and the ethmoid.

The frontal, the sphenoid, the bones of the nose, the lachrymals, the zygomas, the super-maxillary, the pala-
tine bones, the ethmoid, and its turbinated bones, the maxillary j 32 teeth, 8 of which are incisors, 4 angular,
and 20 molar.

1st. THE SHOULDER

formed by

2d. THE ARM,

composed of

Sd. THE FORE-ARM

composed of

■I

4th. THE HAND,

formed by

1st. THE HAUNCH,

composed of

2d. THE THIGH,

composed of

3d. THE LEG,

formed by

4th. THE FOOT,

formed by

■{

}

}

{

1st. The clavicle ;
2d. The scapula.

The humerus.

1st. The cubitus.
2d. The radius.

1st. THE CARPUS,

composed of

2d. THE METACARPUS,

composed of

Sd. THE FINGERS,

each composed of
The hip-bone.

The Femur.

1st. The Tibia.
2d. The Perone.
3d. The Rotula.

1st. THE TARSUS,

composed of

' 8 bones in two rows, which are counted from th«.
thumb, and which are called :

, X Ti (1st. The scaphoid, 2d. the similunar, 3d.
1st Row. { , ./ , ,

\ i the cuneiform, 4th. the pisiform.

2d Row ^ ^^^' ^^^^ trapezium, 2d. the trapezoid, Sd,
i OS magnum, 4th. the unciform.

5 bones of the metacarpus.

3 phalanges (2 in the thumb), which are counted from
the metacarpus ; and which are called Phalanges,
Phalangines, Phalangettes.

The two hip-bones, with the sacrum and coccyx, form
the pelvis.

1

f 7 bones : the astragulus, the calcaneum, the scaphoid,
i^ the 3 cuneiform bones, and the cuboid,

2d. THE METATARSUS, C

, ^ < 5 bones of the metatarsus.

composed oj i

3d. THE TOES, r 3 phalanges (2 in the great toe), vf\i\ch. ^ve counted

each composed of ■< from the metacarpus, and which are called Pha-

(^ langes, Phalangines, Phalangettes.

[ 74 ]

MUSCULAR SYSTEM.

76. Our organs are moved by means of mufcles.
The greater part of the carneous mafs, the mea-
gre and fibrous portion of the fltfli of animals,
conflitutes the mufcles. They are compofed of
fibres in bundles.

The fibres of the mufcles are fubdivided in an
Indefinite manner. ' Each fibre, and each bundle
of fibreSj is enveloped by a cellular m.embranej
which is a tiffue of veflels. Each mufcle alfo is
furrounded by a cellular membrane of greater
thicknefs.

The mufcles are continued, and generally termi-
nate in a fmooth, white, fhining fubfiance, of a
very compa6l fibrous texture^ round or flat, and
always of lefs fize than the body of the mufcle.
That portion of a mufcle which terminates in a
cord is called a tendon-, and that which fpreads
itfelf into a broad flat furface is diftingulfhed by
the name of aponeurofts. It is generally by thefe
tendinous or aponeurotic parts that the mufcles
are fixed to the bones.

The gelatinous, albuminous, and fat fubfiance,
contained in the cells o{ this fi/fue, produces fullnefs
of the mufcles. •

The cellular tifiue, interpofed between the fibres

of

MUSCULAR SYSTEM. 75

of the miifcles, varies both in regard to its nature
and quantity in different animals, in their diffe-
rent parts, and according to the different circum-
liances of health or difeafe.

In the mammalia the mufclesareof a darker or
lighter red colour; in the gallinaceous they are
paler, and in reptiles and fifhes almoft white.

The mufcular fibres have the property of con-
tradling, of becnming Ihorter, of carrying with
them the moveable points to which they are fixed,
and of producing, in this manner, various move-
ments.

The mufcles of reptiles and of fifhes, which have
white fibres, contrac!:! with much greater force
and velocity than thofe with red fibres of other
animals,

Mufcles are never found but in parts which
perform very flriking movements ; and they are
ftronger and of greater length, according as thefe
ipovements are greater and more energeiic.

The movements performed by our different parts
are always a refult of the form of the bones, of
the peculiar difpofition of their articular furfaces,
of the different points by which the mufcles are
afiixed to thefe bones, and of the dire(Sfion of the
mufcular fibres. Conk-quently a knowledge of
the ratio of the articular furtaces of the bones of
any part, and of the nature of the motions which
it performs, may always lerve to deter anne, in a

general

76 ORGANIC STRUCTURE.

general manner, the fize, form, and dired^ioij-'of"
the mufcles of that part. But as the mufcles do
not alvvaj's prodace their a6iion in a ftraight line;
as they often a6l by points of reflection ; to have a
fufficiently corre«5l idea of them, it is neceffary to
know minutely their pecuhar difpofition in man.

77. In the different animals the pofition of the
mufcles, which are fixed to the vertebral column,
varies according to the motions which are per-
formed by that part. Thus the mufcles are op-
pofite to the fpinal and praefpinal face of the ver-
tebraSj when the vertebral column bends forwards
or is thrown back, as in the mammalia, birds, and
reptiles. In animals which perform only lateral
movements with the fpine, fuch as fiflies, thefe
mufcles are fituated on the fides of the rachis or
fpine. In animals which make the vertebral co-
lumn, or one of its parts, move in all directions,
as is the cafe with the bodies of ferpents, the neck
and tail of many of the mammalia, mufcles are
found on the four faces of that part. In thofe
parts of the vertebral column which perform no
motion, mufcles are wanting : this is the cafe with
the fpinal face of filhes, the dorfal region of birds,
sr.d the praefpinal face of the dorfal and lumbar
vertebrce of moft animals.

78. Muscles in man. In man, the mufcles

MUSCULAR system;, 77

affixed to the vertebral column, in order to make
it move, are placed chiefly on the fpinal face.

79. Mufcles which produce motion in the verte"
hral column. A very thick mufcle, which extends
from the os facrum to the atloid vertebra, runs
along the fpinal face of the rachis. This raufcle
is tingle inferiorly, and is fixed to the polterior
part of the os facrum, and the edges of the os
ileum. When it reaches the lumbar region, it
divides itfelf into three parts : the firft is inferted
in the tranfverfe apophyfes of the lumbar Vertebra?,
at the angle of the ribs, and in the tranfverfe apo-
phyfes of the laft cervical vertebras : the dorso—
TRACHELIAN ov facro-lumhar portion ; the fecond
part adheres to the tranfverfe apophyfes of the
lumbar and dorfal vertebrae, as well as to the in-
ferior edge of the laft eight ribs : the costo-
TRACHELrAN or long dorfal fart ; this portion
comprehends another, which extends from the
tranfverfe apophyfes of the laft five vertebrse oi
the neck to the firil four or five of the back :
accejfory of the long dorfal or great tranfverfe muf
cle of the neck; the third portion is inferted in the
tranfverfe articular and fpinal apophyfes of all the
vertebras : the lumbo-cervical portion of
tranfverfe fpinal *.

* The particular name of axoido-atlo'tdian haf5 been given to
that which proceeds from the tranfverfe apophyfis of the axoid to
'tbc fpinal apophyfis of the atloid. »

This

7S ORGANIC STRUCTURE,

" This mufciC, in contracting, bends the vertebral
column backwards, or keeps it in a ftate of recti-
tude : THE SACK.OSPINIAN*.

So. The fpaces comprehended between the fpi-
nal apophyfes of the vertebrae of the neck are fill-
ed by miifcles which are fixed to thefe apophifes.
They keep the neck ftraight, and draw it back-
wards. Interspinian of the NiiCK, fniall fpi-
nal of the ?ieck.

8 1. In the cervical and Inmbar recrions, the
mufclcs are fixed from one tranfverfe apophylis to
the other. When thofe on one fide a6t by them-
felves, they bend the vertebral column towards
the fame fide ; w4icn they ad fimullaneoufiy they
keep it in a fi:ate ofre6fi[ude. Inter-transver-

SIAN OF THE NECK AND LOINS. '■

82. Amafcle which proceeds before the bodies
of the firfi: three dorfal veftebrse, along the cervi-
cal vertebrae, is inferted in the anterior tubercle of

* In defcrlbing the mufcles we fliall retain the nomenclature
of Chaufller. This methodical nomenclature of the mufcles is
founded on the points to which they are attached. 1 hus the
name of every muCcle is compofed in generdl of two words,
which indicate the'e two piints : the firft indicates the point
which is the mult fixed, and the fecond that which is moft
mpveable ; fo that the name is a fort of concife defcription. We
Ihail adopt alfo, for the names of the muflles, the unitorm ter-
mination in ien^ which Diimeril has given to them. [The
Engliih tranOator has changed thefe terramalionb into ian.'\

the

MUSCULAR SYSTEM. 79

the atlas.; it . bends the neck forwards. Pr^-
DORSO-ATLOiDiAN ; Jofig jimfch of the necTt»

83. To the body of the laft vertebra of the neck
is fixed a thin mufcle which is frequently want-
ing. This mufcle defcends in an oblique direc-
tion on the fide of the lumbar vertebrae, paiTes be-
fore the ilium, and is inferted by a flat tendon in
the ilio-pubic eminence. It tends to bend the
fpineon the pelvis. PuBio-PRiELUMBJAN, ihefmall
pfoas,

84. From above the upper and pofierior edge of
the ilium rifes a mulcle, which is fixed to the
tranfverfe apophyfes of the firfi: four vertebrae of
the loins, and to the lafi: rib. It ferves to bend,
the vertebral column on the pelvis. Ilio-trans-
.VERSIAW, fquare of the loins.

85. Two fmall mufcles extend from the fpine
of the ifchium to the fides of the coccyx : thefe
mufcles tend to carry that fmall bone backwards.
Ischio-coccygian, idem.

86. M'lfdes which give motion to the hreajt.
The breafi: is moved by means of numerous muf-
cles fixed between the ribs, or which extend fi'om
the ribs to the vertebrae ; from the ribs to the Her-
num, and even from the ribs and the fternum to
the bones of the pelvis.

The mufcles which extend from the breafi to
the pelvis form in a great part the fides of the
lower belly.

In

$0 ORGANIC STRUCTUlRf.

In Ibme clafTes of animals the breafl and tovnet
belly form only one cavity, as is the cafe in birds i
Itnt in the greater number, thefe two cavities are fe-
paratedby a broad, thin mufcle called iht diaphragm.

In the different animals^ all thefe mufcles ex-
perience variations analogous to the different con^
figurations of the fkeleton ; they are in a great
meafure wanting in thofe which have no breaft
properly called.

87. hi 7nan, the interval between the ribs Is
filled up by two layers of mufcular fibres, which
adhere to the edges of the ribs, and are dire6led
obliquely in a contrary diredlion. The inter-
COSTiAN, inter'' cojiajy exterior and interior..

88. To the tranfverfe apophyfes of the laft five
Tertebrss of the neck is fixed a mufcle, which is
inferted in the middle pofierior part of the three
firft ribs, by as many digitations. The tra-
CB.'Ei.o-cosT I Ai^jfcalene.

89. Twelve mufcles proceed from the tranf-
verfe apophyfes of the laft vertebra of the neck,
and from the iirft eleven of the back, to the angle
of the ribs. Transverso-costian, elevators of
the rihs.

90. A mufcle extends from the fpinal apophyfes
of the lafl two vertebra? of the neck, and the firft
two of the back, to the angle of the firft five ribs
(the firft excepted). Dorso-costian, fmall in-
dented pofteiior, fuperior. All thefe mufcles tend,
in an elTential manner, to elevate the ribs.

91. To

MUSCULAR SYSTEM.' 81

91. To the fpinal apopbyfes of the laft two ver-
tebras of the back, and the firft three of the loins,
is fixed a mufcle which extends to the lafl four
ribs, and tends to deprefs them. LjUMEo-costian,

fmail indented pojierior inferior.

92, A mufcle of a triangulsr form proceeds
from the interior furface of the fternum, and ex-
tends to the lafl: five fl:ernal ribs : it contributes
alfo to deprefs the ribs. Sterno-costian, /ri-
angidar cf the Jiemum.

g2' The thorax is feparated from the abdo-
men by a large odd mufcle, which forms its dia"
phragm.

This broad, thin mufcle, tendinous in the mid-
dle and flefhy on the edges, is fixed to the lower
part of the fternum, the cartilaginous contour of
the ribs, the tranfverfe apophyfes of the lafl: verte-
bra of the back, the firfl; of the loins ; and to the
lateral parts of the bodies of the firfl: two or tliree
lumbar vertebrae, by two flefhy pillars. This muf-
cle, convex on the fide towards the breaft, is
pierced with three holes : the one on the right af^
fords a paflage to a large vein (vena cava); the other
enters the pillars, and gives paflage to a large artery
{^the ventral aorta)^ to ihe canal of the chy'e and
lymph, and to the azygos vein ; the third receives
the alimentary canal and a nerve (eighth pair). It
retains the name of diaphragm. This mufcle^
becoming flat, by its continued and fucceilive con-

voL. I. G tradions.

82 ORGANIC STRUCTURE,

traftions, increafes the capacity of the thorax, and
thus contributes to infpiration.

The mufcles here defcribed produce the move-'
ments performed by the thorax during refpiratioD.

94.. From the ilium and the pubis proceeds a
large mufcle which rifes in an oblique dircciionj
and is fixed to the lad eight ribs by as many digita-
tions. This mufcle unites and is confounded with
that of the oppofite lide by a very flrong aponeu-
rotic expaniion, which forms longitudinally on the
middle of the abdomen a line called the median.
Thcfe mufcles in contrac^insr tend to lower the

O

breaft, and to diminifli the capacity of the lower
belly. 1 1,10-puEio-cosTiAN, exterior obVique or
large ohhque.

95. Thcfe mufcles cover two others which pro-
ceed alfo from the ridges of the ilium to the carti-
lages of the aflernal ribs j they are fixed behind to
the fpinal apophyfes of the laft two vertebra3 of the
loins, and to the os facrum ; they are united be-
fore by a double aponeurotic expanfion along the
median line^ and have the fame acSlion as the prece-
ding. Ilio-costian, interior oblique QxJniallolUque.

96. Between the aponeurotic leaves of the two
preceding mufcles, there are two mufcular bands
which extend from above the pubis to the -fi-cr-
num ; to its appendix, and to the cartilages of the
laft iternal ribs.

The aponejLirotic leaves which receive thefe
j; mufcles

■■H?

MUSCULAR SYSTEM. 83

rnufcles adhere to them in fome points, and pro-
duce on them three or four tranTverfal tendinous
lines. They bend the bread on the pelvis. Pu-
:bio-st ETi'^iAi^ f Jrraight of thd lozver helly.

97. A mufcle, fixed by a long aponeurotic ex-
panfion to the tranfverfe apophyfes of the iirll
three lumbar vertebras, proceeds, in a crofs direc-
tion, to the median line. It adheres alfo to the
cartilaginous edge of the thorax, the n'dgc of the
OS ileum, the crural arch, and the pubis. Thefe
mufcles comprefs the fides of the abdomen.
LuMBO-AB DOMINI AN, tranfverje of the lower
hlly,

98. From above the pubis rife alfo two fmall
mufcles, which terminate in a point below the na-
vel. PuBio-suB-UMBiLiAN, pyramidal.

99. Mufcles which move the head. The difJDO-
fition of the mufcles, which ferve to move the head,
varies according to the manner in which the head
is articulated with the neck.

Thcfe mufcles, in animals which have the neck
long, fuch as the inofl part of birds, or thofe which
have no thorax, as ferpcnts, are fixed to a point in
the neck : in the mammalia they are fixed to the
neck, the breafl, and the fhoulders.

In quadrupeds, whofe head being often \&vy
large is fufpended before the vertebral column,

G 2 and

84 ORGANIC STRUCTURE.

and has need of being continually fupported, ihefe
mufcles mufl be very ftrong *.

loo. In many the mufcles which move the head
have their fixed points of adhefion in the neck,
the breail^^ and fhoulders : they are fituated before,
behind, and on the fides.

The rhufcles which have a lateral pofition move
the head when they a6l fingly ; when they a6l
limultaneoufly they direct it forwards or back-
wards, or keep it fixed : the latter are the mofl
numerous.

I or. To the fummit of the fternum and a part
of the clavicle are fixed two portions of a mufcle,
which unite, and afcend obliquely outwards -and
backwards, in order to be inferted by a broad flat
tendon at the bafe of the mafi:oid apophyfis. The
aflion of one of thefe mufcles makes the head turn
on one fide : when they a6l together they bend it
forwards. Sterno-mastoidtan, idem.

102. A mufcle is fixed before to the tubercles
of the tranfverfe apophyfes of the lafl; five verte-
brae of the neck, by the fame number of fmall
bands, which unite in afcending. This mufcle is
joined to its fellow before the firfl vertebra, and

** The head of thefe animals js retained chiefly by a verj
broad and thick ligament^ which is attached to the Ipinal apo-
phyfes of the back and neck, and is fixed to the occiput \ it is
known by the name of the cervical ligament.

both

MUSCULAR SYSTEM. 83

both are inferted before the large occipital fora-
men. They raife the head when inclined back-
wards, and bend it forwards. The large tra-
CHELO-suB-occiPiTiAN, anterior large Jiraight ,

103. Behind this miifcle is another very fmall
one, fixed before and to the tide of the atloid,
which afcends within and is inferted before the
large occipital foramen. It has the fame a6lion
as the preceding. Small trachelo-sub-occi-
PiTiAN, anterior fmall Jtra'ight,

104. Another fmall mufcle, fixed before the
tranfverfe apophyfes of the atloid, is inferted near
the maftoid apophylis. It a<5ls like the preceding.
Atloido-mastoidian, lateral fmall Jlraight.

105. A mufcle is fixed behind along the fpinal
apophyfes of the firft five vertebrae of the back, the
lafl vertebra of the neck, and to the cervical liga-
ment ; it then rifes, becomes broader, and is in-
ferted in the tranfverle apophyfes of the laft two
vertebrae of the neck {cervical fortiori), and the
mafloid apophyfes {majloidian portion) ; it carries
the head backwards. Cervico-mastoidian,

fjjlenius of the head.

1 06. To the firft four vertebrae of the back and
thofe of the neck, the firft excepted, are fixed the
fame number of fmall tendinous bands, which
unite in afcending. This mulcle proceeds back-
wards, and is inferted by a flat tendon towards the
middle of the occipital arch clofe to its neighbour,

G 3 from

S6 ORGANIC STRUCTURE.

from which it is feparated only by the cervical li-
gament. It keeps up the head, and pulls it back-
wards. Trachelo-occipitian, large complexus
and d'lgajlric of the neck.

107. To the tranfverfe apophyfes of the firfl
vertebra of the back, and the laft four of the neck,
are fixed the fame number of fmall tendinous and
flefhy bands, which unite in afcending. The muf-
cle which they form is inferred by aflat tendon be-
hind the maftoid apophyfis. It has the fame adlion
as the preceding. TRACHELo-MASTOiDiAN,y»?(2//
complexus or lateral majlo'idian,

108. To the tranfverfe apophylis of the firft
vertebra of the neck, is fixed behind, by a thick
tendon, a mufcle which becomes much broader,
afcends obliquely behind and on the fide, and is
inferted in the lower part of the occipital arch near
the mafioid apophyfis. Thefe mufcles elevate
the head. Atloido-sub-mastoidian, y/z^mor
oblique or fmall ohliqiie.

109. A mufcle, which grows broader as it rifes,
and is inferted on the fides of the occipital arch,
below the preceding mufcle, is fixed to the fpinal
apophyfis of the fecond vertebra of the neck : it
elevates the head. Axoido-cccipitian, ^o/^mor
large fir aight.

no. In the fpace comprehended between the
preceding mufcles is a fmaller one, which proceeds
from the pofterior tubercle of the atloid, expands

as

MUSCULAR SYSTEM. 87

as it rlfes, and is inferted on the fides of the occi-
pital arch, behind the preceding : it has the fame
a6lion. Atloido-occipitian, pojierior fmall
Jlraight.

III. There are fome mufcles alfo which pro-
ceed from the head to the fcapula ;. but^ as they
a^ more powerfully on the fhoulder, we (hall in-
troduce them in another place.

All the mufcles here defcribed fcarcely ever atfl;
iinglj, but always in concurrence with a greater
or lefs number of others ; and it is the indefinitely
varied combination which may take place between
all thefe portions of force, that gives rife to the
pliability and variety of motion of which the parts
of our bodies are fufccptible.

IIS. Mufcles which move the face. In all ani-
mals the face is overfpread with mufcles which fur-
round the eyes, the nofe, and the mouth; and
thefe mufcles, covered by a flefhy panicle, have
no other a6^ion than that of enlarging, contract-
ing, or flmtting the apertures of thefe different
organs.

But in man, thefe mufcles compofe a niovcablc
phyfiognomy, the features of which become the
living expreffion of the various fenfations he ex-
periences.

113. The head of man is covered in the middle
by a thin aponeuiotie mufcle, which is fixed alone;

04. the

gS ' ORGANIC STRUCTURE,

the occipital arch, and, proceeding towards the
forehead, extends to the eye brows and the con-
vexity of the nofe. This mufcle corrugates the
Ikin of the forehead, and elevates the eye brows,
OcciPiro-FRONTiAN, e^lcranius and fyramidal
of the nofe.

114. Two fmall mufcles, inferted in the nafal
projedions of the os frontis, lofe themfelves in the
fubftance of the eye-brow. They elevate and
corrugate the eye-brows, Froistto-supercilian^

fu^erciliar.

115. A fmall mufcle ilTues from the bottom of
the arch of thp orbit, and expands over the upper
edge of the tarfal cartilage of the upper eye-lid.
Itraifes it when Ihut. ORiUTo-pALPEBRALiANa
^levator of the upper eye-lid.

116. The eyes are furrounded by a mufcle, the
femi- elliptical fibres of which feem to itfue from
the interior angle of the orbits where they adhere,
in order to proceed to the exterior angle : by
contra6ting they fhut the eye-lids. Palpebra-
iiAN, orhicular of the eye-lids,

117. A fmall mufcle, fixed to the maxillary
bone, proceeds in a tranfverfe diredlion on the
carti!ao;e of the nofe : it ferves to dilate the nof-
trils. SuPER-MAXiLi.o-NASiANj tranfverfe of the
nofe.

I J 8. Below the alveoli of the upper incifive
teeth is a fmall mufcle, fixed to the alae of the

nofe.

MUSCULAR SYSTEM, Sg

nofe, which it tends to deprefs. Alveolo-na-
siAN, myrtiform,

lip. From the zygomatic arch arife two muf.
cles, which defcend obliquely towards the angle
of the lips : by contracting they carry the lips up-
fvards and backwards.

The frnaller of thefe two mufcles is placed abo^e
the other. Zygomatic-labian^ greater and
LESS, great 2iX\dfmaJl zygomatic.

1 20 Three fmall mufcles are fixed to different
points of the fub-maxillary bone : the largejl
arifes on that bone towards the interior angle of
the eyes J proceeds to the upper lip, and leaves
Ibme fibres on the fides of the nofe : the middle
one is inferted on that bone, below the orbitar
cavity, and expands equally over the upper lip ?
the lejfer is fixed above the alveolar edge near the
angular tooth, and proceeds to the angle of the
lips. I hefe mufcles ferve to elevate different
points of the upper lip, and even the noflrils,
Super MAXiLLO-LABiAN, gheater, mean, and
LESS ; I ft, Elevator of the ala naft and of the upper
Up ; 2d, Incifive or proper elevator of the upper
lip , 3d, Canine^ or elevator of the angle of the lips.

121. From the part of the maxillary bone which
correfponds to the chin, arifcs an odd mufcle of a
fquare form, which proceeds through the fub»
ftance of the lower lip. It depreffes that part..
MEKT0-LA3iAN,y^z/^r^ of the chin*

122. At

00 ORGANIC STRUCTLTRS,

122. At the bottom of the lower jaw, and on
the fides, arifes a mufcle, which expands as it
afcends, and proceeds to the angle of the Hps. It
depreffes that part. Maxillo- labian, triatigular,
or deprejfor of the angle of the lips.

123. At each fide of the mouth Is a thick
mufcle, which is fixed at the top and bottom to
the alveolar fides of the two jaws, and behind to
the inter-maxillary ligament : all the fibres of
this ;nufcle take a crofs direction, and expand
towards the angle of the lips : by contra6t:ing,
thefe mufcles fwell out the cheeks. They were
called buccinators^ becaufe they are thofe princi-
pally put in aclion when a trumpet is founded.

BUCCO-LABIAN.

124. Around the lips is an odd mufcle, the
femi-oval fibres of which crofs each other towards
the angles 1 they concur to form the thicknefs of
the lips : by contra6ling they leflen the aperture
of the mouth. Labian, orbicular of the lips ^ or

fniall incifive of the upper and lower lip.

125. All thefe mufcles of the face are covered,
and their int-ervals are filled up with a greafy
tifiiie, exceedingly fine, and of a nature altogether
peculiar : the fibres of thefe mufcles crofs each
other in many points; and this difpofition increafes
the relation of thefe parts, and gives them a great
degree of mobility.

126. A broad thick mufcle occupies the whole

temporal

MUSCULAR SYSTEM". gl

temporal fofTa and a part of the zygomatic. This
mufcle, which is covered within by a ftrong apo-
neurofis, is formed interiorly of two layers of
fibres which unite below in a thick tendon: this
tendon embraces the coronoid apophyfis of the
maxillary bone, below the zygomatic arch. This
mufcle tends ftrongly to elevate the lower jaw.
Temporo-maxillian, crotaphite or tenipo7-al»

127. At the bottom, and on the fides of the
cheek, is a thick mufcle, which is fixed below
the zygomatic arch, to the os zygoma, and to
that part of the fuper-maxillary bone united to it.
This mufcle defcends along the branch of the
maxillary bone, and is inferted in the exterior and
inferior fide of the angle of the jaw. It has the
famea61ion as the preceding. Zygomato-maxil-
LiAN, majfeter.

128. In the cavity of the pterygoid apophyfis
of the fphenoid is fixed a mufcle which defcends
outwardly, becomes thick, and is inferted in tlie
interior fide of the angle of the maxillary bone.
It elevates the jaw, and tends to draw it back-
wards. Great ptef.ygo-maxillian, great or
mterior pterygoidian,

1 29. The pterygoid apophyfis receives alfo on its
exterior fide a fmall mufcle, which proceeds hori-
zontally before the condyle of the maxillary bone,
to which it is fixed as well as to the articular cap-
fule. This mufcle tends to draw the condyle of

the

gl ORGANIC STRUCTUSE.

the jaw forwards. Small pterygo-maxillian^
/mall or exterior pterygoidian.

130. A mufcle extends from the maftoid apo-
phyfis to the middle of the interior face of the
jaw ; it defcends by a flefhy portion towards the
angle of that bone, where it prefents a tendon^
which continues with another flefhy portion in-
ferted in the genian apophyfes.

This digaliric mufcle tends to deprefs the jaw.
Mastoido-genian, digaflric.

131. Beneath the fkin, between the breaft and
the chin, is a thin mufcle which originates below
by a few fibres under the clavicle, and the acro-
mion : thefe fibres approach each other, and rife
nearly to the chin, where they crofs the fibres of
the oppofite mufcle : the action of this mufcle is
not fenfible.

This mufcle is much ftronger and more ex-
tended in animals ; it fpreads itfelf over the face,
Stod forms the carneous panicle, which, as already
faid, covers the mufcles of that part. It ftrongly
corrugates the fldn of the neck, Thoraco-
FAciAN, cut emeus.

132. Muscles OF THE limbs. The limbs of
animals have different ufes, and perform various
motions ; the rcfult not only of the configuration
of the bones which form them, but of the peculiar
difpofition alfo of the mufcles fixed to them.

ThuSj in apes, it is not the peculiar fl:ru6lure

MUSCULAR SYSTEM, gS

of their bones that prevents them from Handing
perfectly erd6l, with the leg extended^ and the
fole of the foot entirely refting on the ground,
but the peculiar difpoiition of the mufcles, which
keep the .thighs half bent on the pelvis, and the
heel raifed up. The cafe is the fame with other
animals ; they all perform movements, which are
the refult of the peculiar flrudture of the bones
and mufcles of which their limbs are formed.

The thoracic limbs of birds, covered with fea-
thers, form win'gs proper for flying; their pelvian
limbs ferve them for walking; and in fome they are
furnifhed with membranes, and anfwer the purpofe
of fins. ^ .

Thofe of oviparous quadrupeds ferve for pro-
greffion.

Thofe of amphibious and cetaceous animals,
being fhort and flat, are fitted for natation. Thofe
of bats, covered with broad membranes, perform
the fame office as wings. In the greater part of
quadrupeds, however, they ferve only for walk-
ing. In the quadrumana, the thoracic limbs ferve
for walking and grafping.

In fome genera of animals the limbs have alfo
peculiar ufes: by carnivorous animals they are em-
ployed for catching and tearing their prey ; by
others they are employed for climbing trees, dig-
ging in the earth, &c.

In man the thoracic limbs ferve for apprchen-
8 lion.

g4 ORGANIC STRUCTURJS,

lion, and the pelvian for walking ere6l : he is the
only animal who does fo.

l^horacic Llmhs.

133. Mufcles which move the fooulder on the
Ireajt. In man, the mufcles which give mvOtion to
the fhoulder are fix on each fide.

A mufcle of a trapezoidal form proceeds on the
one hand along the fpinal apophyfes of the verte-
brae of the back, from the feventh of the neck to
the cervical ligament, and as far as the occiput ;
and on the other extends along the upper edge of
the fpine of the fcapula, and is fixed to its acro-
mion apophyfis, and the humeral extremity of
the clavicle. The fuperior part of this mufcle,
the fibres of which defcend obliquely before,
elevates the fhoulder ; the middle portion, which
has tranfverfb fibres, draws it backwards; the lower
part, the fibres of which afcend by proceeding
forwards, tend ta lower the fhoulder. The total
adion of this mufcle is to pull the fhoulder back-
wards ; and when it remains fixed it moves the
head in the fame direction, by being conne61ed
with the occiput. This mufcle is united to its fel-
low along the vertebrae, and both together repre-
fent a fort of lozenge. Dorso-super-acromian^
trapezius, -

134. Below this mutcle is a fmaller one, nearly
of a rhomboidal form, which defcends obliquely

from

MUSCULAK. SYSTEM. 05

from the fpinal apopbyfes of the lafl; two or three
cervical vertebrae, and the iirfl: three or four ef the
lumbar, and proceeds along the pofterior edge of
the fcapula below the fpine of that bone.

This mufcle elevates the bafc of the fcapula by
drawing it backwards; and thus lowers the ante-
rior angle of the flioulder. Dorso-scapulian, v
rhomboid.

135. Higher up than the preceding mufcle is
another, which is inferted in the tranfverfe apo-
phyfes of the firft four vertebrse of the neck, and
defcends obliquely towards the pofterior angle of
the fcapula to which it is fixed, as well as to the
portion of the pofterior Q,dgQ which is above the
fpine of that bone. This mufcle raifes the fhoulder,
as the preceding one does, by caufing it to make a
kind of movement like that of a lever, which de-
prefles the humeral angle. Traghelo-scapu-
LiAN, angular.

136. To the anterior part of the four ribs
which follow the firft, are fixed, near to their
cartilages, the fame number of mufcular digita-
tions, which afcend obliquely behind, and unite
in a flat tendon inferted in the coracoid apophyfis*

This mufcle carries the fhoulder forwards, by
depreffing its humeral angle. Costo-coracoi-
DiAN, anterior ferrate J ox fmall 'perioral.

137. Above and between the firft eight or nine
ribs is fixed, by the fame number of digitations, a

large

g§ ORGANIC STRUCTURE*

large mufcle, which becomes narrower, proceeds
backwards, palling under the feapula, and is in-
ferted in the poftcrior edge of that bond.

All the portions of this mufcle tend to draw the
fhoulder ftrongly forwards, at the fame time that
its upper part raifes and its lower deprefies it,
CosTo-sc AP uLi AN, largcjer rated.

138. A fmall mufcle extends obliquely from
the anterior edge of the firft rib to the middle of
the clavicle ; lituated between thefe two bones, it
appears that it ought to fix the claviclco Costo-
c LAV I AN, Jub-clav'iar.

139. A {imple indication of thefe different
mufcular forces, and of the combinations which
can be formed of them, ferves to acQOunt for the
variety of motions of which the (houlderis fufcep-
tible. It is to be remarked that the fFioulder has
this peculiarity, that the bone of which it is ef-
fentially formed is in a manner free, and fuf-
pended amidft mufcles which fuftain it, and give
it motion ; and that it is on this bone that the arm
is articulated. In the different actions of the
mufcles of the fhoulder we mull always keep in
mind that the fcapula is confined by the clavicle^
which regulates its progrefs, and often occalions
very compound motions on the principle of the

^ lever.

140. Mufcles which 7nove the arm on the JhouU

der»

MUSCULAR SYSTEM. gj

df.r. The mufcles which move the arm on the
fhoulder are fixed to the bones of the fhoulder^
and of the breaft ; to thofe of the vertebral co-
lumn, and even to thofe of the pelvis.

141. To the fternal portion of the clavicle, the
llernum, the firfl feven or eight ribs and their car-
tilages, is fixed a broad mufcle, the digitated por-
tions of which extend in a tranfverfe diredlioa
over the bread.

This mufcle, while it proceeds towards the
arm, becomes narrower; the inferior fibres ar«
folded back behind, and at the top on the fupe-
rior ones, and terminate in a broad, flat tendon
which is inferted on the fuperior quarter of the
humerus, along the exterior edge ; and groove of
that bone. This mufcle, which forms the ante-
rior edge of the cavity of the arm-pit, fervcs to
pull the arm f^rongly forwards, and towards the
fides of the breaft, by making it turn on itfelf
from without inwards. Sterno-humerian,^;-^^/
peroral,

J 42. Above the fhoulder is a thick mufcle,
fixed before the humeral extremity of the clavicle,
to the acromion, and along a part of the lower
border of the ridge of the fcapulum. The fibres
of this mufcle pafs above the articulation of the
arm with the Qiouldcr ; the anterior and pofterior
fibres are folded back under the middle fibres,
and they all terminate in a tendon which is

YOL. I. H inferted

QQ ORGANIC STRUCTURE.

inferted in the rough line at the bottom of the
groove of the humerus. This mufcle elevates
ftrongly the arm. Sub-acromio-humerian,
dellold.

143. From the coracoid apophyfis arifes a fmall
mufcle, which is fixed- within the humerus to-
wards its middle part. It tends to pull the arm
forwards, by brino'ins; it near to the trunk.. Co-
:. A G o H u M E R ! A N , CO f a CO -bra ch'iaU

144. The face of the fcapula, which is above
its ridge, ferves to lodge a mufcle, the carneous
fibres of which terminate anteriorly in a tendon,
which pafies above the jun61ion of the acromion
with the clavicle, and defccnds to fix itfelf to the
trochiter. This mufcle, fituated below the fub-
acromio-huinerian , concurs towards the fame aClion.
Superior super-scapulo-trochiterian, fu-
per-Jp'inal,

145. Another very broad mufcle, fixed to the
ridge of the hip bone and the os lacrum, afcends
along the fpinal apophyfes of the lumbar vertebrae
and the laft feven of the back: it extends over the
laft four ribs by as many digitations. AH the
fibres of this mufcle approach each other, and
proceed towards the arm, where tbey terminate
in a flat tendon, which is turned round on itfelf,
and inferted at the bottom of the trochin, on the
interior edge of the groove. This mufcle enve-
lops the trunk behind: it forms at the top the

poflerior

MUSCULAR SYSTEM. gQ

pofterior edge of the cavity of the arm -pit t by
contra6ling it tends to pull the arm downwards
and backwards, making it turn inwardly on its
axis. LuMBD-HUMERiAN, greaf dorjal or very
large of the hack.

146. To the inferior angle of the fcapula is fixed
a mufcle, which afcends obliquely before, and
terminates in a flat tendon : this tendon pafles
behind that of the preceding mufcle, around which
it turns, and is inferted on the interior edge of the
humerus below its head. The action of this
mufcle is analogous to that of the preceding.
ScApuLO-HuMERiATsr, large round.

147. To the face of the fcapula, fituated below
its ridge, is fixed another mufcle, the fibres of
which terminate before and at the top in a tendon
that pafl^s over the exterior fide of the head of
the humerus, and proceeds to infert itfelf in the
trochiter. This mufcle tends to make the head of
the bone turn outwards. Inferior super-sca-
PULO-TROCHiTERiAN, fiihfp'mal, an d fmaJl round,

148. The interior or coftal face of the fcapula
receives, in its whole extent, a thick mufole,
which produces before a large tendon that pafles
over the interior fide of the head of the humerus,
and is fixed to the trochin. This mufcle tends to
make the head of the humerus turn inwards.
SuB-scAPULO-TROCHiNiAisr, fub-fca^ular,

149. Mufcles '■juhl.ch move the fore-ar??i on the

H 2 arrtu

100 ORGANIC STRUCTURE.

arm. The fore-arm is moved on the arm back-
wards and forwards : two irtufcles bend it, and
one extends it.

150. One of the bending mufcles is compofed
of two carneous portions united below. At the
top, the interior portion of this mufcle is fixed by
a tendon to the coracoid apopbyfis ; it then de-
fcends to about the lower third of the humerus*
The exterior portion exhibits a larger tendon,
which furrounds^ at the top and within, the edge
of the glenoidal cavity of the fcapula : it pafles
above the head of the humerus in the infide of
the articulation^ and, after contra6ling itfelf^ iiTues
from it to lodge in the groove of that bone, along
which it defcends. Thefe two portions unite into
one mufcle, which foon becomes narrower, and
gives birth to a round tendon : this tendon pafles
before the articulation, and is infer ted in a tuber-
cle, which is below the neck, and at the interior
part of the radius. This mufcle bends the fore-
arm on the arm, and by making the radius turn
inwards and outwards it contributes to the motion
oi fuphiations Scapulo-radian, biceps.

151. Before the bone of the arm, at its middle
and exterior part, is another thick mufcle which
defcends towards the bending of the arm, paffing
below the preceding mufcle : it terminates below
in a tendon, which is inferted in the coronoid
apophyfis of the cubitus: it bends the fore-arm on
the arm. Humero-cubitian^ interior hracUal,
7 ' Thefe

MUSCULAR SYSTEM. 10!

Thefe two flexor muicles are covered with a
very thin aponeurotic membrane.

152. Behind the humerus is a broad,, thick
mufcle, which adheres at the top by three feparate
portions : one exterior and fomev'/hat anterior is
fixed below the trochiter : the middle one, which
is larger, is fixed by a flat tendon to the anterior
edge of the fcapula, below its glenoidal cavity :
the interior and pofterior, which is fliorter, is in-
ferted behind, below the head of the humerus.
Thefe three portions unite towards the middle of
that bone, embrace it, and adhere to it nearly as
far as the articulation, where this mufcle changes
into a tendon, which pafl^s behind the articulation,
and is fixed to the olecranon. This mufcle alone
extends the fore-arm on the arm. Scapulo-ole-
CRANiAN, brachial triceps.

153. On the exterior flde of the olecranon is a
very fmall mufcle, which is fixed to the epicon- '
dyle, and proceeds obliquely over the exterior fide
of the OS cubitus, in a fmall part of its extents
The a(ftion of this mufcle is very weak. Epicon-
DYLO-cuBiTiAN, fmall uncomus,

154. Mufcles which make the radius turn on ihs-
OS cubitus. Four mufcles make the radius turn on
the OS cubitus ; two of them by pulling it in-
wards, and two by drawing it outwards.

155. Before, and at the bottom of the epi-

H 3 trochlea.

102 ORGANIC STRUCTURE,

trochlea, is fixed a mufcle, which defcends ob-
liquely without, to infert itfelf before in the mid-
dle of the radius. Epitrochleo-radian, round
pronator,

156. Before the two bones of the fore-arm and
below, is placed, in a deep fituation, a thin broad
and carneous mufcle, which extends tranfverfely
from the interior edge of the cubitus to the exte-
rior edge of the radius. Cubito-radian, fquar&
j)ronator,

Thefe two mufcles make the radius bone turn
before the cubitus, and thus produce the motion
of 'pronation,

157. The bottom of the epicondyle gives birth
to a mufcle which adheres alfo td the neighbour-
ing articular ligaments : it proceeds outwards and
inwards, around the head and neck of the radius,
which it embraces, and defcends to infert itfelf
along the interior edge of the fuperior quarter of
that bone : it draws the radius outwards, Epi-
CONDYLO-RADiAN, Jhort fuphiator.

158. To the exterior and inferior edge of the
humerus, and before its epicondyle, is fixed a
flender mufcle, which defcends along the con-
vexity of the radius, and is- iinferted on the
outfide, in the inferior extremity of that bone.
This mufcle, which evidently tends to pull the
radius outwards when it is before the os cubitus,
C^n alfo drciw it inwards when thefe two bones

are

MUSCULAR SYSTEM. ' 103

are parallel. HumerO'Super-radian, longfupi-
nator.

Thefe two mufcles pull the radius outwards
when it has been drawn before the cubitus : they
thus produce the motion o^ fupination.

The movements of pronation and fupinatlori
are produced, in an eflential manner, by the a61ion
of the radius ; but the os cubitus, and even the
humerus, yield to thefe motions in a fenfible
manner.

159. Mufcles which . move the wr'i/i on the fore-
arm. Four mufcles move the wrift on the fore-
arm ; two by bending, and two by extending it.
On the interior fide of the fore-arm is a long
llender mufcle, which is fixed at the top to the
humerus behind the epi trochlea, clofe to the ole-
cranon : it defcends along the os cubitus, and
terminates below in a tendon inferted before the
laft bone of the firft row of the carpus (ffiformej,
Epitrochlo-carpian, interior cubital.

160. Before the epitrochlea is fixed another
mufcle, which defcends obliquely on the fore-part
of the arm; rejoins the radius, and accompanies
that bone two thirds towards its lower part. This
mufcle is terminated by a long tendon, which
glides in the groove of the firfb bone of the carpus.
(unciforme), and is inferted in the .fecond bone
of the metacarpus. Epitrochlometacarpian,
interior radial,

H 4 The

104 ORGANIC STRUCTURE.

The action of thcfc two mufcles tends, in an
efTential manner, to bend the wrill on the fore-
arm.

i6i. On the exterior fide of the arm is a thick
mufcle, which proceeds above from the epicon-
dyle ; defcends a little inwards, and is fixed along
the exterior edge of the cubitus, to which it
itrongly adheres. This mufcle terminates in a
tendon which pafi^es inferiorly behind the cubitus,
and is inferted on the exterior fide of the fuperior
extremity of the laft bone of the metacarpus.
The action of this mufcle tends to pull the wrift
backwards, by inclining it on the cubitus. Cu-
BiTO-supER-METACARPiAN, exteHor cubital.

162. On the exterior fide of the arm there are
alfo two mufcles, fixed fuperiorly to the ei)icon-
dyle, which defcend together along the exterior
edge of the radius, and become tendinous to-
wards the middle of that bone. Thefe two ten-
dons proceed together towards the lower part of
the radius, and in that place feparate : one of them
is inferted without on the fummit of the fecond
bone of the metacarpus, and the other on the
fummit of the third. This double mufcle ex-
tends the wrift backwards, by inclining it on
the radius. Epicondylo-super-metacarpian,
j^r^ andjecond exterior radial.

When thefe three mufcles a6l together they
extend the wrift dire(?Hy backwards.

S63. Of the four mufcles here dcfcribcd (the

laft

MUSCULAR SYSTEM. 105

laft two being confidered as one), it is feen that
the two fituated before have a tendency to bend
the wrift on the fore-arnij and that the two fitu-
ated behind have a tendency to pull it back : but
when the one before, and that behind, fituated on
the exterior edge, adl together, they bend the
wrift towards that fide : the cafe is the fame with
the other two, fituated on the interior edge. The
varied adlion of thefe four mufcles is ftill combined
with that of the mufcles which ferve for pronation
and fupination. The variety of the motions that
can refult from the combination of thefe different
forces may give fome idea of the great mobility of
which the wrift is fufceptible.

164. The mufcles of the arm are covered with a
thin aponeurofis, which envelops the arm beneath
the fkin : it is confounded above with the tendons
of the mufcles, and terminates below towards the
articulation of the elbow.

The mufcles of the fore-arm are alfb covered with
an aponeurofis, which is fixed fuperiorly around the
articulation of the elbow, and chiefly to the epitro-
chlea. This aponeurofis is very ftrongon the interior
fide of the fore-arm, where it furnifhes the mem-
branous prolongations which penetrate between the
fcapulo-radian and the humero-cubitian mulcles,
and fupplies them with points of adhefion. It is thin
on the exterior fide of the fore-arm, as well as to-
wards the wrift, where it entirely difappears, This

aponeurofis.

105 ORGANIC STRUCTURE.

aponeurofis, by enveloping the mufcles, confines
them, fapports them, and thus favours their
a61ion.

The mufcles, which ferve for the motion of the
fingers, and which extend from the arm and fore-
arm to the hand, have tendons which pafs over the
circumference of the wrift. Thefe tendons are
lirongly retained in that place by an aponeurotic
annular ligament, broad, and in the form of a
bracelet, which prevents them from feparating.

The tendons of thefe mufcles are alfo received
in that place in fheaths, or tendinous grooves^
along which they glide as far as the lower point,
by which they are fixed: of thefe flieaths fome
are common to feveral tendons, and others are
peculiar to particular ones.

The mufcles of the infide of the hand are co-
vered with a very ftrong a^oneurofts, which lies
immediately beneath the flcin. It feems to arife,
from the interior part of the annular ligament,
and expands on the inlide of the hand as far as
the fingers.

The interior face of this palmar apoiieurofis.
feems alfo to give birth to membranous prolonga-
tions, which form partitions along the bones of
the metacarpus, and thus feparate the tendons
, that pafs over thefe parts.

165. The palmar aponeurofis feems to con-
tinue itfelf fuperiorly along v/ith the tendon of a
9 long

MUSCULAR SYSTEM. 107

long and flender mufcle,- which ftill remains to be
defcribed. It is fixed above to the epitrochlea :
it is carneous for a fmall fpacc, but foon becomes
tendinous : the flender and fiat tendon of this
mufcle defcends along the interior edge of the
fore-arm, and pafles over the interior face of the
annular ligamentj where it adheres by fome ten-
dinous fibres : it then expands, and feems to lofe
itfelf, and to be confounded with the palmar
aponeurolis. This mufcle can contribute to the
flexion of the wriil, and feems to be capable of
flretching the palmar aponeurofis. Epitrochlo-
PALMiAN, pahnaris longus^ Jle?ider cubital.

i66. Beneath the fkin of the palm of the hand
is obferved alfo a fmall mufcle, exceedingly thin,
the tranfverfe fibres of which feem to lofe them-
felves under the palmar aponeurofis, and in the
thicknefs of the fkin : its allien mufl be very
weak. Palmo-cutian, ■pahnaris cutaneus. >

1 57. Mufcles 'which produce motion in the fingers.
The mufcles which make the fingers move are very
numerous : fome of then ferve for bending, and
others for extending them ; and there are fome
which make them move on all fides. Some of thefe
mufcles are common to feveral fingers ; others are
peculiar to one : fome of them alfo are very long,
and fixed to the fore-arm; while others, much fhort-
cr, are fixed to the carpus and metacarpus.

168. Along

108 ORGANIC STRUCTURE.

1 68. Along the interior part of the fore-arm is
a mufcle fixed fuperiorly, by a very thick carneous
part, to the epitrochlea, the interior fide of the
cubitus, and the fore- part of the radius. This
mufcle defcends till towards the middle of that
bone, where it feparates into four difiin6l portions,
which terminate inferiorly in the fame number of"
thin, flat tendons. Thefe four tendons pafs to-
gether before the wrift, and then feparate to pro-
ceed to the laft four fingers. They glide before
the bones of the metacarpus and the firfi: pha-
langes, where thefe fmall tendons are perforated ;
they then unite, and are fixed along the interior
face of the fecond phalanges. This mufcle ferves
to bend the fecond phalanges on the firfi, the
firtgers on the hand, and the wrifi: on the fore-
arm. Common epitrochlo-phalangian, j/«^-
lime or perforated flexor.

169. Below this mufcle is another analogous, to
it, thin above and thick in the middle. It is
fixed along the interior edge of the cubitus, and
divides itfelf into four portions, which terminate
in as many tendons. Thefe tendons proceed
below thofe of the preceding mufcle, as far as the
place where the latter are perforated, traverfe
the fiffures of them, and are conneded to the in-
terior edge of the laft phalanges. This mufcle,
which has the fame adion as the preceding, can
bend alfo the third phalanges^ to which it is fixed.

COMMOlf

MUSCULAR SYSliJEM. 10^

Common cubito-phalangettian", profound ot
perforating flexor,

170. Towards the fuperlor extremities of the
bones of the metacarpus, between the two com-
irion flexors of the fingers, are fixed four fmall
rnufcles, which proceeding from the tendons of
the profound flexor, are inferted along the inte-
rior edge of the firfl: phalanges of the fingers.
They are auxiliaries to the two mufcles between
which they are placed. Palmo-phalangian,
Itmibrlcales .

171. The interval comprehended between the
bones of the metacarpus is filled, in the infide,
by three fmall mufcles, which proceed from the
carpus to the firfl phalanges. They contribute to
bend the fingers. Interior metacarpo-super-
PHALANGiAN, inferior OX hit ei'ior inter-ojfeous,

lyi. Along the exterior face of the fore-arm Is
a mufcle fix.ed to the epicondyle : it grows larger
below the point where it is fixed ; and when it
reaches the middle of the radius, ife divides itfelf
into four portions, each of which covers its neigh-
bour, and becomes tendinous. Thefe four ten-
dons pafs behind the carpus, and feparate from it
to proceed to the convex face of the third pha-
langes of the fingers. This mufcle extends the
four fingers which follow the thumb. Common-

fiPICONDYLO-SUPER-PHALANGETTIAN, COmMon

extenfor^

173. The

no ORGANIC STRUCTURE.

173. The interval between the bones of th6
metacarpus is filled up without, by fovir fmall
mufcles, which proceed from the carpus to the
phalanges. They contribute to the extenfion of
the fingers. Exterior metacarpo-super-
PHALANGIAN, fupeuor Or exterior inter-offeous.

174. Before the upper third of the radius, and
along the interior edge of that bone, is fixed a
thin mufcle, which terminates below in a flat ten-
don. This tendon paffes to the exterior edge of
the carpus, and proceeds to the laft phalanx of the
thumb. This mufcle bends the two phalanges of
the thumb on the bone of the metacarpus, and
even that bone on the carpus. Radio-pha-

lANGETTIAN OF THE THUMB, long fieXor of the

tJjumh,

175. A thick mufcle is fixed to the bafeof the
firft bones of the carpus, palles before the firft,
and even the fecond bone of the metacarpus, and
envelops the firft phalanx of the thumb. It tends
to bend the thumb. Carpo-phalangian op the
THUMB, JJjort flexor of the thumb,

176. To the top of the cubitus, on the outfide
and for a part of its length, is fixed a mufcle, the
tendon of which pafles behind the firfl: bone of
the metacarplis, and is inferted in the firft pha-
lanx of the thumb. The adlion of this mufcle
is to extend the thumb. Cubito-super-pha-
lanqiaN, long extenfor of the thumh.

]77. Another

MUSCULAR SYSTEM. Ill

177. Another mufcle, much fhorter and thin-
ner, proceeds in the fame dire6lion, and has the
fame a61ion as the preceding : its tendon termi-
nates at the fecond phalanx of the thumb. Cu-

BITO-SUPER-PHALAXGIAN OP THE THUMB, Jhort

extenjor of the thumb.

178. Along the interior fide of the third bone
of the metacarpus is inferted a mufcle, which pro-
ceeds in a tranfverfe diredion, and is fixed to the
cubital edge of the firft phalanx of the thumb.
li brings the thumb towards the other fingers, by
pulling it forwards. Metacarpo-phalangian,
adduSlor of the thumb.

179. To the exterior face of the cubitus is
fixed fuperiorly a mufcle, which extends between
the two bones of the fore-arm, and terminates
inferiorly in a tendon, often divided, which is
implanted in the fummit of the firft bone of the
metacarpus, towards its radial fide. This mufcle
removes the thumb from the other fingers. Cu-

BITO-SUPER-METACARP.IAN OF THE THUMB,

long abduBor of the thumb,

180. A fmall mufcle is inferted before the two
firft bones of the \.\<!0 rows of the carpus, and
proceeds outwards on the radial edge of the firft
phalanx of the thumb, which it embraces. This
mufcle removes the thumb from the other fino^ers.
Carpo-super-phalangian, pjort ahdu^or.

i8i. Before

112 ORGANIC STRUCTURE.

18 1. Before the firfi: two bones of the two
rows of the carpus is fixed a mufcle, which is in-
serted on the radial edge of the metacarpian
bone of the thumb. This mufcle makes the bone
of the metacarpus turn on its axis, and pulls the
thumb towards the hollow of the hand, in order to
oppofe it to the other fingerst Carpo-metacar-
piAN OP THE THUMB, tnetacarpan of the thumb ^
or oppofer,

182. To the middle part of the cubitus with-
out is fixed a mufcle, the tendon of which pafles
over the convexity of the hand, to proceed to the
laft phalanx of the index-finger. It extends the
index-finger. Cubito-super-phalangettian
OP THE INDEX, exteufor of the index.

i8g, A fmall mufcle, fixed to the proje(5ling
part of the lafi; bone of the fecond row of the
carpus, proceeds along the cubital edge of the
hand, towards the firft phalanx of the little finger,
"jj^his mufcle bends the little finger by pulling it
a little towards the reft. Carpo-super-phalan-

GETTIAN OF THE LITTLE I lUfiGEKy Jhort ^eXOr

of the little finger,

184. A thin mufcle, attached to the epicon-
dyle, furnifhes a fecond tendon to the little fin-
ger. Epicondylo-super-phalangettian of
THE LITTLE FINGER, exteufor of the little fing£r,

185. At the lower part of the laft bone of the

firft

MUSCULAR SYSTEM. 113

fivCt row oC the carpus is fixed a mufcle, which
proceeds along the cubital edge of the laft bone
of the metacarpus, and is inferted in the firfi:
phalanx of the little finger. This mufcle bends
the Ij-ttle finger, by pulling it flight ly outwards.
Carpo-phalangian of the little PINGEP^j
ahduBor of the little finger.

186. Below the preceding is often found an-
other mufcle, which extends from the cubital edge
of the fifth bone of the metacarpus, as far as the
proje»51ion of the laft boneof thefecond row of the
carpus, and proceeds along the cubital edge of the
hand towards the firft phalanx of the little finger.
This mufcle pulls the little finger before the reft,
Carpo-metacarpian op the little finger,
oppofer of the little finger.

187. As the ofleous piece which receives the
bone of the thigh is not moveable, like that
which receives the bone of the arm, it has no
mufcles proper for moving it ; but it forms a point,
to which are attached all thofe that give motion
to the thigh on the pelvis, and a part even of
thofe which move the leg on the thigh.

*

188. Mufcles which make the thigh move on the
pelvis. The mufcles which ferve merely for mov-
ing the thigh on the pelvis are attached to the

VOL. r. I trochanter^

]14 ORGANIC STflUCTURE.

trochanter, the trochanti?i, and the fe}?ioral ridge.
Thofc attached to the trochanter form the thick-
nefs of the hips.

189. The moft voluminous, that which covers
the reft, is attached above, along the pofterior
half of the edge of the hip bone ; it defcends
behind along that edge, and along that of the
facrum and coccyx. All the fibres of this mufcle
approach each other, and terminate inferiorly in a
broad tendon which is inferted behind the femur,
below the trochanter. This mufcle ferves to pull
the thi2;h backwards and outwards* Sacro-pe-
MORI AN, gluteus maximus.

This mufcle, the fize of which is confiderable
in man, is proportionally fmaller in apes and the
other mammalia ; fo that thefe prominences, called
buttocks, are found only in man.

190. Below this mufcle, but placed more for-
wards, is another of lefs fize, the form and direc-
tion of which are nearly the fame : it is fixed to
the exterior face of the hip bone, and along the
anterior half of its edge. Its fibres terminate
inferiorly in a fort of tendon, which is inferted in
the fummit of the trochanter. Its a61ion is nearly
the fame as that of the preceding. Great ilio-
trochanterian, gluteus medius.

191. Below the preceding is alfo another

fmaller

MUSCULAR. SYSTEM. 115

fmaller mufcle, which adheres to the exterior
face of the broad portion of the hip bone : its
fibres terminate inferiorly in a flat tendon, which
is inferted before the fummit of the trochanter.
Its adlion is the fame as that of the preceding.
Small ilio-trochanterian, gluteus nimimus^

192. On the fides of the interior face of the os
facrum, between the holes of that bone, is at-
tached, by three or four digitations, a mufcle,
which being broad in that place paffes through
the lefler pelvis by the ifchiatie notch : it then,
becomes narrovVer, and defcends obliquely to inlert
jtfelf by a long tendon in the fummit of the cavity
of the trochanter. This mufcle makes the thigh
turn outwards, when extended, and removes it
when bent. Sacro-trochanterian, pyri-
formis.

193. Two other mufcles are fixed along the
pofterior edge of the ifchium, and are inferted
together in the fummit of the cavity of the tro-
chanter : they have the fame a6lion as the preced-
ing. Ischio-trochanterian, gemmi.

194. In the infide of the lefier pelvis, along the
interior edge of the fub-pubian foramen, is fixed
a broad mufcle, which changes into a flat tendon.
This tendon turns round on the notch which is
between the fpine and the tuberofity of the if-
ehium ; then pafles between the two preceding

1 2 . mufcles,

]l6 ORGANIC STRUCTURE.

mufcles, as in a fheath, and is inferted in the
fummit of the trochanter. This mufcle has the
fame a6^ion as the preceding, and exercifes it by
gliding on the notch of the ifchium as on a ful-
crum. Interior sub-pusio-trochanterian,
interior ohturator.

195. A fmall flat mufcle, applied before and
around the fub-pubian foramen, proceeds back-
wards by a tendon, which pafles below the coty-
loid cavity, and is inferted behind the neck of the
femur, in the cavity of the trochanter. This
mufcle has the fame action as the preceding.
Exterior sub-pubio-trochanterian, exterior
obturator.

196. To the tuberofity of the ifchium is fixed
a thin flat mufcle, which is inferted behind the
trochanter : its a61ion is the fame as the preced-
ing. It tends to make the thigh turn outwards.

IsCHI0-SUB-TR0CHANTERIAM5y^Z^^/-^q/'/i'^ thighs

The other mufcles proceed from the pelvis to
the trochantin, and the femoral ridge ; they are
placed at the interior and fuperior part of the
thigh.

197. To the fides of the bodies of the lumbar
vertebrs and the bafe of their tranfverfe apo-
phyfes is fixed a thick mufcle, which defcends^
growing fmaller^ and proceeds laterally on the
iliac portion of the hip bones : it then advances

towards

MUSCULAR SYStEM. II7

towards the pubis, and pafTes above the arch
which that bone forms above the fub-pubian
foramen. This mufcle then glides on the interior
lide of the articulation of the femur, which it
covers, turns round below the neck of that bone,
and terminates before the trochantin. It bends
the thigh forwards on the pelvis. Pr^elumbo-

TROCHANTINIANj pfotlS, "^

198. A broad thick mufcle, attached to the
circumference of the os ilium, and to a part of
its interior face, defcends anteriorly towards the
pubis, and terminates there in a tendon which is
united to that of the preceding mufcle, as far as
its infertion into the trochantin. It has th6 fame
a(5lion. Ilio-trochantinian, iliac.

199. Below the f)'i^phyfis of the pubis is fixed
a thin mufcle, which defcends before that bone,
and proceeds backwards in an oblique dire^lion to
infert itfelf, by a flat tendon, behind the trochan-
tin. It has the fame adion as the two preceding.
Super- pubio-femori an, fe^lnalis.

200. Three mufcles are attached 'before the
pelvis : the firft towards the fymphyfis of the pu-
bis ; the fecond below, in the fore-part of that
bone clofe to the fub-pubian foramen ; the third
ftill lower, before and above the tuberofity of the
ifchium. Thefe three mufcles proceed behind
the thigh^ and are inferted along the femoral

I 3 ^idge,

3 18 ORGANIC STRUCTURE.

ridge, in fuch a manner that the firft pafles before
the fecond, and is inferted farther down into the
femur. The third "defcends lower than the other
two, and is fixed about the lower third of that
hone. Thefe mufcles pull the thighs inwards, by
bringing them towards each other. Pubio-, Sub-
PUBIO-, and Ischio-pemorian, f/je three adduce
tor S3 ov femoral triceps,

so I. Mufcles which move the leg on the: thigh.
The greater part of the mufcles v/hich ferve to
move the leg on the thigh are attached to the
pelvis, and fome of them to the femur: thofe
which extend the leg on the thigh are fixed to the
rotula ; thofe which bend it are almoii ail attached
to the interior fide of the head of the tibia,

202. A mufcle fituated before the thigh ad-
heres fuperiorly by two tendons : one, which is
fhort, to the tubercle placed before the edge of the
ilium and above the cotyloid cavity ; the other
to the circumference of that cavity. This mufcle
becomes thick in the middle, then contra(51:s, and
terminates in a flat tendon, which is inferted in
the fummit of the rotula. It extends the leg.
Ilio-rotulian, firaight ox flender anterior.

203. Below this mufcle is another very broad
and thick one, which envelops the femur before
and on the fides. This mufcle is feparated fupe-

riorlv

MUSCULAR SYSTEM. Up

riorly into three portions : the middle portion is
fixed before the trochantin ; the interior, attached
to the fame place, defcends along the femoral
ridge, and along that which proceeds to the inte-
.rior condyle : the exterior portion is attached be-
fore and at the bottom of the trochanter, and con-
tinues along the exterior edge of the femoral
ridge, and the ridge which defcends to the exte-
rior condyle. Thefe three portions unite in the
middle of the thigh, and terminate in a large flat
tendon, which is inferted in the fummit of the
rotula. This mufcle by its a6lion ftrongly extends
the thigh. Tri-femoro-rotulian, vaji interior,
vajl exterior^ and crural ; or crural triceps.

The mufcles which bend the leg are more nu-
merous.

204. Before the tuberofity of the ifchium is at-
tached a very ftrong and tendinous mufcle, the
tendon of which is continued backwards obliquely,
as far as the middle of the thigh, where it be-
comes carneous. This mufcle defcends before the
poflerior part of the interior condyle of the femur,
where it is changed into a flat divided tendon,
which is fixed behind the interior condyle of the
head of the tibia. This mufcle bends the leg.
IscHio-suB-TiBiAN, femi-membranous.

205. Behind the tuberofity of the ifchium is
fixed a mufcle, which is carneous as far as the

14 lower

. 120 ORGANIC STRUCTURE.

lower third of the thigh, where it is changed Into
a {lender round tendon, which pafics behind the
interior condyles of the femur and the tibia, turns
itfelf inwards -around the latter, and is inferted in
the upper part of the tibia near its anterior edge.
It has the fame a61ion as the preceding. Ischio-
PR^^TiBiAN, Jemi-nervous>

In apes the two preceding mufcles are fixed to
the tibia, much lower down than in man, and
keep the leg in a continual flate of flexion, which
prevents walking erecl.

ao6. On the outfide of the thigh behind, is a
mufcle divided inferiorly into two portions : one
longer than the other is fixed to the bottom of
the tuberofity of the ifchium by a broad tendon,
which defccnds obliquely behind; becomes broader
and unites towards the middle of the thigh with
the fhort carneons portion : the latter is inferted
in the middle of the femoral ridge; continues
along this ridge, and that which proceeds to the
exterior condyle. This mufcle terminates in a
ftrong tendon, which paffes behind the exterior
fide of the knee, and is inferted in the head of
the perone. It bends the leg. Ischio-peronian",
J amoral bleeps.

207. Behind the articulation of the knee is a
fhort mufcie, deeply fituated between the bottom
of the exterior condyle of the femur, behind the

articular

MUS'CULAR SYSTEM. 121

articular eapfule, and the pofteiior and fuperior
part of the tibia. It tends alio to bend the leg.
PoPLiTO-TiBiAN, fopUlean.

ao8. To the anterior angle of the ridge of the
ilium is fixed a thin and very long mufcle, which
defcends before the thigh ; pafles on the interior
iide of the knee, and is inferted in the upper part
of the tibia, on the interior fide of its ridge, be-
low the tubcrofity of that bone. This mufcle
bends the leg on the thigh by pulling it inwards,
as if to make it crofs the other ; it makes the
thigh and leg alfo turn outwards when the mem-
ber is extended. iLio-PR^-tTiBiAN, (tayhr mnj-
fle^) fartorms.

2,09. A thin long mufcle attached before the
ifchium and the pubis, by a broad flat tendon,
defcends ■along the interior part of the thigh, and
terminates in a round flender tendon, which
pafles behind the condyles of the femur and the
tibia. This mufcle then tarns round on the inte-
rior fide of the knee, and is inlcrted in the top of
the ridge of the tibia, near its tuberofity. It bends
the leg. PuBio-PRi®T7BiA]si, Jhnder or Jtraight
piierior.

i\Q, All the mufcles of the thigh are enveloped
and maintained in their pofitions, by a very ftrong
fort of aponeurotic covering, which extends over
the pelvis before the pubis, the ifchium, the an-
terior .

122 ORGANIC STRUCTURE.

ierior ansfle of the ilium, the exterior face of that
bone, that of the facriim and the coccyx, and
over the articulation of the head of the femur.
This femoral aponeurojis is very ftrong on the ex-
terior fide of the thigh ; adheres behind along the
femoral ridge, and defcends on the knee, which it
'envelops on all fides. It fends out prolongations
betvv^een the mufeles, and feparates them without
adhering to them. It ftrongly fecures the mufeles
which it envelops, furnidies them with a firm point
of fupport during their contra6tion, and in this
manner greatly contributes to favour their adlion.
This aponeiiroiis exhibits at its upper part two
difdn6l laminse, between which is lodged a parti«
colar mufcle. This mufcle is fixed towards the
top of the anterior angle of the ilium, and de-
fcends between the two laminasof the aponeurofis
as far as the middle of the thigh. The principal
a61ion of this mufcle is to ftretch the aponeurofis,
and thus to fuftain with more force- the mufeles of
the thigh. Aponeurotic ilio-femorian, mufcle
of the fafcia Jala, and aponeurofis of the fafcia lata.

211. Mufeles ivhich move the foot on the leg.
The mufeles which make the foot move on the leg
extend, and bend it^ or pull it to either fide.

The feet are extended by the mufeles which

form the calf of the leg. Two of thefe mufeles

Q are

MUSCULAR SYSTEM. 123

are placed clofe to each other : the interior, which
is thicker and longer, is fixed behind the interior
condyle of the femur ; and the exterior behind
the exterior condyle of that bone : both of them
become very thick along the upper half of the leg ;
they then decreafe, are confounded, and terminate
in an exceedingly ftrong and thick flat tendon
which is inferted behind the calcaneum. Their
adlion is to extend ftrongly the foot on the leg.
Bi-FEMORO-CALCANiAN, gemellus^ gafirocnemian,

^12. Below thefe two mufcles is another^ al(b
very thick, which is fixed at the top, behind the
head of the perone, and below that of the tibia.
This mufcle becomes very broad, and defcends
behind along the tibia, to which it adheres in a
fmall part of its extent : its inferior tendon is con-
founded with that of the preceding mufcle, and both
have the fame a6^ion. TiBio-CALCANiAN',y&/^«j'.

Thefe mufcles, the gemellus, and the foleus,
are thofe which exercife the moft eflential a6lion
in progreflion, running and jumping. By extend-
ing the foot, thefe mufcles raife the heel and ele-
vate the body, which for a moment refis only on
the point of the foot. The carneous fwelling of
thefe mufcles, which conflitutes the calf of the
leg, is obferved only in man : this firu61:ure, by
increafmg the flrength of the leg, adds greatly to
the beauty of its form.

^13. There

124 ORGANIC STRUCTURE.

213. There is alfo another xtvy Jlender mufcle
which is attached on the fide of the exterior con-
dyle of the femur ; it is carneous in its upper
fourth, then changes into a fmall tendon which
defcends between the two preceding mufcles, and
is confounded with them below on the interior
edge of their common tendon. It exercifes the
fame a6lion. Femoro-calcanian, t'lhial or

Jlender plantarh.

In apes, the tendon of this mufcle does not ad-
here to the calcaneum, but pafTes below, and conti-
nues with the aponeurofis plantaris,as the epitrochh^
falmaris continues with the aponeurofis pajmaris in
man ; fo that thefe animals cannot place their heel
on the ground without bearing on this tendon,
which prevents them from refting the whole fole
of their foot on the ground: a condition neccflary
for walking on two (qqU

214. Below and behind the upper articulation of
the bones of the leg is attached a mufcle which
defcends along thefe bones, and adheres to them :
iris terminated inferiorly by a tendon which pailes
on the interior fide of the malleolus, and is in-
•ferted on the interior fide of the os fcaphoides and
of the firft OS cunciforme. This mufcle extends
the foot, by pulling it inwards, Tibio-sue-
TAR SI AN, tihialis poficus,

215, On the fide of the tibia^ below its exte-
6 rior

MUaCULAR SYSTEM. 125

rior condyle^ i$ attached a mufcle which proceeds
on the exterior fide of the perone, and adheres to
it for three-fourths of its length at the upper ex-
tremity. This mufcle is bulky in the middle, and
terminates below in a tendon, which pafles behind
the exterior malleolus, glides on the fide of the
calcaneum, then proceeds below the os cuboides,
and pafles obliquely below the foot to infert itfelf
under the tarfian extremity of the firft bone of the
metatarfus. This mufcle extends the foot and
pulls it outwards. Peron^o-sub-tarsian, long
^eronaus,

a 1 6. Before the leg, and a little on the outfide, is
a mufcle attached fnperiorly along two-thirds of the
exterior edge of the ridge of the tibia. This mufcle
terminates inferiorly in a tendon, which proceeding
obliquely on the infide, pafies before the articula-
tion of the foot, and is inferted on the interior
fide of the firfl os cuneiforme. It bends the foot
by pulling it gently outwards. Tibio-su3-tar.-
giAN, anterior tibial.

2,17. Before and on the exterior fide of the
lower two-thirds of the perone is fixed a mufcle,
the lower tendon of which pafl!es behind the ex-
terior malleolus in a groove, common to it with
the preceding mufcle. This tendon proceeds on
the exterior fide of the calcaneum, before and
along the exterior edge of the os cuboides, and is

inferted

126 ORGANIC STRUCTURE.

inferted in the tuberofity which ferves as the
tarfian extremity of the fifth bone of the meta-
tarfus. This mufcle bends the foot by drawing it
outwards. Great peron^o-super-tarsian,
middle ^eronceus.

2x8. Before the lower half of the perone is at-
tached a mufcle, thin at the top and thicker in the
middle : the tendon in which it terminates de-
fcends before the convexity of the foot, patles in a
groove common to it with another mufcle, and
proceeds on the outfide to infert itfelf along the
exterior edge of the fifth bone of the metatarfus.
The a61ion of this mufcle is the fame as that of the
preceding. Small peron^o-super-tarsian ;
Jmall peronaus.

2.1C). The mufcles of the leg are enveloped in
an aponeurofis, very ftrong before, but much
thinner behind, and particularly below, where it
difappears. This tibial aponeurofis is attached fu-
periorly around the knee, where it feems to be con-
founded with that of the thigh : its anterior face
throws out membranous prolongations, which are
interpofed between the mufcles of the anterior part
of the leg, and adhere to it.

The tendons of all the mufcles, which proceed
from the leg to the foot, are fecured by two annular
ligaments, finiilar to that which, as already faid,
furrounds the wrift in the form of a bracelet. One

of

MUSCULAR SYSTEM. 127

of thefe ligaments is at the bottom of the leg^ and
the other above the foot : they fecure the ten-
dons, which they cover and confine in their places.
Below the foot is an aponeurofis, limilar to the
aponeurofis pahnaris. It begins under the calca-
neum, where it is very thick, and proceeds expand-
ing itfeh^ towards the anterior extremity of the
bones of the metatarfus. This aponeuroiis plan-
taris is furnifhed with feveral prolongations, which
penetrate between the mufcles, fnpply them with
numerous points of adhefion, and are fixed on the
iide of the articulations of the bones of the me-
tatarfus with the firfl phalanges of the toes.

220. Mufcles which give motion to the foes. The
mufcles of the toes, like thofe of the fingers, are
exceedingly numerous : they bend or extend the
toes, or make them move tov^^ards the fides.
They are common to feveral' toes, or are peculiar
to fome : in a word, they are affixed to the bones
of the leg, or to thofe of the foot.

221. A mufcle, attached behind and towards
the upper part of the tibia, is changed towards
the lower part of that bone into a tendon, which
pafTes in a groove behind the interior malleolus :
it defcends below the calcaneum, and proceeds'
outwards beneath the middle of the foot : in that
place it receives a flefhy expanfion, which arifes
from the calcaneum (acceffbry or fquare portion):

this

128 ORGANIC STRUCTURE*

this tendon then divides itfelf into four fmall flat
tendinous bands, which proceed towards the heads
of the metatarfuS; where they enter a groove
common to tour other perforated tendons, through
which they pafs, to proceed to the bottom of the
third phalanges of the lad four toes. It bends or
deprelles the toes. . Common, tibio-phalan-
G E T T s A N 5 common long flexor of the toes.

222. Below the large tuberofity of the calca-
neum is fixed a mufcle^ which proceeds before
and divides itfelf into four tendons : the extre-
mities of thefe tendons are cleft to afford a paf-
iz<gQ to thofe of the preceding mufcle, and they
are infertcd in the fecond phalanges of the laft
four toes. The action of this mulcle is the fame
as that of the preceding. Common calcaneo-
suB-PHALANGETTiAN, comnion fjort flcxor of the
toes.

223. The interval comprehended between the
bones of the metatarfus is occupied inferiorly by
three fmall .mufcies, analogous to thofe between
the bones of the metacarpus ; they contribute to
the flexion of the laft four toes. Inferior meta-
TARSO-iNTEK-PHALANGiAN, inferior ifiter-offeous.

224. Between the common flexors are four
fmall mufcies, as in the hand : they proceed from
the tendons of the long flexor, and are inferted
below and on the interior flde of the fii*!!: pha-
langes

MUSCULAR SYSTEM. 129

langes of the laft four toes. They bend thefe parts,
by bringing them near the great toe. Planti-
suB-PHALANGiAN, lumhrical,

225. Below the exterior condyle of the tibia is
attached a mufcle which defcends and adheres
along the interior face of that bone ; along the
interior edge of the perone,, and on the inter-
ofleous ligament. On its paflage it divides itfelf
into three parts, which terminate in tendons :
thefe tendons defcend on the convexity of the
foot, and pals in the groove which receives that
of the fmall peroneo.super-tarsian. One of
thefc tendons divides itfelf into two, which are
fixed on the phalanges of the two toes, ne:;t to
the great toe : the other two are infcrted in thofe
of the laft two toes. This mufcle extends or
llraightens the toes. Common peroneo-super-
PHALANGETTIAN, common long extenfor of the toes.
226, On the exterior face of the large tubero-
fity of the calcaneum is attached a mufcle, which
proceeds inwards obliquely on the foot : it be-
comes broader and divides itfelf into four tendons,
which crofs and pafs under thofe of the preced-
ing mufcle, with which they are fixed on the firft
phalanges of the laft four toes. This mufcle ex-
tends thefe toes by pulling them outwards. Com-
mon CALCANEO-SUPER-PHALANGETTIAN,^^<^/0Z<^

OX jhort common extenfor of the toes.

227. The intervals between the bones of the
VOL. I. K metatarfus

130 ORGANIC STRUCTURE.

metatarfus are filled fuperiorly by four fmall muf-
cles, analogous to thofe found between the bones
of the metacarpus ; they contribute to the exten-
fion of the laft four toes. Superior metatar-

so-iNTER-PHALANGiAN,^^^mor iyiter-ojfeoiis.

2,28. A fmall mufcle is attached in a tranfverfe
dire6lion below and between the articulation of
the bones of the metatarfus with the firll pha-
langes 5 it bi'ings together the heads of thefe
bones, and caufes them to form an arch. Trans-
verse METATARSO-SUB-PHALANGIAN, iranfvet'f&

of the toes.

229. Behind the lov^er two-thirds of the perone
is attached a thin mufcle, the tendon of which
defcends obliquely on theinlide, palTes behind the
lower extremity of the tibia; glides in a groove,
which is behind the aftragaius, and proceeds to
the interior fide of the calcaneum of the foot, to
fix itfelf on the interior fide of the laft phalanx
of the great toe. It bends that toe. Peroneo-

SUB-PHALANGETTIAN OP THE GREAT TOE, long

flexor of the great toe.

2JO. Under the interior edge of the tarfus,
and principally below the firft os cuneiforme, is
attached a thick mufcle, which advances and di-
vides itfelf into two parts ; thefe parts diverge
from each other, and terminate in two tendinous
portions, which are iuferted under the firft pha-
lanx of the great toe. This mufcle bends that

part.

MUSCULAR SYSTEM. 13i

part. . TaRso-sub-phalangian of the great
T0£, Jl:)ort fiexor of the great toe,

231. Before the perone, and along its lower
half, is attached a mufcle the tendon of which
paffes over the foot, and is inferted on the two
phalanges of the great toe ; it extends that
part. Peroneo-super-phalaistgettian OF the
GREAT TOE, exte?ifo?' of the great toe.

232- On the interior fide of the large tubero-
lity of the calcaneum is attached a mulcle, which
proceeds before, along the interior and inferior
edge of the foot, and is fixed by a tendon
below and on the fide of the firft phalanx of
the great toe. It bends that part, by pulling
it from the other toes. Calcaneo-sub-pha-

LANGIAN OF THE GREAT TOE, ahduBor of the

great toe,

233. Below the lafi two cuneiform bones, and
the heads of the bones of the metacarpus corre-
fponding to them, is a mufcle which pafl^es before
and inwards, and by a tendon proceeds to the ex-
terior fide of and below the firft phalanx of the
great toe. It bends that part by pulling it to-
wards the other toes. Metatarso-sub-pha-

LANGIAN of THE GREAT TOE, ahdu^lor of' the

sreat toe.

234. On the exterior fide of and below the
laft bone of the metacarpus, is a very fmall muf-
cle, which proceeds under the firft phalanx of the

K 2 little

132 ORGANIC STRUCTUREo

little toe. It bends that part. Tarso-sub-pha-

liANGIAN OF THE LITTLE TQ-E, Jhort fieXOT of the

little toe.

235. On the exterior fide of the calcaneum,
before its fmall tuberofity, is attached a mufcle,
which proceeds along the exterior and inferior edge
of the foot : its tendon furnithes a tendinous por-
tion, which is fixed behind the large head of the
lafl bone of the metacarpus ; then continues
along that bone, and is inferted below and on the
outfide of the firft phalanx of the little toe. It
bends that part by pulling it from the other toes.
Calcaneo-sub-phalangian of the little
T0E5 abduBor of the little toe,

236. The mufcles are compofed of bundles of
fibres ; each mufcle, each fibre, and each fubdivifion,
is feparated by a cellular covering ; the fibres are
divided and fubdivided into fmaller fibres ; and
this indefinite fubdivifion always efcapes the eye,
even when aflifted by the befl microfcope; fo that
the real intimate firu(5lure of the mufcular fibre is
unknown.

To determine the chemical compofition of the
mufcular flefh, it may be analyfed in the follow-
ing manner : Suffer the flefh to macerate well in
cold water, and when it is taken out, heat the
water, and there will be coagulated a certain
quantity of albumen^ which is feparated by filtra-
tion.

The

MUSCULAR SYSTEM. 1^3

The Hefh thus deprived of a part of its albumen
mull then be boiled in a large quantity of water^
employing that in which it was firft heated. When
the ebullition has been maintained for a confider-
able time, there will be ftill coagulated a fmall
portion of albumen, which may be feparated : a
certain quantity of fat alfo will be difengagcd,
which muft be feparated by cooling.

The mufcle then exhibits only a coriaceous
fubftance, which is fibrous matter. The water dill
contains a large quantity of gelatin, which muft
be precipitated by the tanning principle : levefal
faline fubftances are alfo found in this water in
fmall quantity.

The white fibrous parts by very long ebullition
are reduced almoft entirely to gelatin.

K 3 TABLE

TABLE OF THE MUSCLES

OP THE TRUNK, THE HEAD, AND LIMBS.

MUSCLES WHICH MOVE THE VERTEBRAL COLUMN,

Bt/ raising it tip and pulling it bachxvcmJs-

NEW NAMES.

OLD NAMES.

1. Sacro-spiniih.

2. Inter-spinian.

3. Inter-transversian.

4. Prjedoiso-atloidian.

5. Pubio-praelumbian.

6. Ilio-transvcisian,

7»,Ischio-coccygian.

/Socro-lumhart
Long dorsal and its accessory, or ireat transverse of
% the tied.

^Tramvene spinous,
, . . . mter-spnous,

Bt/ bending it towards the sides.

r. niter-transxitrse.

Bi/ bending the nechfortoards,

; . . . Long of the neck.

jBj/ bending the spine on the pelvis.

. small psoas. •

, . Square of the loins.

By pulling the coccyx backwards,

, . . . . The Same.

1. Inter-costian.

2. Trachelo-costian.

3. Transverso-costian.
*. Dorso-coscian^

5. Lumbo-costian.

6. Scerno-costian.

MUSCLES WHICH MOVE THE BREAST,
By raising the ribs.

. , . , . Intercostal, interior and exterior.

- Scalene.

. . . Ele^iators of the rilts.

. Small indented posterior, superior.

By depressing the ribs.

Small indented posterior, inferior.

. Triangular of the sternum.

By diluting and contracting the breast, and separating it from the
lower belly.

7. Diaphragm. > .... The same.

By bending the breast on the pehis, and forming the sides of the
abdomen.

8. Ilio-pubio-co£tian. . . . ~. . Exterior oblique, or great oblique.

9. llio-costian, .... . . Interior oblique, or small oblique,

10. Pubio-sternian. . ..... Right of the lower bell}.

11. Lumbo-abdominal. ...*.. Transverse of tht lovjer belly.

12. I'ubio-sub-umbUical. . . , - . Pyramidal,

MUSCLES

TABLE OP THE MUSCLES, 135

JMUSCLES WHICH MAKE THE HEAD MOVE ON THE NECK,
Bi/ bending it fortvards, and toxoards the sides.

NEW NAMES. OLD NAMES.

1. Sterno-mastoldian. ..„,,- The Same,

2i GreaE-trachelosub-occipitian Grr'at straight, anterior,

3. Small-crachelo-sub-occipician. , . . Small straight, anterior.

4. Atloido-mastoidian. . . • . . Small straig/i:, lateral.

By lehding it backwards, and totvards the sides.

5. Cervico-rtiastoidian. . * . . Splenius of the head.

C. Trachelo-occipitian. ..... Great complex-us , and digastric of the tieek.

'7. Trachelo-mastoidian. Small complexus, or lateral moitoiiian,

8. Atloido-sub-mastoidian. ..... Superior obliqHe, or small oblique.

9. Axoido-occipitian. ... ... Great straight, pcstericr.

1*?. AtioidO'OCCiiTitiaii. S7n.-dl straight y posterior.

MUSCLES WHICH MOVB THE FACE,

By co7'rugating the forehead, and raising the eye-broxvs and eye-lids,

1. Occipito-fiontian. . . . . i . Epicranian and pyramidal of tht r.ose,

i, Fronto-supercilian. . . . . . . Superciliar,

3. Orbito-palpeljralian Elex<ator of the eye-lids.

By shutting tfie eye-lids.

4. Palpebralian Orbicular of the eyc-lijs,

, By dilating and depressing the nostrils.

5. Super-maxillo-aasian. Transverse of the r.ose.

6. Alveoio-nasian. . .... Myrtiform.

By distending the cheeks.

1. Bucco-labian. . . Buccinator.

By drawing the lips upwards and backwards.

8. Zygomato-labian, great and small. . . . Great and small zygomatic.

9. Super-maxillo-labiah, 1st. great, 2d. middle, J '"'• ^'""^"^ of the ala of the nose, and upper lip.
3d. small. ] '^- '^'"'^'' or proper elevator of the upper lip,

I, 3rf-. Canine, or elevator c/tht angle of the lips.

By depressing the lower lip.

10. Mcnto-labian Square of the point cf the chin.

11. MaxiUo-labian. . . . •. . Triangular, r,r depressor of thi angle of the lips.

By contracting the aperture of the mouth.

( and lower lip.

By elevating the lower jaw.

13. Tcmporo-maxillian Crctaphite, or temporal.

14. iCygomato-maxiUian, . . . . , Masseter.

Is. Great plerygo-maxill/an. - . . . Great pterygoidian, or interior,
16. Small pteryjo-maxillian Smalt pterygoUian, or exterior.

K4

B^

136 ORGANIC STRUCTURE.

NEWN|iMF.S. OLD NAMES.

By Mispressing the lower juw.

17. Masroido-genisr. . ..... DisasMc*.

A nmsde almost wUhout action, situated under the shin of the necL

18. Tlioraco-tacian,

Cutan^vs^

I

MUSCLES »VHiCH MOVE THE SHOULDER ON THE BREAST,
By pulling it hach-wards.

1. Dorso-super-jcromian.- . ,,,_.. Trape%ium,

2. Dorso-scapiili:in. ... ... RhomhoUelis.

3. 'I'laclielo-scapulian Angular.

B?/ pulling it forwards.

4. Costo-coracoidian. ^ntrrhr itukntei, or small pectoral.

5. Costo-scai>ulian. ... ... Grtat indented,

S. Costo-clavian Suli-clavian.

MUSCLES WHICH MOVE THE ARM ON THE SHOULDER,

By pulling foi'xcards.

1. Sternn-humcrian. . , ', . . . Great pectoral.

By pulling it upwards.

C. ?ub-acromio-humerian. .- . . . . DelfAJ.

3. foraco-hiiiTierian. - , Coraca-brachhI.

4. Supei-ic.ipulo-tiOLhiiei ian, superior. . . Super-spimu!.

By pulling it bachxoards.

-.h. Lumho-humerian. . . .... Great dorsal, or very large cf the back,

6, Scapiilo-humerian Great round.

By ?nahing it ticrn outxcards.

". ^upcr-scjpulo-trocliiterian, interior. . . Subspinous and imall round.

■ By making it turn inwards.

^. Sub scapu!o-tiochinian. • . ... Sub-scapular,

MUSCLES WHICH MOVE THE FORE-ARM ON THE ARM,

By bending it.

1. Scapiilo-raili-n; *..... Biceps,

2. lliiTnero-cul)itian. ... . . • Brachial, interior.

By extending if.

'i. ^^capul.i-^ilccrnnifln, ...... Brachial triceps,

^ r.pi(.ondylo-cu!)irian. ..,.,. Small anconeus.

J *- Tilt: u hur rauiclcs v.hich lower the taw tie attached tp the os hyoidesj a deicriptipn of them wilA
he fouM uniii! till hcnii S}Stem of Di.iesli.n.

M5)SCLES

TABLE OP THE MUSCLES. 1-37

MUSCLES WHICH MAKE THE OS RADIUS TVRN ON THE
OS CUBITUS,

JBj/ carn/ing itforxcardsfor pronation.

NEW NAMES. OLD NAMES.

4.' Epitrochlo-radun Round fronatcr.

3. Cubito-radian Square pronator,

Bj/ pulling it outwards for supination.

3. Epicondylo-radian. > Short supinator,

4. Humero-super-ratiian. ..... Long supinator.

MUSCLES WHICH MOVE THE CARPUS OR WRIST ON THE

PORE-ARM,

Si/ bending it.

-J. Epitrochlo-carpian Cubital, inferhr,

a. Epitrochlo-metacaipian Raiial inKrhr.

By pitUing it backtcards.

"}. Cubito-super-metacarpian. , . . . Cubital, rxter'ior,

4. Epicondylo-iuper-metacirpian 1st and 2ri. . Radial, rxterhr Yst and id.

Brachial, anti-brachial and palmar aponeurosis ; annular ligament ,
muscles xvhich seem to act on t/ie palmar aponeurosis.

5. Epitrochlo-palmar • . Slfnder cubital, long palmar,

i, Pklmo-cutian • • . Cutaneous palmar.

MUSCLES WHICH CONTRIBUTE TO THE MOTION OF THE
FINGI'.RS,

By bending the last four fingers.

\. Common epitrochlo-phalangian, . . . Sublime or prrf orated firxor .

2. Common cubito-phalangettian. , . . profound or perforating fiexor,

3. Falmo-phatangian. .... Lumbricaf.

4. MeUcarpo-phalangian^ interior. . » . Interosseous interior or inferior.

By extending the last four fingers.

5. Epicondylo-sapcr-phalangettian, common. . Common extensor of the fingers.
§. Metacarpo-phalangiaHj exterior. . . . interosseous, superior or ixierior.

By bending the thumb,

T. EaHio-phalanjettian of the thumb. . . . Lcnz flixor of Ihe thumb.
8. Cirpn-phalangian of the thumb. , . . Short fiexor of the thumb.

By extending the thumb.

9. Cubito-!upcr-pha!angePian of the thumb. . Lmg extensor of the thumb,

iO. Cubito-jupcr-phalangian of tiie thumb. . . short extensor of the thumb.

By bringing the thumb nearer the other fingers.

:■.. M-tacarpophalans'ar. 01 ihi ;h-ijnib. . . Adductor cf the thurai.

By^

138 • ORGANIC STRUCTURE.

Bj/ removing the thumh from the other fingers.

NEW NAMES. OLD NAMES.

12. Cubito-super-metacai-pian of the tHumb. , tons abductcr of the thumli.

13. Caipo-super-phalangian of the thumb. . lihort abductor of the tJiumh,

Br/ carrT/'ing the thumb before the other fin f^ers.

14. Carpo-metacarpian of the thumb. . , -Metacarpianof the thumh ^ or oppossr^'

By extending the index finger.

15. Cubito-saper-phalangeftian of the index. . Proper extensor of the index,

JBy bending the little finger.

16. Carpo-super-phaiangettian of the little finger. Short flexor of the little fift^er,

Bi/ extending the little finger.

n. Epicondvlo-super-phalangcltian of the little 7

> Proper extensor of thelittlejitiger.
finger. ....... y

By removing the little finger from the rest.

38. Carpo-phalangian of the little finger. . . Abukctor of the little finger,
ly. Carpo-metacarpian of the little finger. ... Opjtoser of the little finger.

MUSCLES WHICH MAKE THE THIGH MOVE ON THE PELVIS,

JBy 'pulling it hacktoards and outx:ards.

1. Sacro-femorian Gluteus maximus.

2. Greater ilio-trochanterian. .... Gluteus mediiis.

3. Lesser ilio-trochancerian. .... Gluteus minimus.

By making it turn outxvards.

4. Sacro-trochanterian. ..... Pyramidal.

5. Iscliio-trochanterian. ..... Gem-ini.

6. Sub-pubio-trochanterian, interior. . j . Interior obturator.

7. Sub-pubio-trochanterian, exterior. . . Exterior obturator.
S. Ischio-sub-trochanterian. . . . ^ square of the thighs.

■ By bending if forwards.

9, Pr^elumbo-trochantinian. .... Psoas.

10. Ilio-trochantiiiian. ..... Iliac,

11. tjuper-pubio-feuiorian. ..... Pectinalis.

By pulling it inwards,

12. FublO", sub-pubic-, and Ischio-femorian. . . Three adductors, or triceps adductor.

MUSCLES WHICH MOVE THE LEG ON THE THIGH,

By extending it. "

I, Ilio-rotullan. . ; Straight or slender anterior.

2. Triferaoro-rotuliaa.

Vast interior, vast m terior^ and crural or triceps
crural.

By

TABLE OP THE MUSCLES. 13§

Bt/ he7iding it.

f.T;W NAMES. OLD KAMES,

5, Ischio-sulj-tibian. . ..... Semi-rtiembranous.

A, Ischio-pi^etibian Seml-tendmsus.

5. Ischio-peronean • • B'.ceps.

€. Poplito-tibian, . . - ... Popiitian.

Bi/ bending it and pulling it intvards.

■7. Ilio-praetLb^2n. ; ,. Sartorius.

». Pubio-oraetibian. Slender intirhr.

FEMORAL APONEUROSIS AND MUSCLE WHICH ACTS ON IT,

Bi/ contracting it.

1. Aponeurotic-ilio-feniorJan Miuck of the fascia Utj.

MUSCLES WHICH MAKE THE FOOT MOVE ON THE LEG,

By extending it.

1. Bi-femoro-calcanean Gemellus, gastrocnemius.

"i. Tibio-calcanean Soleus.

3. Femoro-cakanean Tibialis cr slenier plantaris.

By exteiiding it and pulling it in'wards.

A. Tibio-sub-tarsiar. Tihidlis posticus.

By extending it and pulling it out~.vards.

5. Pcroneo-sub-tarsUii. . . , '. . Lon^ peroneas.

By bending it.

f:. Tibio-sub-ursian Tibialis amicus.

By bending it and pulling it ouiti-ards.

7 Greater peroneo-supcr-tarsian. . . . Middle peroneus,

• I.ess pcroneo-snper-tarsian. .... Less peromus.

Tibial and plantar aponeurosis and annular ligaments.

MUSCLES WHICH SERVE TO MOVE THE TOES,

By bending the last four toes.

1. Tibio-phaUngeftian, common. . . . Long common flexor.

2. Cilcaneo-sub-phalangettian, common. . . Short common fiexor,

3. Mctatarso-inter-phalangian, infenor. . , Infrrior interosseous.

4. Planti-sub-phalaniian Ltmbrical.

By straightening the last four' toes.

5. Peronco-supei-phalangettian, common. . Long common extensor of the toes.

6. Calcaneo-super-phalangettian, common. . Pedious, orshort common extensor cf the tees.
1 Macatarso-inur-phaUngianj superior. , . Superior interosseous

Bi/

140 ORCANIC STUUCTUREi*

By hringmg the articulations of the bones of the metatarsus closer
to the Jirst phalahgesy in the form of an arch.

NEW NAMES. OLt) NAMES.

8. Trjnsverse-metatarso-phalangian. , . . Transverse cf the toes.

By trending the great toe.

9. Pcronco-sub-phalangettian of the great toe. . L!:ng flexor ofthr ^rtat toe.
10, T»rso-sub-phalansian of the sreat toe. . . Short flfxor of the great toe^

By straightening the great tocj

It. Peronco-jTiijcr-phalangettian. of the great toe. Extensor oftht great toe.

By bringing the great toe nearer to the rest.

12. Metataiso-sub-phalangian of the great toe. . Adductor of thf%reat toe.

By removing the great foe from the rest,

■13. Cilcaneo-sub-phllangian of the gieat toe. . AMuctor of the great toe.

By bending the little toe.

14. Tarso-sub-fhalans'ian of the little toe. . . Short flexor of the little' toe.

By removing the little toe from the rcsi^

ij. Cilcaneo-sub-phalanjian of the littk toe. Abiuctirof the VttU tu>

CEREBRAL

[ I'll 1

CEREBRAL AND NERVOUS SYSTEM.

S3 7" The cerebral and nervous fyjtem in animals.
The cerebral and nervous l}'(lem in zoophytes,
has the fame appearance as the other parts ; for
the gelatinous and homogeneous confidence of
the fubilance of thefe animals prevents their dif-
ferent organs from being diftinguifhed. It can-
not, however, be fuppofed that this fyflem is
wanting in animals, which have the fenfes of
touching and fmell exceedingly delicate, and
which are fenfible to the impreffions of the light,
heat, and moifture : it is probable that it is equally
difleminated throughout their whole fubftance ;
and as thefe animals can be divided into feveral
parts, fufceptible of increafe and life, this opinion
feems thence to acquire a further degree of
ftrcngth.

The cerebral fyflem begins to be obferved in
worms, the nereids and amphinoma j it confifts
of a long cord divided by knots ; in the leech
the knots are more perceptible, and appear to
be ganglions. Thefe ganglions are very diftindl
in the aculeated aphrodite (aphrodita acuJeata),
where theyatTume an arrangement which is found
among infedls.

In the mollufca acephaJuy fuch as the oyfler, the
cerebral fyftem confifts of two ganglions U'nitcd
by two nervous cords.

142 ORGANIC STRUCTURE.

In the gafteropoda, fuch as the fnail and the
flug, this fyftem confifts of a cerebral ring around
the cEfophagiis, and a greater or lefs number of
ganglions, fcattered throughout the different or-
gans. Thefe parts have a communication with
each other by means of a cord, and give birth to
the nerves.

In the mollujca cephalopoda^ fuch as the cuttle-
£fh (fip'id officinalis and/epia o^opiisj, the cartilage
of the, head contains a peculiar cavity, in v;hich
is lodged the cerebral collar, and this cartilage is
pierced with holes to afford a paffiige to the
nerves.

Infe6ls and the crujlacea have a brain, confiiiing
of two lobes, from which proceed nerves for the
eyes, the antenns and the mandibles : this brain
then furnifhes two nervous cords, which furround
the Gsfophagus, and proceed to a feries of gang-
lions, more or lefs numerous, united by a cord,
and giving birth to the nerves which are diflri-
buted to the other parts.

238. In vertebral animals^ the cerebral and ner-
vous fyitem is more com.plex ; and notwithftand-'
ing the great variety of configuration which mull
occur among animals fo different as tithes, rep-
tiles, birds, and the mammalia, this fyflem
feems to be eftablifhed in them all, according to
a uniform^ plan. It always confifts, ift, of an
- organ contained in the cavity of the cranium
r encephaJon ;

CEREBRAL AND NERVOUS SYSTEM. 143

encephaJon; 2d, of a prolongation lodged in the
hole or cavity of the vertebral column : the cere-'
hral or rachidian prolongation ; '^di, of a nervous
cord^ or a feries of ganglions, united by a nervous
cord, fituated interiorly on the fides of the ver-
tebral column : trifphnchmc. Ganglions alfo are
found in various parts. Nerves diflributed to all
the organs proceed from thefe different fources.

2,39. Eifcephalon. The encephalic fyllem, and
its prolongation, are inclofed in a double mem«
brane ; tiie exterior, which is thicker, is called
the meninx of dura mater .-the interior (men'mghie)
confifts of two membranes, the exterior one of
which is called the arachnoid, and the interior the
pia-mater.

The encephalon always exhibits the two lobes of
the brain, the layers of the ocular nerves, the
cerebellum, and the commencement of the cere-
bral prolongation. Thefe parts are very different-;
in the various elatlesj but they almoft always give
birth to twelve pairs of nerves which proceed from
the cranium, to dillribute themfelves to the fame
number of organs.

The fiVft pair proceed to the noftrils, by tra-
verting the os ethmoides. The ethno'idql.

The fecond pair to the eye, where they form
the retina. The ocular.

The third pair to the mufcles of the eye. The
common cculo-mufculdr.

The

144 ORGANIC STRUCTURE.

The fourth pair to the large oblique mufcle of
the eye. The interior oculo-mujcular.

The fifth pair divide themfelves into three
branches, which are diftributed to different parts
of the face. The trifacial.

The fixth pair proceed to the right exterior
mufcle of the eye. The exterior ocido-mnjcidar.

The feventh pair proceed to the face. The
facial.

The eighth pair, to the labyrinth of the ear.
The lahyrinthic.

The ninth pair, to the pharynx and mufcles of
the tongue. The fharyngo-glojfian.

The tenth pair, to the organs of refpiration and
digellion. The pneumo-m/iric ,

The eleventh pair, to the tongue and its muf-
cles. The hyo-gloffian.

The twelfth pair arife from the rachidian pro-
longation, and afcend into the cavity of the cra-
nium, from which they are diftributed to the cer-
vical and dorfal regions. The trachelo-dorfal.

In fifhes, birds, and reptiles, the different parts
of the ehcephalon are more or lefs di(lin6l and
feparated ; fo that thefe parts often touch each
other only in one point : in the mammalia they
approach each other, and arc in fome mcafure
contbunded.

\vi quadrupeds, the brain, which is flat and
fliort, leaves the cerebellum uncovered behind.

In

CEREBRAL AND NERVOUS SYSTEM. 145

In apes it aflumes more thicknefs, and is conti-
nued backwards on the cerebellum. This arrange-
ment is more apparent in man.

In fifhes, reptiles, and birds, the furface of the
brain is fmooth ; in the mammalia it exhibits cir-
cumvolutions. In man and the dolphin thefe cir-
cumvolutions are numerous and deep : in apes
and carnivorous animals they are lefs vifible, and
in the rodentia fcarccly appear.

In fiflie?, the encephalon is very fmall ; it oc-
cupies only a part of the cavity of the cranium,
and is compofed of a double feries of tubercles,
united in a point. Two of thefe tubercles repre-
fent the lehes of the brain j two others form the
ocular layers ; that which conftitutcs the cere-
bellum is comparatively very large ; in the laft
place, - there is one which produces the con;j-
mencement of the cerebral prolongation.

The encephalon of fifhes-has behind the cere-
bellum various other fmall lobes, which give birth
to fome pairs of nerves, not found in the other
clafl^s.

The encephalon of reptiles varies greatly in the
different genera of this clafs ; but it is ahvays
formed of diftindl tubercles for the lobes of the
brain, the ocular layers, the cerebellum, and the
cerebral prolongation.

In birds the encephalon eonfids of fix tuber-
cles : two of thefe form the lobes of the brain ;

VOL, X. L two

146 ORGANIC STRUCTURE.

two others the ocular layers : one conftitutes
the cerebellum, and the laft the cerebral prolon-
gation.

In the mammalia thefe parts approach each -
other, To that the lobes of the brain are almoft
united ; the ocular layers are confounded with
the brain ; but the cerebellum remains difliniil.

Each lobe of the brain has in the middle a
cavity : 'ventricle. The ventricles of the brain
affiime various configurations, and the fides of
them have feveral prominences : that found in all
vertebral animals is a protuberance marked vi'ith
ftrias ahernately gray and v^'hite in the infide,
among the mammalia j and with fome whiter
lines, in the other claffes : corpora Jiriata^Jiriated
bodies. Thefe bodies are very large in birds, and
conftitute almoft alone the whole lobe of the
brain. '

The upper part of the lobes of the brain, w^hich
is continued with the ftriated bodies, and forms
the hemlfpheres, is thin in fithes, reptiles, and
birds : in the mammalia it alTumes more thick-
oefs, and in man its thicknefs is confiderable.

Thefe ventricles have in the iniide alfo feveral
prominences, which in different ciailes of animals
are wanting, either in v/hole or in part ; and
which we Oiall examine minutely in man.

In fifhes, reptiles, and birds, the layers of the
ocular nerves are diftincl, feparated, and exhibit

ventricles

k

• CEREBRAL AND NERVOUS SYSTEM. 147

ventricles in the infide : in the mammalia tbacy
are found in the fubfiance of the lobes of the brain,
and have no ventricles. Below and between the
ocular layers is a third ventricle.

The cerebellum in all animals is a diftinc^ part :
in fifhes it is round and very large ; in birds it is
flatted in a tranfverfe direction. In the mamma-
lia there are two lateral lobes and a middle lobe.
In mauj the middle lobe^ which is very fmall, is
concealed by the other two.

In fifhes,, reptiles, and birds, the furface of the
cerebellum is fmooth ; in all the mammalia it is
marked with tranfverfe and parallel furrows. The
cerebellum is united to the brain by two tranfverfe
peduncles ; and the latter proceed to two longitu-
dinal peduncles, by means of which the brain is
continued with its cerebral prolongation.

The commencement of the cerebral prolonga-
tion is generally marked by a diftincl tubercle, of
a different form.

Between the cerebellum and the rachidian pro- .
longation is 2l fourth ventricle, in which is always
obferved a thin medullary lamina, called impro-
perly a valvula.

All the ventricles have a communication with each

other by foramina, the fides of which are contiguous.

In birds, the anterior ventricles are fhut on the

interior fide by a thin and radiated partition.

The conduit which forms a communication bc^

L 2 tween

148 ORGANIC STRUCTURE.

tween the third and fourth ventricle is called the
aquedu^ of Silv'ius. The ventricles of the ocular
layers have a communication, by this aquedu(5l,
with the other ventricles.

Before and behind the third ventricle is always
found a tranfverfe cord : the two comnujfurae,
the anterior of which is generally longer and thin-
ner, the^o/^mor larger and ftiorter.

Before the third ventricle is a funnel-like exca-
vation, which is direded downwards, and conti-
nues with a tube that adheres to a tubercle. This
tube and tubercle are diflinguifhed by the naqie
of the pituitary gland.

In all vertebral animals is found a tubercle,
C2Mtdiht pineal gJa7id.

In the mammalia arc obferved fome parts
which are not found in the other claiTes.

In the bottom of the interval, which feparates
the two lobes of the brain, is a large band, the
extremities of which are folded downwards: nie^
foJohe,

Below, is found a triangular protuberance, arch
with three pillars : two of its angles are prolonged
backwards and downwards j the third is tbrmed of
two cords, united, which proceed forwards and
downwards. This trigone is continued inferiorly
and anteriorly with a thin partition, called the
feptiim lucidnm. This partition, which feparates
the two ventricles of the brain, is formed of two
6 contiguous

CEREBRAL AND NERVOUS SYSTEM. 14g

contiguous laminae ; the triangular fpace left be-
tween them is known by the name of the j^ftb
'ventricle.

In a part of the ventricles of the brain is found
an elongated protuberance, which in quadrupeds
is larger than in man^ cornna ammonis (ram's
horns). x

Above the aqueduct of Silvius there are four
tubercles [tubercula quadrigemina)^ which are alfo
larger in quadrupeds than in man. The two an-
terior {nates), which are higher, are much larger in
graminivorous than in carnivorous animals: on
the other hand, the two pofterior {tejles) are much
more voluminous in the carnivorous than in the
graminivorous.

Fiihes and birds have alfo four tubercles ; but
they are placed before and above the ocular
layers.

In apes and in man, the ventricles of the brain
are continued backwards, with a cavity {digitalis)
which lodges a protuberance {thefpiir),

240. Cerebral or rachidian prolongation. The
cerebral prolongation gives birth to as many pairs
of nerves as there are inter-vertebral fpaccs.
Each rachidian nerve arifes from two roots, fepa-
rated by a thin membrane ; thefe two roots pafs
through the meninx, and proceed to a ganglion
which gives birth to two nervous branches.

L 3 The

150 ORGANIC STRUCTURE.

The rachldian or vertebral pairs are diilin-
guifhed into cervical, dorfaJ, limihar, pelvian, and
caudal; and are ditiributed to different parts of
the trunk.

The laft cervical and the firft dorfal pairs unite
to form a plexus, which furnifhes the nerves of the
thoracic member. The lad lumbar and the firft
pelvian form the plexus^ which furnifhes the nerves
of the pelvian member.

'1^1, Trlfplanchnic. All vertebral animals, on
the fides of the prasfpinal face of their vertebral
column, have a nervous cord in the fame manner
as fifhes ; or a feries of ganglions united by a ner-
vous cord, in the fame manner as the mammalia
and birds. This lyilem has a communication, by
filaments, with all the vertebral and with fome of
the encephalic pairs : it furnifhes branches which
are difiribuled to the veflels of the three large
cavities.

242. Cerebral aiid nervous Jyjlem of man. In
man, the cerebral and nervous fyflem is compofed
of the encephalic organ, the cerebral prolongation,
the trifplanchnics and various ganglions and nerves
which proceed from thefe different parts.

Encephalon. The encephalic organ compre-
hends the brain, the cerebellum, the mefence-
phalon, and the commencement of the cerebral
prolongation. It has the form of the cavity of the

cranium.

M

CEREBRAL AND NERVOUS SYSTEM. 15 i

cranium in which it is contained ; it is foft, and
its gravity is to that of water as 13 lo is to 1000,
It forms the thirtieth part of the weight of the
body in adults, the feventh or eighth part at the
period of birth, and nearly one hah*" of its total
weight during the firfl months of conception. Its
furface exhibits a number of deep finuous anfrac-
tuofities over which the fanguine vefTels are fpread.
The blood which arrives at this oro;an has been
efli mated at nearly the feventh or eighth part of
that which ifTues from the aorta. The cerebral
arteries are exceedingly fiexuous, and thei;; tides
are very thin : at the bafe of the cranium they
form an anaflomotic circle ; they then expand over
the whole furface of the brain, divide and fubdi-
vide themfelves into communicating branches, and
terminate jn very delicate ramifications, which
penetrate into the fubftance of the brain, and in a
great meafure difappear from the fight.

The blood returns by veins without valves ex-
ceedingly flexuous, which prefent frequent anafto-
mofes, and do not follow the dire6lion of the ar-
teries ; they form diftincSt branches, which, inftead
of uniting to conftitute trunks, pour the bJoDd
obliquely, in the inverfe diredtion of its courfe,
into linufes or membranous ducts.

Though we do not know what takes place be-
tween tbefe two orders of circulation ; though the
encephalic organ prefents itfclf under a pulpy and
L 4 homo-

152 ' ORGANIC STRUCTURE,

homogeneous appearance, and though microfcopic
obfervation (hows nothing in it but a colledlion of
very fine globules, every thing announces the
moft perfedl organization^ and the moft import-
ant fecretion.

In the interior, the encephalic organ exhibits a
ilru61ure altogether peculiar; the fides of the ca-
vities are lined with a thin membrane ; there are
found alfo protuberances, fmall bands^ cords, ftriae
of different forms, colours and dcniities ; holes, fif-
fares and conduits, which have a communication
with each other ; and the whole of thefe forms,
exceedingly numerous, exhibits a confiant regu-
larity.

In the lafl place, this encephalic organ and its
rachidian prolongation are covered by a double
membranous tunic, and enclofed in flrong ofleous
cavities ; they give birth to numerous pairs of
nerves, which proceed to every part of the body ;
thefe nerves divide themfelvesinto branches, which
are fubdivided into very delicate ramifications,
that fpread in all the organs, penetrate into every
part of them, where they terminate in different
ways, and carry thither the principle of a6fion and
of life.

As we are unacquainted with the particular ufe
of the different parts which enter into the compo-
fition of the encephalic organ, the defcription of
them is merely graphic.

243. The

CEREBRAL AND NERVOUS SYSTEM, 1^3

2,43. The double membrane which envelops
this organ {men'mx and men'mg'me) form folds which
are interpofed between its lobes.

The 7nemnx {jdura mater) is a thick, femi-tranf-
parent membrane, over which the meningian ar-
teries are fpread : it lines the interior face of the
cranium, to which it ferves as periofteum and
ilrongly adheres to it, efpecially along its futures
and at its bafe. Its interior face covers the me-?
ningine, without adhering to it.

The meningine (pa mater) confifls of two lami-
nae, clofely united ; the interior of thefe laminae
furnifhes different folds, of which there are three
principal ones. One of them extends from the
ethmoidal ridge to the occipital protuberance, and
forms a partition between the tw^o lobes of the
brain : 7nedian feptum ; falx of the brain.

Another is placed below the pofterior part of
the brain, which it feparates from the cerebellum ;
it extends from the occipital protuberance to the
fuperior edge of the apophyfis petrofa; it is
pierced before with a hole for the mefencephalon :
trarifverfe feptim of the cereheJliim j tentorium of th^
cerehellum.

A third extends from the occipital protuberance
to the occipital hole, and feparates the two lobes
of the cerebellum * : median fepum of the cerehel-
lum {falx of the cerehellum).

The

* The meninx furnifhes alfo two foIJs, which extend from

the

354 ORGANIC STRUCTURE.

The meninx is prolonged through all the holes
of the bafe of the cranium, and accompanies the
parts which ifllie from them. It furnifhes chiefly
a meningianjljeath to the rachis': this (heath adheres
along the vertebral canal, envelops the rachidian
prolongMion, and furrounds the origin of the
nerveswhich proceed from it.

The meninx in different parts of its thicknefs
has difierent conduits, often of a triangular form
{/mils'), vv'hich receive the blood of the veins, and
pour it into the gulf of the jugular. Thefe
linufes are very numerous : but there are reckoned
to be four principal ones : one of them extends
from the ethmoidal ridge to the occipital protu-
berance, along the upper edge of the median fep-
tum of the brain: median finus [fuperio?' longitu^
d'maljlnus). It there divides itfelf into two lateral
fmufes hollowed out in the thicknefs of the adhe-
ring edge of the tranfverfe feptum of the cerebel-
lum, which extend as far as the occipito-petrean
hiatus, and proceed to the jugular foflae. Thefe
Unufes exhibit in the interior fome tranfverfe fraena,
and a few fmall granulous bodies.

At the bafe of the med'an feptum of the brain,
and near the tranfverfe feptum of the cerebellum,
is a clmridlan fmus (Jiraightfmus), which tranfmits
into the lateral finufes, the blood it receives
from the choroidian veins, and from ihe inferior

the anterior cIlMoid apophyfes, to the pofterlor, and two others
which ruix along the fmall alss.of the fphenoid.

longitudinal

CEREBRAL AND NERVOUS SYSTEM. 155

longitudinal finus. The latter proceeds along the
median feptum of the cerebellum*.

The meningine is a thin tranfparetvt membrane^
fituated beneath the meninx, and which envelops
the encephalicorgan and its prolongation ; it is
formed of two laminae, between which are di-
iperfed a great number of veflels.

The exterior lamina {arachnoid) covers the ex-
terior face of that organ ; it accompanies, to the
place where they iiTue, the nerves which proceed
from it; and then bends back on the interior face
of the meninx, in the fame manner as the ferous
membranes-]-. This lamina has feveral prolonga-
tions : one of them penetrates into the lateral
ventricles, and covers the different prominences,

* The meninx forms alfo feveral fmall finufes, fomc of which
run along the pofterior edge of the median feptum of the cere-
bellum. Occipital Jinufes ; others are placed along the upper
edge of the petrous apophyfis : fjipsrior petrous finufes. Be-
low the preceding, there are two others which extend along the
articulation of the petrous apophyfis with the occipital : Inferior
fetrousfimifes : they empty themfelves direftly into the gulf of
the jugular.

hfmus is fituated tranfverfely on the bafiliar apophyfis, and
communi-cates with the two preceding ones.

Two ca'venious fniifes are lodged in the carotid canals, and
open into the petrous fimfes. In the laft place XMioJmufes., one
before and the other behind the fella turcica, communicate
with the cavernous, and form a circle (coronarj) around that
part.

f See Traitil des Membranes, du C. Richat.

obferved

166 ORGANIC STRUCTt^RE.

obferved m them. Another covers, vvith thd
meninx, the rachidian prolongation; accompa-
nies to the place where they iiTue the nerves
which proceed from it, and bends back on the
interior face of the meninx. The interior lamina
of the ineninglne ip'ia mater) produces prolonga-
tions which penetrate into all the anfradtuofities
of the brain. It accompanies the meninx in its
different paflages, and produces along the verte-
bral canal indented expanfions, which are inter-"
pofed between the anterior and pollerior bundles
of the nerves o( the rachis.

The furface of the brain exhibits numerous flex-
nous and deep anfradliiofities, and is divided Xoa-
gitudinally, at the fummit, into two lobes, fepa-
rated by the median feptum. Each of thefe lobes
may be divided inferiorly into three lobules.
The firil reils on the orbitar arches; the fecond is
lodged in the temporal fofiae ; it is feparated from
the flrfl by a deep fcilTure: the third reiis on the
cerebellum, from which it is feparated by the
tranfverfe partition of the meninx.

When the two lobes of the brain are feparated,
there is feen a large white band, which unites thefe
two bodies near their bafe. C. Chauifier has given
it the name oi mejohlie* : (^corpus callofum).

The

* We ftiall provlfionally adopt the more rational language
which C. Chauflier ha$ fubllitutcd for the whimfzcal and ridicu-
lous

■M

CEREBRAL AND NERVOUS SYSTEM. J s;-

The fuperior face of the melblobe is covered by
the fharp edge of the longitudinal -feptum^ and by
fanguine vefleis ; it exhibits in the middle a fort of
future, and on the fides tranfverfe ftriaa.

The pofterior extremity of the mefolobe, which
is broader than the ant(Jrior, forms a thick, round
roll. The mefolobe occupies nearly the middle
half of the fpace comprehended between the fore-
head and the occiput ; it is, however, nearer to the
former. It continues on the fides with the whiie
fuhjiance (medullary) of the lobes of the brain. This
part forms in the middle of the lobes an oval centre,
furrounded by the gray fubflance (cortical).

Below the mefolobe are the two ventricles of the
brain (lateral ventricles). Thefe cavities, the fides
of which are contiguous, defcribe in their paflfage
two oval furrows, interrupted before, placed back to
back internally, and feparated from each other by a
thin lamina : median fejytum of the ventricles^ {Jeptum
lucidum).

Thefe furrows, taken towards their anterior and

lous nances employed by the antients to denote the different parts
of the encephalic organ. But, it muft be confefled, that zootomy
will never be in poffeffion of a nomenclature completely fatisfac-
tory, and fufceptible of being generally adopted, until intelligent
anatomifts employ themfelves, as the modern chemifts have done,
to reform the language of their fciencej and until, after adopting
a method of nomenclature, they fhall have given to the different
parts names fuited not only to the organs of man, but alfo to the
fimilar or analogous parts in animals, fo as to conncft by lan-
guage two bri^ncheg of natural hiftory, which ought never to be
feparated.

interipF

158 ORGANIC STRUCTURE.

interior extremity, proceed backwards till they ap-
proach near to the pofterior lobes, where they are
refledled outwards, and return in the thicknefs of
the middle lobes, directing themfelves forwards and
downwards.

The ventricles of the brain are broad at their
entrance, and terminate in a point behind; in their
paiTage they defcribe the portion of a curve, th6
convexity of which is turned outwards.

The median feptum is formed of two very thin
laminse : thefe laminae, which are not contiguous^
leave between them a vacuity, in which a ferous
matter is fometimes colled ed. Ventricle ofthefep'*
lum, {^th ventricle).

The fides of the ventricles of the brain have pro-
tuberances and cavities, which are fitted to each
other, fo as to leave no vacuity between them ; they
are lined with a very fine ferous membrane, which
is a coritinuation of the meningine, and which fe-
cretes a lymphatic dew ; when this lymph is col-
letHed, it diflends the fides of the ventricles, and
forms of them real cavities.

Along the bafe of the ventricles proceeds a
membrano-vafcular^/^^z/j. of a reddiOi colour, free
and floating at the top, which adheres by its inte-
rior face to the ferous membrane that covers the
ventricles. This body feem.s to be formed by the
union of the arteries which proceed from the mid-
dle lobar, and the veins which convey the blood
into the choroidian finus : choroid plexus.

Q Below

CEREBRAL AND NERVOUS SYSTEM. 15^

Below the median feptum and the choroid
plexus, and at the inferior fide of the ventricles, is
a body of a white fabftance, which has the form of
a right-angled triangle, cerehral trigone, (arch with
three pillars). The anterior angle terminates in
two cords, which defcend between the layers of
the ocular nerves. The two pofterior angles turn
backwards and outwards, and terminate in a point
in the exterior and inferior part of the ventricles.
The inferior face, which is flightly excavated, ex-
hibits a triangular fpace, on which are obferved lon-
gitudinal ftrise in the form of a Jyre.

On the fides of the ventricles there are two
broad, round eminences, which approach each
other before, and terminate gradually in a point
behind. The outfide of them is formed of a grayifh
fubftance, interfperfed in the interior with white
ilrias, which proceed from a centre of the fame ,
colour, pyriform eminences, (ftriated bodies).

Towards the middle of the ventricles of the
brain, below and behind the pyriform eminences,
are two whitifh ovoid protuberances, covered by
the choroid plexus, and the cerebral trigone, layers
of the ocular nerves, (layers of the optic nerves). ■
They are confounded on the outfide with the lobes
of the brain ; and the exterior part of them coniifts
of a white ftratum, which mixes itfelf with the gray
fubftance in the centre.

The pyriform eminences, and the layers of the

ocular

l60 ORGANIC STRUCTURE.

ocular nerves, are feparated, on each fide, by a fur-
row, which lodges a fmall grayifh femi-circular
band. Thefc fmall bands are thicker and nearer
each other before than behind. Small bands of the
fyriform eminences, (fmall femicircular bands).

In that part of the ventricles, which is turned
pofteriorly outwards and downwards, are two
whitifh, oblong, cylindric protuberances, thin and
narrow behind : their anterior extremity, which cor-
refponds to the termination of the ventricles, is
broader and thicker, and exhibits three or four light
tubercles, feparated by furrows : cylyndro'id p-otu-
herances, cornua Ammonis, ranis horns.

On the interior fide of the cylindroid protube-
rances, at the termination of the poflerior pillars of
the trigone, is obferved a grayifh lamina, indented
and free towards its exterior edge. The bordered
or fringed bodies, (corpora fimbriata). The exte-
rior fide of thefe protuberances exhibits an emi-
nence, broader behind than before, which corre-
fponds to an anfra6luofity of the inferior part of the
brain. The accejfories of the cylindroid frotube-
ranees, (accefibries of the cornua Ammonis).

Above and behind the cylindroid protuberances
are two cavities, in the form of a bag, hollowed out
in the fubftance of the pofterior lobes of the brain,
appendices of the ventricles, (digital cavities). In
thele cavities is obferved an unciform enmence,
broad before, terminating in a point behind, and

bent

CEREBRAL AND NERVOUS SYSTEM. i5l

bent inwards, (the f pur) which is formed by a pro-
minence of a gray fubftance, cov&red by a white
flratum.

The fides of the ventricles are lined with a
very fine ferous membrane, overfpread with arte-
ries and veins. The veins unite to thofe which
proceed from the choroid plexus, and form in
each ventricle a choroldiah vein (vein of Galen),
which approaches that on the oppolite fide, be-
tween the layers of the ocular nerves. Thefe
veins proceed backwards, and anaftornofe in a
connmon fhort trunk, which enters the anterior
extremity of the right finus.

The lavers of the ocular nerves leave between
them an interval in the form of a fifiure, the third
ventricle. This interval is bounded at the top by
the cerebral trigone, and at the bottom by the
mefencephalon. The ocular layers are united at
the bottom by a foft grayifh tubercle ; before
this tubercle is obfervcd an elongated aperture :
anterior aperttire (vulva) ; and behind a round
aperture, pojierior aperture (anus) : thefe apertures
cdmrnunicate with the lateral finufes, and arc
cbvered fuperiorly by the cerebral trigone. The
lateral finufes are bounded at the bottom by the
rhefencephalon.

Before the anterior aperture is a whitifh cord,
which extends profoundly, in a tranfverfe direc-
tion, into the fubftance of the middle ventricles

VOL. I. M of

iu2 0RGA^3IC STRUCTURE.

of the brain, and turns in the form of a bow «
anterior coimni[jura .

Below the anterior commiffara is a funnel-
Qiaped excavation ; the bottom of this excavation
is continued with a folid grayifh peduncle, which
terminates at a round tubercle, refting on the
body of the os {^hcvio'ides-. juperf2he7ioidal -peduncle
and appendix (pituitary peduncle and gland).

Below and behind the pofterior aperture of the
third ventricle is afecond whitifh cord, larger
and (liorter than the anterior, which extends
tranfverfely in the ftrata of the ocular nerves :
pGJlerior commijfura.

. Behind the pofterlor commifllira is a fmall
grayifli conical body, of the lize of a pea, foftilh,
and often containing .gravel in the infide : tlje
conarium (pineal gland). The bafe of the cona-
rium, which is turned forwards, feems to adhere
to two very fine white cords, which pafs over "the
pofterior commifllira, and arc continued on the
interior fides of the ftrata of the ocular nerves:
pedwicJes of the conarium (the kidneys).

The conarium refts above the four vt'hite tuber-
cles: tubercles uf the mefencephalon (tubercula
quadrigemina). The two fuperior and anterior
of thefe tubercles, which are oval and larger
(nates), are continued before with the pofierior
commifiLira. The two inferior ones, which are
round and fmallcr (teftes), are continued with the

fuperior

CEREBRAL AND NERVOUS SYSTEM, l63

i\iTp&v\oY prolongations of the peduncles of the cere-
bellum, and with a vvhitith lamina, rounded at the
top and covered with horizontal Arise: medullary
lamhia of the cerebellum (valvule of VieutTens),

Below the polterior commifTura and the tuber-
cles of the mefencephalon is a canal, which pro-
ceeds downwards : intermediate canal of the ven-
tricles (aqueduct of Sylvius). It proceeds be-
tween the fides of a fourth cavity : fourth ven-
tricle.

This ventricle is fituated below and between
the peduncles of the cerebellum. It exhibits be-
fore, a longitudinal groove and two lateral ones,
which terminate obliquely in a point on the firfl-,
and refemble thfe cut part of a pen (calamus
fcriptorius). Behind, this ventricle is clofed by the
medullary lamina of the cerebellum ; the bafe of
it correfponds to the cerebral prolongation, and
at its fummit is found the aperture which con-
ducts to the third ventricle.

The third and fourth ventricles contain a fmall
choroid plexus; their fides are contiguous, and
lined Vv^ith a feroiis membrayie, overfpread with
fanguine veflcls. This membrane continually
pours forth a lymphatic dew, which is fome-
times found in a pretty large quantity, and whiah,
in this cafe, diftends the fides of thefe cavities.

In the lafi: place, the brain exhibits below and
in the middle two large peduncles (prolongations

M 2 of

104 ORGAN-IC STRUCTURE.

of the brain, crura of the brain, crura of the me-
dulla oblongata) j thefe peduncles arife from the
inferior part of the pyriform eminences. They
feparate at their origin, and are placed behind the
fuperfphenoidal fhank j they unite with thofe of
the cerebellum, and concur together to the for-
mation of the mefencephalon. Before thefe pe-
duncles, there are two round tubercles tituated
clofe to each other, which refult from the bifid
termination of the anterior pillar of the trigone :
pyriform tubercles (mammillary eminences).

244. The cerebellum is lodged in the occipital
(o^dd, which determine its form : it is fituated un-
der the pollerior lobes of the brain, from which it
is feparated by the tranfve^fe feptum ; its volume .
is nearly the eighth or ninth part of that of the
cerebrum. It is divided pofteriorly, into two lobes,
by a fcifTure, which lodges the medimi feptum, and
on its furface has deep tranfverfe furrows, which
interfe(5t each other at an acute angle.

The furface of the cerebellum exhibits alio a
pretty large number of mammillary protube-
rances ; in general, there arc five on the upper
face, ten on the inferior, and two or three
behind.

Between the lobes of the brain before is a pro-
tuberance, placed behind the quadrijumelli tuber-
cles : 7yiedlan protuberance of the cerebellum (fuperior
vermicular eminence) ; at the bottom and in the

middle

CEREBRAL AND NERVOUS SYSTEM, 105

middle is found the median lohde (inferior ver-
micular eminence).

The number of laminae produced by thefe an-
.fra(5luolities, is from 25 to 30 on each face. Be-
tween thefe laminae are found others itnaller
and thinner.

The laminas of the cerebellum are formed of a
gray fubftance, and ramifications of a white fub-
ftance; the white ramifications of feveral laminag
unite and form branches. Thefe branches pro-
ceed to a white nucleus, placed in the middle of
each lobe of the cerebelkim (arbor vita).

The middle and anterior part of the cerebellum
furnilbes two large cords or peduncles^ which arife
in the white centre of its two lobes. Thefe pe-
duncles become larger, and each divides itfcif into
three btmdles : one afcends before, and unites
with the inferior tubercles of the mefencephalon ;
the other proceeds to the lateral parts of the bulb
of the cerebral prolongation ; the third, which is
much larger, concurs towards the formation of
the mefencephalon : fuperior, middJe^ and inferior
prolongations of the cerehelhm.

The peduncles of the cerebellum are formed of
a very white fabflance, which towards the centre
contains a yellowilli. gray fubflance. They unite
with the peduncles of the brain to form the ?nefen-
cephahn (annular protuberdnce — pojis Varolii).

245. The mefencephalon is found below the
M 3 brain

]66 OPvGANIC STRUCTUREo

brain and before the cerebellum; its fuperior face,
inclined backwards, correfponds to the third ven-
tricle, and the intermediate canal of the ventri-
cles ; its inferior face, which is rounded, refi;s on
the balillary eminence of the occipital bone. On
its middle part is obferved a longitudinal furrow
or raphe, which lodges the trunk of the mefen-
cephalic artery. Its anterior convex part is con-
tinued with the peduncles of the brain ; its pofterior
concave part correfponds on the fides to the pe-
duncles of the cerebellum ; and in the middle
gives birth to the cerebral prolongation. The
exterior part of its fubllance confifts of white
fibres, which lofe themfelves in the gray fubftance
of the interior part. It. exhibits tranfverfe or hori-
zontal fibres, interfedled at right angles by two bun-
dles of a whitifh fubllance ; one on the right, the
other on the left. Thefe bundles traverfe the mefen-
cephalon, expand and proceed before to the pyriform
bodies, and behind to the cerebral prolongation.

246. The commencement of the cerebral or
rachidian prolongation is feparated from the me-
fencephalon by a tranfverfe furrow; its- form is
pyramidal and quadrilateral ; its anterior face, in-
clined downwards, has in the middle a longitu-
dinal furrow, on the fides of which are obferved
the pyramidal eminences, Thefe eminences are
feparated by a longitudinal furrow from two other
em'mcnccs called the OJivana'ru
' \ ' 7 The

CEREBRAL AND NERVOUS SYSTEM. ] 6/

The diameter of the rachidian p-oVongation
(medulla elongata) is to that of the brain as i to
7 ; it has the form of ihe cavity which contains
it. At its entrance into that cavity it is large, and
decreafes towards the fourth cervical vert&bra, but
increafes towards the following ones. It then
decreafes along the dorfal vertebrae, and again
becomes larger towards the laft of that region.
This prolongation terminates, towards the iirti:
Inmbar vertebra, in two tubercles, fituated before
the other, and feparated by a groove : they give
birth to a bundle of nerves which occupies the
reft of the vertebral canal.

The cerebral prolongation is of a fofter con-
iiftence than the brain ; its fubftance is white,
And in the infide has a grayifh furrow. It gives
birth to thirty pair of nerves, which ifTue through
the vertebral holes.

247. Encephalic nerves. The brain, at its
bafe, gives birth to twelve pair of nerves, which
ifTue through different holes of the bafe of the
cranium.

248. Thtfrjt pair arife from the inferior and
anterior part of the brain, by three filaments ;
two of which coriie from the interlobar fciffure ;
the third, interior, ifilies before and below the
pyriform eminences. Thefe filaments unite into
a thick triangular cord, which foon becomes
fmallcrt this nerve advances under a furrow of

M 4 the

l6g ORGANIC STRUCTURE.

the anterior lobe oX the brain, and approaches
that of the oppofite lide ; it becomes larger and
terminates on the fides of the ethmoidal lidge, in
a round tubercle^ e'xceedingly foft, femi-tranfpa-
rent and grayifh.

This tubercle gives birth to from 20 to 24
very delicate filarnents^ which traverfe the holes
of the cribriform plate of the os ethmoides, de-
fcend along very fmall canals, and proceed to the
pafal foiisq. A part of thefe nervous filaments
are diilributed within, on the feptum, and with-
out, on the fuperior and middle cornets: they
then become fo flender and pulpy, that they
efcape the fight. Ethmoidal nerve, olfa6Iofy.
Xhis nerve, in moll quadrupeds, is hollow.

249. The fecond fair arife from the pofterior
and- inferior of the ocular firata.

The cords of which they are compofcd feparate
by bending around the peduncles of the brain,
and approach each other before the anterior com-
ipiflura ; they then again feparate ; proceed ob-
liquely towards the ocular holes, and penetrate
into the orbit enveloped in a ftieatb, furnifhed by
Ihe meninx.

The ocular nerve paffes between the tendons
of the four ftraight mufcles; when it arrives behind
the lobe of the eye, it pierces the fclerotica and
the choroid, becoming fmaller, and then expands
to form the retina : Ocular nerve, opiic.

• 250. TIk,

CEREBRAL AND NERVOUS SYSTEM. igp

250. The third pah' arife from an excavation
found between the peduncles of the brain, near
the mefencephalon, and ilTue in feveral filaments,
which unite into a cord. This nervous cord di-
verges from that on the oppofite lide, advances
behind the pofterior clinoid apophyfes, pafles
through the fphenoidal fiffure, and penetrates into
the orbitar cavity, where it feparates into two
branches : one of tbcfe, called the fuperior, dif-
tributes itfelf by feveral filaments to the fuperior
flraight mufcle, and proceeds to the orbito-palpe-
bralian ; the other branch, which is larger, divides
itfelf into three fmaller branches : the firll^ or
inferior, which is the largeft, diftributes itfelf to
the interior ftraight mufcle, palling under the ocu-
lar > nerve; the fecond, or exterior, which is
longer, firft furnifhes a ramus to the orbitar gan-
glion, and then diftributes itfelf to the fmall oblique
mufcle ; the third proceeds to the inferior right
mufcle : CaMMON oculo-muscular, common
mover.

251. The fourth pair arife by two or three
fmall filaments, clofe to each other, between the
peduncle of the cerebellum, and the inferior tu-
bercles of the mefencephalon ; turn round on the
fides of the mefencephalon ; advance along the
cavernous finus, in a canal formed by the meninx,
and penetrate into the orbit by the fphenoidal
riifure. This nerve pafi[es under the common

oculo-

170 ORGAJNIG STRUCTURE,

oculo-mufcnlar, proceeds towards the" upper and
interior tide of the orbit, and diflributes itfelf to
the large oblique mufcle: Interior oculo-mus«
cuLARj pathetic.

252. The fifth 'pair arife from the inferior and
anterior part of the peduncles of the cerebellum,
near the mefencephalon, in two portions: one,
behind, coniifts of about thirty filaments united ;
the other, before, which is fmaller, confiils offe-
veral lax filaments. This nerve pierces the meninx
towards the petrous apophyfis, and form.s there a
plexus, which gives three branches. The tri-
facial, the trigemn'i.

Of thefe three branches one penetrates into the
orbit by the fphenoidal fiffure : the orhlto -frontal ;
the other proceeds to the face by the large round
foramen ; the fuh-maxillary : the third diftributes
itfelf to the lower jaw : the maxillary'.

A, The OKBiTO'FRO'S'TA'L, ophthahnic of inilis,
on entering the orbit divides itfelf into three rami.

a. One proceeds over the periofieum of the
arch of the orbit; iffues through the faper-orbital
foramen, and diftributes itfelf to the eye- lid and
the fore-head : the palpehro-frontal (frontal or fu-
percilian). In its palTage, it divides itfelf into two
rami : the interior' rainus fends out a filament
which uni'es to another of the nafal ; it ifibes
from the orbit above the cartilaginous pulley
f/r^f^'i J .'.and feparates into a great number of

foiall

CEREBRAL AND NERVOUS SYSTEM. I7I

fmall branches^ which are diftribnted to the
fronto-fupercilian mufcle, the occipito-frontian, the
integuments, and the bulbs of the cilia.

The exterior ramus, which is larger, follows
the diredlion of the mufcle that raifes the eye-
lid i ifllies through the fuper-orbitar foramen, and
divides itfelf into a great number of filaments,
diftributed to the eye-brows, the fore- head, and
even to the fummit of the head : a filament unites
to a branch of the facial in the fubflance of the
eye-lid.

h. The other ramus proceeds along the exterior
fide of the orbit, diftributes itfelf to the lachry-
mal gland and the upper eye-lid : lachrymal. In
its paffage it throws out a filament which ifTues
again through the fpheno-maxillary fifTure, and
communicates with another of the fuperior maxil-
lary ; a fecond filament pafles through a hole of
the OS jugale ,and anaflomofes with another of
the facial ; the trunk then traverfes the gland, and
lofes itfelf on the conjund^ive membrane.

c. The lad, the nafo-palpehral (nafal), throws
out a filament on its entrance into the orbit:
this filament unites to another which comes from
the fuperior cervical ganglion of the trifplanchnic^
and both proceed to the orhitar ga7iglio7i. The
nafo-palpebral nerve then proceeds towards the
interior fide of the orbit, and divides itfelf into
two rami.

The fitO paffes through the anterior orbitar

hole,

172 ORGANIC STRUCTURE.

hole, and penetrates into the cranium^ traverfing
the cribriform plate of the os ethmoides ; it then
re-enters the nafal foflae, by another hole of that
bone ; gives fome filaments to the anterior ethmoi-
dal and frontal cells f defcends behind the- bones
of the nofe along their cartilages, and expands on
the lobe of the nofe.

The fecond proceeds towards the interior angle
of the orbit, where it unites to a filament of the
frontal ; it then paffes under the cartilaginous
pulley of the great oblique mufcle, diflributes it-
lejf to the neighbouring parts, and terminates at
the eye-lids : palpehral.

The ORBiTAR GANGLION, ophthalmic or lenticu-
lar, is very fmall ; it is found on the exterior fide of
the ocular nerve, near its entrance into the orbit. It
receives the two filaments already mentioned and
another very fhort one tranfmitted to it by the
common oculo-mufcular : there proceed from it
ten or twelve filaments, which furround the optic
nerve ; traverfe the fclerotica in different parts,
creep over the choroid, and expand on the irisi
irici?2>

B. The super-maxillary, fuperior maxiU
lary, ifTues from the cranium, through thefuperior
maxillary tbramen. On ifiuing from that hole, it
throws out a ramus which penetrates into the or-
bit, by the fpheno-maxillary filTure; the orhitar :
it then proceeds towards the exterior fide of that
cavity, and divides itielf into two filaments : one

of

CEREBRAL AND NERVOUS SYSTEM. IJg

of thefe unites to the filament of the lachrymal,
which traverfes the os jugalis ; the other pierces
the orbitar portion of that bone, and penetrates
into the temporal fofla, where it unites with a fila-
ment of the inferior maxillary.

The fuper-maxillary nerve penetrates into the
fumrait of the zygomatic fofla ; and furnifhes two
filaments, which proceed to \he-fphenoidal ganglion.
It throws out alfo feveral others which proceed
behind the maxillary fin us : fome penetrate into
the tuberofity of that bone, and terminate in the
den tar cavities of the lalt molar teeth {pojierior
dentary), the relt are diftributed to the gums and
the buccinator mufcle.

The fuper-maxillary then enters the fuper^
orlniar canal, along which it gives out a ramus {^in-
terior dentary) that divides itfelf into feveral fila-
ments. Thefe filaments pierce the alveolar edge,
and diftribute themfelves to the roots of the other
teeth : one of thefe filaments communicates with
another of the pofterior dentary.

The fuper-maxillary nerve then ifTues through
the fub-orbitar foramen, and divides itfelf into a
great number of rami, which have- a communica-
tion with each other and with filaments of the
facial ; their aggregate forms a fort of plexus, the
ramifications of which are diflributed to the muf-*
cles of the nofe, the lips and the cheek.

The SPHENOIDAL GANGLION, fpheno-pahtbie,

is fituated at the fummit of the zygomatic fofla ;

5 , it

174 ORGANIC STRUCTURE.

it receives, independently of the two filaments
furnifhed to it by the fuper-maxillary, a ramus
formed by the union of a filament of the facial
and another of the upper cervical ganglion.

The firft filament (the fuperior ramus of the
vidiari) ifTuesirom the injlex canal of the os tem-
pofis, through the hiatus of that bone, efcapes
from the cranium through the anterior foramen
lacerum, and unites itfelf to the fecond filament ;
the latter (the inferior branch of the vidian) arifes
from the fuperior cervical ganglion of the great
iympathetic, afcends along the carotid canal, and
its union with the firft produces the pterygoidian
(vidian) nerve ; this nerve traverfes the canal of
the fame name, and proceeds behind the Jphenoi-
dal ganglia?!.

The fphenoidal ganglion furniflies feveral rami
or filaments.

a. The largeft of thefe proceeds towards the
pofterior palatine canal, which it penetrates, after
throwing out one or two filaments that pafs
through the holes in the fuberofity of the palatine
bone ; thefe filaments diftribute themfelves to the
guttural conduit of the ear, to the velum palatiy
and to the uvula. The gulturo-^alatine (palatine).
This large ramus then traverfes the pofterior pala-
tine canal, and on ifTiiing from it divides itfelf into
feveral filaments, which are diftributcd on the
palatin^e arch : the fuperior palatine.

h. The other filaments, furniflied by the fphe-
noidal

CEREBRAL AND NERVOUS SYSTEM. I7S

noidal ganglion, arife fram the interior pari of it ;
penetrate into the nafal foilaSj through the fpheno-
palatine foramen, and dillribute thcmfelves on the
exterior fide of that cavity : The ethmoidal (fphe-
no-palatine). One of thefe filaments defcends in
the infide on the partition of the nofe, to the bot-
tom of the entrance of the noftrils, where it pafles
into the anterior palatine foramen, unites to that
on the oppofite fide, and forms a bulb or ganglion,
which correfponds to the palatine arch behind the
dentes incifores : the nafo-palatine.

c. The MAXILLARY, inferior maxillary, is the
largeft branch of the trifacial : it ifi^lies from the
cranium by the inferior maxillary foramen, pene-
trates into the zygomatic fofi^a, and fends out a
great number of rami, which form two bundles.
The firfi: or fuperior one fiarnifiies :

a. A ramus which defcends below the exterior
pterygoidian, pafi^es before the condyle of the jaw,
and expands in the zygomato-maxillian mufcle :
the fuh- zygomatic.

h. Two filaments, which afcend in the temporal
fofia, difi:ribute themfelves to the mufcle which
covers it, and unite with a filament of the orbitar :
the iem'poro-mufcular .

c, A ramus which defcends between the pterygo-
maxiliian mufcles, gives fome filaments to the
fmall pterygo-maxillian, as well as to the tempore-
maxillian \ pafies behind the coronoid apophyfis of

the

l'^6 ORGAWIC STRUCTURE.

the jaw, expands into ieveral filaments, in the
bucco-labian mufcle, communicating with the fa-'
cial and the fub-orbitar : tBe hueco-lahian,

d. In the laft place a dehcate and profound
ramus which defcends before, and didributcs itfelf
to the grand pterygo-maxilhan mufcle : theperygO"'
mujcular.

The fecond or lower bundle furniihes :

a, A ramus which defcends behind the condyle
oi the jaw, fends out a filament to the auditory con-*
duitj and another which communicates with the
facial at the place where it ifTues from the flylo-
iDaftoidian foramen. This ramus is then refledled
before the ear, and divides itfelf into two filaments^
which are diftributed to the temporo-maxillian
mufcle, accompanying the fupcr-facial temporal
artery, and communicating with filaments of the
facial : the cutaneous temporal.

h. A ramus which defcends obliquely behind
the ramus of the lower jaw, pafles under the fiib-
maxillary gland on the mylo-hyoidian mufcle, pro-
ceeds to the fides of the tongue, and lofes jtfelf at
the point of it : the I'mgual.

In its pailage, this ramus receives the tympanic
ramus arifing from the facial : it then throws out
two or, three filaments which form a plexus or
ganglion, whence proceed other filaments which
are diftributed to the fub-maxiilary gland and fur-
round .the fub-lingual artery: the fub -maxillary y

In

CEREBRAL AND NERVOUS SYSTEM. 177

In the laft place, it furniflies fome filaments
which are diftributed to the fab-lingual gland,
and others which proceed to the membrane of the,
mouth, and communicate with filaments of the
hyo-gloiiian mufcle.

The lingual then feparates into two rami ; one
of which fends out filaments that proceed to the
mufcles of the tongue ; the other furnifhes fome
which are ramified on the fides and at the tip of
it, and tvhich, by their termination, form the papiliss
of that organ.

c, A third ramus, which arifes from a trunk,
common to the preceding, the maxillo-dentary^
defcends behind the condyle of the jaw, and pro-
ceeds towards the maxillary canal. Before it en-
ters this canal it gives out a filament which is dif-
tributed to the maxillary gland, the mylo- and
genio-hyoidian mufcles {the rnylo-hyoidian) : this
ramus then runs through the dentary canal, and
in its pafi^ge fends out filaments, which proceed
to the dentary cavities of the large and of the firft
of the fm^Il dentes molares {dentary). When it
comes oppofite to the hole of the chin it furnifhes
a filament which follows the diredlion of the den-
tary canal, and is diftributed to other teeth: it then
ifl'ues through that hole, is refledled upwards, and
divides into feveral filaments, which expand to the
mufcles of the lower lip and the cheek.

253, ThQ fixth pair arife in feveral united fJa-
VOL. I, N ments

ly.S ORGANIC STRUCTURE.

men ts from the furrow which feparates the mef-
encephalon from the cerebral prolongation. This
nerve is fiat, advances towards the point of the
petrous apophylis, and pierces the meninx to pro-
ceed into the cavernous finufes, where it receives
two filaments^ which embrace the anterior cere-
bral artery : thefe filaments, which arife from the
fuperior cervical ganglion of the tri-fplanchnic,
form a. plexus around that artery ; it then pene-
trates into the orbit by the fphenoidal fiffure, and
diftributes itfelf to the exterior right mufcle of
the eye. Exterior oculo-muscular, exterior
motor,

254. The /eventh pair arife from the triangular
foilet which is found between the mefencephalon
and the exterior fide of the bafe of the rachidian
prolongation, near the olivarian eminence : it pro-
ceeds outwards with the labyrinthic nerve, then
, bends forwards and proceeds to the auditory fora-
men. This nerve foon feparates from the laby-
rinthic to penetrate into the fpiroid canal of the
temporal : it paffes through its different windings
and gives feveral rami, which are diftributed to
the face. The facial, the hard portioii of the
feventh pair.

a. One enters the cranium by the hiatus of the
temporal bone, iffues through the anterior foramen
lacerum, and unites to a ramus which afcends ^
from the fuperior cervical ganglion of the tri-

Iplanchnic

CEREBRAL AND NERVOtJS SYSTEM. l^Q

fplanchnic by the carotidian canal : it then pro-
ceeds to the fphenoidal ganglion ; the pUrygoidian.
h. Others very fmall proceed to the mufcles of
the fmall bones of the tympanum.

c. A third, which is very delicate, penetrates
into the tympanic cavity, pafies between the incus
and the malleus, applies itfelf to the membrane of
the tympanum^ iffiies from that_ cavity by the
glenoidal fcifllire, and forms a communication
with the lingual nerve of the maxillary: tlfe tym-
fame: (cord of the tympanum.)

d. The facial nerve ifllies from the fpiroid canal
by the ftylo-maftoidian foramen, and immediately
produces feveral rami : one afcends before the
raaftoid apophyfiSj and diftributes itfelf behind the
ear, the pqfierior auricular \ others defcend be-
low the fterno-mafioidian mufcle, and proceed to
the tracbelo-occipitian and the ftylo-hyoidian muf-
cles : the fuh-majtoidmyi, and Jiylo~hyoid'ian : the
former communicates with the pharyngo-gloffian
■mufcle.

The facial nerve then defcends in the fubftancc
of the parotid gland, where it divides itfelf into
two branches. ,

e. The firit proceeds upwards, palfes before
the articulation of the jaw^ and divides itfelf into
feveral rami^ fome of which are diflributed on the
temples: the fuper-orlntar. Others are diftributed
belov/ the eye and lofe themfelvcs in the orbicular

N 2. and

180 ORGANIC STRUCTURE.

and zygomato-Iabian mufcles: the fuh-orhttar ^
the third proceed acrofs on the cheek, and expand
into a great number of filaments on the mufcles
of that part and on thofe of the lips, the lahiah
thefe rami are anafiomofed with the preceding
and with an orbitar ramus of the maxilla^y.

f. The fecond branch defcends behind the
angle of the jaw, and divides itfelf into fevera!
rami: fome proceed before the zygomato-maxillian
jnufcle, the mentonmary and divide into a great
number of filaments which are diftributed to the
mufcles of the chin : they communicate with the
filaments of the fuperior branch and rami of the
buccal. Others defcend under the chin : thefub-
mentonniari and expand on the cutaneous mufcle
into a great number of filaments, which communi-
cate with fome arifing from the firfi: cervical pairs.

255. The eighth pair are placed behind the
preceding, to which they are connected by fome
filaments : the root of them is turned back on
the pofterior edge of the median protuberance of
the cerebellum : it is confounded behind with that
of the oppolite fide.

This nerve accompanies the facial to the interior
auditory foramen, which it abandons towards the
orifice of the fpiroid canal, and penetrates into the
vefiibulumj where it divides itfelf into twobranches ;
one proceeds forwards and expands in the form of
fi br Lifh i[] the ramps of the cochlea ; the othef

proceedv*^

CEREBRAL AND NERVOUS SYSTEM. 181

proceeds backwards and divides itfelf into three
rami, which are diftributed in the veftibulum and
in the interior of the femi-circular canals. The
LABYRiNTHic ^'E'B.YE, fofl portion of the feventb
fair.

256. The ninth pair of nerves arife in three or
four filamenis, from the peduncle of the cerebral
prolongation, near the olivarian eminence. This
nerve iflues from the cranium by the pofterior
foramen lacerum, and immediately receives a fila-
ment from the facial, and another larger from the
pneumo-gaftric. It defcends along the ftylo-glof-
iian m'ulcle, throws out filaments which follow the
divifions of the maxillo-facial artery, and which
concur to the formation of the plexus furrounding
the divifions of that artery. This nerve gives out a
great number of filaments, which diflribute them-
felves to the mufcles of the pharynx, and its in-
terior membrane, the pharyngian. Some unite to
others arifing from the pneumo-gaftric, the handle
of the hyoidian and the tri-fplanchnic, and form
a plexus on the fides of the pharynx.

The nerve of the ninth pair then defcends be-
tween the fiylo-pharyngian and ftylo-gloffian
mufcles, gives filaments to them as well as to the
tonlillas, and is lofi: by diftributing itfelf to the
mufcles which are at the root of the tongue.
The pharyngo-glossian, glosso-pharyn-
GiAN, hranch of the eighth pair,

, N 3- 257. The '

182' - ORGANIC STRUCTURE.

2-5 7. The tenth pair arife from the cerebral
prolongation by ten or twelve filaments^ which
ifTue immediately behind thofe of the preceding
nerve. Thefe two nerves pafs together through
the pofterior foramen lacerum, where they are fe^
parated by a membranous produftion.

This nerve defcends before the neck, and pene-
trates into the thorax, where it gives out rami to
the lungs. It then iffues from that cavity with
the oefophagus, enters the abdomen, and diftri-,
bates itfelf to the flomach and liver. The
PNBUMO-GASTRic, eighth pair, wandering pair.

Qn its iiTuing from the cranium, this nerve far-
nidies filaments which communicate with ^the
pharyngo-gloffian, the hyo-glollian, and the tri-
fplanchnic ; it then defcends before the neck, and
gives out a large ramus, which pafies behind the
anterior cerebral artery, and which proceeds to
the larynx, where it divides itfelf into two rami:
one of thefe is diftributed to the mufcles of the
pharynx and to the oefophagusi the pharytigian :
the other, which is larger, penetrates into the
larynx, enters the os hyoides and the thyroid
cartilage, and divides itfelf into feveral filaments,
which are diftributed to the mufcles and the iiiv
terior membrane of that organ : the laryyigian.

The pneumo-gaftric nerve then defcends on
the exterior fide of the anterior cerebral artery;
furniflies one or two filarnents to the cardiac

plexiiSj

C,EREBRAL AND NERVOUS SYSTEM. 183

plexus, and penetrates Into the breaft. It pafTcs
before the fub-claviar artery, and on the left before
the aorta, where it give§ a large recurrent ramus ;
the tracheal. This tracheal ramus proceeds in-
wards, is refle6ied on the fub-claviar artery or
aorta, and furnifhes feveral filaments to the cardiac
plexus: it then afcends again on the fides of the
tracheal artery, gives numerous filaments to it as
well as to the oefophagus, the oefophagmi ; and at
length reaches the larynx, into v/hich it penetrates
between the cricoid and the thyroid cartilages,
vs'here it terminates in feveral filaments, which are
diflribufed to the mufcles of that organ, forming
a communication with thofe of the laryngian nerve.

This nerve furnifhes alfo a very great number of
filaments, which concur to the formation of the
pulmonary plexus.

The two pneumo-gaftric nerves delccnd along
the oefophagus, one before (that on the left) and
the other behind (that on the right). They reci-
procally throw out a great number of filaments,
which form a plexus around that canal. When
they reach the abdomen, the one hefore divides
itfelf into feveral filaments, vv^hich follow the fmall
curvature of the fiomach, and expand on its dia-
phragmatic face. Some of thefe filaments proceed
to the liver, and concur towards the formation of
the hepatic plexus. The one hehind divides itfelf
^Ifo into numerous filaments, fome of which are
N ^ diftributed

184 OR<JANIC STRUCTURE,

diftributed to the orifice of the oefophagus and the
inferior face of the ftomach : the reft concur to the
formation of the coeliac plexus.

258. The eleventh pair arife towards the middle
of the furrow placed between the pyramidal and
the olivarian eminences, and lower than the latter,
in feparate filaments, which foon are colledled
into two or three bundles of a pyramidal form.
Thefe bundles unite, and, iffuingfrom the cranium
, through the anterior condyloid foramen, are dif-
tributed to the neck and the tongue. Hyoglos-
SI AN, ninth pair, great hypoglojfn, lingual.

On iflliing from the cranium, the hyogloflian
Bcrve accompanies the pneumo-gaflric, the direc-
tion of which it foon crofles. It receives a ramus
of the fub-occipital, at the height of the tranfverfe
spophyfis of the atloid, and defcends obliquely
before the anterior cerebral artery.

Towards the middle of the neck this nerve gives
out a branch which unites to one or two filaments
of the fub-occipital, and to filaments furnifhed by
the fecond, third, and fometimes the fourth cervi-
cal pair. Thefe parts form together a reticulated
arch of the hyoidiam nerves, the convexity of which
turned downwards, gives birth to four or five twigs
forihe depreffing mufcles of the os hyoides.

The trunk then throws out a branch to the
hyo-thyroidian mufcle, the hyo-thyroidian ; then
palTes between the mylo-hyoidian and hyo-gloflian

mufcles.

CEREBRAL AND NERVOUS SYSTEM^ 1^6

mufcles, and penetrates under the tongue, where
it divides itfelf into feveral filaments : fome of
thefe communicate with the lingual nerve, and
others are diftributed to the mufcles of the tongue,

259. The tiv elf ih ■pair avKe, in feveral feparate
filaments, from the iides of the cerebral prolonga-
tion, towards the middle of the trachelian region,
Thefe filaments afcend along the rachidian canal,
unite at a very acute angle, and form a common
trunk, which ifTues through the pofterior foramen
lacerum, on the exterior fide of the pneumo-
gaflric nerve.

In its paflage, or on its ifTuing from that hole,
this nerve gives out or receives a ramus, which,
united to feveral others of the pneumo-gaftric,
diredls itfelf inwards on the anterior cerebral ar-
tery, furnifhes fome filaments to the plexus v/hich
furrounds the divifions of that artery, and ex-
pands on the fides and in the top of the pharynx.
This nerve defcends before the tranfverfe apo-
phyfis of the atloid j traverfes the fterno-mafloi-
dian, after having furnifhed fome filaments of
communication to the firfl cervical pairs, and dil^
tributes itfelf to the dorfo-fuper-acromian mufcle.
The trachelo-dorsal, the fpiiial or aecejjhry
of Willis.

2.60. Vertebral nerves. Thefe nerves are
in number thirty on each fide, viz. eight Mn the

cervical

ISD ORGANIC STUUCTtTRE.

cervical region^ twelve in the dorfal, five in the
lumbar, and five in the facral.

Thefe nerves arile from the cerebral prolonga-
tion in a great number of filaments united into
two bundles, the pofterior of which is larger than
the anterior : both thefe proceed to a ganglion
which gives out only one nervous trunk. This
nerve foon divides itfelf into two branches, which
ifiue through the vertebral holes, and proceed, the
one behind and the other before,

%6i. The cervical pair&. The poderior branches
of all the cervical pairs^ the firft excepted, have
a communication with each other, and pafs be-
tween the trachelo-occipitian raufcles and the
tranfverfe of the neck. The two firft are then
refle61ed, and lofe themfelves in the teguments of
the occiput, while the reft are didributed to thofe
of the neck.

The anterior branches have alfo a communica-
tion with each other, and all prefent one or more
filaments of communication with the trifplanchnic,
- The firft cervical pair arifes between the occi-
pital and the atloid ; its anterior branch proceeds
above the tranfverfe apophyfis of the atloid ; fur-
rounds it in part, and anaftomofcs before it with
a ramus arifing from the anterior branch of the
fecond pair.

The pofterior branch, which is larger, dire 6ls

ititlf

ia

CERIBRAL AND NERVOUS SYSTEM. ] 8/

jtfelf towards the triangular interval left between
the atloido-occipitian, the atloido-fub-maftoidian,
and the axoido-atloidian mufcles, where it diftri-
butes itfelf, and becomes loir in the mufcles
which cover the former.

The anterior branch of the fecond pair fiib-
divides itfelf into three rami, one of which unites
with the anterior branch of the firft pair, and con-
curs to form the nervous arch which is obferved
before the tranfverfe apophylisof the atloid. From
this arch arife filaments, which proceed to the
trifplanchnic, the hyo-gloxTian and the pneumo-
gaftric. The fecond ramus unites to a filament of
the third pair, to form the nervous arch of the
hyoidian nerves ; the third, after giving out fome
filaments to the praedorfo-atloidian mufcles and the
great-trachelo-occipitian, concurs to the formation
of the trachelo- cutaneous plexus.

The anterior branch of the third pair fends out
a filament to the nervous arch of the hyoidian
nerves i it then unites to the fourth, and concurs
towards the formation of the idsvi^ -plexus.

The anterior branch of the fourth pair furnidies,
in general, a filament to the diaphragmatic nerve,
and concurs alfo to the formation of that plexus.

The TRACHELO-CUTANEAN PLEXUS is (ituatcd

on the fides of the neck, at the height of the
fourth cervical vertebra, and expands under the
thoraco-facian. It is compofed of two bundles of

nerves,'

2S8 ORGANIC STRUCTURE.

serves, one of which proceeds towards the bead,
aed the other defcends on the thorax.

Th^jirji divides itfelf into three branches, which
afcend, turning back on the pofterlor (tdgQ of the
ilerno-maftoidian : ihs cephalic.

One of them gives out filaments to the thoraco-
facian and the teguments of the anterior and fupe-
rior part of the neck : the fuh-mentonniar.

The other proceeds before the ear, and divides
itfelf into feveral filaments, which are diftributed
to the parotid gland, the auditory conduitj and the
Dcighbouring integuments. Thefe filaments com-
municate with the facial : the zygomafo-auricuJar.

The third proceeds towards the maltoid apo-
phyfis, and divides itfelf into feveral filaments,
which are dif^ributed behind the ear and to the
neighbouring integuments: the occ'ipk a- auricular.

The Jecond bundle of the trachelo-cutanean
plexus, the th&racic^ divides itfelf, like the firfl^
into three branches.

One of thefe brancheSj which is often double^
defcends before the flerno-mafioidian, pafles on
the clavicle, and expands in the neighbouring in-
teguments : Z^^'^^rw^^/.

The other, which is larger, defcends dire^lly,
and expands in the fubftance of the fkin v^hich
furrounds the fhoulder: the acromiaji.

The third is formed of feveral filaments, which
defcend deeply behind^ and diftribute themfelves

CEREBRAL AND NERVOUS SYSTEM, Igg

to the mufcles of the fhoulder: thefe filaments
communicate with the trachelo-dorfal : the fca-

The anterior branch ofthefifrh pair gives out
a filament to the diaphragmatic nerve ; it then
fnrnifhes feveral rami, which proceed backwards,
fend out fome to the trachelo-fcapulian^ dorfo-
fcapulian, and dorfo-fuper-acromian mufcles, and
contribute to th© form.ation of the Irachial phxus.

The DIAPHRAGMATIC ucrve is formed by fila-
ments tranfmitted to it by the anterior branches
of the fourth, fifth, and fometimes the fixth cer-
vical pairs ; it defcends along the neck, gives out
a filament to the trifplanchnic, and penetrates
into the breaft between the artery and the fub-
clavian vein. It runs over the fides of the medi-
aftinum, and reaches the diaphragm^ on which it
expands into feveral filaments.

The anterior branch of the fixth cervical pair
unites to that of the fifth, feventh, and eighth,
and to the anterior branch of the firft dorfal, and
concurs towards the formation of the brachial
plexus.

The BRACHIAL PLEXUS, fituatcd on the infe-
rior and lateral part of the neck, is formed of two
bundles, a fuperior and an inferior.

The fuperior bundle refulta from the union of
the three firft pairs : the iaft two compofe the,
firft. Thefe tv/o bundles approach and crofs each

other.

3gO ORGANIC STkUCTtTR'E.

other, and pafs under the clavicle, embracing tW
fub-claviar portion of the brachial artery. From
tliis plexus then proceed nine diftin6^ nerves or
nervous bundles, vi'hich are diilributed to the
thoracic member.

262. Nerves of the thoracic member*
The firft arifes from the fifth trachelian pair,
proceeds backwards, towards the fuperior ^dge. of
the fcapula, paffes through the notch or hole ob*
ferved in it, and fends filaments to the fuperior
fuper-fcapulo-trochiterian mufcle; it then defcends
under the acromion, enters the fub-fpinal foffa,
and divides itfelf into feveral filaments, which
proceed to the inferior fuper-fcapulo-trochiterian
and the dorfo-fuper-acromian mufcles : the fuper-
fcapuJary.

The fecond, which are- three in number, and
fometimes four, arife from the feventh and eighth
pair. '

One of them defcends obliquely before, and
diftributes itfelf to the iterno-humerian and cofto-
coracoidian mufcles.

The other pades behind the axillary veffels, aiid
divides itfelf into feveral filaments, which proceed
to the cofto-coracoidian mufcle, and the neigh-
bouring integuments.

The third, which, is longer, paffes under the
plexus, and, proceeding to the fides of the thorax,
divides itfelf into feveral filaments^ which expand

CEREBP.AL AND NERVOUS SYSTEM. igi

on the cofto-fcapulian mufcle : the Jleryio-ihrjracic
{thoracic).

The third, the principal ones of which are three
in number, diftribute themfelves in the following
manner: one proceeds to the cofto-fcapiilian muf-
cle, another to the lumbo-humerian, and the fub-
fcapulo-trochinian, and the laft to the fuper-fca-
pulo-humerian and the inferior fuper-fcapotb-
trochiterlan* : the fub-fcapulary .

The fourth ifiues from the pofterior part of the
brachial plexus, and arifesfrom the two laft trache-
lian pairs and the iirft dorfal ; it paifes before the
fub-fcapulo-trochinian, and gives fome rami to it
as well as to the fcapulo-humerian : this nerve then
turnsf round under the bead of the humerus, and
proceeds to the fub-acromio-humerian : the fca-
pulo-humeral (^axillary, ch'cwnfiex).

The fxfth arifes from the fifth and fixth trache-
lian pairs, defcends to the interior fide of the arm,
fends out a filament to the coraco-humerian-muf-
cle, which it traverfes, and glides under the fca-
pulo-radian, to which it fiirnifhes filaments as vveli
as to the humero-cubitian. When it approaches
the articulation it ifllies under the tendon of the
fcapulo-radian mufcle, defcends along the radial
edge of the fore-arm, fending filaments to the
t^^guments of that part, and terminates towards the
ihnmb : the radio- cutaneous {nuif ado-cutaneous).

The fixth is the fmalleft of tbofe furnidied by
7 th^

ig2 ORGANIC STRUCTURE.

the plexus ; it arifes from the laft tracheliart pair
and the firft dorfal. This nerve defcends along
the interior part of the arm, and the fore-arm, to
the little finger. In its paflage it firft fends out
a ramus, which follows the direction of the fca-
pulo-radian mufcle, and diftributes itfelf to the
palmary face of the fore-arm : when it approaches
the articulation of the elbow, it fends out one or
two rami, which pafs before the epitrochlea, are
refledied, and diftribute themfelves on the fuper-
palmary face of the fore-arm. This nerve then
diftributes itfelf along the cubital edge of that
part, as far as the little finger: tj[;e mUto-cutaneous
{interior cutaneous) »

The feventh is the largeft of the brachial
plexus : it arifes from the laft three trachelian
pairs. This nerve defcends obliquely behind^
turning round the humerus ; it then advances
along the radial edge of the fore- arm, and termi-
nates on -the convexity of the hand : the radio^
digital {radial).

This nerve defcends in the fubftance of the
fcapulo-olecranian mufcle, and furnifhes three
rami, which divide themfelves into filaments, and
are, difiributed to three portions of that mCifcle.

Towards the middle of the humerus this nerve
turns round ; pafles between the humero-fiiper-
radian and the cpitrochlo-metacarpian mufcles,
and furnifhes a long cutaneous ramus, which pro-
ceeds

CEREBRAL AND NERVOUS SYSTEM. Ig3

ceeds to the wrift;, and along the fuper-palmar
face of the fore-arm : it gives fome branches alio to
the epicondylo-radian and fuper-metacarpian.

Near the articulation of the elbow the radio-
digital nferve gives out a large branch, which pe-
netrates deeply i furnifhes filaments to the epi-
condylo-metacarpian and the epicondylo-radian
mufcles, traverfes the latter, and is diftributed in
feveral filaments to the mufcles of the fuper-
palmar face of the fore-arm : one of thefe filaments
pafTes under the annular ligament, and expands
on the carpus and the metacarpus. Having fur-
nifhed this branch, the radio-digital nerve conti-
nues under the humero-fuper-radian mufcle along
the radial edge of the fore-arm as far as its mid-
dle part, where it proceeds beneath the fkin, and
divides itfelf into two rami : one of thefe defcends
along the firft bone of the metacarpus, and fepa-
rates into two filaments, which are diftributed on
the fides of the thumb and the radial face of the
index finger. The other proceeds on the con-
vexity of the hand, and divides itfelf into feveral
filaments, which proceed to the cubital face of the
index finger, the two fides of the middle finger,
and the radial face of the ring finger.

The eighth arifes from the laft trachelian pair
and the firft dorfal. It defcends on the interior
fide of the arm, pafTes behind the articulation pf
the elbow, continues along the cubital edge of

VOL. I. o the

]f)4 ORGANIC STRt/CTURE,

the fore-arm, and terminates at the lafl finger's ;
the cubito-digital {cuh'tial).

This nerve follows the interior edge of the fca-
piilo'olecranian mufcle, gives fome filaments to it
near the articulation of the elbow, as well as to the
neighbouriog integuments; then palTes between
the olecranon and the epitrochlea, where it runs be-
neath the ikin, and is refle<5led between the mufcles
on the palmar face of the fore-arm. When it
reaches the lower third of that part it fends out a
ramus, turns round on the back of the hand, and
divides into two filaments, one for the \\\.\\^ finger,
the other for the ring finger and the middle
finger.

The cubito-digital nerve iffues from below the
cpitrochlo-carpian mufcle, paiTes before the annu-
lar ligament, advances towards the palm of the
band;, and divides into two branches.

The firfl is fuperficial, and divides itfelf into
two rami, one of which proceeds to the cubital
fide of th€ little finger and to its mufcles ; the
other feparates into two filaments, which proceed
©n the correfponding fides of the laft two fingers.

The fecond proceeds profoundly below the ten-
dons of the common epitrochlo-phalanginian muf-
cle, and of the common cubito-phalangettian, and
diftributes itfelf, by a great number of filaments,
to the metacarpo-fuper-phalanginian mufcle and
Jo the cubito-fuper-metacarpian of thjjj^ jMinb-

CEREBRAL AND NERVOUS SYSTEM. 3Q5

The ninth arifes from the laft two trachelian
pairs and the firft dorfal pair: it receives a ramus
from the mufculo-cutaneous. This nerve de*
fcends along the interior part of the arm, pafles
before the articulation on the middle of the palmar
face of the fore-arm, and is diftributed to the fin-
gers : tie digital median {median) .

In its paflage along the arm, this nerve accom-
panies the humeral artery ; pafles with it oil the
aponeurofisof the fcapulo-radian mufcle, near the
articulation, and fends numerous rami to the muf-
cles of the fore-arm. One of thefe rami defcends
before the inter-ofleous ligament with the artery
of the fame name ; and, when it reaches the wrift,
traverfes with it that ligament, and is refledled on
the convexity of the hand.

After having furnifhed thefe rami, the digital
median nerve traverfes the epitrochlo-radian muf-
cle, defcends profoundly along the fore-arm till
towards the wrift,. where it becomes fupcrficial,
and gives a ramus to the integuments of the palm
of the hand. It then pafles under the annular
ligament ; becomes broadex and divides itfelf into
five rami, the fv*ft of which is diftributed to the
mufcles of the thumb, and the fecond to the ra-
dial iide of that finger. The third pafl^cs between
the firft and fecond bone of the metacarpus, gives
a filam.ent to the firfl: palmo-phalangian mufcle,
proceeds to the radial fide of the ind^xflnger and

o 2 the

igg ORGANIC STRUCTURE^

the cubital fide of the thumb. The fourth pafTes be-
tween the fecond and third bone of the metacarpus^
gives a filament to the fecond palmo-phalangian
mufcle, and terminates on the correfponding faces
of the index finger and middle finger. The fifth
pafi^es between the fourth and the fifth bone of
the metacarpus, gives a filament to the third pal-
mo-phalangian mufcle, and another of communi-
cation with the cubito-digitalj and terminates by
two filaments on the oppofite faces of the ring and
middle fingers.

263. Dorfal pairs. The twelve dorfal pairs
arife, like the cervical, by two bundles, which
unite to form a ganglion, whence two branches
proceed.

The . pofierior branches proceed between the
tranfverfe apophyfes of the dorfal vertebrae, and
give out rami to the mufcles of the back, which
they traverfe -to diftribute themfelves to the inte-
guments that cover them. The fame difpofition
prevails in regard to all the dorfal pairs.

The anterior branches, which are larger, pafs
between the heads of the ribs, and communicate
by two filaments with the thoracic ganglions of
the large fympathetic nerve.

Thofe of the firft ribs fend filaments to the
inter-cofial mufcles, which they traverfe near the
fi:ernum, and expand before the upper part of the
thorax. Thofe of the laft, which are larger and

more

CEREBRAL AND NERVOUS SYSTEM. I97

more oblique, are diflributed in the fame manner
to the inter-coftal mufcles, which they traverfe to
proceed to the integuments of the abdomen.

We fhall here give a view of the peculiarities
which the anterior or fub-coftal branch of each
pair exhibits.

The firfl pair gives a large cord to the brachial
plexus.

The fecond pafTes under the fecond rib ; about
its middle fends out a ramus which ilTues from
the thorax, and communicates with a filament of
the brachial plexus^ from which refults a long,
Ilender nerve, dillributed along the cubital edge
©f the arm.

The third, in like manner as the preceding,
furnifhes a ramus which is diflributed to the in-
teguments of the axilla : cutaneous of the axilla.

The fourth gives a ramus which divides itfelf
into two filaments : one proceeds to the. integu-
ments of the anterior part of the thorax, and to the
mammilla; the other proceeds towards the fpinal
part of the back.

The fifth and fixth divide themfelves alfo in
their middle into two rami, one of which is diflri-
buted to the lateral parts of the thorax, and the
other proceeds towards the ficrnum.

The Icvcnth gives alfo two rami, one of which

diftributes itfelf to the integuments of the inferior

part of the thorax ; and the other expands in feve-

0 3 rai

JQ8 ORGANIC STRUCTUREe

ral filaments fo the inter-coftian and fterno-coftiaa
mufcles.

The fub-coftal branches of the eighth, ninths
tenth, and eleventh dorfal pairs divide themfelves.
alfo into tvi^o rami, the firfl of which is fubdivided
into tvi^o filaments. One of thefe is refleded on
the fides of the thorax ; the other proceeds on the
mufcles of the abdomen. The fecond ramus is
diflributed alfo among the mufcles v^^hich form the
fides of the abdomen.

The twelfth communicates with the firfl: lumbar
pair; then fends out fome rami, which fupply the
diaphragm and the ilio-tranfverfian mufcle, and
diflribute themfelves, in feveral filaments, to the
mufcles of the abdomen.

2.64. Lumhar pairs. The five pairs of lumbar
nerves are furnilhed by the rachidian prolongation,
in the fame manner as the cervical and liorfal ;
their two bundles produce a ganglion, from which
arifes a trunk that divides itfelf into two branches.

The pofterior branches pafs between the tranf-r
verfe apophyfes of the lumbar vertebrae, defcend
obliquely behind in the fubftance of the mufcles of
that region, and proceed to the integuments of the
nates and. thighs. ,

The anterior branch of the firft lumbar pair di-
vides itfelf into three rami ; one traverfes the prse-
lumbo-trochantinian mufcle, proceeds towards the
anterior angle of the hip-bone^ and feparates into

fevera^l

CEREBRAL AND NERVOUS SYSTEM. IQQ

feveral filaments, which are diftributed to the
mufcles of the abdomen, to the fuperior and ex-
terior part of the thigh, and towards the pubis
{fuper-pihian). The fecond traverles, in an
obhque dire(5lion, the prgekimbo-trochantinidl
mufcle and the ihac fofia, below the peritoneum ;
proceeds towards the anterior angle of the hip-
bone, glides between the mufcles of the abdo-
men, and Jofes itfelf in the integuments of the
groin (inguino- cutaneous). The third defcends
on the interior fide of ihe other two j proceeds
towards the crural arch, and divides itfelf into
feveral filaments, fome of which accompany the
tefticular cord and proceed to the fcrotum :
the reft pafs under the crural arch, are diftri-
buted to the integuments of the interior and fu-
perior part of the thigh, and communicate with
the crural plexus.

The anterior branch of the fecond lumbar pair
divides itfelf into two rami : one proceeds towards
the crural arch, and terminates in feveral filaments,
which diflribute themfelves to the fafcia lata, and
the integuments of the anterior part of the thigh ;
the other, which is kirger, defcends on the body
of the fecond lumbar vertebra, and unites to the
third pair, to concur towards the formation of the
crural plexics.

ThQ anterior branches of the third, fourth, and
« 4 fifth

200 ORGANIC STRUCTURE.

fifth lumbar pairs unite alfo. for the formation of
the fame 'plexus.

i6i^. Saaral^^airs. The five facral pairs arife
from the end of the cerebral prolongation. They
are formed, like the other pairs, by two bundles,
which unite to produce a ganglion, Avhence pro-
ceeds a trunk which divides itfelf into two
branches.

The poflerior branches ifTue through the holes
of the fpinal face of the facrum, traverfe the facro-
femorian mufcle, and terminate at the margin of
the anus and a part of the nates.

The anterior branches, which are larger, ifTue
through the holes of the pelvian face of the facrum,
and by their union concur to the formation of the
hypogajiric plexus and the crural plexus.

The anterior branch of the fourth pair fends
alfo fome rami to the ilchio-coccygian mufcle and
to thofe of the anus. That o{ the fifth, which is
very fmall, iffucs between the facrum and the
coccyx, and diftributes itfelf to the mijfcles of the
anus.

The HYPOGASTRIC PjCExus is formed by feve-
ral rami of the third facral pair, gnd a great part
of the fourth, and communicates with filaments
of the ttri-fplanchnic : it is fituated on the fides of
the bladder, and furniflies a great number of fila-
ixjcnts, which are difiributed to that organ, to the

proftate

CEREBRAL AND NERVOXTS SYSTEM. 201

proftate gland, to the redlum, and to the genital
parts contained in the pelvis : the fdvlart.

The CRURiA.'i.^#LEXus is formed by the laft four
lumbar pairs and the firft four of the facral c it foon
divides itfelf into two others, viz. the /w^w^i^r plexus
diuA Xh& facraL Thefe two plexus, each furnifh
four diilindl nerves, which are diftributed to the
pelvian limb.

166. Nerves of the pelvian limb. Of
the four ner\'es furnifhed by the hanhar plexus to
the pelvian limb :

, The firft traverfes the pr£elumbo-trochant!nian
mutcle, and the iliac fofla, proceeds towards the
anterior tubercle of the ilium, and diftributes itfelf
to the integuments of the fuperior and exterior
part of the thigh and haunch : the exterior cu^
taneous.

The fecond is formed of from three to five fila-
ments, which iiTue through the crural arch, and
diftribute themfelves to the integuments of the
groin and the organs of generation, as well as to
the interior and fuperior part of the thigh: the
inguinal.

The third, the largeft of the nerves furnirtied
by the crural plexus, is formed by the firft four
lumbar pairs : it is placed behind the prselumbo-
trochantinian raufcle, which it traverfes obliquely,
and iftues from the abdomen by the crural arch,
op the exterior fide of the femoral artery.

This

503^ ORGANIC STRireTURE*

This nerve divides itfelf in that place into a
very great number of rami ; the Juferfic'ial ones
are diftributed to the integuments of the anterior
and interior part of the thigh, accompanying the
faphene vein. Of the profound ones, fome defc^nd
between the ilio-praslibian, the rlio-rotulian and
the trifemoro-rotLiiian mufcles, and are fubdivided
into a great number of filaments, which diilribute
themfelves to thefc mufcles. The reft accompany
the crural artery, and proceed to the fuper-pubio-
femorian and the pubio-prastibian mufcles. One
of thefe rami proceeds along the ilio^prstibianj
and paifes on the interior fide of th&knee: it then
defcends along the leg, the t'lhio- cutaneous {Japhene)%
fends out filaments to the anterior face of that
part ; accompanies the faphene vein, and termi-
nates on the convexity of the foot : femoro-fratU
hi a I ^crural).

The fourth arifes, for the moft part, from the
fecond, third, and fourth lumbar pairs ; it defcends
along the interior edge of the praelumbo-trochanti-
nian mufcle, penetrates into the lefler pelvis, and
ifllies from it by the fub-pubian-hole ; giving out
a ramus to the fub-pubio-trochanterian mufcles.

On iflliing from the fub-pubiaq hole, this nerve
divides itfelf into two rami ; the anterior one
pafles between the pubio-rand fub-^pubio- femorian
mufcles, and proceeds to the integuments of the
anterior part of the thigh : the pofterior branch

defcends

CEREBRAL AND NERVOUS SYSTEM. 203^

defcends between the fub-pubio- and tbe afchio-
femorian mufcles, and divides itfelf into a great
number of filaments, which are loft in thefe muf-
cles I ihe fub-fubh'femoral.

Tht,fa(:ral plexus furniflies the other four nerves
of the pelvian Hmb.

The firft afifes from the third and fourth facral
pairs. It ilTues through the ifchiatic notch, and
diftribiites itfelf to the perinseum and the penis ;
ihe ifchio-feman.

This nerve defcends obliquely between the
facro-fciatic ligaments, and divides into two
branches. The inferior one feparates into a
great number of filaments, which proceed to the
mufcles and integuments of the anus ; to thofe of
the perinaeum, to the urethra, the fcrotum and the
dartos. The upper oge proceeds towards the
fciatic tuberofity, patles between the roots of the
cavernous bodies, runs along the afcending branch
of the ifchium and the pubis ; and, on its pailage,
throws out rami which are diflributed to the in^-
terior fub-pubio-trochanterian mufcle, the bulbo-
and the ifchio-cavernous, the ifchio-perinzean, and
the urethra. This branch then continues on the
penis, where it is ramified, and furnifhes filaments
to the glans and prseputium. In the^ female, this
nerve, the ifchio-cTitorian^ exhibits the fame diftri-
bution: its inferior branch proceeds to the large
labia, and the fuperior to the clitoris.

The

^04 ©RGANIC STRUCTURE.

The fecond is compofed of two rami which
ifTue from the pelvis through the ifchiatic notch,
and diftribute themfelves to the facro-femorian
and ilio-trochanterian mufcles : the fejjiers.

The third arifes from the fecond and third facral
pairs, and iffues from the pelvis by the ifchiatic
notch : the Jmall femoro-.poplitean. It firft fiirnifhes
two or three rami which proceed to the mufcles
furrounding the ifchium and the trochanter : the
ijchm-irochanterian ; it then defcends between the
large trochanter and the tuberofity of the ifchium,
and divides into two rami : the interior is refledled
below the ifchium, and diftributes itfelf inwards,
about the upper part of the thigh, to the perinasum
and the penis : the cutaneous fuh-pelvian. The ex-
terior expands beneath the Ikin of the pofterior
part of the thigh, and extends to the ham.

The fourth, which is the largeft, diftributes i|-
felf to the mufcles of the pofterior part of the thigh,
the \&gy and the foot : the great femoro-pop-
LiTEAN. It arifes from the lafl two lumbar pairs
and the firfl three facral, and iffues through the
ifchiatic notch.

It firft furnifhes rami \o the mufcles which make
the thigh turn outwards; it then pafTes between
the great trochanter and the ifchium, and defcends
profoundly along the pofterior part of the femur,
as far as the ham, where it becomes fuperficial.
In its paflage it furnifhes feveral rami to the muA
' cles

CEREBRAL AND NEJIVOUS SYSTEM.' 205

cles of the pofterior and interior part of the thigii.
This nerve, when it reaches the ham, divides itfelf
into two branches, which are diftributed to the
leg and the foot.

A. One of thefe branches, the peroniar^
fends out a ramus around the articulation of the
knee : it furnifhes one or two alfo beneath the
aponeurofis which covers the calf of the leg,
the peroneo-culaneous, and feparates into two
other rami, below the fuperior extremity of the
perone.

a. One, the prat ihio- digit aJ, defcends between
the peroneo-fub-tarfian and the common peroneo-
fuper-phalangettian mufcles, and gives rami to all
the mufcles which are before the leg: when it
reaches the middle of that part it becomes fuper-
ficial, and divides itfelf into two branches. The
interior proceeds obliquely towards the tibial edge
of the foot J fends fome filaments to the integu-
ments of that part, communicates with the tibio-
cutaneous ramus of the femoro-prastibial^ and fe-
parates into two rami, one of which proceeds on
the tibial fide of the great toe ; the other pafles
over the convexity of the foot, and diftributes it-
felf to the oppofite faces of the firft two toes. The
exterior proceeds on the convexity of the foot,
where it divides itfelf into three rami, one. of
which pafles between the fecond and third bone
of the metatarfus, and divides into two filaments,

which

■205 ORGANie StRUCTUREe

which pfoceed to the oppofite faces of the two
correfponding toes. The fecond defeends, in like
manper, between the third and fourth bones of
the snetatarfus, and diilributes itfelf to the corre-
fponding toes ; the laft follows the fame diredlion
between the laft two toes.

h. The fecond branch of the peroniar, the pra-
pUofuper-phniaris, pafTes between the tibio-fu-
per tarfian and the common peroneo-fuper-pha-
langettian mufcles, and defeends before the inter-
oileous ligament, on the interior lide of the tibia!
artery. In this paflage it fends filaments to feveral
mufcles of the anterior part of the leg, and to the
periofteum. This branch then patles under the
annular ligament, and divides itfelf into two rami,
the exterior of which glides under the common
calcaneo-fuper-phalangettian mufcle and the lafl:
fuperior metatarfo-inter-phalangian. The inte-
rior pafles between the firft and the fecond bone
of the metatarfus i fends filaments to the firft
fuperior metatarfo-inter-phalangian mufcle, and
divides itfelf into two rami, which proceed to the
oppofile faces of the firft two toes.

B. The fecond branch of the great femoro-
poplitean, the tibial, which is larger, defeends in
the hollow part of the ham, on the poplitean vefiels,
where it fends out a very ftrong ramus: theperdneo-^
digital.

This ramus defeends behind the bifemoro-cal -

canean.

CEREBRAL AND NEUVOtJS SYSTEM. 20^

canean mufcle^ and proceeds along the tibial edge
of the calcanean tendon, accompanying the ex-
terior faphene vein, tt then paflfes behind the ex-
terior malleolus, fends filaments to the integu-
inents of the heel; is refie(?i:ed on the convexity
of the foot, and proceeds between the fourth and
fifth bones of the metatarfus to diftribute itfelf
between the correfponding toes.

After fending out this ramus, the tibial nerve
defcends between the bifemoro-calcanean mufcles,
and furnifhes a great number of rami, which are
diftributed to the articulation of the knee and the
fuperior part of the mufcles that form the calf of
the leg.

This nerve then pafles behind the malleolus of
the tibia ; gives fome filaments to the integuments
of the heel ; proceeds under the arch of the cal-
caneum^ and divides itfelf into two rami.

The interior advances on the metatarfo-phalan-
gian mufcle of the great toe ; gives fome filaments
to it, as well as to the common calcaneo-phalan-
gettian, and divides itfelf into four filaments, the
firll: of which proceeds to the tibial edge of the
large toe : the three others, each divide into two,
and proceed on tne faces comprehended between
the firft four toes.

The exterior proceeds obliquely between the

mufcles, towards the fifth bone of the metatarfu?,

and divides itfelf into two rami ; one which is

7 ■ fu^er^cial

208 OJIGANJ^C STRUCTURK.

Juperjiclal fubdivideSj and a filament proceeds on
the exterior edge of the little toe: the other pro-
ceeds between the two laft toes. The profound
ramus throws out feveral filaments, which are dif^
tributed to a part of the profound mufcles of the
fole of the foot,

267. Tri-splanchnic. Along the lateral and
anterior parts of the bodies of the vertebras, from
the bafe of the cranium to the facrum, is a feries
of ganglions united by a nerve which retains
nearly the fame iize throughout.

Thefe ganglions, and the nerve which unites
them, receive feveral filaments of the rachidian
pairs, and xommunicate with fome encephalic
pairs : ihey furnijh numerous filaments which form
plexus, and diftribute themfelves to the veflels and
organs of the three large cavities : the i-sai-'
SFLA'^CHNic, great fympatbeiic, inter-cojial nerve.

The firft ganglion^ the j'w^mor cervical^ is at the
Tuperibr part of the neck ; it is fituated before the
tranfverfe apophyfis of the atloid, and behind the
anterior cerebral artery: it is very large and elon-
gated.

It 7-ecei'tes feveral filaments of the pneumo-gaf-
tric, the hyo-gloliian and the nervous arch, formed
by the fecond and fometimes the third cervical
pair. ■

It furmjbes, fupericrly, four filaments^ which pe-
6 netrafc

CEREBRAL AND NERVOUS SYSTEM. 20^

netrate through the inflex canal of the temporal,
and which form a plexus around the anterior cere-
bral artery : one of thefe filaments proceeds to
the orh'itar Fan^lmi, uniting; itfelf to the nafo-
palpebral of the orbito-frontal ; the fecond unites
itfelf to the pterygoldian filament of the facial,
and both concur to the formation of iho. jp/je?iou/al
■ga?igUon : the two other filaments unite with the
exterior oculo-mufcular in its pafTage through the
■linus cavernofus.

The fuperior cervical ganglion gives out, be-
fore, fome filaments which unite with thofe form-
ing the plexus that farrounds the divifions of the
maxillo-facial artery. From its inferior part arifes
a filament, which concurs to the formation of the
cardiac plexus. This ganglion continues with the
portion of the tri-fplanchnic which defcends be-
hind the anterior cerebral artery : it communi-
cates, on the outfide, with filaments of tiie fourth
and fifth cervical pairs, and within fends out fome
filaments to the'oefophagus, and one or more fila-
ments to the cardiac plexus.

At the height of the fxtlh or fixth vertebra q(
the neck, the tri-fplanchnic generally prefents a
firiall ganglion or plexus^ the 7mddle cervical. This
ganglion or plexus communicates with a filament
of the fixth cervical pair, and fends out a great
number of filaments,: fome of thefe form a plexus
around \the thyroidian artery; oth.rd unite to

VOL. I. p , thofe

210 ORGANIC STRUCTURE.

thole which the fuperior cervical ganglion fur-
nifhes for the cardiac plexus : the laft defcend
behind and before the fub-cjaviar artery, which
they embrace, and proceed to the inferior cervical
ganglion.

The portion of the tri-fplanchnic which unites
tli/e middle cervical ganglion to the inferior is very
fhort. The inferior ganglian is fituated before the
neck of the firft rib ; it is round, fmaller than the
fuperior ganglion, and more voluminous than the
middle one. It communicates with filaments of
the laft three cervical pairs, and of the firft dor-
fal : it fends out filaments which concur to the
formation of the pulmonary plexus, and others
which concur to that of the cardiac plexus.

The filament of the fuperior cervical ganglion
which unites itfelf to thofe arifing from the plexus
of the cephalic artery, defcends along that artery,
and unites itfelf to fome filaments of the tracheal
and tri-fplanchnic. This union produces a nerve
which joins thofe filaments arifing from the mid-
dle cervical ganglion and the pneumo-gaftric.

This nerve gives fome filaments to the pericar-
dium, and defcends on the origin of the aorta,
where it divides itfelf into a very great number of
filaments : thefe filaments form a pkxus, the laft
diftributions of which lofe themfelves on the pul-
monary ventricle, and the aortic auricle of th&
heart : the. anterior cardiac plexus,

Froiij

CEiEBRAL AND NERVOUS SYSTEM. .21 1

From the middle cervical ganglion, and parti,
cularly the inferior, as well as from the pneumo-
gaftric, proceed numerous filaments which de-
fcend before the tracheal artery, unite to fome fila-
ments of the left tracheal, furround the pulmonary
artery, before which they form 2i plexus (the pulmo-
nary), and terminate on the right auricle and the
aortic ventricle : the fojierior cardiac plekus.

From the inferior cervical ganglion, the trl-
fplanchnic penetrates into the thorax, and defcends
on the fide of the bodies of the vertebra, in the
pofterior fpace of the mediaftinum.

In this pafTagC, it exhibits final! ganglions,
which correfpond between the heads of the ribs,
and which receive two filaments fi"om the dorfal
pairs. It gives within, towards its fiiperidr part^
fome filaments to the aorta ; and from the fifth to
the eleventh intercoftal fpace it fends out five or
fix filaments. Thefe filaments unite to fi^rm the
great fplanchnic, vi^hich penetrates into thd abdo-
men, between the pillars of the diaphragrri, and
proceeds to an afi^emblage of ganglions fituated on
the abrtai and the pillars of that mufcle • iHE
CCELi AC GANGLION, /emi-lunar.

The tri-fplanchnic fends out alfo, towards the
eleventh and twelfth doi-fal vertebrsg, one Or two
filaments, which conftitute the friall Jplanchnic^
This nerve penetrates into the abdomen, and
Unites itfelf to others more numerous, arifing

I*. 2 from

'212 ORGANIC STRUCTURE.

from the ganglion and cosliac plexus. Thefe
nerves form a plexus on the artery of the kidneys,
which they accompany in all their divifions:,
they give alfo fome tilaments to the capfular arte-
ries, and others to the fpermatic artery.

From the coeliac ganglion arife numerous rami
of nerves, which proceed on the aorta, where
they form a confiderable plexus : the cceliac
TLEKUSy foleus I at the top it furnifhes filaments
which accompany the inferior diaphragmatic ar-
tery : it fends out filaments which unite with
thofe of the oppofite fide, and fome of the
pneumo-gaftric, to form plexus, which furround
on all fides the divifions of the opillo-gaftric artery
and the fuperior mefenteric : tbe gajlric plexus,
hepatic, fplenic, dind fuperior mefenteric.

Thefe numerous filaments fpread over the divi-
fions of thefe arteries, embrace them, and accom-
pany them in all their diftributions.

The coeliac plexus furnifhes a great number of'
filaments, which dcfcend before the aorta, as far
as the inferior mefenteric artery, where they unite
to filaments of the lumbar portion of the tri-
fplanchnic, and form around that artery a plexus,
the numerous filaments of which accompany it
m all its diftributions : the inferior mefenteric
plexus. . ~

This cogliac plexus furnifhes alfo filaments

which unite with fome arifing from the fourth and

I ~ fifth

CEREBRAL AND NERVOUS SYSTEM, 213

fifth facral pairs, to concur towards the formation
of the hypogajiric 'plexus.

The tri-fpranchnic, after fending out filaments
which form the great and fmall fplanchnic, pene-
trates into the abdomen, on the exterior fide of
the pillar of the diaphragm, defcends on the fide
of the lumbar vertebras, as far as the facrum, and
exhibits ganglions, which correfpond to the inter-
vals between the vertebras.

In its paflage it receives one or two filaments
from the anterior branch of each lumbar pair,
which proceed to its ganglions.

It fends out filaments, before, to the inferior
mefenteric plexus, and fome to the other plexus
furnifhed by the coeliac ganglion.

The tri-fplanchnic then penetrates into the
lefier pelvis, and defcends before the facrum,
where it prefents ganglions as in its other parts :
it receives two or three filaments from the anterior
branches of the facral pairs.

It furnijhes very delicate filaments, which pro-
ceed to the hypogaftric plexus, and others which
are diftributed to the re6lum and to the neigh-
bouring cellular tiffue. It terminates either by
being, confounded with fome facral pairs, or by
uniting with that of the oppofite fide on the
coccyx.

268. The cerebral organ, whether encephalic
p 3 or

^l4 ORGANIC STRUCTURE.'

or rachidian, has the appearance of a pulpy and
homogeneous fubflance. The great tenuity of
its organic texture prevents its interior fl:ru(5ture
from beipg known. This organ is inclofed in a
(double membranous covering (the menin>; and
meningine).

The nerves have the appearance of whitifh
cords^ compofed of fibres in himdles ; thefe fibres
are furrounded by a firatum of cellular tiffiie,
which dividing them from each other, ferves to
unite them. This cellular tiffue forms alfo a com-
rnon covering around the nervous cords. Not-
withftanding this fibrous appearance, their compo-
lition feems to be analogous to that of the brain.
Each fibre indeed of a nerve feems to be formed
of a pulpy fubftanccj contained in a membranous
vagina or fheath : the pulpy fubflance of the nerves
continues with that of the cerebral organ, and theic
membranous fheath (neurolemma.) with the menin-
gine.

Reil has proved this mode of f^rudure, by
plunging the nerves either into dilute nitric acid,
or into an alkaline ley (of potafh or foda). In the.
firll cafe, the nervous covering becomes diffblved^
and the pulpy fubftance remains concrete. In the.
iecond cafe, the pulpy matter is dilTolved, and the
jnembranous tube remains empty.

The nerves are diilributed to the different parts

■ by

CEREBRAL AND NERVOUS SYSTEM. 215

by the mere reparation of their numerous fmall
fibres ; it does not appear that thefe fmall fibres
ever divide themfelves info ramufculi.

At their termination, the nerves feem to aban-
don their membranous covering-, and to lofe them-
felves in the fubftance of the different organs, by
an expanfion of their pulpy fubftance.

Towards the cerebral organ, the nerves ahb
leave their covering, which is continued with the
meningine, and their pulpy fubftance is confound-
ed with that of the brain, the mefencephalon, or
rachidian prolongation.

Scemering fays, he traced the encephalic nerves,
and particularly thofe of the organs of the fenfes,
as far as the lides of the ventricles of the brain ;
from which he concludes that the fluid contained
in the interior of the ventricles mull be confidered
as the centre of fenfation.

From various chemical experiments made on
the pulpy fubftance of the cerebral organ, it refults,
that this fubftance is almoft entirely a fort of albu-
men in a ftate of femi-concretion.

P 4. TABLE

TABLE OF THE CEREBRAL SYSTEM.

Ithe cerebral system eontists of the encephalic organ^ the cere^
hrai prolongation^ the tri-fplanchnic and fome ganglhns.

Tl^e encephalic organ comprehends the cerebrum, the cerebellum,
the mesencephalon, ah^ the CQmmeiicem.ent of the cerebral pro-
longation. It has the form of the cavity of the cranium in -which it is
contained; its surface exhibits numerous winding and deep anfrac-
tuositfe?, over which the sanguine vessels are spread; it is inclosed
m a double covering-, the exterior, -which is very strong', is called

NEW NAMES. OLD NAMES.

Themeninx. . • . . ... Sura mater,

and the interior, much thinner,

.... ( Arachnaii.

Meninsme. > . . - 'J

J Via mater.

The meninx is formed of two laminae closely united ; the exte-
rior adheres to the cranium, and serves it as a periosteum; the
interior is prolonged between the divisions of the cerebrum, and forms
different folds, cH which there are three principal ones :

One of them is between the two lobes of the cerebrum :

', Median septum of the cerebrum. . . ■ . Falxofthe certbrum.

The other is placed between the cerebrum and the cerebellum :

Transverse septum of the cerebellum. .' , ^ jTertionum of ths cerebellum. ,

The third is interposed between the two lobes of the cerebellum :

Median septum of the cerebellum. , 1 . Falx of the cerebellum.

The rneninx is prolonged irx the cerebral canal ; adheres to its
sides ; serves them as a periosteum, and surrounds the vertebral
nerves at their origin : it is reflected also into the different holes of
the cranium, and confounded with the neighbouring periosteum.

The rneninx exhibits, in different parts of its substance, sinuses ,
which receive the blood of the veins, and pour it into the jugular j
of these sinuses, which are vesy nunjerous, there are four principal
ones :

Oni5

TABLE OP THE CEREBRAL STSTSM. fUJ

One of them runs along the superior edge of the median septum

of the brain :

NEW NAMES. - OLtl If AMEA

The median sinus. . . . , . Ssperkr tons'itui'mal sinus.

It is continued with

The lateral sinuses. . . , , . The savie.

The third is at the base of the medito septum of the train :

. Choitidiajvsinus. ..... Straight sinus.

And the fourth runs along the longitudinal septum of the cere-
"bellum:

Inferior longitudinal sinus *. . . ■ . Th! same.

The meningiue is formed of two veiy thin lamins, one of "which
envelops only the exterior surface of the encephalon :

" The arachnzil.

The otlier is prolonged throughout all its anfractuosities :

Pia mater. ■'

The encephalon is composed, in the interior part, of a tuJiite sub-
stance, covered by a thick stratum of a gray substance :

■White substance. ..... MeiuiUxry substance,

Cray substance. . , . . Cortical sUbstanie.

Tlie brain is divided longitudinally, on the summit, into two
lobes ; and each of these is divided into three lobules : the antenor,
middle, and posterior. The first two are divided inferiorly by a
transverse scissure :

Inter-Iobar scissure Scissure of Sylvius.

Between the lobes of the brain is found a broad white band :

Meiolobe. . . ... . . Corpus calksum.

Below these are two ventricles, the sides of which are contiguous:

Ventricles of the brain. lateral ventticles.

They form two ovoid furrows, incomplete before, placed back to
back within, and separated by a thin lamina:

Median septum of the ventricles. . . . Septum lucidum.

* The others arc thp occipital sinuses; the superior petrous sinuses; the inferior f«(tous sinuses ; the
lltniTeHe sinus ; the cavei nous sinus; the coronary sinaiei.

This

0,1$ ORGANIC STRUCTURE,

This lamina is formed of hvo contiguous thin leaves, the sepa*
ration of which can produce a triangular cavity :

ySEVf NAMES. OLD Iv'AMES.

Ventricle of the septum. .... Tlfth ventricle.

The ventricles of the brain communicate, behind, with another
cavity, the sides of which are contiguous:

Appendix of the ventricics. . . . , Digital cavities.

Along the base of the ventricles of the brain runs a membranouSjg
vascular, and reddish plexus.

riexus choroicles. . . . '. . Tm same.

Below the septum, at the base of the ventricles, is a part of ^
triangular form :

Cerebral trigone. . . > « . . Fornix zcith tiires pillars.

On the sides of the ventricles are two oblong grayish bodies,
placed back to back ;

Pyriform eminences. . . . , .' . Striates boil's.

Towards the middle of the ventricles of the bi-ain, below and be-
hind the pyriform eminences, are two whitish ovoid protuberances,
united by a small, soft, and grayish cord :

Strata of'the ocular nerves, , ., . Strafaof the optic nemes.

The pyriform eminences, and the strata of the ocular nerves, are
separated by a furrow, which lodges a small grayish band :

Small band of the pyriform eminences. . . Small semi-circular band.

In the exterior part of the ventricles of the brain there are two
protuberances, of the form of these cavities :

Sylindroid protuberances. . . . Cornua Ammonis,,

On the interior side of these eminences is a grayish serrated
lamina :

Fringed body.

On the exterior side are two other protuberances:

Accessories of the cylindroid protuberancp^'. . Accessories of the cornua Ammonis,

In (he appendix of the lateral ventricles is observed

I?]'^ unciform eminence. . o . . The spur.

Between the strata of the optic nerves is found the trunk of

'Ihe choiridian vein. : . . ... Vein oj Galen,

The strata of the ocular nerves leave between thern -m inter v;ii_
inihe form of a fissure :

Third vcn'.ric:e, ■ , , , . , 'Chi 'arie,

TiiJ5-

TABLE OP THE CEREBRAL SYSTEM. 210
This ventricle eontains a small choroid plexus ; it presents before

NEW-NAMES. OLD NAMES.

It; anterior aperture Vulva,

It exhibits at the top and behind

Its posterior aperture. . , , . , Anus,

Before the anterior aperture is a long, -whitish cord, which ex-
tends across it, in the form of an arc :

Anterior commissura. • ,' , , • ° T!:e same.

Below this commissura is a funnel-formed excavation :

Infandihulum.

The bottom of this excavation is continued with a grayish cord,
adhering to a round tubercle, which rests on the body of the
sphenoid :

Super-splienoidal peilur.cle and appendix. . . Fit-dUcry peduncle ani glan.l.

Below and behind the posterior aperture of the third ventricie is
another thick and short transverse cord:

JPosteriov commissura. , , > , , The same.

Behind the posterior commissura is a small conical and grayish
body ;

Conariom. . .<•..•. Pineal gland.

It seems to adhere to two very fine cords, which pass over the
posterior commissura, and proceed on the ocular strata :

pedanculiofthe conatiam. .... Pedunculi of tk jiinea! gland.

The conarium rests on the mesencephalon, below four white
tubercles :

Tubercles of the mesencephalon. • . . 5 ^■'»"-«''' J''''*'^""'''"'.

^ Testes et nates.

The two inferior are continued with a whitish lamina, round at
the top and striated:

JrteduCary lamina of the ceretiellum. ... ValvulaofVieusens,'

Below the posterior commissura is

The intermediate canal of the ventricl;s. . , Aqueduct of Sylvius,

This canal proceeds to

The fourth ventricle, The same,

yfhich is situated between the pedunculi of the cerebellum and the
cerebral prolongation.

This ventricle contains a small choroid plexus : it exhibits behind

a Ion-

^2© ORGANIC STJ5.UCTURE*

a longitudinal and two lateral grooves, •which terminate in a point
on the former :

^-EV/ NAMES. OLT) NAMES.

Calavius scriptorius^

The contiguous sides of ths ventricles of the brain are lined with
a serous membrane, which is a continuation of the meningine;
this membrane continually secretes a Ij^mphatic moisture, which
lubricates its surface. In the last place, the brain presents below,
and in its middle,

C Prohngathn'of tht brain, crura (■/ the }rra:a, anm

Itstwopedancuh. > '^ ,,i , „ ,,

- (_ Ff the vieduUa oblongata*

Before the junction of the pedunculi are found

The pisiform tubercles Mammillary eminences.

The cerebellum presents on its surface mammillarj' eminences,
"and transverse and lamellar anfractuosities, ^vhich intersect each
other at an acute angle. The centre of this organ is formed of a
•white substance, which is prolonged and ramified between the gray
substance and its laminas :

Arisf vitis.

Between the lobes of the cerebellum appears before*

TliB median pvotubeiMUce. . . . . Superior vermicular eminence,.

Below and in the middle of it.

The median lobule. ... . Inferi'.r vermicular etninencf.

From the white centre of each lobe arise before.

The pedunculi of the cerebellum, ... Trolcngaticnff the cerebellum,

\ "vvliich are divided into three bundles :

superior, middle, and inferior proUmgatiyn],

The pedunculi of the cerebellum unite to those of the brain to
form

The mesencephalon. . « „ . . . S ■^^"'^''''>'- P^f^l^""-"^-

C. Pons Varolii.

The mesencephalon is continued with the commencement of

The cerebral prolongation, ..... Medulla oblongata,

from which it is separated by a transverse furrow.

The commencement of the cerebral prolongation is of a pyrami-
dal form ; it exhibits before and in its middle a longitudinal fur-
row, on the sides of which are observed

The

TABLE OP THE CEREBRAL SYSTEM. 221

NEW NAMES. OLD NAI.IES.

The oliyarian eminences. ..... The same.

Close to these eminences is another furrow, which separates them
from

Itic pyramidal eminences. ...... The same.

The cerebral or rachidian prolongation has the form of the ver-
tebral canal in which it is contained ; it terminates towards the first
lumbar vertebra in two tubercles, and a loose tufted nervous bundle ;

Sondlc of Che lumbar and sactaj Acrvcs. . . Cauda equina.

It exhibits before and behind a longitudinal groove 5 it is whit^
©fa soft consistence, and in the middle has a grayish furrow.

The encephalon gives birth to twelve pairs of nerves, and th'3
£/;rebral prolongation to thirty.

TABLE

TABLE OF THE NERVES,

All fhe nerves originate from the encephalic organ, therachi-
dian prolongation, the tri-splanchnic, and some ganglions.

The encephalic organ gives birth, at its base, to twelve distinct
pairs of nerves; the rachidian prolongation to thirtj', and the tri-
splanchnic to an indeterminate number.

EN-CEPHALIC NERVES.

NEEVE WHICH PROCKEDS ON THE SIDES OF THE NASAL
CAVITIES.

I Pair : arise by three filaments, tv^of Avhich come from iti
interlobular scissure, and the third from the striated bodies :

NEW NAMES. . OLD NAMES.

Ethmoidal. ... . .... Olfactory.

NERVE WHICH PROCEEDS TO THE EYE, AND FORMS THE
RETINA.

II Pair : derive their origin from the posterior tubercles of the

ocular strata:

NERVES V/HICH PROCEED INTO THE ORBIT,
Distriduting themselves to almost all the muscles of the eye,
III Pair : arise by several filaments from the excavation between
the peduncuii of the brain, near the mesencephalon,

Common_oculo*mu!cular. ..... Common motor.

Distributing thcmsehes to the great oblique muscle of the eye.
IV Pair: arise by two or three small filaments close to each
other, between the peduncuii of the cerebellum, and the inferior
tubercles of the mesencephalon.

Jntcrior oCulo-muscuUr. . „ . . . Pathetic,

NERVE WHICH PROCEfiDS TO THREE PARTS OF'THE FACJ:.

V Pair: it issues from before the peduncuh of the cerebellunij,
Hear the mesencephalon : ,

tiSscia!. . . i . o . .' . Tii^emersi,

TABLE OF THE NERVES. 223

This nerve divides itself intothree branches :
The first distributes itself to the eyes and the forehead,

NEW NAMES. " OLD NAMES.

A. Orbito-ffontal. ophthalmic cf Willis.

It divides itself iiito three rami z

1. The paljicbro-frontal, ..... Frontal or iuperjliar,

which gives a palpebralian ramus, that, expands in ciliar rarauscuil :

2. The lachrymal. ... ... Th-' same»

S. The naso-palpebral -Vajji.

The latter gives a filament to the orbitar ganglion — a ramus to
the nasal — eth?noidal filaments — naso-lobar filaments — a palpebral
ramus.

GANGLION SITUATED NEAR THE INSERTION OF THE OCULAR
- NERVE INTO THE EYE.

Orbiter janjUon ; - . Ophthalmic cr lenticular ganglisru

It receives
A filament from the naso-palpebral — a filament from the superior
cervical ganglion — a filament from the common oculo-muscular.

It furnishes
Ten or twelve filaments which proceed to the eye, and distribute
themselves behind the iris : "**

The irian. . . . . .... The r/'jr.

The second ramus of the trifacial distributes itself to the middle
part of the face :

B. The super-maxiUarv Supiriar maxillary.

. It gives, .
First, An orbitar ramus, from which proceeds ajugaland a tem-
poral filament ; second, one or two filaments to the sphenoidal
ganglion; third, anterior and posterior den tar filaments; fourth,
the sub-orbitar nerve.

GANGLION SITUATED AT THE SUMMIT Of THE ZYGOMATIC

yossA:

Sphenoidal ganslion. . .,•... Sphino-palatine g.ini'.ion..

It 7'eceives It gives

Two filament? ffom the super-maxillary, a ramus I _ .. , . . •„ i.

" I Two fitamints if the tuptnor maxilla'}, the

formed by a pte.yBO.Jian filament of the tri- ^ ftery^oU^ano, viiioniranch,
•lili/..:tn;c, and a pJetysoJdian raiaus of the facial, J

It

|24 ORGANIC STRUCTURS.

I

Jt gives
Nerves which proceed to the guttural region of the phavjnx and t®
the palate:

NEW NAMES. OLD NAMtS..

■ ■ ■ ' ~ f PO^^-'"!!-

■ J

To the nasal fossa^ :

The gutturo-palatine
Ther superior palatine

The ethmoidal. .. .... . '. . Spheno-fdlatiKt.

Naso-palatine. -<.#«. . . Jhi iame^

The third branch of the trifaeial distributes itself to the inferior
jaw :

C. The maxillary. , . • . .■ . Inferior maxillary.

It gives two bundles :

The superior one furnishes

Isr, The siib-zygomatic; 2(1, the temporo muscu- ist. The massftrriji; 11, the UmporD-propuiUf ZS^
fcsr; 3d, Uiu bucco-labial ; 4th, the ptcrygo-m-js- the iu^'cal; itH, the ft/rygoHian.

ealar.'

The inferior gives

lit, Tht cutaneous temporal ; 2d, the lingual, from lit, The superficial temporal ; 2d, the lingual ; 3i, iht
which proceed tlie sub-maxillary ; 3d, the maxil- inferior dentary.

io-dentar,. from which proceed the mylo-hyoi-
uliaii and the dcntarj'. .....

NERVE WHICH PROCEEDS INTO THE ORBIT,
A7td dlstrihutes itself to the inferior right tnuscle.
VI Pair: it arises between the mesencephalon and the cerebral
prolongation, in several filaments united :

Exterior oculo-muscular. . . ' , • . Exterior motor.

It reeeives
Two filaments, which united to two others of the snperior cervical
ganglion, form a plexus around the divisions of the anterior cere-
bral artery.

I NERVE WHICH DISTRIBUTES ITSELF TO Tllr. FACI,

Passing through the splrold eanal of the temporal Lone,
VII Pair : it issues from the triangular facet which is found be-
tween the mesencephalon and the exterior side of the base of the
jachidiaix prolongation :

ThcUcial, . . ... ... Hard portion of the seventh pair.

It

TABLE OF THE NERVES. 225

It gives

ffEW NAMES. ■ OLD NAMES.

1st, A pter>'soidian filament; 2d, filaments to the 1st, Superior ramus of the vidian ;

small bones of the tympanum ; 3d, a t> mpanic Qd, The same ;

ram:.-5, posterior auricular filaments, a sub- 3i, Cord of the tympanum ; temporal, milar ani

mastoidian ramus, a stylo-hyoidian ramus, buccal rami,
super-orbitar, labia], mentonniar and sub-men-
.tonniar rami.

NERVE WHICH PROCEEDS INTO THE EAR,,

Distributing itself in the labyrinth:
VIII Pair : it arises from the sides of the fourth ventricle, be-
hind the seventh pair, with which it is connected by some filaments :

The labyrinthic ■ Soft part of the sez'enth pair.

NERVE WHICH PROCEEDS TO THE TONGUE,

Distributing itself to the phari/nx, and to the muscles at the root of
the tongue ;
IX Pair: it originates in three or four filaments from the pe-
dunculus of the rachidian prolongation, near the olivarian emi-
nence :

The pharynso-slossian Thegksso-pharyns.ianorbratichofth!eiihthfa:r,

It gives

The pharynsian

NERVE WHICH PROCEEDS TO THE LUNGS AND THE STOMACH,
Distributing itself along the necJc, in the thorax and abdomen :
X Pair : it comes from the base of the rachidian prolongation,

in ten or twelve filaments :

The pneumo-gastric. .... . . Eiihth pair or jar vaptm.

It furnishes

On the neck, pharyngian rami, a laryngian ramus,

filaments to th<; cardiac plexus, a tracheal ramus. The recurrent.
To the ihorax, filaments for the pulmonary plexus;
In the abdomen, rami to the stomach. . . The stomachic anterior and fOiterijr,

NERVE WHICH PROCEEDS TO THE NECK AND THE TONGUE,

DistriLuting itself to the muscles of the tongue, and to the greater
part of those attached to the os hyoidesi
XI Pair : it arises towards the middle of the furrow placed be-
tween the pyramidal and olivarian eminences :

Hyo-Blo:sian. . . , . . , . Ninth^air, ^teat h/pogbssus, lisgua!.

VOL. I. Q If

226 ORGANIC STRUCTURE.

It ftirnishes
A branch for the plexuous arch of the hyoidians — a hyo-thyroidian
ramus — filaments to the muscles of the tonuiue.

KERVE WHICH DISTRIBUTES ITSELF TO THE STERNO-M AST 01-
DIAN AND THE DORSO-SUPER-ACROMIAN :

Xll Pair : it arises towards the middle of the trarJielian region,
and the sides of the rachidian prolongation, by several distinct fila-
ments, -which unite into one trunk : this trunk enters into the cra-
nium through the occipital hole, and issues through the posterior
foramen lacerum :

NEW NAMES. OLD NAMES.

Traclielo-dor.-al. .... . . . Sfinal, accessory of iVillii-

VERTEBRAL NERVES.

These arise from the cerebral prolongation, by a great number of
filaments, united into two bundles, the posterior of which is larger
than the anterior ; both proceed to a ganglion, from which one
trunk of nerves then issues ; this nerve soon divides itself into two
branches, which issue through the foramina of the rachis. The
posterior branches proceed to the spinal face of tlie rachis, and dis-
tribute themselves to the muscles and the neighbouring integu-
ments. The anterior branches, soon after they issue from the
vertebral foramina, unite with each other by filaments of communi-
■cation, and all of them send one or more filaments to the tri-
splanchnic.

NERVES which PROCEED TO THE NECK.

The eight cervical pairs.
Distributing themselves to the 77iuscles and the integume>its of the
spinal Jace of the neck :
The posterior branches.

Which distribute theinsehes behind the head and the neck :
The anterior branches.

These furnish
1st, The nerves which form the trachelo-cutanecus plexus, and
which are : the branches of the second, third, and fourth cervical
pairs. 1

This

TABLE OP THE NERVES„ 227

This plexus furnishes, 1st, mentonniar, zygomato-auricular,
and occipito-auricnlar branches ; 2J, sternal, acromian and scapu-
lar branches.

2d, The rami which form the diaphragmatic nerve, and "vvhich
-are : the anterior branches of the fourth, fifth, and sometimes the
sixth cervical pairs.

3d, The nerves which form the Irachial plexus, and which are ;
the anterior branches of the last four cervical pairs, and of the
first lumbar.

The nerves which proceed to the thoracic member arise from

NEW NAMES. OLD NAMES.

The brachial plexus. . . i ... The same.

This plexus divides itself into nine branches or bundles.

1st. nerve which proceeds to the shoulder.

Distributing itself to the siiper-scapido-trochiterian, and dorso-super-

acromian muscles :

The fuper-scapular The same.

2C. NERVES WHICH PROCEED TO THE STERNAL FACE OF THE
THORAX,

Distributing themsehes in three filaments ^ Isf, to the sterno-hume-
rian ; 2d, to the costo-coracoidian ; 3d, on the side of the thorax :

Tlic scerno-thoracic. ...... Thoracic.

3d. nerves which PROCEED TO THE SHOULDER AND THE
ARM,

Di.<;triduting themselves hy three filaments : 1st, to the costo-scapic-
It'atz; 2d, to the hunho-humerian and the siih-scapiilo-trochinian ;
3d, to the scnpulo-humerian, and the inferior super-scapulo-
trochiferian tnuscles :

The sub-scapular. ^- . . . . . The sam.

'4TH. NERVE WHICH PROCEEDS AROUND THE SCAPULAE.
ARTICULATION OF THE HUMERUS,

Distributing itself : 1st, to the sub-scapulo-trochinian muscle ; <2d, to
the sub-acromio-humerian ; Sd, to the radial edge of the ar?n :

ILe :i-3pulo-tiumciian. . . • , . Axillary cr circumflex.

5TH. NERVE WHICH PROCEEDS TO THE ARM ANt» FORE-AP.M,
Distributing itself superficial!!/ to the interior side of the arm, alon.g
the radial edge of the fore-arm as far as the thumb *

Die radio-cutarieoui. ^ MuKulo-eutrnisiui.

<^ 2 6th. nep.ve

•228 ORGANIC STRUCTURE.

6th, nerve which proceeds to the arm and fore-arm.

Distributing itself superficially/ along the cubital edge of the arm

and fore-arm, as far as the little finger ;

NEW NAMES. OLD NAMES.

The cubito-cut2neoii5. ..... Intiriar cutaneous.

7th. nerve which proceeds to the arm, the fORE-ARM,
AND HAND,

Distributing itself a7^ound the humei'us, behind, along the radial edge
of the fore-arm y on -the conxexity of the liand, and to the first three
fingers :

The radio-digital. . . . . - . Radial,

8th. nerve which proceeds to the arm, the FORE-ARMy
AND THE HAND,

Distributing itself to the interior side of the arm, behind the articu-
lation of the elbovj ; along the cubital edge of the fore-arm, and to
the ixvo last fingers :

The cubito-dijital Cubital.

9TH. NERVE WHICH PROCEEDS TO THE ARM, THE FORE-ARM,
AND THE HAND,

Distributing itself to the interior of the arm, before the articulation
of the elboxo ; on the middle of the palmar face of the fore-arm f
and to the fingers :

Digital median, , . , . . . . Mf.Har,

NERVES WHICH PROCEED TO THE DORSAL REGION, AND TO
THE sides of the THORAX AND ABDOMEN :

The twelve dorsal pairs.
Which distribute the?nselves to the integuments of the back:

The posterior branches.
Which pass bettveen the ribs, and distribute themselves before the
thorax, to the muscles and integuments of the abdomen :

The anterior branches.

NERVES WHICH PROCEED TO THE LUMBAR REGION, TO THE
SIDES OF THE ABDOMEN, AND INTO THE PELVIS :

The five lumbar pairs.
Which distribute themselves to the muscles of the lumbar region and
to the integuments of the nates i
The posterior branches.

Which

TABLE OF THE NERVES. 22g

Which distribnte themselves to the sides of the abdomen and the pelvis,
and furnish some to the crural plexus :
The anterior branches.

NERVE WHICH TRAVERSES THE PELVIS, AND PROCEEDS TO THE
REGION OF THE GROIN : .

The anterior branch of the first lumbar pair.

It gives,
1st, A ramus wb.ich proceeds to the muscles of the abdomen
and to the pubis, suh-pubian ; 2d, a ramus to tlie integuments of
the groin; 3d, a ramus which follows the contour of the ridge of
the ilium, and proceeds to the scrotum, along the testicular cord.

NERVES WHICH ISSUE FROM THE OS SACRUM:

The five sacral pairs.

Which distribute tliemsehes to the nates and to the anus :
The posterior branches.
Which supply the hypogastric and crural plexus, and distribute them-
selves to the coccijx and anus :
The anterior branches.

NERVES WHICH FORM THE HYPOGASTRIC PLEXUS:

The anterior branches of the fourth and fifth sacral pairs, and
filaments of the tri-splanchnic.

The7/fu?mish
The pelvian, which are distiibuted to the bladder, the rectum,
and the genital parts contained in the pelvis.

NERVES WHICH, FORM THE CRURAL PLEXUS:

The anterior branches of the last four lumbar pairs, and of the
first four sacral.

The nerves distributed to the pelvian memljers arise fom the
crural plexus, which divides itself into two other plexus : 1st, the
lumbar plexus ; 2d, the sacral plexus : tliey each furnish four prin-
cipal branches to the pelvian member.

y 3 NT." VLS

230 ORGANIC STRUCTURE.

KERVES ARISING FROM THE LUMBAR PLEXUS:

1st, Nerve which proceed'^ to the thigh,
Passing near the anterior tubercle of the ilium, and sending out ram i^
jications to the exterior part of the thigh and the leg :

NEW NAMES. OLD NAMES.

The interior cutaneous. . , ... Crural.

2d. Nerves which distribute themselves in three, four, or five
filaments to the glands, the integuments of the groin, and to the
genital parts :

The insuinal. . , , . , ; . Crural,

Sd. Nerve which proceeds to the thigh, the leg, and the fqot.
Descending behind the pralumho-trochantinian muscle, passing
through the crural arch, and distributing itself to the integuments
of the anterior par't of the thigh, and by a long ramus (tibio-cuta-
iieous) to the muscles and integuments of the leg and the foot :

T!ic fcnoro-proEtibial. ..... Crural.

4th. Nerve which proceeds to the interior part of the thigh,
passing through the sub-pubian hole, and distributing itself to the
7nuscles and integuments of the anterior and interior part of the
thigh :

The sub-pubio-femoral. ..... Obturator.

NERVES AiflSING FROM THE SACRAL PLEXUS :

1st. Ner\-e which proceeds to the penis and the clitoris,
Passing through the ischiatic notch, and distributing itself to the
perinawn, to the penis, and the ciit oris :

Ischic-pejiiarij ischio-clitoriun. . . . . Pullzal,

2d. Nerve which proceeds to the nates,
Distributing itself to the sacro-femoral muscle, the ilio-troehanterian
fnuscles, and to the integuments of the thigh :

The fes.*<iers. . . . . s . ,

3d. Nerve wiiich proceeds to the posterior part of the thigh.
Giving, 1st, two or three ischio-^trochanterian rami to the nmscles
.. situated in the neighbourhood of the ischium and tite trochanter ;
Q.d, the cutaneous sub-pelcian, tvhich proceeds to the integuments
of the sub-pekian region and the interimr part of the thigh ; 3d,
the posterior cutaneous of the thigh, a lo7ig ramus tohich is distri-
buted'

TABLE OP THE NERVES; 231

butcd to the integuments of the popUteanface of the thigh, and ex-
tends as far as the ham :

NEW NAMES. OLD NAMES.

The small femoio-popUtcan. . .. , .

4tli. Nerve which proceeds to the posterior face of the thigh, to
the leg and to the foot,
Giving tv>o branches: one (the }^tTom.2L'c) furnishes ; \sf, the peroneo-

cutaneous ; 2d, the pi'atibio-digital and the fratihio-sub-plantar.

The other (the tibial) gives; 1st, the digital peroniar ; 2d, the tlbio-

plantar.

On the anterior and lateral parts of the bodies of the vertebrae,
from the base of the cranium to the sacrum, is a series of ganglions
united by a nervous cord :

The ui-splanchnic. . .' Ths great sympathetic or intercostal nerve.

The ganglions of the cervical region are :

1st. A superior, very large and fusiform.

2d. A middle one, very small, and often even a simple plexus.

Sd. Aninferior, round, and situated before the neck of the first rib

The ganglions of the other regions are disposed in such a man-
ner, that they correspond nearly to the sides of each inter-verte-
bral space.

The nerves which communicate with the tri-splanchnic are :

Some encephalic pairs, and the thirty rachidian : they each send
to it, one, two, three, four, and even five filaments.

The nerves furnished by the tri-splanchnic, either from its gang-
lions or the cord which unites them, are distributed chiefly to the
arteries of the organs contained in the three large cavities.

In their distribution these nerves form, or contribute to form, a
great number of plexus ; such as,

1st. The plexus, which surrounds the trunk of the anterior ce-
rebral artery, in its passage along the inflex canal of the temporal.

2d. The plexus cardiaci.

From the fifth to the eleventh intercostal space the tri-splanchnic
gives five or six filaments, which unite and form the great splanch-
nic : this nerve penetrates into the abdomen, and proceeds to. an
assemblage of ganglions, situated on the aorta and the pillars of
the diaphragm :

Ottliic ganglion Seni-tanar,

q4 The

232 ORGANIC STRUCTURE.

The numerous filaments which proceed from the coeliac ganglion
form, on the aorta, the divisions of the opisto-gastric artery, and
on the superior mesenteric artery, a considerable plexus.

NEW NAMES. OLD NAMES.

Cctliac plexus. . . ..... Solar.

The filaments which proceed from this plexus are distributed on
the trunks of the principal arteries, surround them, and form on
them the s:astr'ic, hepatic, splenic, mesenteric, &c. plexus, and ac-
company them in all their distributions.

Towards the eleventh and twelfth dorsal vertebrff!, the tri-
splanchnic gives also one or two filaments, which constitute the
small splanchnic : this nerve penetrates into the abdomen, unites
to others of the coeliac plexus, and forms a plexus around the renal
and spermatic artery.

The tri,-splan'.hDic penetrates into the pelvis, ^i^d unites on the
sacrum with that on the opposite side.

SYSTEM

[ 233 3

SYSTEM OF THE SENSES.

OF VISION.

27 ^* The organ of fight confifts efientially of a
very thin membnane, placed at the bottom of the
eye. This membrane has the property of per-
ceiving the adiion of the light refle(?led from ex-
ternal bodies^ and refracfted on it by the tranfpa-
rent liquids of the eye.

The eyes feem to be wanting in zoophltes,
feveral of the articulated worms, in fome of the
larvae of infe6ts, and in the acephala mollufca.

All vertebral animals have two eyes, fituafed in
the cavities of the bones of the face*. They are
compofed of two or three tranfparent fluids of dif-
ferent denfities, placed the one before the other,
each of which is contained by a thin pellicle ; and
they are covered at the back by the fine mem-
brane which perceives the contadi of the light.

This apparatus is contained in a common, thick,
double covering, for the mod part blackifh in
the infide, having in it an aperture fufccptible of
contraction, before which is placed a membra-
nous and tranfparent fegment of a fphere.

*■ The eyes of infe6ls are very numerous, and have a peculiar
ftrudture, which cannot be known on account of their fmallnefs.

This

234 ORGANIC STRUCTURE.

This organized dioptrical apparatus is nearly
round in all animals j but its anterior part, more
or lefs truncated, is covered by a tranfparent
Ipherical fegment called the cornea,

1^1. The cornea is nearly round; but its tranf-
verfe diameter is often fomewhat longer : it is com-
pofed of laminae cemented together, and is thicker
in the middle than at the edges. In fidies, the
cetacea, and the greater part of reptiles, it is very
much flattened; fo that the eye of thefe animals
is often a hemifphere. In the terreftrial mam-
malia the cornea is a fhort fegment of a fphere,
fmaller than that of the eye ; and this organ is
nearly round. The cornea of birds is a narrow
bemifphere, and the eye has a greater degree of
projection.

Behind the cornea, and before the eye, the
mammalia and birds have an aqueous humour, fome-
what faline, the denfity of which is nearly equal
to that of water : it feems to be contained in a
very thin pellicle.

This aqueous humour is often wanting in fifhes %
the fmall quantity of it found fometimes in the
eye of thefe animals is always vifcous : it does not
exift in the fepias.

2 73- CryJialUne humour. Behind the aqueous
humour, in the mamraaha and birds, and behind
the cornea of aquatic aninjals, is a thick, diapha-
nous fubftance, heavier than water, and enveloped^
9 without

SYSTEM OP THE SENSES. 235.

without adbefion, in a very fine membranous
capfule : the cryjtalline humour.

In fifties, the cryflalh'ne humour is nearly
round ; in the mammalia it has a lenticular form ;
it is more flattened in birds, and ftill more fo in
man. In all thefe animals this body is formed of
two fpherical fegments, the pofierior of which is
fmaller. Its convexity is in the inverfe ratio of
that of the cornea. The cryf^alline is harder, the
greater its convexity ; and its confiftence decreafes
from the centre to the circumference.

'1"}^. Vitreous humour . The cry ftalline is lodged
in a depreflion prefented to it by another body of
lefs deniity, having the confifi:ence of the white of
an t^gi which occupies the greater part of the
bottom of the eye, and is enveloped by a thin
diaphanous membrane. This fluid is called the
vitreous humour.

From the tranfparent membrane (memhrana
hyaloideajy which envelops the vitreous humour,
proceed internally a great number of thin lamina},
which crofs each other in ditFerent directions, and
form lenticular cells containing the vifcous fluid.

The denfity of this fluid, which conftitutes the
vitreous humour, is greater than that of the aqueous
humour, and lefs than that of the crydallinf. This
fubHance hardens and becomes opake by heat and
by alcohol.

The anterior furface of the vitreous humour is
feparated into two lamincC. one of which paffcs

behind

236 ORGANIC STRUCTURE,

behind the cryflalline, and the other is refle6^cd
on its fides.

275. The retina. The vitreous humour is en-
veloped, behind and on the fides, by an exceed-
ingly fine membrane, of little confiftency, which
receives the impreffion of the rays of light. It is
only an expanfion of the optic nerve; and is di-
ftinguifhed by the name of the retina.

The retina expands difTerent ways on the vi-
treous humour ; but in all animals it terminates
around the aperture of the cornea, and does not
pafs before the cryftailine.

The aque^s humour, the fubflance of the
cryftailine, and the vifcous fluid contained in the
cells of the vitreous body, are fecreted by the fiir-
faces of the membranous capfules which contain
them.

Thefe three tranfparent bodies are contained in
a common double covering.

276. Sclerotica. The exterior tunic, called the
fclerotica, is foft, thin, and of a clofe texture in
the greater part of the mammalia ; and the eye
has that round form which all fluids contained in a
flexible membrane naturally tend to afRime ; but
among animxals, in which the configuration of the
eye is different, the peculiar form of that organ
depends on the greater thicknefs or firength of
this tunic, or on its being fupported by fmall
bones.

This external tunic of the eye is hard and very
' 6 thick

SYSTEM OP THE SENSES. 237

thick in fbme aquatic animals, fuch as the whale,
and particularly the flurgeon, where it is thicker
than the reft of the eye : in other fiflies it is thin,
but has the confiftence of a cartilage.

In birds this tunic is thin, and is divided be-
fore, into two fmall leaves ; between thefe leaves
are received fmall ofleous laminae which lap over
each other, and form a circle or oval, proper for
fuftaining it.

The fclerotica has always in the fore-part. a
large aperture, fhut by the cornea, v^'ith which it is
united: behind, it affords a pafThge to the optic
nerve by a hole or canal..

277. The choroid memhrane. The interior face
of the iBierotica is lined by another thin tunic,
called the choroid, united to it by a lax cellular
tiffue : before, it adheres with greater force around
the aperture which covers the cornea, where there
is a whitifh vifcous and foft ring, called the ciliary
Tigamenf.

The choroid membrane is then turned forwards,
• and feems to conftitute two folds : one of them,
exceedingly thin, is folded back and difpofed in
the form of radii (the ciliary p-ocefs) ; it palTes
before the vitreous humour, in which it is deprefled
into a hollow, and terminates on the edges of the
cryftalline humour. This arrangement does not
take place in fiflies : the other fold, called the

238 ORGANIC STRUCTURE,

uvea, proceeds more forward, and forms an ex-
panfion pierced with a hole, known by the name
of the ^uj)il : it is covered before with a fibrous
membrane which adheres to it clofely, and whieh
prefents ftrise of different colours : the iris*-.

The iris has the property of dilating and con-
trading, for the purpofe of diminifliing or enlar-
ging the pupil.

In the flate of dilatation, the pupil is generally
round ; but when the iris dilates, this aperture, in
contra6ling, often changes its form. In man^
apes, many carnivorous animals, and birds, it
retains its round form ; in cats it aflumes that of
a lozenge, which goes on always con trading, and
at length becomes a vertical line. In the horfe,
the ox, and the whale, it afFeds the fame form,
but in a tranfverfe diredion.

The pupil of fome animals is fafceptible alfo
of afTuming various peculiar configurations, by
the expanfion of the iris.

The ray and the torpedo have at the top of the
h'is a membrane, folded back, which is fufccpti-
bie of falling down, fo as to fhut the pupil by
expanding itfelf like a curtain or blind. This
peculiarity has been remarked in thefe animals
only.

* In moft of the mammalia the iris has a brown colour j
and" in birds it is ornamented with the moft beautiful tints.

It

SYSTEM OF THE SENSES, 23^

It has been obferved, that the pupil in the foetus
of feveral animals is fhut by a thin membrane
{the fuplJIary), which is deftroyed and difappears
Ibme time before birth.

All this part of the choroid, which forms the
uvea and the iris, is generally plane, and fome-
times a little convex 5 between it and the cornea
the aqueous humour is lodged.

The choroid, which is much thinner than the
Sclerotica, is formed o( a beautiful vafcular tifTue :
in the mammalia a part of it is often coloured.

In fifhes with fixed branchiae it is compofed of
two diftindl laminae, between which is a foft glan-
dulous cylindric body, very often of a beautiful
red colour.

The choroid is generally covered with a blackifh,
mucous fubilance, often very thin, which does not
prevent from being feen through it the beautiful
colours with which in fome animals * it is orna-
mented ; it covers alfo the interior face of the
ciliary procefs of the uvea. This blackifh, mucous
fubftance, which is found in almoft all animals, is
wanting in the Albinos, among whom a ftate of
whitcncfs is always a difeafe.

* In the ox this part is of a beautiful golden green changing to
ikyrblue ; in the horfe, the goat, the cervine antelope, and the ftag^
it is a filvery blue changing to violet ; in the fheep, of a pale
golden green, and fometimes blueifh ; in the lion, the cat, and
the dolphin^ it is of a pale golden yellow ; In the dog, the wolf^
and the badger, it is pure white,, bordered with blue.

278. TU

240 ORGANIC STRUCTURE.

2,78. The orhlts. In all animals the eyes are
placed in cavities of greater or lefs depth, called
the orbitar foffe, or orbits.

The orbits of fifhes are not very diflindl, being
confounded externally with the temporal fofTse;
the inferior edge of them is formed of one ofleous
piece, or a feries of fmall bones, which, for the moft
part, are five in number. In birds they conlift in
a depreffion interrupted at the bottom. In reptiles
the exterior edge of the orbits is formed, in whole
or in part, by an offeous branch, behind which the
temporal foffe are confounded with the orbitar.

In quadrupeds 'is obferved alfo an afcending
branch, which forms, on the outfide, a complete
border to the orbits ; but behind this border the
exterior fide is wanting, and the orbitar and the
temporal foffie are united. In man and apes thefe
orbits are complete.

In apes, and in man, the edges of the orbits are
formed by the frontal, the fuper-maxillary, and the
jugal bones. The fides are formed by the fron-
tal, the ethmoid, the lacrymal, the palatine, the
fuper-maxillary, the jugal, and the fphenoid : the
cavity which they compofe is a cone, the apex or
point of which is turned backwards.

The orbitar foffe fometimes are feparated from
each other only by a thin lamina, which is often
in part wanting, as is the cafe in fifhes; but, in
general, they are feparated by the noflriis.

Thefe

SYSTEM OF THE SENSES* 241

Thefe foflae, in moft animals^ are turned more
or lefs towards the fides; in fome reptiles and fe-
veral fifhes* they are turned upwards, and in the
quadrumana and man they look almoft dire6lly
forwards.

The eyes reft in the orbits on a fmall ciifhion of -
very fine fat, which permits them to glide with
great facility; this cufliion is thicker in the mam-
malia, the orbits of which are deeper. In fiflies
it is formed of a gelatinous fubftance, enveloped
by a lax cellular tifTue ; but in the ray and fhark
the eyes are articulated on a cartilaginous pedun-
cle, v/hich is itfelf articulated in the bottom of the
orbit.

279. Mufcjes vf the eye. The eye, in man,
apes, birds, and fifhes, is moved by fix mufcles ; in
moft of the mammalia by feven. Thefe mufcles
are fixed to the bottom of the orbit, and are at-
tached before on the contour of the fclerotica.
Of thefe mufcles, four 2ive.Jiraighty and placed on
the four fides of the orbit ; the two others have au
oNlque dire61ion.

280. Eye-Jids. In fifbes, ferpents, and fome
other reptiles, the eye-lids are wanting; lizards
and the moon-fifh have one of a circular form ; in
the mammalia there are two. Birds and feveral
reptiles have three; in thefe animals the third eye-

* The pleurone6les have the two orbits on the fame fide of
the head 5 but only one of them is perfeft.

VOL. I. R lid^

242 ORGANIC STRUCTURE.

lid, 7nemhrana niBltans, is found towards the in-
terior angle ; it is thin, and extends over the eye
like a curtain, by a I'^'ufcular arrangement altoge-
ther peculiar: this tine eye-lid permits birds to fee
through it, and to look at the fun.

The mammalia, towards the interior angle of
the eye, inftead of the third eye-lid of birds, are
furnifhed with a membranous fold, which in man
and apes is very fmall, and has the form of a cref-
cent. In the other mammalia it is larger, femi-
lunar, and porous ; and in part of its extent has the
appearance of a cartilaginous lamina.

The eye-lids feem to be merely a prolongation
of the fkin : the interior face of them is reflected
on the eye, and forms the white of it, called the
membrana conjunB'iva.

The eye-lids are clofed by the a6lion of a muf-
cle, called the ^alpehralian, the fibres of which are
difpofed in the form of radii: in birds they have
alfo in their thicknefs a membrane which lines the
infide of the orbit.

In moft of the mammalia, the edge of the eye-
lids is terminated by a cartilaginous circle, the
tarfus, furnifhed with hair, eye-lajbes. In thefe
animals the upper eye-lid is the largeft^ and, by
falling down, covers the greater part of the eye :
it is raifed by a particular mufcle called the^^^/vor
orhtO'palfiehralian,^ which is attached in the bot-
tom of the arch of the orbit.

The

SYSTEM OF THE SENSES. 113

The eye lids of birds have, in general, a con-
trary difpofition : the lower, which is the largeft, is
Jined by an ovoid, cartilaginous membrane, and by
rifing up covers a great part of the eye : it is pulled
down by a particular mufcle, which is attached
to the bottom of the orbit.

The eyes of animals which live in the air are
continually moiftened by a fluid (tears) fecreted
from a particular gland, called the lacrymal. This
gland is fituated at the top, and often around the'
orbit ; it is of a white or grayifli colour, granulated,
and often divided into feveral follicles, from which
proceed very fine fmall du6ls. having their aper-
tures near the interior edge of the eye-lids.

The liquid which diftills from them, being dif-
fufed over the eye, ferves to moiften it; and the
fuperfluous part, proceeding towards the interior
angle of the orbit, is in general abforbed by two
fmall tubercles, having each at the fummit a filtu-
lous hole, fiin6ia lacry mafia : thefe holes are con-
tinued in two fmall du6ls, which proceed to a
common excavation, Jaccus lacrymalis^ and termi-
nate at the nofe in a particular du61 called the najal.

In fome fpecies, fuch as hares and rabbits, the
tears trickle down by a finuous and cartilaginous
furrow, which ends in a common bag furnifhed
with a valvula.

In the mammalia the edge of the eye-lids is
furniflied alfo with a great number of glandulous

R 2 , follicles^

244 ORGANIC STRUCTURE.

follicles^ which fecrete an un(5tuous humoor calfed
the gum of the eyes. Birds^ and fome of the mam-
malia, towards the interior angle of the orbit, have
a fmall gland of a different formj which fecretes a
thick humour, yellowifh in birds, and whitifh in
the mammalia. This gland, called that of Har-
deruSj pours the produ6l of its fecretion through
an aperture fituated behind the third eye-lid, or its
reprefentative : it is the largeft of thofe of birds.

The mammalia have alfo, towards the nafal
angle, a fmall reddifh body confifting of feveral
glandulous follicles, caruncula lacrymaliSi which
fecretes a thick and whitifh humour,'

281. Inmariy the eyes are placed in complete
orbits, which have the form of a cone irregularly
flattened ; the bafe forms the entrance, and the
apex is turned iny/ards and backwards.

At the bottom of the upper iide is the ocular
foramen, and below and within this hole is the
fphenoidal Jiffura. Along the exterior and inferior
angle is the fpheno-maxUJary filTure, before which
is the fub-orbitar canal : towards the interior angle
is obferved alfo Xhtfojfa lacrymalis.

The orbitar fofla prefents alfo fmall holes, which
afford a paffage to veiTels and nerves, and an ex-
cavation which lodges a gland. ^

The eye has a round form, Ibmewhat deprefled
at the top, at the bottom^ and on the fides.

The

SYSTEM OP THfi SENSES. 24&

The cornea is the fegmcnt of a fmaller fphere
than that of the eye; it is tranfparent, cartilagi-
nous, and unites with the fclerotica by an edge
cut externally into a bevel.

The aqueous humour, which is diaphanous, and
nearly of the fame denfity as water, is lodged be-
tween the cornea and the iris ; and a fmall quan-
tity of it is contained even between the iris and
the cryftalline. It appears to be fecreted and con-
tained by an exceedingly fine membrane.

The cryftalline is lodged behind the aqueous
humour, in a depreffion of the vitreous body.

It is lenticular, and more convex behind ; it is
from four to five lines in diameter, and fomewhat
more than two lines in thicknefs ; it is rounder in
the foetus, and with age becomes flattened, yellow,
and muddy. Its denfityjncreafes from the centre
to the circumference; it appears to be formed of
fibrous ftrata, placed one above the other : the
capfule, by which it is enveloped without adhering
to it, is moiflened by a humour called that of Mor'
^agni, which is rarer before.

The vitreous humour fills up behind, the greater
part of the eye; it occupies l.\. of its whole axis ;
while the cryflalline occupies only -'-, and the
aqueous humour .^^r its denfity is greater than
that of water.

The hyaloid membran': which retains it, gives
birth to a great many expanfions; and thefe bj

R 3 crofling

246 ORGAtnc STRUCTURE,

crolling fonn regular cells which communicate
with each other.

The hyaloid membrane is divided before into
two laminas, one of which pafles behind the cry-
flalline humour; the other proceeds before, under
the ciliary procelles, which imprint on it blackifh
Uriae, and is confounded with the anterior part of
the capfule of the cryfiialline. The circular fpace
comprehended between thefe two laminae forms, on
the edge of the cryftalline humour, a triangular
plaited canal, which is rendered apparent by
forcing into it fome bubbles of air.

The retina, which is an expanfion of the optic
nerve, is a membrane of a white a(h colour, and of
a foftifh confiftence : it feems to be fibrous and
vafcular without, and villous within..

Soemering difcovered in the potterior part of the
retina a very fmall hole, the edges of which are
plaited, and of s. jellow colour: this hole, which
has been found in the ape, has not been obferved
in other animals. ,

The retina, after enveloping the whpole vitreous
humour, continues before, and terminates behind
the ciliary procefles.

The humours of the eye are contained in two
membranes.

ifl. The fclerotica, which is thick, white, and
of a clofe texture ; it ha^ before a large aperture^
dofed by the cornea with which it is united.

Behind^

SYSTEM 0-P THE SENSES. 247

Behind, it affords a paiiage to the ocalar nerve,
and is traverfed in an oblique dire6lion, through -
out the reft of its extent, by vefiels and nerves.

id, The choroid, which covers the fclerotica
internally : it appears under the form of a delicate
membrane of little confillence, compofed of an
exceedingly fine and beautiful vafcular reticula-
tion. Its exterior face, which is reddifh, adheres
to the fclerotica by a loofe cellular tiffue, and by
vellels and nerves: the interior face, which is vil-
lous, is covered with ablackifh coating j it is ap-
plied to the retina, and affords a paffage to the
ocular nerve.

^efore, the choroid is confounded with the
fclerotica around the corneaj where the ciliary li-
gament is found, under the form of a thick
fpongy and whitifh ring.

Below this ring arife the ciliary procefles, which
appear to be a continuation of the choroid. They
expand before the vitreous humour, and terminate
in a- ferrated border around the cryftalline.

The ciliary proceffes are compofed of a radiated
membrane, fmooth before, and plaited behind ; the
projeclionsof the folds are covered with a blackilh
fubftance, like the choroid, and are depreffed into
a hollow before the vitreous humour. This black-
\ii\ fubilance, or varnifh, remains on the vitreous
humour when the ciliary procelfes are removed,

R 4 and

''i4S ORGANIC STRUCTXyRE,

and produces a radiated ring formed of black
UricC.

Before the ciliary ligament is the commence-
ment of the uveous membrane, which feems to be
a continuation of the choroid ; it proceeds dire6liy
towards the axis of the eye, before the ciliary pro-
cefles, and produces the aperture of the pupil.

Behind, this membrane is compofed of fibres,
which converge from the ciliary ring towards the
pupil ; it is covered by a blackifh varnifh, in the
fame manner as the choroid.

Before, it is covered by numerous fmall fibres,
difpofed in the manner of rays, and which form the
iris. Thefe fmall fibres are fufceptible of elon-
gation and contradlion, for the purpofe of con-
tra6ting or enlarging the aperture of the pupil :
this contraction, in all probability, is produced by
a fpontaneous afflux of blood towards that part.

In man, the colour of the iris varies.

The eyes may be covered by both the eye-lids:
the upper, which is larger, is a continuation of the
eye-brows.

The eye brows reft on the fuperciliary arch ;
they are formed by the fuperciliary mufcles, and
by the fkin, which in that part is covered with
hair: thefe mufcles deprefs the eye-brows by bring-
ing them nearer to each other.

The eye lids are formed by the fkin and the pal-
pebral ian

SYSTEM OF THE SENSES. • 24^

pebralian mufcle; the upper one has alfo a proper
elevating mufcle. When the eye-lids are broaght
together, the upper one falls down as four, and
the lower one riles as one.

The free edges of the eye-lids are furnifhed
with a cartilage {tarjus), retained by a thin liga-
ment, the palpebral. The tarfian cartilage has a
great many farrows, which ferve to lodge glandu-
lous follicles, called the glands of Mclhomius : they
are of a yellowifh white colour, and fecrete the
gumaiy matter. This thick, undluous humour
iflues through a great number of pores called the
ciliary pores. Towards the interior commifTuraj
behind the membrana nicStltans, is a fmall, red-
difh, conical, villous tubercle, compofed for the
moft part of feven fmall follicles, cemented two
and two, with an odd one called the canmcula
lacrymalis.

The edges of the eye-lids are furnifhed with
<6ne or two rows of eye-la(Iies.

The fliin, which forms the eye-lids, feems to be
refle6ted interiorly, and then to be continued be-
fore on the lobe of the eye, to form the conjunc-
tive membrane, which appears to be continued as
far as the cornea.

The conjun61ive membrane is formed of a clofe,
fmooth tiflue, tranfparent on the cornea : it conti-
nually fecretes a ferous matter, which moiftens the
eye. Towards the interior commifTura of the eye-
lids

^50 ' ORGANIC STRUCTUKE.

lids is a fold in the form of a crefcent, which con-«
ftitutes a fort of membrana niditans.

The lacrymal gland, which is oblong and of a
whitifh gray colour, is fituated in the upper part
of the orbitj towards its exterior angle, and is ap-
plied on the lobe of the eye. The excretory du6ls
of this gland open on the interior face of the up-
per eye-lid near its edge, where there are fix or
feven fmall apertures, which pour the tears upon
the eye, Thefe tears are difFufed over the whole
furface of the eye by the a6lion of the orbit oal-
pebralian mufcle, which always brings them back
towards the interior commiflura.

The free edge of each of the eye-lids has, to-
wards its interior angle, a small hole, the projed:-
ing mouth of which is cartilaginous. When the
eye-lids are ihut thefe two holes correfpond ; they
are continued by two duels, which proceed to the
face us lacrymal is.

This membranous bag is lodged in the lacry-
mal fofla, and is continued inferiorly with the nafal
canal.

The eye is moved by fix mufcles, four of which
are Jiratght and two oblique. The four ftraight
mufcles are attached to the bottom of the orbit,
at the circumference of the ocular hole; they then
proceed forwards, and each terminates in a broad
tendinous expanfion on the fclerotica, embracing
the contour of the globe of the eye before.

Of

SYSTEM OF THE SENSES. 251

Of thefe four mufcles the fuperior elevates the
eye ; the inferior deprefles it ; the interior pulls it
inwards, and the exterior outwards. Of the two
oblique ones, the fuperior, which is larger, is at-
tached to the bottom of the eye, on the interior
edge of the ocular hole, and changes to a tendon,
which is refie61ed on a cartilaginous lamina fixed
at the interior angle of the os frontalis. This ten-
don receives in that part a Iheath, and then pro-
ceeds outwards, paflTing over the fuperior right
mufcle, and is fixed at the top and behind to the
exterior fide of the eye, which it caufes to turn in-
wards and downvv^ards.

The inferior oblique mufcle, which is fmaller,
is attached to the bafe of the orbit, and to the bot-
tom of the lacrymal canal ; it proceeds backwards
in an oblique direction, paffing under the depref-
for, and fixes itfelf to the pofterior and exterior part
of the eye, which it pulls upwards and outwards.

OF

OF HEARING.

282. The organ of hearing is obferved in fome
of the mollufca, fome infeds, and in all vertebral
animals. It confifts chiefly of a membranous cap-
fbile, containing a vifcous fluid, in the middle of
which the auditory nerve is expanded.

This capfular apparatus is found in the ear of
all animals : in crabs, and the fepias, it exifls
alone.

In fifhes, the capfule, for the mod part, is di-
vided by leveral contra61:ions ; and contains one,
two, or three fmall bones of different denfities^
fufpended in the middle of the vifcous fubftance.
In thefe animals are obferved three bent or femi-
circular veflels, the extremities of which proceed
into the interior of the capfule.

In the greater part of fifhes the whole of this

. apparatus is contained in the common cavity of the

cranium, which has depreflions fitted for receiving

it, and fome furrows which ferve to lodge a part

of the femi-circular vefTels.

In fifhes with fixed branchiae, this apparatus is
contained in the thicknefs of the bones of the
cranium, and the capfule communicates with a-
eonduit, which traverfes the cranium behind. The
aperture of this conduit is covered, on the out-
fide.

SYSTEM OF THE SENSES. 253 -

lide, by a thin membrane called the ^nmibrana
tym^ani, and by the Ikin,

The fpace comprehended between this membrane
and the capfule is called the barrel or tympanum.

In fome reptiles the barrel is covered only by
the Ikin: in the greater part of them it is furnifhed
with a membrana tympani ; and in all, the fala-
manders excepted, this cavity communicates with
the capfule by an aperture covered with an ofTeous
plate, and with the mouth by a particular conduit
called the guttural conduit, Eujlachian tube.

In birds, the femi-circular veflels have not a
direct communication with the membranous cap-
fule, but with an intermediate cavity, known by
the name of the vejiibulum. In thefe animals, the
capfule exhibits alfo a conical prolongation, beat
and divided by a membranous partition into two
cells, which communicate with each other: one of
thefe proceeds into the vejiibulum, and the other
into the barrel or tympanum, by an aperture co-
vered with a very fine membrane.

In the mammalia, the organ Vv'ith two cells is
formed of two fcalce, divided by a membranous
or ofTeous partition : thefe fcala3 make feveral
turns in a fpiral form, fo as to reprefent the fhell
of a fnail, and on this account are called the
cochlea.

The membranous apparatus of the cochlear the
femi-circular canals, aud the vejiibulum, conilitute

the MEMBRANOUS LABYRINTH.

In

254 ORGANIC STRUCTURE,

In fifhes with fixed branchice, this lahyrinih is
enveloped by an ofleous ftratum of the fame form,
very wide, and in the middle of which thefe
parts are free, and as it were fufpended. In moft
reptiles, in birds, and in the mammalia, it is en-
veloped by a thin ofleousftratum, which embraces
it clofely, and feems to have been moulded on the
form of its parts : this folid covering conftitutes
the ojfeous lahyrinih.

In young mammalia, the ofieous labyrinth may
be difengaged from the body of the bone, which
only furrounds it ; but in adults it is confounded
with it, and feems hollowed out in its fubltance.
The veflibulum is pierced with Xqsqw apertures,
viz. five for the three femi-circular canals, becaufe
the two extremities of one of thefe canals unite
before they reach the veftibulum ; the fixth com-
municates with one of the fcalae of the organ
isjtth f"iVo cells, or of the cochlea ; the feventh
opens into the barrel or tympanum, and is co-
vered by a fmall bone.

\n moil of the mammalia, the cochlea makes
two turns and a half in a fpiral form ; in cetaceous
animals it is fhort and plane, and makes only one
turn and a half; in the Guinea pig, the cabiai,
and porcupine, it is of a turreted form, and
makes three turns and a half.

The barrel or tympanum, which is very large
in birdSj is extended in the thicknefs of the
bones of the cranium. In the mammalia, it is for

SYSTEM OF THE SENSES, 255

the mofl part fingle, but fometimes divided^ as m
the s:enus of the cat, and of the civet-cat.

In moft reptiles, in birds, and in the mamma-
lia, the barrel has four apertures : one is that of
the veftibulum, which is covered by an ofleous
plate ; the fecond is that of the cochlea, which is
clofed by a membrane ; the third is the hole or
canal that communicates with the mouth ; and
the fourth, which is larger, condufis to the out-
iide, and is fhut by the membrana tympani. AH
thefe apertures are of different iizes, and alTume
different forms and diredlions, in the different
kinds of animals.

In fifhes with free branchiae, and in falaman-
ders, the membrana tympani, and alfo the barrel,
are wanting. This membrane, which in fifhes
with fixed branchise, and in fome reptiles, is on a
level with the head, is covered only by the fkin,
which in that part is often thinner.

Birds, and particularly the mammalia, have the
membrana tympani placed at a greater depth in the
thicknefs of the bones: in thefe animals it is fixed
on an offeous frame, fufceptible at a young age
of being feparated from the body of the bone:
this frame, for the mofl part, is incomplete. The
membrana tympani affects alfo different forms :
in fpme reptiles it is plane ; in birds it is convex
on the outfide, and in the mammalia it projed^s
inwards.

The

256 ORGANIC STRUCTURE.

The ofleous plate which covers the aperture of
the vefiibulam is for the moll: part continued in
a handle, or feries of fmall bones, one of which is
applied to the membrana tyrapani, to which it ad»,
Beres.

Salamanders, on the aperture of the veftibulunij
bave only a fmall cartilaginous piece covered by
the flefti.

In ferpents and the camelion the handle of fmall
bones traverfes the f\e(h, and re(is againfl: the
bone which fupports the lower jaw. In all thefe
animals the membrana tympani is wanting.

Birds and fome reptiles have only one fmall
bone I in the frog and the toad there are two, and .
in all the mammalia there are four.

Thefe four fmall bones are : the malleus, incus,
Jlapes, and os orVtculare,

The plate of the Jiapes covers the aperture of
the veflibulum ; and the handle of the malleus
adheres to the membrana tympani.

Thefe fmall bones are moved by one or more
fmall mufcles, which are often fcarcely percepti-
ble. Birds have one, and the mammalia three i
in the latter, two are attached to the malleus, and
one to the ftapes.

Fitbes and reptiles have no exterior auditory
conduit.

Birds have one, which is very fhort : the exterior

orifice is furrounded and covered by a (tvj very

Q line

SYSTEM OF THE SENSES. 257

fine feathers^ difpofed in a manner altogether pe-
culiar.

In the mammalia, the auditory conduit is of
greater extent, and afFecis various diredlions : it is
in part ofieous, and is generally terminated on the
outlide by a cartilaginous espanfion, concha^ of dif-
ferent forms and lizes, and more or lefs moveable
by means of particular mufcles.

Cetaceous animals have for auditory conduit
a very fmall, twifted, cartilaginous canal, which is
lodged in the thicknefs of the fat.

In feveral of the mammalia the concha is
wanting.

2,83. In man, the organ of hearing confifls alfo
of a membranous labyrinth contained in an ofleous,
one, a barrel or tympanum, an auditory conduit,
and a concha.

The membranous labyrinth is compofed of a
capfule containing a vifcous fluid, in which is
found the labyrinthic nerve : this foft and pulpy-
nerve expands into a reticulatioif in the different
excavationsof that part.

The membranous labyrinth has the fame form
as the offeous one in which it is contained. It
confifts of a cochlea, a veftibulum, and three femi-
circular canals. All this apparatus, contained vn
the petrous portion of the temporal bone, feems,
in the foetus, to be feparated from the reft of the
bone; but in the courfe of time it becomes con-

'^01.-. X, s founded

258 ORGANIC STRUCTURE.

founded with it, and appears to be hollowed out
in the fabftanceof it.

The cochlea is placed over and correfponds
with the carotid canal ; its cavity prefents a double
fpiralj which makes two turns and a half. The
bafe of the centre of the fpiral correfponds nearly
with the acouftic foramen ; it is pierced with fe-
veral holes to afford a paffage to the filaments of
the labyrinthic nerve, and its fummit drre6^ed out-
wards, and upwards terminates in a fort of funnel.

The partition which feparates the two fcalse of
the cochlea rs half ofleous and half membranous s
the ofleous part is towards the axis.

Of the two fcal^ of the cochlea, the interior,,
■which is larger and fhorter, is terminated at the
bafe by a round aperture that proceeds to the
barrel or tympanum : foramen of the cochlea.

The exterior one, which is narrower and Ion-
ger^ ends at the veftibulum : thefe two fcalse
communicate with each other at the fummit of the
cochlea.

The three femi-circular canals, fituated b-ehind
the cochlea, are feparated from that part by the
cavity of the veftibulum. They form three arcs^
the two extremities of which are widened and pro-
ceed into the veflibulum. The three lemi-circu-
lar canals give only five apertures in the vefiibu-
lar cavity, becaufe two of them^ are confounded
together on entering it,

6 The

SYSTEM OF THE SENSES. 250

The veftibulum forms an intermediate cavity
between the cochlea and the three femi-circular
canals. It is of a round form, and prefents in the
infide : the five apertures of the femi-circular ca-
nals ; the orifice of the exterior fcala of the coch-
lea; an oval hole which enters the tympanum;
and a fmall triangular aperture which penetrates
into the cranium. This aperture is terminated by
a flit towards the middle of the fuperior edge of
. the apophyfis petrofa, where it condu(5ls to a re-
ceptacle formed by the two laminae of the meninx,
and which contains a ferous matter : aquedu5l of
the vejlibulum or of cotunnl.

Near the aperture of the interior fcala of the
cochlea is another very fmall one^ which proceeds
to the interior of the cranium, opening in the
middle of the pofterior edge of the apophyfis pe-
trofa : aquedii6l of the cochlea.

The offeous labyrinth communicates with the
tympanic cavity by the aperture of the cochlea
and that of the veflibulum.

The tympanic cavity correfponds with the ex-
terior fide of the labyrinth ; it is round, contains a
feries of four fmall bones, and exhibits feveral
apertures.

Of the apertures which enter the tympanic ca-
vity, one of them, of a round form, communicates
with it at the bottom of the interior fcala of the
cochlea; the other, which is oval, opens into the

s 2 veflibulum:

260 ORGANIC STRUCTURE,

veftibulum ; it is covered by the bafe of the ftapes,
Thefe two apertures are feparated by a round emi-
tience called the promonlury.

The tympanic cavity exhibits alfo before, an
aperture divided at its entrance by an ofleous plate
fhaped like the mouth of a fpoon : this aperture
affords a paffage, above the plate, to the interior
mufcle of the malleus, and below to the guttural
conduit of the ear.

This conduit, which Is very narrow, ifTues from-
the temporal above the inflex canal of that bone;
It becomes cartilaginous, and forms a fort oiEuJia^
clnan tube, which proceeds to the bottom of the
mouth behind the nafal fofTae. This conduit,
which ellablifhes a communication between the
back part of the mouth and the tympanic cavity^
is lined with a mucous membrane.

Behind, the tympanic cavity prefents a triangu-
lar aperture, which proceeds into the malloidiaii
cells ; thefe cells are not very apparent in infancy,
but expand with age. At the top and behind, it
exhibits a fort of pyramid, having at its bafe an
aperture which communicates with the fpiroid
canal of the temporal bone, and affords a paffage
to the tympanic nerve. At the bottom it has a
imall flit through which pafs one of the mufcles
of the malleus and the tympanic nerve, glenoidal
fjpire. At the lower part it has feveral fmali holes
for the pafTage of the fanguine vefTels..

The

SYSTEM OF THE SENSES. 2'6l

The four fmall bones, contained in the cavity
of the tympanum, are the ftapes, the os orbiculare,
the incus and the malleus.

Th&Jlapes has exadlly the form indicated by its
name ; the bafe of it is applied to the oval aperture
of the veltibulum, where it is retained by an ex-
panfion of the periofteum. On the fummit it has
a fmall cavity which receives the os orbiculare.

This bone^ which is exceedingly fmall, is found
between the ftapes and the long branch of the
incus.

The incus confifis of a body and two branches ;
the body has an elliptic cavity, v^hich receives the
head of the malleus.

The malleus has the form of a club ; its head,
turned upwards and backwards, is articulated
with the body of the incus ; its neck has a long
flender apophyfis, and its handle another fhorter
one, which is turned outwards and upwards. The
extremity of the handle of the malleus is fixed to-
wards the middle part of the membrane of the
tympanum.

Thefe bones are moved by three mufcles, two
of which belong to the malleus, and the third to
the flapes.

Of the two mufcles of the malleus, the inferior
one is attached to the apophyfis placed below the
neck of that bone, and proceeds in the canal of the
guttural conduit of the ear : it feems as if intend-

S3 ed

262 ■ ORGANIC STRUCTURE.

ed to pull the malleus inwards and forwards, and
to ftretch the tympanic membrane. The anterior,
which is lefs apparent, is attached to the long apo-
phyfis of the neck of the malleus; iflues through
the glcnoidal fifTure, and is attached to the exterior
fide of the guttural conduit : it feems intended to

O

pull the malleus outwards and forwards, and to
relax the tympanic membrane.

The mujcle of the Jiapes is the fmalleft % it
is attached, on one fide, to the fummit of the
pyramid, and on the other to the neck of the
ftapes. Its adion feems to be t6 pull the ftapes
outwards, and to firetch the membrane which
retains the bafe of that bone around the aperture
of the veftibulum.

The four fmall bones, by their union, form a
chain between the aperture of the veftibulum
and the tympanic membrane.

This membrane forms the exterior fide of the
tympanic cavity. It correfponds, without, to the
bottom of the auditory conduit, and feparates the
interior from the exterior part of the ear. In the
foetus, it adheres around an ofleous ring incom-
plete at the top. This ring, in adults, is con-
founded with the body of the bone, and is con-
verted into an ofleous conduit.

The merabrana tympani has an oblique direc-
tion ; it proje61:s outwards, and in the middle ad-
heres to the extremity of the malleus ; it is thin

and

SYSTEM OP THE SENSES. 263

and tranfparent, and Teems fiifceptible of being
feparated into four thin leaves.

On the exterior fide of the membrana tympani
there is found, in adults, an ofleous conduit of
eight or ten lines, flightly bent downwards. This
conduit, which is broad at the bottom, has after-
wards a fort of contraclion, and becomes wider on
the outiide.

The edges of the exterior orifice of this oileous
conduit are unequal, and have attached to them a
cartilaginous cornet, which becomes uider^ and
forms a cavity : concha.

The exterior edges of the concha are produced
by a cartilaginous thick roll, called the aritheUx,
This roll is fingle towards the lower part of the
ear, and at the upper is divided into two grooves,
which leave between them a fmall fofla, called the
navicular.

From the upper part of the concha arifes another
cartilaginous roll, which proceeding upwards, and
then backwards, marks out the contour of the ear:
helix. It is terminated, at the bottom, by a foft
flexible appendix. The interval between the two
rolls is marked by a groove.

Before theconchais a triangular eminence, which
riles above the middle of its cavity, tragus ; oppo-
fite to this eminence is another, towards the lower
part of the anthelix : it is feparated from the for-
mer by a deep groove, antitragus. The whole dif-

s 4 pofitiou

264 ORGANIC STRUCTURE,

polition of the exterior ear is fuch, that the fono-
rous radii, which fall on thefe different parts, are
reflected towards the auditory conduit.

The exierior ear, which is formed of a cartila-
ginous fubftance covered by the fkin, is retained by
three ligamentous expanfions, and exhibits the
elements of feveral mufc)es.

Of three ligaments which proceed towards the
cartilage of the ear, the upper one arifes from the
exterior aponeurofis of the temporo-maxillian
mufclci {heanterior^ from thebafeof the zygomatic
apophyiis; and the pq/ierior, from the bafe of the
maftoidian apophyiis.

Of the mufcles of the ear, three are fituated
around the exterior part of it, and could move it if
they were more prominent : one of them is at the
top, the other below, and the third behind. Exterior
mufcles.

The reff, fiill lefs apparent, are fituated on the
interior part, and do not extend beyond it. In^
ter'ior mufcles.

2,84. The exterior mufcles. The fuperior ex-
tends from the aponeuroiis of the occipito-fron-
tian, to the navicular fofia, temporo-auricidmn : it
would tend to raife the cartilage of the ear.

The anterior extends from the aponeurofis of the
occipito-frontian, above the zygomatic apophyfis,
as far as the anterior part of the helix : the zygO"
7natQ aurkuliiin: it would draw the ear forwards.

The

SYSTEM OF THE SENSES. 265

The. pojierior, which is the moft apparent, varies
both in its form and pofition, and is often divided :
it extends, in general, from the maftoid apophytis
to the pofterior part of the concha, the majioido-
^uricuTian ; it would tend to pull the ear back-
wards. In fome perfons this mufcic has been
feen to perform very ftriking movements.

The mufcles called interior confift of fome
pale flefhy fibres, fcarcely fen(ible, diffufed over
the helix, the tragus, the anti-tragus, and the
concha ; the great and ihQf?nall heJifian, the tra-
gian, the antl-tragian, and the tranfverfian.

The Ikin of the interior part of the concha, and
that of- the exterior auditory conduit, contain a
great number of glandulous follicles, which fecrete
a thick humour of a yellowifli colour, and limilar
to wax, called the cerumen.

The entrance of the auditory conduit is co-
vered alfo with very fine hairs, proper for inter-
cepting fmall bodies which might be introduced
into that cavity.

OF

[ 266 ]

OF SMELLING.

285. The organ of frnelling confifts chiefly of a
membrane called the olfa&ory^ which lines the
folds of the nafal fofFae, and which has the pro-
perty of perceiving the contadl of certain mole-
culse of matter.

The nafal foffe ferve always for affording a
palTage to the air, in the refpiration of animals
with lungs ; in fifhes thefe foflse are hollowed oat
only in the thicknefs of the fnout.

The organ of Imell feems to be ftronger, ac-
cording as the olfadory membrane is of greater
extent.

The nafal fofTae of the mammalia are formed by
the OS ethmoides, its anfra6tuofities and its tur-
binated portions, the vomer, the bones of the nofe,
the fuper-maxillary bone, the inter- maxillary, the
fpbenoid, and the palatine.

The nafrd fotiie arc of greater or lefs extent,
being fometimes broad and fometimes narrow :
the entrance of them is generally turned forwards;
in cetaceous animals, and birds, they are turned
upwards.

Some fifhes, fuch as the toad-fifh, have their
noftrils fupported by pedunculi,

The

SYSTEM OF THE SENSES. 267

Thefize of the noflrils is much increafed by the
numerous tvvifted folds, communicating with each
other, of the ethmoid ; and of its turbinated por-
tions, which have a fpiral form. Thefe turbinated
bones, in mod of the mammalia, are very large, and
turned round in a very lingular manner: in birds
they are, for the mod part, cartilaginous, and large,
efpeciall}^ in birds of prey.

Reptiles have fome membranous laminae, which
enlarge the furfaces of their nafal fofTse.

In fifhes, thefe furfaces are enlarged by mem-
branous prolongations, which are indefinitely fub-
divided in wonderful order.

In the mammalia, the nafal folTse have a com-
munication with cavities formed in the thicknefs
of the frontal bone, the maxillary and the fphe-
iveid ; thefe cavities, which communicate with
the nafal fofTee by narrow apertures, are diftin-
guifhed by the names of: the frontal, maxillary^
and fphmoidal finuft's, according to the bones in
which they are formed.

The frontal -finufes are wanting in fome of the
rodentia, fome edentia, and feveral other animals;
they are very fmall or are wanting in apes ; in
man, and in many of the mammalia, they aipe very
ilriking ; and in fome carnivorous animals, fuch
as the dog, wolf, and fox, and particularly in fome
ruminating anim,als, as the ox, the goat and the
fhcep, they are of great extent : they arc very

large

0,58 ORGANIC STRUCTURE.

large alfo in the fvvine, and exceedingly large in
the elephant.

The maxillary finnfes are generally very fmall in
carnivorous animals, in moft of the rodentia and
edentia. In ruminating animals^ and in feveral
more of the mammalia, they are very large.

Th^Jphenoidal fnmfes are wanting in moft ani-
mals, and particularly in thofe which have the
body of the fphenoid very much flattened. They
are fmall in the fwine and the hippopotamus, and
very large in the elephant.

Cetaceous animals have no finufes. In birds
the cavities of the bones of the cranium have a
communication with the ears, and not with the
noftrils.

The nafal cavities and their numerous folds are
covered by a periofleum, like all the other bones.
But this periofleum is lined with a fungous, thick
and very red membrane, on which is expanded a
beautiful vafcular reticulation ; it is furniflied
with glandulous follicles, which fecrete a peculiar
kind of mucous matter, and adheres very ftrongly
to the periofleum.

The membrane v,'hich covers the infide of the
finufes, and ferves them as a periofleum, is very
thin : it is fmooth, and feems to be of a texture
different from that which lines the noflrils.

The fummit of the ethmoid bone, which cor-
refponds to the bafe of the cranium, in all the

mammalia.

SYSTEM OF THE SENSES. 260

mammalia^ cetaceous animals excepted, is pierced
with a great number of fmall holes : in other ani-
mals it has only one hole or canal. Thefe boles
afford a paffiige to branches of the ethmoidal
nerve, which expand over the whole furface of the
iiafal membrane.

The number and iize of thefe holes feem to be
proportioned to the power of fraelling : in car-
nivorous animals they are very numerous.

To the fore- part of the bones, which form the
anterior edges of the nafal cavities, and the offeous
plate which fcparates thefe cavities, are attached
cartilages, which are prolonged in order to form
the edges of the noftrils. Thefe cartilaginous
edges are of different fizes, and aflume various
configurations in different animals; in the greater
part of the marnmalia they are moved by fome par-
ticular mufclcs, fixed on the cheeks, and which
tend to dilate or to contrail the entrance of the
nafal cavities, and to move, in different dire(?fions,
the projecting muzzle of fome fpecies, fuch as
the fvvine's fnout. ^

In the elephant, the noftrils affe6l a configuration
altogether peculiar; they are continued in the form
of a very elongated cone, which conftitutes the
trunk. This canal, which is broader at the root,
and divided by a partition, has two fpiral turns to-
wards its bate, and communicates with the ofleous
noftrils by means of a valve, which can be raifed.

The

'270 ORGANIC STRUCTURE,

The trunk of the elephant is lined with an apo-
neurotic membrane, pierced with holes through
which oozes a vifcous liquid. The fides are formed
of two layers of fibres^ one of which proceeds, in
a radiated form, from the interior aponeorofis to-
wards another aponearolis beneath the Ikin : thefe
fibres, by contracting, render thinner and extend
the fides of the trunk, without diminifhing its ca-
vity ; the other layer conlifts of fhort longitudinal
fibres, placed quite around it, and proper for (hort-
ening the trunk partially.

Moft reptiles have fome fmall mufcles for di-
lating or contracting the entrance of the noftrils.
In birds, the aperture of the noftrils is furrounded
only by a roll of the fkin. In fithes, they are nar-
rower at the bottom, and fufceptible of fome
movement.

In cetaceous animals, the noftrils exhibit no pro-
je(9:ing folds in the infide, and have no communi-
cation with the finafes; they are Imed with a thin
membrane of a clofe and fmooth texture, the
ftru6iure of which has no refemblance to that with
■which thefe cavities are covered in other animals t
the ethmoid has no aperture, and there is no
olfadlory nerve ; fo that it is highly probable that
the noftrils in thefe animals cannot ferve as the
organ of fmelling. Their peculiar ftru6lure renders
them proper for another purpofe^ they are divided,
.at their ofileons entrance^ by a valve which can

SYSTEM OF THE SENSES. ^/l

be raifed ; the inferior parr, or that which cor-
relponds to the pharynx, is provided with a very
llrong mufcular apparatus, and in the fuperior
or external part is a cavity, the contrad:ible
fides of which terminate outwardly in the narrow
aperture of the nofi:rils. Thefe animals, by means
of this arrangement, can throw up' the water,
which they have in their mouth, to a very great
height, through the noitrils.

In the guttural conduit of the ear of cetaceous
animals is obferved a pretty wide hole, terminating
in a large cavity, lined with a foft, mucous, and
blackifb membrane, which has a communication
with the frontal llnus. The nerves of this cavity,
as well as thofe of the noftrils, proceed from a pair,
(the fifth) which, in all the mammalia, fend out
others to the noilrils ; fo that it is very probable
that this peculiar apparatus ferves as the organ of
fmelling to thefe animals.

286. In man, the olfaclory membrane is of a
moderate lize, and of a rofe colour; is thick, of a
villous texture, and contains a great number of
mucous follicles, which fecrete the mucus o( the
noftrils. This membrane receives a g-reat number
of fanguine vefTels, which arife chiefly from the
fpheno-palatine and ethmoidal arteries.

The ethmoidal nerve, when it arrives near the
ethmoid bone, becomes thicker; alTumes a pulpy

conlifteQce,

271 ORGANIC STRUCTURE,

confiflencCj and penetrates to the noftrils by a
great number of fmall holes or ofleous tubes, ex-
hibited by that bone. This nerve feems to be exclu-
iively appropriated to the fenfe of fmelling'. The
fifth pair furnifli, in the nofe, feveral nerves which
feem to be deflincd only for the life of that organ.
The tiafal foflk have a communication with the
frontal, maxillary, fphenoidal,and ethmoidal iinus-
es ; and the membrane which lines thefe iinufes
is of a ftru6inre different from that which lines
the infide of the nofirils : it has a finer texture, is
fmoother and tranfparent : it adheres weakly to
the bones, and ferves th'em as a periofteum.

• The parts on which the olfactory membrane ex-
pands conftitute the nafal fofTae. Before and at the
top, they are formed by the bones of the nofe ; on.
the fides, by the fuper-maxillaryj lacrymal, and
ethmoid bones, and by theinferior turbinated bones;
behind by the fphenoid ; at the bottom by the fuper-
maxillary bones, and thofe of the palate. They
are divided alfo longitudinally in the middle by
the vomer, and the perpendicular plate of the eth-
moid, and before by the cartilage by which thefe
bones are continued : this plate is very often
warped.

The nafal {bf[k are not very apparent in infancy^
and do not attain to their complete fize till the
period of full growth ; at which time they are

nearly three inches in extent from before back-
wards.

SYSTEM OF THE SENSES. 273

wardsj and two inches from the top to the bot-
tom.

The lateral fides of the nafal foffe approach
each other at the top, and diverge at the bottom.

The narrovv fummit of the noftrils exhibits an
arch of three planes. The anterior, which is in-
clined forwards, conftitutes the arch of the nofe ;
the middle one, which is horizontal, exhibits the
orifice of the ethmoidal holes ; and the poflerior
correfponds to the aperture of the fphenoidal
linufes.

On the lateral fides of the nafal foffe there are
thrte turbinated bones, two of which belong to
the ethmoid bone : the inferior one, for the moil
part, is free.

The fuperior turVinated hone adheres to the
arch of the nafal foffie, and is feparated from the
middle one by a large groove^ ihc fuperior meatus.
This groove exhibits before, the aperture of the
pofterior ethmoidal cells j and behind, the fpheno-
palatin foramen.

The middle turVinated hone, larger than the pre-
ceding, fwells out before, and terminates in a
point behind ; it is feparated from the lower one
by a broad groove, called the middle meatus. Be-
fore, this groove exhibits the common aperture
of the ethmoidal cells, and of the frontal finufes;
and in its middle part an aperture, which pro-
ceeds into the maxillary finufes.

VOL. I, T The

274 ORGANIC STRUCTURE.

The inferior iurhinated lone, lefs twlded and
wider than the other two, has below it a large
furrow, called the inferior meatus, which exhibits
before the aperture of the nafal canal.

To the bones, which conftitute the anterior
aperture of the noftrils, are affixed two cartilages,
which form the arch and alas of thenofe ; and an-
other which produces, before, the middle portion.
Thefe cartilages are covered on the outfide by the
Ikin, and on the infide by the olfa61ory membrane :
in that part, this membrane is thinner and lefs
villous than in the reft of its extent, and it exhi-
bits there fome very fine hairs.

The cartilages of the nofe are moved by the occi-
pito-frontian, fuper-maxilIo-nafian,the great fuper-
maxillo-labian, and the alveolo-nafian mufcles, the
ufes of which are common to the other parts.

The pofterior aperture of the nafal foflae corre-
fponds to the back part of the mouth ; and, at the
moment of deglutition, is clofed by the velum
palati.

The finufes expand with age, and give more
extent to the face. The two frontal finules arc
divided, in the middle, by a longitudinal partition
for the moft part warped. Their extent varies a
great deal j fometimes they occupy the whole
frontal region, and fom.etimes they are fcarcely
apparent.

The two fphenoidal finufes are hollowed out in

the

SYSTEM OP THE SENSES. 275

the body of the fphenoid, the whole extent of
which they foinetimes occupy, and they open be-
hind the fuperior turbinated bone.

The two maxillary finufes are the largefl: ; they
occupy the whole thicknefs of the fuper-maxiJIary
bone; they afte6l a triangular form, and open into
the middle meatus.

■ The four ethmoidal cells correfpond to the
top and fides of the nafal foflas, and have a com-
munication with each other. The two exterior
open into the middle meatus, with 'the frontal
finus; the two pofterior proceed into the fuperior
meatus.

T 2, • SYSTEM

[ 276 ]

SYSTEM OF DIGESTION.

287. iHEfyJiem of dig eft ion in animals. The fy-
ftem of digeftion confifts chiefly of a membranous
bag, the fides of which fecrete a particular juice.
The aliment, introduced into this bag, is there
transformed into a kind of pulp, which contains
the nutritive juice. This juice is diflributed to the
different parts of the body, where it becomes mixed
with the blood, and the reliduum is difcharged.

Some animals have merely an alimentary bag
with one aperture. In the greater number, the
apparatus of digeftion confiils of one canal with
an aperture for entrance, and another for efcape.
This apparatus, however, is rarely fo fimple : it
is rendered complex by feveral dilatations, and
confifls of different pieces.

In fome animals the alimentary canal exhibits
fmall dilatations ; but in others thefe dilatations
are of confiderable lize, and conflitute ftomachs.
When animals have a difiin6l ftomach, the name
of (sfophagus is given to that part of the alimen-
tary canal which proceeds into it ; and that of
inteftine to the one which proceeds from it.

The juice of the alimentary canal appears to be
the only one which in feme animals ferves fordigef-

tion %

SYSTEM OP DIGESTION. 277

tion ; but in the greater nnmber this canal alfo re-
ceives the liquors fecreted by the liv^er and by the
pancreas.

The entrance into the oefophagus is fometimes
a fimple aperture ; but, for the moll part, this en-
trance is a mouth, formed of jaws, and furnithed
with teeth, a tongue, falivary glands, &c.

2,88. Jaws are found in crufiaceous animals, in-
fers, and in feveral of the mollufca; but in thefe
animals they exhibit a peculiar ftru6^ure, which
has very little relation to that of the fame parts in
the mammalia. In fome zoophytes, fuch as the fea
hedge-hog and fea-nettle, there are tbund alfo an
organ of maftication, and teeth moveable by the
means of mufcles.

All vertebral animals are provided with two
jaws * : in birds, fiOies, and ferpcnts, they are both
moveable. In fome reptiles, as the crocodile and
the lizard, and in all the mammalia, the lower one
alone is moveable.

In the mammalia, the lower jaw exhibits a con-
dyle, which is articulated in a cavity of the tem-
poral bone.

In fifhes, reptiles, and birds, the jaw and man-
dible are each furnifhed with a cavity ; and thefe
two cavities receive an intermediate bone (fqiiarc
hone), which ferves as the means of union, and
fupplies the place of a condyle.

* Crabs have four, five, and fometlrnes ten pairs of jaws >

T 3 In

27S ORGANIC STRUCTURE.

In all vertebral animals, the jaws move vertically
and horizontally ; in infeds they move tranfver-
fally.

In ferpentSj the jaws, which are moveable from
above downwards, can be feparated alfo in a lateral
dire6lion, which produces an aperture capable of
receiving an obje6l of prey.larger than their whole
body.

Some fifhes have jaws which, without any move-
ment of the head, -can be carried fuddenly for-
wards to catch their prey ; as is the cafe in the ray,
the (hark, and fome reptiles.

In the mammalia, the condyles are of greater of
lefs breadth and flattened ; in ruminating animals,
their tranfverfe diameter is greateft ; in the roden-
tia it is greateft from before backwards ; and in
mat), the ape, &c. it is greateft in an oblique di-
reftion. In animals which do not mafticate, the
condyles are not very apparent ; in the large carni-
vorous animals they are very ftrong, and are lodged
in deep cavities, in which they are inclofed and
retained by a roll and an ofleous capfule.

The mufcles which move the jaws vary with
refpedl to their number in the different clafies of
animals. In the mammalia, thefe parts are elevated
by four mufcles^, and deprefted by a greater number.
The former are : the crotaphite, the mafleter, and
the two pterygoidian ; the latter are attached to the
OS hyoides, the bafe of the cranium, and to the

fternum.

SYSTEM OP DIGESTION. 2/9

flernum. Of tiiefe, the digaftric of man and of apes
is monogaftric in carnivorous animals. In moll of
the carnivorous animals, fuch as the hyena and the
tiger, the crotaphite mufcles extend as far as the
fummit of the cranium, vi^here they are fixed to a
ilrong ofleoLis ridge. The mafleter, which is very
large, is attached to. a prominent and extenfive
zygomatic arch. Thefe two mufcles, in thefe ani-
mals, move the jaws from above downwards; and
in graminivorous make them perform lateral move-
ments.

Quadrupeds have lips which ferve to clofe the
mouth, and to retain the aliments j in man, they
contribute alfo to fpeech and to the adion of the
phyfiognomy.

289. Teeth. Fifhes, reptiles, and the mam-
malia, have jaws provided with teeth, implanted in
the bodies of the maxillary bones, or retained only
in the gums.

Fifhes have teeth not only in the jaws, but alfo
in the palate, the throat, on the bones which bear
the branchiae and the tongue, and even on the
tongue itfelf. If this difpofilion is favourable to
maftication, it cannot be fo for tafting. In thefe
animals the teeth, which afFe6l different forms, are
fupported by an offeous tubercle covered with a
membrane. When this membrane is deftroyed,
the tooth and tubercle drop out, and the place of
both is afterwards fupplied by others,

T 4 In

'280 ORGANIC STRUCTURE*

In the mammalia, the teeth are of three kinds :
the fharp ones in front are called incifors; na*
turalifls always give the name of incifors to thofe
implanted in the inter-maxillary bone ; others cut
into feveral faces correfpond to the angles of the
lips, and are the angular teeth ; and the large flat
ones, placed backwards and on the fides of the
mouth, are the grinders on molar teeth.

In fome animals, the teeth are fo large, and of
{o lingular a conformation, that they cannot
be diltinguillied by that name: fuch are the
lufks of the narval and the hippopotamus ; thofe
which proceed from the mouth of the wild boar,
and thofe which fall back even on the head of the
barbyroufla.

The grinders exift in all animals furnifhed with
teeth. The prefence of the reft is not conftant:
grinders only are found in the edentia ; incifor
teeth are wanting in thefloth,and angular teeth in
the rodentia. Ruminating animals have incifive
teeth only in the lower jaw. The three kinds are
obferved in the folipeda, feveral of the pachyder-
mata, the carnivorous, the quadrumana, and in
man. In the lad place> the ant-eaters are defti-
tute of them.

Several animals, fuch as the folipeda, have a
part of their jaws without teeth, interdentium. It
is in this part that the bit of the horfe is placed.

In the hare, the fox, and often in children, the

incifors

SYSTEM OP DIGESTION. 2S f

incifors are ferrated ; in bats, thefe itidentations are
fometimes fo deep, that they refembie the teeth of
a comb ; in the rodentia they arc long and curved ;
the didelphis marotarfas has the angular teeth
cfhorter than the reft ; in moft apes the angular
teeth begin to be lengthened, and in the large
carnivorous animals they are ^o long that they
crofs each other, and are received in the indenta-
tions which they mutually prefent.

The large furface of the grinders has various
configurations ; in carnivorous' animals it is co-
vered with points in one or more rows ; in the
pachydermata it is tuberculous, and in the large
graminivorous exhibits falient lines : thefe lines in
the rumirtantia form feveral crefcerits, and in the
folipeda a double feftoon.

Carnivorous animals, the quadrumana and man
bave the teeth formed of an ofleous fubftance, co-
vered on the outfide by a coating of enamel. In
the folipeda and ruminantia the teeth confift of an
ofleous fubftance, enveloped in the membranous
follicle which originally contained them. The
bodies of the teeth are covered with an enamel of
a golden yellow colour : the membranous follicle
oflifies, and forms around the teeth a very hard
cortical covering.

In the elephant and the hippopotamus, when
young, they are compojed of vertical laminae,
placed on each other without adhefion. Thefe

ofTeous

28'2 ORGANIC STRUCTURE.

olTeous laminas, cut unequally at the rummit, foon
unite by means of an en am el ly juice, which infi-
nuatcs itfelf between them, and they then form a
folid tooth compofed of plates of enamel and
oileous plates. «»

By the efFeft of maflication, the edge of the
ofleous planes fooin becomes worn, and in the
courfe of a tew years the furface of the teeth is
covered with falient and unequal lines of enamel.
This difpofition, analogous to that of millllones, is
exceedingly proper for maftication-

In the orySierope the teeth have the porofity of
reeds : they are foft, and can be eafily cut.

The name of root is given to that part of the
teeth which is inferted in the jaw; the part with-
out is called the crown; and the ftridure which
often feparates thefe two parts is called the neck.

The fingle teeth are hollow during the tirfl:
years of their growth ; the cavity lined with a thin
membrane, over which the yeflels and nerves are
fpread, is filled with a gelatinous fubftance, and
becomes partly clofed up with age.

The part firft produced is the body of the tooth;
it foon fliows itfelf without, and begins to be worn
before the root has attained to its full growth.
When it has ceafed to grow, the capacity of the
alveolus decreafes, and is gradually filled upj the
root is deflroyed in the fame proportion, and the
tooth thus worn at both ends becomes very (hort
6 at

SYSTEM OF DIGESTIONT. 2S3

at an advanced age: it then turns loofe in the
focket, and at laft drops out.

In the ruminantia and folipeda the body of the
tooth is fometinnes completely worn out, and the
roots are feparated. In thefe animals the decay
of the teeth is much more rapid than in the car-
nivorous ; in man, this decay takes place in a very
ftriking manner. The wearing out of the teeth,
which goes on in a conftant and regular manner,
ferves to indicate with precifion the age of the fo~
lipeda and ruminantia.

In a great number of animals, a part of the
teeth drop out, and their place is fupplied by
others.

Some fidies, fuch as the fhark, have their teeth
inferted in the flefh, and fufceptible of being re-
newed four or five times : thefe new teeth are con-
cealed behind thofe the places of which they are
intended to fupply. The fame difpofition is ob-
ferved in fome reptiles, as may be feen by the
venomous dart of the viper.

In the mammalia, a part of the teeth drop out
at a determinate period j the germs of thofe which
fucceed are placed behind the firft. In the cro-
codile, the teeth are conical and hollov^, and re-
ceive in their cavities thofe which are to fucceed
them.

The roots of the teeth which drop out are
fpeedily deftroyed ; they become loofe in the

fockcts.

284 ORGANIC STRUCTURE,

fockets, and are forced out by thofe which aflame
their place. This fecond dentition, ferves to indi-
cate the age of the animals.

2CO. The to7io-ue is a mufcle which affedls dif-
ferent forms : in fome of the mammalia it is broad
and fiiort ; in feveral birds it is long and narrow %
in moft ferpents and feveral lizards it is forked.

In mofi: of the mammalia the tongue is covered
by a mucous membrane, furnifhed with nervous
papillae proper for perceiving the impreffion of
favours. In feveral reptiles, it is covered by a
fcaly fubftance, and in ibme fifhes it is furnifhed
with teeth.

The tongue ferves for maftication, for deglutition,
for the voice, and for fpeech. It is fixed to the os
hyoides by mufcles, and the point of it is gene-
rally directed forwards : in the batrachians, how-
ever, it is turned backwards. To the os hyoides,
which is free and fufpended in the back part of
the throat, the mufcles of the pharynx and of the
jaw are affixed. It appears, for the moft part,
under the form of a portion of a cartilaginous
Cylinder ; but in feveral animals this form varies.

The tongue, in general, poflefies great mobi-
lity ; in molt animals it can be conveyed beyond
the mouth, and by reptiles in a very remarkable
manner.

In the green wood-pecker, the tongue, which
is contained in a membranous fheath, and armed

SYSTEM OF DIGESTION. 285

at the point with hooks, can be extended beyond
the bill of the animal to a greater length thsn that
of its body : it is lengthened and drawn back by a
very curious organic difpofitlon.

291. In fifhes the mouth communicates with
the oefophagus, and with the aperture of thebran-
chi^i in animals with lungs, it proceeds to the
cefophagus, the pharynx, and the noftrils.

In thefe animals, which perform real madica-

j tion, the infide of the mouth is moiftened not only

by the fecretion of the mucous membrane, which

lines that cavity, but alfo by the faliva fecreted

from feveral glands.

In carnivorous animals, the faliva under certain
circumftances afiumes a very venomous quality.
This property is found in the produdlion of a
gland of the viper, and in an analogous liquor of
fome infedls.

The oefophagus is a mufculo-membranous^ ca-
nal, lined with a miiccas membrane: its length
varies as that of the neck ; it proceeds to the tio-
mach.

292. The Jiomach is a dilatation of the ali-
mentary canal. In very ravenous fifhes, and
moft ferpents, this dilatation fcarcely exifts. In
the carnivorous mammalia the ftomach is tingle,
and not very capacious ; in the graminivorous it is'
larger ; in birds it is double, and often triple; in

the

2S6 ORGANIC STIIUCTURE.

the ruminantia it is quadruple ; in cetaceous ani-
mals there are five in fucceffion.

The flomachs of infecls have a great analogy
with thofeof red-blooded animals. In butterflies
the ftomach is merely a dilatation fcarcely lenlible,
or does not exift at all ; in other inre6ls the flo-
raach is fingle, double, or multiple. In thofe
which feed on the juice of flowers, fuch as bees,
ihe fingle ftomach is large ; in infects which fuck
blood, or feed on animal matters, it is of lefs ex-
tent. Double fl;omachs belong, in particular, to
carnivorous infecfls, fuch as the coleoptera of that
genus : in thefe infecls, the firfl: flomach is inuf-
cular, like the gizzard of birds, and the fecond
membranous : in fome there is alfo a fort of crop.
Multiple ftomachs are found in infeds which ex-
ercife a kind of rumination, as is the cafe with
locufls.

The numerous clafs of infedis, with refpedl to
this part, exhibit an organization exceedingly cu-
rious and complex j but we muft confine ourfelves
chiefly to red-blooded animals.

The flomach of carnivorous, and particularly ot
herbivorous animals, which do not ruminate, ex-
hibits alfo one or more dilatations ; but for the
mofl part there are two. In herbivorous animals
thefe dilatations are very large ; in the pojyphaga
they are lefs, and in the carnivorous fmall. In

the

SYSTEM OF DIGESTION. 287

the laH^, the ftomach appears to be only an intefti-
nal dilatation, which has little obliquity ; it is in
general wrinkled, and can be confiderably dii-
tended to receive an ample repaft.

The fides of the ftomach are for the moft part
of a mufculo-membranous nature ; and the inte-
rior part of them is always covered with a mucous
membrane.

In birds, which have two and for the moft part
three ftomachs, the firft, called the crop^ is a
membranous bag, in which feeds remain and be-
come foft ; the fecond, ventnculus fuccenturiatus,
is thicker, but of lefs fize ; it is furnifhed with a
great many mucous glands which fecrete abun-
dance of digeftive juice. It was the juice of this
ftomach which Spallanzani employed in his inge-
nious experiments on the gaftric juice. The third,
ov gizzard y is formed of two very thick mufcles ;
the cavity of it is not larger than the ventricle,
but the thicknefs of it makes it appear much more
voluminous on the outfide. The two mufcles of
the gizzard exhibit, on two faces, a very ftrong
round tendon, from which the mufcular fibres ex-
tend in a diverging form. The cavily of this
ftomach is lined with a very thick mucous mem-
brane, which may be eafily feparated, and which
is fafceptible of regeneration. The gizzard pof»-
feftes a very ftrong contrad^ile force : its adlion
feems to fupply the place of maftication.

Granivorous

2BS ORGANIC STRtCTUKE.

Granivorous birds, in general, fvvallow fmal!
pebbles, and the Itrong and varied con traction of
the gizzard on the feeds, mixed with thefe hard
bodies, effedts in this manner their trituration bv
repeated fri61:ion. In the flomach of the oilrich
and the caflbwary federal pounds of pebbles are
often found intermixed with bits of giafs, iron, &c.
In carnivorous birds the gizzard is much thinner :
in thofe vi'hich feed on -fifla or worms there is
Icarcely any. Thefe birds have no crop ; and the
ventricle which is their principal ftomach is gene-
rally very large.

The gaftrlc apparatus of the mollufca cephalo-
poda and gafteropoda has fome analogy with that
of birds. They have a gizzard preceded by a
crop. The ftomach of the volutas as well as of
crabs is furnifhed with two olleous pieces proper
for trituration.

In the bivalva, fuch as the mytilus, the alimen-
tary canal traverfes the liver, and is dilated in its
thicknefs to form a ftomach. Some of thefe ani-
mals, fuch as the oyfter, have a fecond ftomach.

Ruminating animals have four ftomachs, the
aggregate of which exhibits a very remarkable
fyflem of digeftion.

The firftj veniriculus, called paunch by the vul-
gar, is exceedingly large, and occupies a great
part of the abdominal capacity ; it exhibits infe-
riorly a longiludinal re-entering fold, which di-
vides

SYSTEM OF DIGESTION. ^Sg

vides It into two principal cavities; its interior
furface is furnifhed with large projedling conical
glands. The fecond flomach, the honeycomb. Ion--
net, or hng^s hood, is round and much fmaller ; it
is feparated from the former by a membranous
partition in the form of a horfe-flioe, above which
thefe two Itomachs have a communication with
each other. The inlide of the lonnet exhibits
deep cells of different forms, analogous to the
cells of a bee-hive.

The cefophagus communicates with thefe two
ftomachs towards their upper part, where it forms
an inverted gutter, the thick edges of which can
approach each other to form adu6t.

This gutter, continued with the cefophagus,
conlifts of two folds, which advance in a parallel
diredion as far as the third ftomach, where they
interfedl each other at an acute angle, and prevent
the entrance of coarfe aliment. In this part the
gutter exhibits furrows, which are continued with
the membranous laminae that form the third fto-
mach : omafum or many plies.

The omafum, of an ovoid form, and fome-
wbat larger than the honHet, is divided, in the di-
redlion of its two orifices, by a great many mem-
brajious partitions, which produce furrows deep and
narrow, particularly towards their middle.

The fuperior furrows are deeper and much more
crooked than the inferior ; the inlide of thefe fur-

voL, I, u rows

'2gQ ORGANIC STRUCTURE.

rows is farnifhecl with rugous glands covered with
papillas. The orifices of this ftomach are mucb
lower than its body : the anterior, on the left^
corrcfponds to the horinet, and the poftcrior, on
the right, to the ahomajum or fourth ftomach.

The omafum proceeds into the fuperior part of
the laft ftomach, the abomajuin^ which is much
larger than the preceding two, but lefs voluminous
than the paunch : it is fituatcd under the omafum,
between the bonnet and the paunch : it is fhaped
like the bag of a bag- pipe.

The aperture which forms a communication be-
tween the omafum and the abomafum is furnifbed
with a valvula which prevents the return of the
aliments. The interior part of this cavity is lined
with a thic\ mucous membrane, which forms fe-
veral longitudinal folds. This ftomach is conti-
nued with the duodenum by a pyloric orifice
higher than the preceding.

The aliments coarfcly ehewed at firft are formed
into balls, and conveyed fpeedily into the bottom
of the left cavity of the paunch, from which they
proceed to the bottom of the cavity on the right,
and place themfelvcs immediately below the cefo-
phagian aperture, in the order of their entrance.

Thefe aliments become foft and penetrated with
juices. When the animal has taken a proper
quantity, and is in a ftate of reft and of good
health, it has the faculty of making them afcend

SYSTEM OF DIGESTIOIN, ^Ql

into the mouthy where they are again mafticated :
for this purpofe a portion of the grafs contained in
the paunch palles into the cefophagus; the part
which is moil mafticated falls into the bonnet,
and the coarfeft penetrated with juices is reduced
to a ball, and returns to the mouth. When the
latter phaenomenon takes place, it is obferved that
the animal extends its neck, makes a flrong infpi-
ration, and by the firaultaneous acSlion of the fides
of the paunch, of the abdomen, the diaphragm,
and the cefophagus, it caufes the ball to re-afcend.
with rapidity along the oefophagian canal. When
it reaches the mouth it is chewed again much
more llowly, and with great care ; and the animal
feems to find in thefe alimentary balls, penetrated
with juices, a favour which renders the maftication
of them agreeable.

Rumination, therefore, is produced only by the
firft flomach. The alimentary balls, triturated
and reduced to a fine pulp, re-defcend along the
cefophagus, and pafs into the gutter ; the coarfeft
fall into the bonnet, the reft remain between the
furrows of the omafum, and the moft liquid pro-?
ceed dire6lly into the abomafum.

The adion of the bonnet prepares the aliments
for being received into the omafum, which foftens
them, and renders them fufficiently liquid to pafs
into the abomafum, where real digeftion is per-
fijrmed.

u a When

'202 ORGAMIC STRUCTURi,

When ruminating animals drink, or take very
liquid aliment, and during ladlation, thefe fluid
fubftances are conveyed through the oefophagus
into the gutter, the edges of which unite to form a
du6t, and they proceed dire6lly into the omafum,
from which they pafs into the abomafum.

The paunch of the camel exhibits a peculiar
dilatation, furniO^ied with falient lamincB, like the
omafum, and in which it can preferve, for a very
long time, a large quantity of water.

293. The intejiines. That part of the alimen-
tary canal, which is below the llomach, varies
both with refpedl to its length and to its dia-
meter.

In animals, the length of the inteftines is in the
inverfe ratio of the nutritive quality of the ali-
ments on which they feed.

In fome very ravenous fifhes, fuch as the ray,
the inteftine is fhorter than the body. In the
carnivorous mammalia, it is twice or thrice that
length ; in' the herbivorous mammalia with a An-
gle ftomach, it is equal to ten or twelve times
that of the body.

The capacity of the abdomen, in graminivorous
animals, is for this reafon much greater ; while in
the carnivorous the contrary is the cafe.

In reptiles, the inteftines are of the fame width
throughout their whole extent ; in birds, the
width goes on decreafing towards the ret'rlum.

8 h\

SYSTEM OF DIGESTION, ^QS

In the mammalia, the inteftlnes are flender in
the firft part of the alimentary canal, and large in
the latter.

The large inteflines often exhibit flefhy circular
bands, [which produce conftri6lions5 and make
them appear as if fwelled up.

The inteftinal canal, in different parts of its
extent, has one or more lateral appendices en cuU
de-fac : c cecum.

In reptiles the caecum is wanting. The mam-
malia have one ; birds have two ; and fifhes have
often a very great number.

The coecum of the mam'Tialia is placed at the
commencement of the large in'eftines ; in carni-
vorous animals it is very fhort ; in the gramini-
vorous it is much larger ; and in the rodentia, it
has often more extent than the ftomach.

In man and fome apes, the caecum, which is
fhort, has at its extremity a fmall vermiform ap-
pendix.

Birds have often two coecums on the fides of the
reftum.

Some fifhes have no caecum ; while others have
a prodigious number, placed in general near the
pylorus : they are thick and glandular, and feem
to be organs which fecrete a liquor proper for di-
geftion.

The inteftine terminates, for the moft part, in
an aperture furnifhed with a fphiniSter.

u 3 The

2Q4 ORGANIC STRUCTURE.

The anus is wanting in the zoophytes, which
have only one aperture for the ahmentary canal :
It is commonly placed at the extremity of the
trunk or the tail j but in the mollufca it is found
on the fides of the neck.

The wholeof the alimentary canal is lined with
a mucous membrane, which fecretes a digeftive
juice.

The inteftines receive alfo, fordigeftion, the bile
fecreted by the liver, and the liquor produced by
the pancreas.

294. The liver exifts in all vertebral animalsj,
and in all the mollufca; in infers it appears under
the form of a vafcular reticulation.

The fize of the liver appears, in general, to be
in the inverfe ratio of that of the organ of refpi-
ration^

In all animals the liver occupies a great part of
the abdomen ; the venous blood it receives is that
which returns from almofi: all the abdominal vif-
cera ; the veins of all thefe vifcera unite into a
very large trunk (tl)e vena porta;) y which proceeds
into the liver.

The moft important ufe of the hepatic appara-
tus is, not to fecrete a fmall quantity of bile, but to,
receive a great part 'of the venous blood, and to
make it undergo peculiar changes ; fo that the
hiftory of the liver belongs rather to circulation
than to digeftion. However, as the bile is a liquor

SYSTEM OP DIGESTION. 205

of great importance to digeftion, the organ which
fecretes it is here worthy of attention.

The hver exhibits five orders of vefTels : ill,
the large arterious vein, the Juh-hepattc or ve7^a
forta^ which conveys its blood to the liver ; 2d, a
fmall artery, the hepatic ; 3d, the large vein which
conveys back the blood, the Ju'per-hepat'ic-\ 4th,
the biliary vefTels ; 5th, the lymphatic vefiels.

The canals which carry the bile from every part
of the liver unite into one or more hepatic dadls,
which open into the intefi:inal canal near the pylo-
rus, and very rarely into the flomach.

A part of the bile often proceeds to and remains
in a bladder annexed to the liver.

In the mollufca there is no bladder ; it is want-
ing alfo in fome of the mammalia, fuch as the
flag and horfe ; in fifhes it is found fometimes in
the infide of the hepatic organ.

The bile is carried to the bladder two ways: ifi^,
it is conveyed dire6lly from the liver by peculiar
du6ls, the hepato-cyjiic, as is the cafe in birds ;
id, the hepatic canal has a communication with a
peculiar cyfi'ic du61, along which a part of the bile
flows back to proceed to the bladder, as is the cafe
in the mammalia.

In the firft cafe, the bile proceeds direclly from
the bladder to the intedine by the ducIi/T choledo'^
chus ; in the fecond, it re-defcends from the cyftiq
du6t to pafs into the duBus choledochus.

V 4 295. The

296 ORGANIC STRUCTURE.

295. Tht fpleen is found in all red-blooded ani-
mals ; the blood which returns from it proceeds
to the liver : no other ufe of it is known than
that of funiifhing all its blood to the hepatic ap-
paratus.

296. The pancreas is a glandular body which
fecretes a liquor analogous to the faliva ; this liquor
proceeds into the inteftine by a particular dud)",
which opens near the dudus choledochus .

The pancreas is found in almoft all animals
which have a liver ; it is wanting, however, in the
mollufca, and in all fithes which have a great
number of coecums.

Birds have two or three pancreases, which
pour their liquor into the inteftine by peculiar
du6ls.

297. reritonaum. The gaftric and other organs
contained in the abdomen are enve;loped by a dou-
ble membrane, called the peritonaeum.

In the mammalia, the peritonceum is of a
vafcular texture, lax, tranfparent and greaty : in
fifhes, it is of a clofe texture and opake, has a
brilliant metallic appearance^ and is covered with
a black varnifh.

The exterior membrane of the peritonaeum
lines the tides of the lower belly ; the interior
feems to be prolonged different ways to envelop
each organ^ and to retain it in a determinate.

The

SYSTEM OF DIGESTION. 2p7

The portion of the peritonaeum which covers
the inteftines, forms, after it has enveloped them,
a loofe and fmooth raembrane, which keeps them
fixed to the vertebral column : the mefentery,
■ The periton^euni produces alfo a large mem-
branous fold, which covers like an apron the ante-
rior part of the inteftines: the eppJoon (omentum).

In man, the epiploon defcends as far as the
abdomen, and on the bladder i in apes, which
have an open inguinal ring, it falls back towards
the pelvis, and forms a fecond covering.

Animals fubjedl to winter-lleep have ieveral
epiploons, which become charged with fat : this
fat feems to ferve for their nutrition during their
ftate of torpor.

Birds have no epiploon ; their large membra-
nous and aerian bags become charged with fat.

298. System op digestion in man. In
man, the fyftem of digeftion holds a mean plac«,
in feveral refpe61:s, betv/een that of carnivorous
and that of graminivorous animals.

The fides of the mouth are formed, above
and before, by the maxillary bones, and behind
by the palatine bones, the pterygoid apophyfes,
and the guttural fofla j below, by the under jaw
and the teeth.

299, The teeth. Man has two incifor teeth,
one angular {^cufpdatus), two fmall and three large
molar teeth, on each lide of each jaw.

In

2(38 ORGANIC STRUCTUHE,

In the embryo, the rudiments of the teeth are-
fcarcely apparent ; they are nothing then hot a
mucilage confounded with the other parts ; and
do not expand till towards the fourth month of
geilation : at that period they prefent themfelves
i]nder the form of a follicle or membranous bag,
traverfed by a very great number of veffels, and
iilled with a gelatinous mucus.

The follicles of the incifors firil appear, then
thofe of the angular teeth, and in the laft place
the great and fmall molares. Thefe follicles,
which are of an ovoid form, adherent to the
slveoli, are at firft reddifli ; they then become
v/hite, affume a cartilaginous conliftence, and ex-
pand by a point of offification. The furface which
correfponds to the body of the tooth begins to be
covered with a thin cortical coating of enamel.

Towards the fixth or eighth month after birth,
the lower incifor teeth and the fuperior pafs
through the gums, and fhovv themfelves without i
the angular teeth appear towards the end of the
firil year, and' the fmall molares at the end of the
fecond.

Behind the follicles of thefe firfl twenty teeth
there are others of a fimilar kind, which gradually
increafe, and about the lixth or feventh year *
aflume the place of the firft. At that period the
roots of the firft teeth, in a great meafure deftroyed^

* All thefe periods are fubje<fl to' much variation,

/ become

SYSTEM OF BIGESTION, SQQ '

become loofe, and the teeth drop out *, The
fecond teeth affume the place of the firft, nearly
in the fame order as that in which they appear %
the firfl fmall molar tooth of the firft dentition is
fucceeded by two others, which beconrie the two
fmall molares. The laft four appear at a period
exceedingly variable, often towards the twentieth
yearj and fometimes they remain in the alveoli, or
do not ifllie from them till a very advanced age.

The dentes molares have four roots ; the reft
have only one.

At the period when the teeth appear without
the gums, the (hort truncated roots are hollow ;
and their canal communicates with a large cavity
which is found in the middle of the body of the
tooth. Thefe cavities are lined with a membrane
covered with nerves and veflels ; and they are
filled with a gelatinous juice.

The teeth are formed of a compact, ofieous fub-
flance, of the fame nature as that of the other
bones ; the bodies of them are covered even below
the gums by a coating of enamel, which is thicker
at the fummit, and of a brilliant milk white colour.
This enamel is phofphate of lime dif]3ofed in regu-
lar ftriae, which feem to proceed from the centre
to the circumference.

* When they begin to (hake, it is often neceflary to extrad
them, that their prefence may not oblige the others to affume a
bad pofition.

As

300 ORGANIC STRUCTURE.

As man approaches the period of full growth^j
the roots of the teeth lengthen, and foon increafe
to their full extent ; the enamel then becomes
blueiftij and the tooth acquires greater hardnefs.

The teeth become worn in a fenfible manner by
the fri6lion of maftication ; the incifors, often iti-
dented or notched, exhibit towards the fifteenth
year a fharp edge. From the twentieth to the
thirtieth the cavity of the teeth fenfibly dimi-
niflies ; the enamel afTumes a grayifh tint ; the
tubercles of the molar teeth fubfide, and the other
teeth continue to be worn ; the roots are ihorten-
ed, apd towards the forty-fifth year the teeth have
loft a fourth part of their height.

By the progrefs of age, the enamel afTumes a
yellowifh tint, and proceeds no further thao to
the gums ; the cavities of the teeth are obftru6led
and filled, up with a yellow offeous matter. They
continue to wear away by maftication j and the
tooth which has loft two thirds of its height, aboot
the age of fixty or feventy, exhibits only a circle of
enamel at its circumference, and a large yellow
fpot in the middle. The root continues to be de-
firoyed, the focket becomes fhallovver, and the
tooth, loofened, at length drops out.

300. Infide of ihe mouth. Every part of the
mouth is covered by a membrane which is conti-
nued with the ikin of the gums and of the lips.
This membrane proceeds backwards before a great

SYSTEM OP DIGESTION. 301

Slumber of fmall mufcles, and is refle6\ed on the
tongue, which it entirely envelops. Below that
part it forms a fold, which is fixed to the middle
of the interior fiirface of the jaw^ and conftitutes
the frsenum of the tongue.

The membrane which envelops all thefe parts
is thin, fmooth and moift j it is thicker at the arch
of the palate than on the tongue, where it is inter«
fperfed with papillae of different fizes and forms.

The fmaller papillae are numerous ; of a conical
figure, placed clofe to each other, and terminate in
a point : they give to the tongue a velvety appear-
ance.

Thefe papilla are interfpjerfed with others kfs
numerous, of a larger fize, and fhaped like a mufh-
room; towards the root of the tongue, there are
obferved from eight to iixteen larger and foftiOi
tuberculous papillae, difpofed in one or in two rows
in the form of a V, the point of which is turned
backwards.

All thefe papillse appear to be a nervous and
vafcular expanfion ; they are in an eflential manner
the (tSLt of the ofgan of iq/ie.

301. The tongue (glojfaj is formed of long
mufcular fibres, which terminate in a point on
one fide, and are confounded behind with the
fibres of feveral other mufcles.

The tongue, by contracting, may be fhortened ;
and its point may be bent.

The.

302 ORGANIC StRUCTURE/

The other mufcles, continued with the tonguCj
are attached to different points of the bones of the
cranium, and to a particular bone fufpended in the
middle of the mufcles affixed to it : this bone is
called the 0^ hjoides.
-•^302. The OS hyoides has the form of a bow ; its
hody, or the anterior part of it, is broad; it is arti-
culated on the fides with a thin extended prolonga-
tion, the great horn, which proceeds direcftly back-
wards. Above the articulation of the ereat horns
with the body of the bone are articulated two other
prolongations, the lejfer horns ; which are turned
upwards, and c^ten remain very ihort.

This bone is fufpended by the raufcles, between
the angles of the jav.'S; it is. retained behind by a
ligament, which, proceeding from the extremity of
the large horns, is attached to the flyloid apo-
phyfis. • ■

303. Before and on the fides of the os hyoides
is attached a thin, flat, quadrilateral mufcle, which
afcends before, and proceeds to the fides of the root
of the tongue. It dravv's the root of that organ
downwards and backwards, or pulls the os hyoides
upwards and forwards. Hyo-GLOSSiAN.

304. To the middle of the interior fnrface of the
-lower jaw, towards its genian apophyfis, is affixed a

broad mufcle, flattened tranfverfely, andof a trian-
gular form; this mufcle is feparated from its fellow
^ before, only by a cellular tifliie : both thefe mufcles
9 ^ proceed

SYSTEM OF DIGESTION. 303

proceed downwards and backwards, becoming
broader; after which they are confounded toge-
ther, and their fibres unite to thofe of the tongue.
This mufcle can carry the tongue forwards and
beyond the raoutb, as well as backwards and
downwards: it can alio bend it on itfelf. Genio-'

GLOSSIAN.

305. To the fiyloid apophyfis is affixed a fmall
mufcle, which proceeds downwards and forwards; it
becomes thin and flat, and terminates an the fides
of the tongue from its root till towards the tip of it.
This mufcle, with its fellow, moves the tongue up-
wards and backwards. Stylo- glossian-.

The tongue, which is fixed to the os hyoides, is
moved by the mufcles affixed to that bone.

306. On the fides of the interior face of the
lower jaw, along an oblique line, is affixed, by an
aponeurotic expanfion, a thin jbroad. mufcle, the
anterior (hort fibres of which proceed downwards
and backwards, the poflerior inwards, and both
unite to .affix themfelves, by fliort aponeurofes, to
the OS hyoides : it moves that bone upwards and for-
wards, and depreffes the jaw. Mylo-hyoidian.

307. To the genian apophyfis is affixed a fmall
Ihin mufcle, which defcends behind, and is infert-
ed before the middle of the os hyoides : it raifes
the jaw by carrying it forwards, or deprefies it.
Genio-hyoidian.

J08. To

304 ORGANIC STRUCTURE.

308. To the ftyloici apophyfis is affixed a thin
flender mufcle, which defcends forwards and in-
wards, and is inferted on the fides of the bodies
of the OS hyoides. Near this point it divides, and
fuffers to pafs through its thicknefs the tendon of
another mufcle, the majioido-genian. It moves the
OS hyoides upwards and backwards. Stylo-hyoi-

DIAN.

309. To the upper part of the fternum behindj
and near the clavicle, is affixed a long thin muf-
cle, which proceeds upwards, approaches its fellow
near the larynx, and is inle; ted in the inferior edge
of the body of the os hyoides, which it lowers^
Sterno-hyoidian.

310. On the upper edge of the fcapula, near
the indentation obferved in it, is inferted a thin
flender mufcle, which pafles behind the clavicle^
afcends on the inlide, and is affixed at the bottom
and on the iide of the body of the os hyoides^
which it deprefles. Scapulo-hyoidian,

All thefe mufcles render the tongue fufcepti-
ble of being moved in almoil every diredion. .^

311. From the lateral parts of the root of the
tongue arifes a fmall mufcle, which proceeds to-
wards feveral others lituated at the back part of
the vault of the palate. The aggregate of thefe
mufcles formSj above the tongue, an arch, which
confiitutes the entrance of the alimentary canah

it

SYSTEM OF DIGESTION!?-, 305

it has been diftinguifhed by the name of the velum
^alat'i.

The membrane of the mouth is extended over
thefe mufcles, and forms, in the middle of them, a
round fungous fold, which terminates in a point,
and is fufpended from the fummit of the arch : it
is called the uvula. The mufcles covered by this
membrane extend even into this fold, and move
the uvula.

The mufcles which form the velum palati pro-
duce two layers on each fide, placed one before
the other, and feparated by a fpace which contains
a gland. Thefe two layers are called the anterior
and pofterlor 'pillars.

312. From the (ides of the root of the tongue
arifes a fmall mufcle, which proceeds to the an-
terior pillar of the velum palati : by contradling it
leffens the aperture of the velum. Glosso-sta-

PHYLINE.

313. To the petrous portion of the temporal
bone, near the guttural conduit of the ear, is af-
fixed a fmall round mufcle, which defcends, be-
comes broader, and proceeds to the fubftance of
the velum palati and of the uvula. It raifes the
fummit of the velum behind, and carries it before
the entrance of the noftrils, which may be then
fhut during the time of deglutition. Petro-sta-

PHYLINE.

314. To the bafe of the pterygoid apophyfis is
VOL. la X attached

306 OUGANIC STRUCTURE,

attached a thin fiat mufcle^ which defcends along"
its interior wing : it terminates in a tendon, which
is refle6}ed around the fpine of the pterygoid apo-
phyfis ; it then proceeds inwards, adheres to an
afperi^y of the plane portion of the palatine bone,
and unites with its fellow. This mufcle, which is
found on the exterior fide of the preceding, raifes
and extends the velum palati. Pterygo-sta-

PHYLINE.

315. To the middle and bottom of the arch of
the palate is affixed a fmall mufcle, which defcends
behind ; is confounded witb its fellow, and pro-
ceeds to the uvula, which it raifes and fhortens»
Palatostaphyline.

316. The mouth is continually moiftened by a
vifcous fluid, fecreted from an indefinite number
of glandulous follicles, found in the fides of that
cavity, which pour it out through a great many
fmall pores.

Thefe glands have acquired names from their
pofition ; fuch as the palatine, lingual, molar, labial
and buccal.

But during maftication the mouth receives, in
great abundance, a lefs vifcous liquor, fecreted by
feveral large glands, and which is poured into the
mouth through particular du(Sis.

317. Below the ear, and before the maftoid
apophyfis, is a large gland which appears to be
compofed of lobules, or fmall glands united into

4 lobes

SYSTEM OP DIGESTIOIir. 30^

lobes by a cellular membrane. Each fmall gland is
furrjifhed with an excretory tube : thefe tubes
unite, and form a du6ij which defcends before, tra-
verfes the hicco-laVian mufcle, and opens towards
the fecond or third of the fuperior molar teeth.
This gland is called \a\^ parotid, and its du6l the
'parot'id'ian {th^falivary of St end).

318. The interior furface of the rnaxillary bone
contains, near its angles, another round gland, of
lefs fize than the preceding, but of the fame ftruc- '
ture: it has alfo an excretory du6l, which pafles be-
low the mylo-hyoidiari mufcle, is accompanied with.
a feries of fmall glands, and opens into the mouth
clofe to the frasnum of the tongue. This gland is
called the maxillary, and its du6l XhQ inferior faJi'
vary of iVharton.

319. Below the tongue is found a fmall gland,
from which proceed a great number of excretory
duds that open on the lower fide of the mouth.
Sub- lingual gland.

320. Between the pillars of the velum palati is
another ovoid gland, which pours the faliva through
feveral holes. Tonfdla (amygdala).

321. The pharynx. The mouth has a commu-
nication behind with a large cavity, from which it
is feparated by the velum palati. This cavity (the
back part of the mouth, gullet, or pharynx) is con-
tinued upwards with the back part of the noHirils, "

X 2 and

308 ORGANIC STRUCTURt.

and the guttural conduits of the ear ; it then prO'>
ceeds downwards and backwards.

The pharynx exhibits before, in the middle of
its paffage, and below the os hyoides, the entrance
of a canal which conducts to the lungs : the larynx.

The aperture of the larynx, glottis^ is fhut by a
fort of femi-circular, cartilaginous, elaflic valve
(epiglottis), affixed before towards the root of the
tongue, and which proceeds obliquely upwards.

The epiglottis is deprefled towards the aperture
of the^/o//ij-, by the pallage of aliment, the falling
back of the tongue, and the elevation of the larynx
at the time of deglutition.

The pharynx defcends behind the larynx, and
continues with the oefophagus ; it is lined by a
fmooth membrane, furnifhed with a great number
of glandulous follicles. Its fides are formed by
different layers of mufcular fibres. The longitu-
dinal fibres are attached fuperiorly to different
points of the bafe of the cranium ; in the back
part, before the large occipital foramen ; on the
fides, to the fiyloid and pterygoid apophyfes 5 and
before, towards the middle of the interior face of
the jaw. Below, the mufcular fibres are affixed to
the OS hyoides and to the cartilage of the larynx :
thyroid.

Several layers of thefe fibres are tranfverfe and
obhque ; they crofs each other behind by a more

compadl

SYSTEM OF DIGESTION. 309

compadl tifllie, which forms a median line. This
difpofition allows the pharynx to be fhortened, and
to be contradied in every point.

To the ftyloid apophylis is affixed a round muf-
cle, which defcends and expands over the fides of
the pharynx : it contributes to raife that part.
Stylo-pharyngian.

The pharynx rells againft the trachelian region
of the rachis, on the mufcles which cover it; and
is feparated from it only by a lax cellular tiflue,
which is never greafy.

The pharynx becomes narrower at its lower
part, which correfponds to about the iixth vertebra
of the neck ; it then continues in a fingle canal,
which proceeds to the ftomach : the cefophagus.

322. The cefophagus is lined with a mucous
membrane^ analogous to that of the pharynx : its
lides are formed by two layers of pale mufcular
fibres : the exterior, which is thicker, has its fibres
longitudinal : thofe of the interior layer are thin-
ner, and difpofed in a circular or fpiral form : they
can fhorten or contra(5l that cavity.

The cefophagus defcends a little to the left, be-
fore the bodies of the laft cervical vertebrae; it then
penetrates into the breafi, and inclines gently to
the right, along the bodies of the dorfal vertebrae ;
it then traverfes the diaphragm behind, and ter-
minates in the abdomen by a wide aperture, the,
pefo'^hagian, which is continued with the Aomach.
X ^ 323. The

310 ORGANIC STRUCTURE.

323. The JiQmach, fomewhat wide at firft, is
contained in the left hypochondre : it is confider-
ably dilated, and is folded back on itfeif, fornning
a large convexity : th^ greater curvature : it then
proceeds tranfverfally to the right into the epi-
gaftric region/ where it becomes narrower, and
exhibits a fmall convexity: the hjfer curvature; after
which it terminates in an aperture inclined down-
wards and to the right. Pylorus.

The ftomach, therefore, exhibits the form of a
cone folded back on itfeif, and fituated in a tranf-
verfe, oblique direction below the diaphragm. It
has two apertures. One of them, the cefophag'ian^ is
dire6led upwards, forwards, and to the left : the
other, the, pyloric, which is fmaller, is turned down-
wards, backwards, and to the right. It therefore
exhibits two curvatures, from the one orifice to the
other : one of thefe, vyhich is fmall, is turned up-
wards and backwards; the other, which is larger, is
turned downwards and forwards. The two aper-r
tures of the flomach are very near each other in
the foetus, which renders it, in fome meafure,
fpherical. In the flate of plenitude it moves up-
wards: its large curvature is entirely before, and
its lets behind.

The ftomach is every where covered by i^ferous
membrane, furniQied by the peritonaeum. The
part of this membrane which covers the gafiric
organ before, is united to that Vvhich covers it be-
hind.

SYSTEM OP DIGESTION-. '311

hind, towards the lefler and greater curvatures,
where thefe membranes are applied one to the other,
and form avafcular, plaited and adipofeexpanfion.
The fold whieh is towards the fmall curvature
(lejfer epploon) comes from the portion of the
peritoneum which covers the liver: that formed
towards the large curvature (the great epiploon) \^
very extenfive ; it defcends before the abdomen,
and covers a great part of the inteftines.

When riie ftoniach is diftended by the prefence
of aliment, the laminse of which thefe folds are
formed towards the curvatures of the llomach fe-
parate, and permit that organ to aflume great am-
plitude.

Below the peritonaea! membrane, the fides of the
ftomach exhibit two layers of mufcular fibres : the
exterior extend from the one aperture to the
other ; thofe which are below afTume a circular
and tranfverfe diredlion.

In t^e laft place, the ftomach exhibits interiorly
a thick mucous membrane, full of villofities, which
give it a velvety appearance ; it has in the infide
folds which difappear in the ftate of dilatation.

The fides of the ftomach become much thicker
towards the pyloric aperture, where the interior
membrane forms a thick membranous roll, which
contains mufcular fibres in the form of a ring : this
roll produces a fort oi^ pyloric valvula.

^^4. The intejlines. The fi:omach is then con-
X 4 tinuecl

312 ORGANIC STRUCTURE.

tinued with the inteftinal canal. This canal is
twifled, folded back on itfelf, and is narrow at the
top '.fmall iniejiines : towards the anal extremity it
is larger : the large 'miefrmes : its length is about fix
or feven times that of the body.

The firft part of the intefline, tlie duodenum,
which is continued with the ftomach, is fufceptible
of great dilatation ; it defcribes different curves,
and is in part unprovided with a peritonseal mem-
brane. It has one and often two fmall apertures at
the diftance of fome inches below the pylorus : this
portion proceeds backwards, downwards, and to
the right ; then afcends, and continues with a long
portion of the inteftines : \he jejunum and the ileum.
Thefe inteftines form a great number of circum-
volutions, and occupy the whole anterior, middle,
and lateral part of the abdomen.

They;//*^// inteftines are continued with the large
inteftines, firft by a fhort thick portion called the
coecum\ it is fituated in the right iliac region, and at
its entrance is furnifhed with a circular membra-
nous valvula, which oppofes the return of the fascal
matters : this portion of inteftine has a lateral ap-
pendix, the cavity of which, called the ccecal, termi-
nates like the finder of a glove : the coecum.

This fhort portion of inteftine is continued with
one much longer called the colon: the latter is of
the faiijc fize, and is twifted around all the fmtill
guts ; it rifes from the right iliac region, traverfes

the

SYSTEM OF DIGESTION. 3]3

the abdomen, below the Horn ach, defcends along
the left fide, is refleded on the praelumbo-trochan-
tinian mufcle, and is continued with the laft part of
the inteftinal canal. The latter, called the reBum,
is large, fhort, and upright, and terminates by a
mufcle, the annular fibres of which clofe exa6tly
its aperture. Interior fphin6ler of the anus.

A thin mufcle is placed in the cellular tifTue,
which lines the anus : it is inferted in the coccyx,
by one of its extremities, and at the other is con-
founded with the bulbo-urethral or cavernous muf-
cle : by its action it tends to clofe the anus. Coc-
CYGIO-ANIAN, exterior fphm£ler.

A large thin mufcle forms the bottom of the
pelvian cavity : it is affixed at the top, behind the
pubis, to the upper part of the fub-pubian hole, and
the fpine of the ifchium ; and below to the fides of
the coccyx : it then unites with that on the oppo-
f-iit fide, by an aponeurotic line, and embraces the
lateral part«. It elevates the anus. Sub-pubio-
CoccYGiAN, elevator of the anus. The flru6lure
of the fides of the intefl:inal canal is analogous to
that of the fides of the fiomach. The inteftines
are covered by the ferous membrane, which en-
velops all the vifcera of the abdomen : peritonaeum.

This peritoneal membrane, after having enve-
loped the intefiinal canal, is refleded backwards,
and forms a double wrinkled, vafcular, adipofe ex-
panfion of the breadth of the hand, and much

fhorter

3'!4 ORGANIC- STRUCrURE.

Shorter than that canal : it is affixed before the
bodies of the dorfal and lumbar vertebras, and
thus fecures the inteftines. A part of this mem-
branous expanfion retains all the fmall intef-
tines in a bundle in the middle of the abdomen t
mejentery : the other part confines the large intef-
tines around the former : mefo-colon. The double
membrane of the mefentery is fufceptible of being
feparated near the inteftines, when the latter ac-
quire more amplitude.

Below the ferous membrane of the inteftines is
a- double layer of very thin mufcular fibres: the
exterior longitudinal ones are difpofed in feparate
bands; the interior ones, which are circular, are
alio very thin. The longitudinal layers, which are
little fufceptible of exteniion, confine the fides of
the canal, and produce thofe gibbolities which are
obferved in the large intefiines.

Theoutlide of the alimentary canal is furnifhed
%vith a mucous membrane, analogous to that of
the ftomach. At the entrance of the duodenum
is obferx'ed one or two fmall apertures, v^hich
pour into the inteftine the produ6lof the fecretion
of the liver and of the pancreas.

325. The liver is a glandulous organ of a eon-
fiderable fize ; it occupies a great part of the ab-
domen,. aod- is fituated in the right hypochondre,
the epigaflric region, and a part of the left hypo-
chondre, below the diaphragm^ &;c. This organ-
receives

SYSTEM OF DIGESTICm. 315

receives the venous blood, vv^hich comes from the '
principal vifcera of the abdomen. The blood by
traverlingthis gland undergoes important changes;
it is freed from thofe greafy and albuminous mo-
leculsg which it contained in excefs, : thefe fub-
ftances, by their combination with a fmall quantity
of foda, form the bile, which proceeds from every
point of the liver by a peculiar order of veflels.

If it be confidered that the liver is the heaviefi:
of all the organs, and that the great quantity of
venous blood which it continually receive'?, under-
goes in this organ the moft important changes, it
may be readily conceived that a minute defcrip-
tion of its vafcular ftru6lure belongs rather to the
fyftem of circulation than to that of digeftion. We
ihall, therefore, introduce here only what relates
to the excretion of the fmall quantity of bile pro-
duced by the materials taken from the large quan-
tity of blood which pafles through the liver. The
bile is excreted in all points from the hepatic
organ by ramifications, rami, and branches^ which
decreafing in number, and increafing in calibre,
unite together, and iffne from its tranfverfe furrow
by two or three trunks, which terminate in one
du6l called the hematic.

The hepatic du6l, after proceeding a certain;
way to the left, communicates with another du6l,
the cyjiic, which is refledled upwards and to the
\e% at a very acute angle, and proceeds to the gall-
bladder.

3l6 ORGANIC STRUCTUK.E.

bladder. Thefe two da6ls form, by their union,
a larger du(5):, called the du£fus choledochus, which
proceeds to the left, and opens into the duodenum.

The cyjilc dud, which is an inch in length, is
terminated by a dilatation that conflitutes the gall-
bladder.

This pyriform veficle is lodged in a depreffion of
the gaftric face of the right lobe of the liver ; it
touches the colon, the commencement of the duo-
denum, and the pancreas.

The exterior tunic of it is formed by a prolonga-
tion of the peritoucBum, in every part of it which
does not adhere to the liver ; the interior fide is
villous, interfperfed with folds, and exhibits all the
chara61ers of the mucous membranes.

The du^us choledochus is a continuation of the
hepatic and cyftic du61sj its length is about three
iinger-breadths ; it defcends, on the left, before
the fub-hepatic vein; is inferted obliquely between
the tunics of the duodenum \ often receives in that
part the pancreatic dudl ; and at length pierces
the villous tunic of the intefline, two finger^
breadths below the pylorus.

The (Irudure of the hepatic, cyftic, and cha-
ledocb du(9:s is nearly the fame as that of the
gall-bladder.

326. The I'ik, which proceeds from all parts of
the liver, runs along the hepatic du6V, as far as
the dudus choledochus j the la,tter pours it into

the

SYSTEM or DIGESTION. 317

the duodenum : but when it does not flow into the
duodenum, it may flow back by the cyilic dud, and
be depofited in the gall-bladder, where it acquires
more confiflence, and aflumes a darker colour.

The bile is a liquid of agreenifh yellow colour,
fat, and foft to the touch, vifcous, exceedingly
bitter, mifcible with water like foap, and foluble
in oils, alcohol, and ether.

The chemical corapofition ot' the bile may be
afcertained by the following mode of analyfis :
Pour dilute fulphuric acid over this animal liquor,
and expofe it to heat. You muft then obferve
whether precipitation takes place, and whether a
ialine fubftance remains in the liquor : the preci-
pitate muft be Separated by filtration.

Ths liquor, when properly evaporated, will give
cryftals of fulphate of foda. Then treat the preci-
pitate with alcohol, which will diflblve a part of
it : the other is to be feparated by the filter. If
the alcohol be evaporated, a pure oily matter will
be depofited : the other part of the precipitate,
which remains on the filter, is albumen.

Hence it refults that bile is eflentially formed of
albumen, oil, and foda, in a kmd of faponaceous
fiate.

Difi^erent falts alfo are found in the bile^ in fifiall
quantity, and particularly phofphate of foda.

The bile very often produces concretions in the
gall-bladder.

327. Bi-

3lg dRdAKiC STRUCTURE.

327. Bilious coricretidns are fometimes very nu-
merous; they afFeci, for the moft part, a tetrae-
dral pyramidal form, and, when there are feveral;,
become polyedra by fri6tion. They are brown,
green, or yellow; exceedingly light, and burn^
emitting a thick fmoke.

They affe6l three modes of compofition. Some
are irregular, and confifl: of grains united around
a nucleus : others are angular, and produced by
concentric ftrata of different denfities, and often
very compad. The lait kind are ovoid, exceed-
ingly hard, covered by a white coating, are brilliant,
and appear to be^ cryftallized : this kind are infolu-
bte in alcohol ; they are formed of adipocera ; the
reft are of the nature of bile.

328. Thefplem. The blood which proceeds to
the liver by the fub-hepatic vein comes in part
from the fpleen ; this vifcus, which has an ovoid
form, is of a blueifh red colour. It is placed
lengthwife in the left hypochondre, and is co-
vered by the peritonaeum, the folds of which fix it
to the diaphragm, the flomach, and the mefo-
eolon.

The fpleen is convex on the outfide, and fome-
what concave within, v*?here it exhibits a longitu-
dinal fciflure filled with fat. The artery which
proceeds to this organ (the left branch of the fub-
gaftric or coeliac trunk) is very large, twifled, and
penetrates into its fubftance near the fciflure;

The

SYSTEM OF DIGESTIOS?. 3Jg

The veDOus trunk, which returns from that organ,
IS united to the mefenteric vein ; and both form
the fub-hcpatic vein^ vena porLe^ which proceeds
to the liver.

No other ufe is yet known of the fpleen, than
that of conveying all its venous blood to the
hepatic organ,

329. The pancreas is an oblong gland, very
inuch analogous to the falivary glands. It is
placed, in a tranfverfe diree'-lion, in the left hy-
pochondre, below the ftomach, between the liver
and the fpleen, on the pofterior aperture of the
two membranes of the mefo-colon, which cover
it before: behind it is enveloped only by cellular
tiffue.

The pancreas is of a pale rofe colour, and ap-
pears to be formed of lobes enveloped by a cellular
membrane. Thefe lobes are an aflcmblage of
lobules and glands indeltinitely divided, and are
alfo covered by a ftratum of cellular membrane.

Acrofs the middle of the pancreas runs a du(5t,
on the fides of which fome exceedingly fine fecreting
duels terminate. The pancreatic duel proceeds
to the right, and opens into the ductus choledo-
chus, or very near it, in the duodenum.

The fluid fecreted by this gland appears to be
very analogous to faliva.

30. The peritoneum, v/hich, as already faid,
envelops the whole vifcera of the abdomen, and

the

320 ORGANIC STRUCTURE,

the fides of that cavity, forms a common covering*
Its ftru^lure is fuch, that anatomifls compare it ta
a membranous bag every where fhut. The cavity
of this bag forms the fpace comprehended between
the inteftines and the fides of the abdomen. This
cavity, the fides of which are contiguous, contains
nothing but ferous matter.

The exterior face of this bag lines before, and
laterally, the interior fides of the abdomen ; and
behind it envelops, in its numerous folds, the vif-
cera contained in that cavity.

The ligaments which fix the vifcera of the ab-
domen to the neighbouring parts, are, in a great
meafure, only folds of the peritonaeum.

SYSTEM

JM

[ 321 ]

SYSTEM OF CIRCULATION.

:3:gi. In circulation, the blood, proceeding fron>
a certain point, is conveyed by one order of veilels
to all the parts of the body, and diftributes to them
the materials neceflary for the different changes
which are there continually taking place : it is
then conveyed back to the point from which it
proceeded, by one or two orders of veffels.
r; In this courfe, the blood paiTes either in whole
or in part through peculiar organs, which tend
jn an eflential manner to maintain it in a pro-
per flate of temperature and of liquidity, or to
free it from the reiiduums of organization ,with
which it is charged, or in the laft place to reft ore
to.it thofe e]ffential materials which it has loft. All
thefe organs neceflarily compofe a part of the
iyftem of circulation.

332. Circulation. In plants and zoophytes
no diftin(5lion is remarked in the order of circula-
tion, or in the veftels : the fluids feem to proceed
to the different parts by a kind of fudlion or abforp-
tion.

Infe^ls have a long dorfal tranfparent vcffel
endowed with periftaltic motion : the relation of
this veflel to the other parts is not known : be-

voL. I. Y fides.

322 ORGANIC STRUCTURE,

fides, the tranlparency of all the organs of thefc
animals renders it impofiible to afcertain their in-
timate llrudure, and we are ftill unacquainted
with the nature of their circulation. There are
. obferved, however, in thefe animals organs of fe-
eretion for the bile, feminal liquor, &c. "which
fcem to be formed of floating vafcular packets.

In the worm and leech, a dorfal veflel which
performs the office of a heart is obferved.

In cruilaceous animals, fuch as crabs, the mo-
noculus or water-flea, &c. the heart receives the
blood which returns from the branchiae, and dif-
tributes it to every part of the body ; but it is
never feen to return to the branchiae.

In the bivalves, the blood proceeds into an au*
ricle, which pours it into a ventricle, whence it
iflues by an aorta.

Mufcles exhibit a very Angular organization i
they have two very large tranfparent auricles, and
the inteftinal canal pafles through the heart.

In the aplyfia, the blood, which comes from the
branchiae, unites in a vein the fides of which be^
come arterial. This vcflel then performs the office
of an aorta.

Slugs have on each fide of the body two con-
tradlible apertures, which communicate with two
pulmonary cavities, over which the veins are
fpread. Thefe cavities terminate in an inteftinal
canal I the blood, after traverfing the pulmonary

organ^

SYSTEM OF CIRCULATION. 323

organ, unites in a vein which proceeds into an
auricle; whence it palles into a ventricle farnifhed
with valvulas ; and from this ventricle it iflues by
an aorta, which diftributes it to all the parts of the
animal.

In the fcpia, a large vein divides itfelf into two
branches, which proceed to two auricles farniflied
with a valvula. Thefe two auricles are feparated,
and furnifh an artery which is diftributed to each
branchia. The blood comes from the branchiae
by two veins, which unite in a common trunk ;
and this trunk proceeds to a folitary ventricle,
from which the blood iffues through an arterial
aorta.

333. In the different clafles of animals here
mentioned, the blood appears under the form of
a ferous liquid, more or lefs whitifli, and feldom
red. It feems to return from the different parts
in the fame manner in which it was conveyed
ihither ; that is to fay, by one order of velTels.
But in the other clades of animals, which we are
about to examine, the blood is red ; it is diflri-
buted to all the parts by one vafcular fyflem (the
arteries), and returns by two orders of veflels :
one of them (the veins) brings the greater part of
the blood to a red flate ; the other, much lefs ap-
parent (the lymphatic veflels), colle<51s the ferous
refiduums, and the produ6l of digcftion which
it pours into the veins.

In tithes, two ven^ cavag pour the blood into
Y 2 an

324 ORGAKIC STRUCTURE,

an auricle, whence it paiVes into a ventricle fur-
niilied with two femilunar valvule© (one at its
entrance and the other at the place of exit). The
blood iiTaes from' this ventricle through an artery
which divides itfelf into four branches on each
fide. Thefe arteries are diftributed to the branchiae.
Each branchial artery afcends along each lamina of
the branchi^: when it arrives towards the middle of
them it divides itfelf into two rami, one on the
right and the other on the left : each of thefe
rami then divides into two others^ one of which
defcends, and the other ateends, the whole length
of the lamina. The laft branches furnifli a great
number of very fhort ones, which proceed acrois
and cover the whole furface of the lamina. The
blood returns by veins, which in uniting follow
the fame order as the arteries do in dividing.
The union of thefe veins forms a large dorfal
veflel, which performs the office of an aorta.

In reptiles, the lungs receive only a part of the
blood. In animals of this clafs fubjedt to meta-
morpholis, fuch as frogs, fyrens, and falamandersj
two venae cava? pour the blood into an auricle
furniilied with valvulse, whisnce it ifTues by an ar-
tery furniflied alfo with a valvula. This artery,
which divi^les itfelf, conveys the greater part of
the blood to a ventricle; the other part proceeds
to the pulmonary organ, from which it returns by
the veins to the fame ventricle ; and it then ifTues
from that cavity todiftribute itfclf to all the organs,

111

SYSTEM OP CIRCULATIOJT. ^ 325

In the ftate of tadpole (without paws and lungs)
thefe animals have on each fide of the neck a
branchia in the form of a plume, which receives
the blood; but as thefe animals increafe in growth
the branchiae become obltru(51cd, wither, and drop
off along with the tail: at the fame time the lungs
expand, and pulmonary refpiration takes place.

The tortoife has tw9 auricles and two ventricles,
which communicate with each other. Three venas
cavas pour the blood into one auricle^ furnifhed
vj^ith valvulse, whence it pafles into a ventricle to
be diftributed to the pulmonary organ : it then
returns by veins to an auricle, and pafles into
the fecond ventricle- This fecond ventricle has a
communication with the former, by an aperture
clofed by a valvula. This aperture correfponds to
the arterial aorta, and the arterial blood proceeds
direclly thither without mixing much with the
venous blood, though thefe two forts of blood are
together in the fame cavity.

In the mammalia and birds, the blood proceeds
to an auricle which pours it in:o a ventricle fur-
nifhed with valvuloe. From this ventricle it paffes
through the lungs, and returns by veins which
convey it to a fecond auricle, whence it pafles
intoa fecond ventricle provided v.*ith valvuls : it
ifflies from this cavity by the aorta, which diftri-
butes it to the different parts.

In ihc fiate of fcstus, the mammalia and birds
^ y 3 exhibit

326 ORGANIC STRUCTUkE.

exhibit another order of circulation. The blood
poured into the pulmonary auricle pafles, in part,
into the aortic auricle, by an aperture furniflied
with a vajvula {foramen ovale). The remainder
of the blood flows into the pulmonary ventricle,
whence it iffues by the artery of the fame name.
At that place a part of the blood patTes through
a du6t, which eilablifhes a communication between
that artery and the aorta (arterial du6l) ; the reft
traverfes the lungs, and returns by the veins. The
latter pafles through the aortic auricle and ventri-
cle, and mixes in the aorta vi'ith that which pro-
ceeds diredlly thither through the arterial duel.

The circulation in the foetus of the mammalia
and of birds refembles that of reptiles, as only a
part of the blood pafles through the lungs.

In cetaceous and amphibious animals, the aper-
ture which forms a communication between the
two auricles, clofes more flowly ; but at length it
always becomes obftrudted, as in the mammalia
and birds.

334. It is obferved in all clafles of animals, and
even in plants, that the nutritive fluid, or the
blood, has a temperature peculiar to itfelf. In
the greater part of animals this temperature is not
much different from that of the medium in which
they habitually live ; but it is conftant, and does
not directly follow the variations of thefe me-
diums.

Iq

SYS.TEM OF CIRCULATlOJt* 327

In animals with lungs^ through which the whole
of the blood pafles^ fuch as the mammalia and
birds, the temperature of the blood is much
higher than that of the atmofphere of temperate
climates. This temperature, which is about 40
degrees of the centigrade thermometer, varies only
a degree or two in the moft oppolite latitudes.

325' The principal changes which the blood ex-
periences, during its circulation, take place while
it palies into the kidneys, the liver, and in parti-
cular through the organs of refpiration,

2^6. Urinary system. The blood is freed
from its excefs of aqueous parts, and from different
faline fubflances, by means of the kidneys.

All red-blooded animals have kidneys ; white-
blooded have nothing analogous.

The kidneys are nearly of the fame relative lize
in all animals ; they are however more volumi-
nous in birds.

The renal fyflem, in general, confifts of one
large gland on each fide. The urine fecreted from
every point of this gland ifTues from it by fmall
duels, which proceed to a common canal, called
the ureter, as in fiflies, reptiles, and birds.

In mofl of the mammalia, the urine, which pro-
ceeds from every point of the kidneys, oozes
through fmall funnel-like capfules : feveral of
thefe capfules unite, and proceed into fmall com-

Y 4 nion

32S ORGANIC STRUCTURE,

nion refervoirs or bafons, from which the urine af-
terwards pafles into the ureter.

The kidney, fometimes, is compofed of feveral
fmall glands united without refervoirs, each hav
ing its particular ureter ; as is the cafe in the bear^
otter, and cetaceous animals.

The ureters either convey the urine directly out-
wards, or pour it into a bladder; from which it after-
wards iiiiies by a fecond canal, called the urethra.

Birds have no bladder : the ureters proceed
into a cavity, common to the excrements and the
eggs, cloaca ; and iffue through the anus *.

A bladder is found in fifhes, in reptiles, and m-
the mammalia. In fiflies it is fituated behind the
redlum ; in reptiles it is placed before, and is
fometimes double, as in frogs : in thefe two clafles
of animals the urine proceeds to the rectum.

In all the mammalia the bladder is placed be-
fore the re6lum ; and the canal of the urethra
palles through the parts of generation.

337. Hepatic system. The blood, on its
pallage into" the liver, is freed from feveral fub-
iiances, and in particular from fat and albuminous
matters which it contains in excefs.

The liver feems to exift in infetts under the
form of a vafcular reticulation : it is found in the

* In the oftrlch, the ureter proceeds direftly outwards, near
the aperture of the fphuifter ani, and behind the cloaca.

. , moliufca

SYSTEM OP CIRCULATION. S^Q

mollufca and in all vertebral animals. Its fize in
general is in the inverfe ratio of that of the organ
of refpiration ; which has induced fome to believe
that thefe two organs have analogous fundlions,
and that they can, in fome meafure, fupply the
place of each other in their adlion on the blood.

The liver^ in general, is exceedingly large in
the mollufca; v*ry voluminous and oily in fifhes,
but fmaller in the mammalia and birds. It is ob-
ferved in the foetus of the laft two clafles of ani-
mals, that the liver, comparatively fpeaking, is of
a conliderable fize, and that the fize decreafes
after birth in proportion as the organ of refpiration
is expanded.

The liver, in general, is divided, to a greater or
lefs depth, into two or more lobes.

The venous blood, proceeding into the hepatic
organ, is that which returns from the principal ab^
dominal vifcera by veins that unite into a large
trunk, Xh^fith-Jpepaik vein or ve7ia porta:,, On its
padage through all the abdominal vifcera, which in
general are covered with fat, the blood becomes
charged with adipofe and albuminous m.atters, of
which it is in part deprived in the liver. The bile,
which refults from this particular excretion, be-
comes afterwards one of the mod powerful agents
of digeftion.

The blood, when it has thus palTed through the

liver, and been freed from a part of the fubilances

5 combined

330 ORGANIC STRUCTURE.

combined with it in excefs, returns by numerous
veins, which unite and proceed into the vena cava«

338. System op respiration. It is in the
organ of refpiration, in particular, that the blood
undergoes the mod remarkable changes ; it is
there that it is at lafl freed from the fubftances
foreign to its compolition, and acquires the prin-
ciples it has loft by diftributing itfelf to the dif-
ferent organs. It is in this organ that the blood
pafles completely from the venous to the arterial
ftate, and acquires all the qualities neceffary to
fit it for a new circulation.

The fyftem of refpiration brings the blood con-
flan tly into relation with the circumambient fluid.
There are three forts of refpiratory organs : the
tracheae, branchiae, and lungs.

339. Tracheae. In the cortical part of vegeta-
bles, but dill better in the ligneous, are ob-
ferved fmall thin laminae, twifted into a fpiral
form, and lengthened out like a fpiral fpring.
Thefe trachese may be ealily feen on half breaking
by flexion a young twig. It has been fuppofed
that the circumvolutions of thefe laminae muft form
a hollow cylinder, and that they conftitute air-
veflcls : this hypothelis is not fupported by
proofs.

Tracheae, or elaftic tranfparent filaments, dif-
pofed in a fpiral form and fufceptible of being un-
rolled.

SYSTEM OF CIRCULATION". 331

rolled, are obferved alfo in different parts of in-
fe61s.

In feveral of thefe animals, fuch as flies, bee?,
the cock-chafer, and beetle, are obferved two holes
or wide cells, which end at two refervoirs: the air
which fills thefe refervoirs pafTes into the trachese.

In thefe animals, the tracheae are fubdivided,
and diftribute themfelves to every part of the
body ; they have a brilliant filvery appearance, and
often produce a wonderful efFedt on their different
organs.

340. Branchiae. Branchia; are found in the tad-
poles of reptiles fufccptible of metamorphofis,
aquatic mollufca, and fifhes.

Reptiles in the fiate of tadpole have on each
fide branchiae in the form of a plume : in propor-
tion as the animal expands and acquires perfection,
thefe branchiae become obftruc^ed, wither, fall off
with the tail, and their place is fupplied by the
lungs.

All cruftaceous animals, from the coleoptera to
crabs, have branchiae in the form of laminae.

Aphrodite worms have branchiae in the form of
laminae or of a plume ; other infed^s have tubes
proper for inhaling the air.

In the acephalous mollufcaj the branch icE are
of different forms ; they are fituated either around
an aperture, which ferves as a mOuth, as in the

bivalves.

332 OHGANIC STRUCTURE.

bivalves, or around the anus as in the doris, or
around the body as in the aplyfias, he.

In the gafteropoda, ilugs, and fnails, the
branchi^ are lituated in a large cavity below the
neck.

In the cephalopoda, thel^ranchiaSi which confift
of laminaSj are placed in a cavity on the lides of
the belly.

In filhes, the branchiaa are compoled of laniiniSj
the number of v^'hich, in general, is four on each
lide. The laminse are formed of long narrow leaves
placed at the fide of each other, like the teeth of a
comb^ and are united by a thin membrane to the
half of their height. Each lamina is compofed of
cartilaginous pedicles united fide by lide, for three
fourths of their length.

The laminae of the branchiae are fupported by s
fmall hollow bone, on which refts the tongue, and
which is articulated at the bafis of the cranium.

341. Lungs. In fome reptiles the lungs confill:
only of a large membranous cavity, the inferior
face of which is covered by veflels, as is the cafe in
the filamander*. But, in general, the lungs of

* The cameleon has only a large plaited pulmonary cavhyj,
■fthlch It can Iwell up and diftend to fuch a degree, that it confi-
derably Increa'.es the volume of Its body : it then becomes tranf-
pare:;:, and aiiumes different tints. A fjrailar conformatloa is
obkrved in the marbled lizard.-

reptiles-

SYSTEM OP CIRCULATION, 333

reptiles are a fpongy body, the cells of which are
almoft always vifible to the naked eye. Theie
Iimgs are inclofed in a Ibrt of pleura, and float in
the common cavity of the trunk, which has no
diaphragm. The a?r penetrates into their lungs
by a larynx, without an epiglottis. The aperture of
the glottis is narrow in ferpents, and broad in frogs
aud toads. The males of the latter have membra-
nous bags, which become filled with air when they
emit cries.

The mammalia have on each fide of the breaft
a lung formed of a very fine fpongy tifTue.

The fanguine veflels overfpread and expand
over the- fides of the fmall cells of this tifTue i and
the air penetrates into the interior part of them by
numerous ramifications of branchial du6ls.

Each lung is enveloped and remains free in a
membrane (pleura), which adheres to the fides of
the thorax. The two pleuras produce between them
a fpace which lodges the heart, the cefophagus^ the
aorta and the thymus.

The air penetrates to the lungs by two bron-
chial du<5is, which are ramified in theinfide: thefe
two dud.s are the d4vifion of the tracheal artery.

The tracheal artery and the bronchise are
formed of cartilaginous rings, incomplete behind,
and united by a membrane. This trachea is con-
tinued with the larynx, which is a cartilaginoi^s
{dilatation.

The

334 ORGANIC STRUCTURE.

The larynx communicates with the lower part
of the pharynx, by an aperture (glotlh) covered
with a cartilaginous lamina {epiglottis). This la-
mina falls down on the glottis, during the paffagc
of the aliments ; it ferves alfo to make the air vibrate
when it ifllies with force from the lungs, and is the
principal caufe of the founds produced by animals.

The larynx, in all the mammalia, is formed of
iive cartilages, viz. the thyroid, the cricoid, the
two arithenoids, and the epiglottis. But in fome
animals of this order it exhibits very remarkable
peculiarities, calculated to produce a variety of
founds *.

In the mammalia, the larynx is generally
moved by four or five pairs of mufcles, proper for
lengthening or fhortening the trachea ; and for di-
lating or contracting the trachea and the glottis.

In birds, the lungs are much more extenfivej
-tbcy are not inclofed in a pleura^ but adhere to

* In the orang-cutang the ventricles of the glottis are pierced
•with an aperture, which terminates in two membranous bags.
Mandrils have a membranous bag, the aperture of which is at
the root of the epiglottis. In the howling ape, the os hyoidcs is
Ihaped like an offeous box of the fize of the fift. The afs, at
the. extremity of each ventricle, has a hole correfponding to a
particular bag. The larynx of the fwine exhibits in its length
a deep finus. The air expired with force enters into thefe dif-
ferent cavities, and produces different founds. The horfe, near the
thyroid cartilage, has a triangular membrane, placed in a tranfver-
fal direftioHj which by quivering is capable of producing neighing.

tlie

SYSTEM OF CIRCULATION. 335

the fides of the thorax by a loofe cellular tifTue.'
Thefe lungs communicate with feveral membra-
nous bags, fituated chiefly in the abdomen, which
fcem to be formed by a fold of the peritonaeum.
They are generally fix in number, placed longitu-
dinally between the jnteftines and the abdominal
vifcera: three alfb are found in the breaft, and
two under the axillae.

The lungs have a communication with thefe
bags by particular apertures ; and the bags them-
felves are continued with other cavities of lefs fize,
which are in the thighs, the wings, the fubfl:ance
of the bones of the cranium, in the cavities of the
long bones, and even in that of the tubes of the
feathers.

In birds, the larynx is compofed of fix or four
ofl^ous pieces : the principal one is analogous to
the cricoid cartilage of the mammalia ; but they
have none which correfpond to the thyroid and
arythenoid cartilages : they have alfo no epiglottis.
The only fundlion of this larynx is to open and
fhut the aperture of the glottis. The edges of its
aperture are furnifhed with cartilaginous points
proper for preventing the entrance of the ali-
ments.

The tracheal artery is formed of complete rings:
inferiorly the two apertures of its bronchial bifur-
cation exhibit, on their fides, a projedling mem-
brane, which in part clofes them. This moveable
membrane performs the office of an epiglottis ; it
9 caufes

336 ORGANIC STRUCTURE.'

caufes the air to vibrate in its paflage, and in ihli
place the found is formed : this apparatus conilir-
tutes the inferior hirynx of birds.

The rings of the bronchiee are incomplete^ and
vary both in their iize and figure. The inferior
larynx of birds^ in many of thefe animals, has no
proper mufclcs : fcveral of the latter are furnifhed
Vv'ith ofieous or membranous dilatations. Some
birds have a mufcle which is inferted in feveral of
the half-rings of the bronchia. Others have three
pairs of mufcles, as is. the cafe with perroquets : in
linging-birds and in feveral others there are five
pairs. All thefe mufcles are difpofed in fuch a
manner as to produce indefinite, varintions in the
dimenfions of the larynx and of the bronchia?.

34.2. In man, the apparatus of circulation ex-
hibits an auricle, which receives the blood return-
ing from all parts by the veins and the lymphatic
vefiels. This auricle pours it into a ventricle,
which tranfmits the whole of it to the pulmonary
organ. The blood then returns to another auricle
and a ventricle, from which it is expelled through
the aorta, to be diftributed to every point of the
organization by means of the arteries.

In this double and fucceffive circulation,
through all parts of the body, and through al!
thofe of the lungs, it is obferved that the blood un-
dergoes very remarkable chai-ges from feveral of
the organs.

Duiiog

SYSTEM OF CIRCltLATION. 337

JDiiring its arterial circulation, it frees itfelf from
its excefs of heat by the aiTiftance of the ficin i and
from its excefs of aqueous parts, by tneans of the
kidneys. On its return through the veins, it is
freed from albuminous and adipofe fubftaiices in
the liver. On its paffage in the lungs, it gives off
carbonic acid gas, and takes up oxygen gas. In the
lad place, the ferous matter, which returns by the
lymphatic veiTels, and the produ61 of digeftion con-
veyed by the chyliferous vefTelSj experience eflen-
tial changes on their pafiage through the lympha-
tic glands.

The fyllem of circulation is thus compofed, not
only of cavities or vefiels which ferve fat convey-
ing the blood to every part of the body, but alfo
of organs, v^hich, during itspaflage, make it under-
go changes of great importance to the order of the
organic functions* In our defcription of this
complex fyftem of organs, we fhall therefore fol-
low the progrefs we have indicated in this fhort
view of the parts of which it is compofed.

343. The arterial fydem exhibits a ramified
expanfion, of which the aorta is the trunk. The
fucceffive and indefinite ramifications which feem
to proceed from this trunk, are divided in fuch a
manner, that there is no part of the organization to
which they do not penetrate, and to which they do
not convey the repairing fluid they contain. The
arterial fyftem; as it divides, increafes in capacity;

VOL. I. z and

338 ORGANIC STRUCTURE,

and the blood, which finds itfelf more at freedom,
muft flow with lefs rapidity as it pafTes from the
large arteries into the fmall ones.

The arteries exhibit frequent anaftomofes, and
are ex©eedingly flexuous, efpecially in the parts
fufceptible of extenfionj fuch as the vifcera of the
abdomen.

The (ides of the arteries are of a clofe texture,
compact, elafticj and little fufceptible of extenfion.
Their thicknefs is comparatively greater in the
fmall arteries than in the large ones. They feem to
confifi: of three tunics, the exterior one of which
is cellular, foft, and very loofe : the middle one is
thicker, and conlifts of a clofe yellowifh tiflue, lit-
tle fufceptible of extenfion : the interior one is
only a very thin and exceedingly fmooth mem-
brane.

The blood contained in the arteries is fpumous,
florid, and of a bright red colour ; it appears to be
fomewhat warmer and liMiter than the venous

o

blood, and has not the brown tint of the latter.

»

The arterieSj after dividing and fubdividing
themfelves into exceedingly fine and delicate ra-
mufculi, which proceed to every part of the or-
gans, at lad completely difappear to the eye^ even
when afSfled by the befl microfcope, fo that their
manner of termination is totally unknown.

344. During the arterial circulation, the excels

of the heat of the blood is carried off by the fecre-

6 tion

SYSTEM OP CIRCULATIOH. 33g

tion of the Hun, reduced into vapour at the furface
of the body : its excefs of aqueous parts is expelled,
together with feveral faline fubftances, by the uri-
nary fecretion.

When the blood and all the parts which it
moiftens have too great a quantity of free caloric,
arifing either from a high temperature of the at-
molphere, or from too violent exercife of the muf-
cular fyftem^ or from fome peculiar morbific ex-
citement, the cutaneous organ enters into a6iion
and fecretes abundance of perfpirable matter, the
evaporation of which at the furface of the body
lowers the, temperature, and always maintains it
at about the fame degree. This abundant per-
fpiration frees the blood alfo from a quantity of
aqueous matters, more or lefs conliderable ; it
carries off alfo a little albumen, and feveral faline
fubftances.

The fkin properly fo called {dermis, cutis vera)
confifts of a thick, clofe and whitifh tiffue ; it ap-
pears to be produced by the lymphatic and fan-
guine vefTels eroding each oth^r, and by a large
quantity of nerves. The nerves expand at the
furface of the dermis, in very fine papillae, which
feem to conflitute the organ of touching. The
dermis adheres to the parts which it covers by a
loofe cellular tiffue.

Above the dermis is found a vifcous, foftifli, and

fomewhat thick fubfiance, called the mucous tif-

z 2 fue

340 ORGANIC STRUCTURE,

fue {refc miicofum, corpus reticularey mucus malpighu
anus)^ This fubftancc is of different colours
among different nations^ and is the caufe of- the
diverfity of colour in the Ikin,

The mucous tifTue is covered by a thin mem-
brane, dry and tranfparent, which conflitutes the
epidermis or cuticle. This membrane forms a
covering, in fome meafure inorganic, proper for
feeuring the parts immediately beneath it from the
impreflion of external bodies.

The Ikin exhibits, in its fubftance, fmallglands^,
which fecrete an un^luous humour, with which
the whole furface of the Ikin is, as it were, varnifh-
ed : thefe glands are more abundamt in the par-ts
furnifhed with hair. In the lafl place, the Ikin
contains the bulbs or radicles of the hairs and
briftles, with which thefe different parts are co-
vered. This kind of cutaneous vegetation takes
place with much more energy in animals, whofe
bodies are habitually naked ; and in them this part
of tjie cutaneous organ, whether compofed of
fcales, feathers, wool, or hair, fupplies them with a
thick covering, and becomes to them a very im-
portant apparatus of excretion.

345. When the blood, by the digeflion of too
large a quantity of drink, Jias received an excefs
of aqueous parts, it is freed from this excefs by
urinary fecretion. At the fame time the kidneys
fecrete different faline fubflances, and particularly

-^ matter

SYSTEM OF CIRCULATrON. 341

a matter (ziree) the prefence of which characterizes
the urine of man.

The -kidneys are fituated one on each fide in
the region of the loins. Above them, and behind
the peritonaeum, is a ghndnlous hody, fhaped like
a flattened hemifphere, of a yeilowifh brown co-
lour, but larger and redder in infancy.

This fuper-renal gla?2d receives a number of vef-
fels and nerves ; it is enveloped by fat, and appears
to be compofed of lobules covered by cellular tif- ,
fue : in the infide it exhibits a capfule or cavity of
the fame form as the gland, and which at the bot-
tom has a fmall fold in the form of a ridge. The
fides of this cavity are applied to each other; they
have the appearance of mucous membranes, and
fecrete a yeilowifh liquid. The ufe of this organ
is unknown.

The kidneys are of a reddifli brown colour; they
have pretty nearly the form of a kidney-bean : they
are fmooth in adults; unequal and rough in in-
fants.

They are placed length wife on the edges of thei
vertebral column, and correfpond to the extent of
the bodies of the laft two dorfal vertebrse, and the'
firft two lumbar; They are covered before by the
peritonaeum, and reft behind againfl the fquare of
the loins. The right kidney is lituated below
the liver, and the left below the fpleen. The con-
cave edge correfponds inwardly, and receives the
veffels and the nerves,

Z3 ■ Ths

342 ©RGANIC STRUCTURE.

The kidney is immediately enveloped by a
fmooth, compa(5i: membrane, which adheres clofely
to it, and which is covered by a thick ftratum of an
adipofe tiffue. It receives a very large artery (the
renal), which comes from the abdominal aorta. The
orifice of the two renal arteries is fuch, that it can
admit the eighth part of the blood which iflues
from the aorta.

The kidney, when cleft lengthwife, exhibits a
firfl: exterior ftratum (the cortical) of a dark red
colour, about two lines in thicknefs, confifting of
a compact tiflue. From this tiflbe arife, in dif-
ferent points, fibres or fmall tubes, of a paler red,
which converge internally in fmall bundles, and
terminate in the form of papilLe : the number of
thefe papiilse varies between twelve and eighteen.
The exterior compafl tiftue is continued betweeri
the bundles of thefe- fibres or tubes.

Each of thefe papillge opens into a membranous
and grealy capfule in the form of a funnel. Thefe
funnels unite into feveral trunks, which end at a
common refervoir or fmall bafon.

It appears that the urine is fecreted in the com-
pa6l tifTue o^ the furface of the kidney, that it flows
through the tubulated bodies, oozes from the pa-
pillae, and is poured into the particular capfules
which proceed to the bafon.

Towards the centre of the interior edge of the
kidney, the bafon opens into a very large membra-
nous du61: [ureter), which defcends behind the pe-
ritonaeum

SYSTEM OF CIRCULATION. 343

ritonseum along the^ lumbo-trocbantinian mufcle,
and proceeds into the leiier pelvis below, behind,
and on the fides of the bladder.

The ureter is formed of a white, compa^l, and
llrong membrane, the interior fides of which have
the appearance of mucous membranes.

The bladder, which is capable of containing
a little more than a quart, has a round form, fome-
what flattened at the bottom;, and terminates
at the fummit in a blunt point : in the female it is
fomewhat flattened from before backwards ; and in
infants is more lengthened from the top down-
wards. In the male it is fituated in the lefler pel-
vis, between the pubis and the redium ; and in the
female between the pubis and the matrix : it is
covered at the top and behind by the peritonseum,
the expanfion of which fupplies it, below and be-
hind, with fome ligaments, by which it is fixed to
the neighbouring parts.

The bladder has, at the top, a ligarrient formed of
three cords, which proceed to the navel, raifing up
the peritonaeum ; two of thefe cords are produced
by the obftru(?led umbilical arteries ; the lafi: by a
du6l which, in the foetus, proceeded from the blad-
der to the umbilical cord (urachus). This hollow
organ ftill adheres anteriorly to the poflerior part
of the pubis, by a coinpa6l cellular tJ.flue in the
form of a ligament,

z 4 The

344 ' OR.GANIC STRUCTURE.

The fides of the bladder exhibit outwardly feve-
ra.1 layers of mufcular fibres^ which crofs each
other, and proceed in all diredlions ; thefe fibres
are covered behind by the peritonaeum, and in the
reft of their extent by a cellular tifliie. The
ureters proceed below, behind, and on the fides of
the bladder ; they are difperfed in the fubftance
of its fides, and proceed to the interior part of it.

The interior furface of the bladder is formed of
a thick, villous membrane, furnifhed with a great
number of folds. Below and before, this organ
exhibits an aperture {neck), the fides of which are
very thick ; behind this aperture, the bottom of
the bladder has a triangular fpace (trigone) of a
clofer tifi:ae, and exceedingly irritable. The in-
terior angle of this trigone is continued in the
lower part of the aperture of the neck, by a fmall
round tubercle: the other two correfpond to the
apertures of the ureters.

The exterior aperture of the blad/ier is conti-
nued by a very long du<5l, the urethra^ which in
man runs alono- the vard : in the female it is fhort-
er, and terminates at the furamit of the vagina.

346. The urine varies very much according to
circumftances, in regard to its quantity, its colour,
and its fmell. In general, it is thicker the more
flowly it flows, and the longer it has remained in
the bladder : that voided immediately after meals,

and

SYSTEM OF CIRCULAT10>I» SAS

snd that, in particular, which refults from an ex-
cefs of alcoholifed- beverage, is exceedingly clear^
and contains fcarcely any thing but water.

The human urine has been carefully analyfed by
the modern chemifts. We (hall here give a (hort
view of the principal experiments by which its
compolition has been afcertained.

This animal liquor always contains uree ; 711'icacid;
an animal matter infolublein alcohol; ^vtt, phofpho^
ric acid; phofphates o( lime, oijoda^ oi ammonia, and
o( magnejia; muriates o( foda and of ammonia : the
Julpbates ofpotajb and of Joda are alfo fometimes
found in it. The urine of children always contains
benzoic acid. The pretence of the firft ten fubftanccs
is afcertained by the following means :

The prefence of free fhofphoric acid is afcertained
by pouring urine into tindure of turnfole.

If the phofphafe of lime be feparated by ammo-
nia, this alcali will faturate the free phofphoric
acid, and the phofphate of lime will be preci-
pitated.

By evaporating, to the confidence of iyrup^
urine treated by ammonia and then filtered, and
afterwards combining it with alcohol, the uree and
the muriate of ammonia will be diflblved. The mu-
riate of ammonia may be decompofed by barytes,
and it is then expofed to heat to expel the ammo-
nia. If it be again treated with alcohol, and if
the matter be evaporated to drynefs, nothing will
•be diffolved but the uree. Ammonia may be ftill

poured

346 ORGANIC STRUCTURE.

poarecl over the refiduurr), and after the liquor has
heen filtered it may be concentrated by evapora-
tion. If muriatic or any other acid be then poured
into it, the wic acid will be precipitated in white
flakes, which, when thrown on the filter, affume
the form of. teal es.

Diflblve in water the refiduum of the former ex-
periment, and after filtrating the liquor fubje6t
it to evaporation. You will then obtain, by cryf-
tallization, muriate ^nAphofphate o(foda, combined,
in whole or in part, with phofphate of ammonia.

Tbefe falts may be obtained alfo by evaporating
new urine : in proportion as the evaporation is
effected, the liquor becomes turbid by the preci-
pitation of X\\Q phofphate of lime, becaufe there is
extricated ammonia, which faturates the free
phofphoric acid that held this fait in folution. If
the liquor be then filtered, and the evaporation be
continued, the different falts will cryfiiallize : the
ammoniacal fait \n cuh\c2\ cvy^dXs, on account' of
the uree with which it is combined, and the ma-
rine fait in o<5laedra for tHe fame reafon ; the
phofphate of foda, which is combined in wiiole
or in part with the phofphate of ammonia, cryftal-
lizes in rhombuses.

The prefence of the ammoniaco-magnefian
phofphate may be afcertained two ways : ift, if
the urine be left at reft, {]\\?,falt will very often
be obferved in white cryftalline lamina;' ad, if
potafn be poured into the urine, phofphate of lime

an4

SYSTEM OF CIRCULATION. 34/

and o^magmfia will be precipitated ; by treating this
precipitate with acetous acid, acetite of magnefia
will be formed j and if this acetite be decompofed
h-^ potafh, the magmfta will be feparated.

The animal matter^ which confiantly exifls in
urine^ is infoluble in alcohol : the nature of it has
not yet been properly afcertained.

If urine contains alfo ihtfulphates of foda and of
putajh, they may be obtained in the fame manner
by cryftallization. In the lalt place, if it contains
lenzoic acid, as is the cafe with that of children, it
raufi: be evaporated almoft to the confiftence of
l)Tup ; if it be then introduced into a retort, with
a fufficient quantity of weak muriatic acid, and be
expofed to diftillation, the benzoic acid will pafs
over into the receiver.

Urine contains alfo fometimes gelatin , albumen,
oxalate of lime and of ammonia; bat all thcie
fabftances are found only very rarely.

In fome difeafes the urine contains a great deal
of gelatin : the prefence of it may be afcertained
by the infoluble precipitate which it forms with
tannin.

What characierizes the urine of man, in an ef-
fential manner, is the prefence of uree and of
the uric acid. Thefe fubflances are found only
in this liquid. Urec produces, in a great meafure,
all the phsenomena which urine exhibits; it cryf-
tallizes in lamina: like the muriate of barytes -, it

combines

34S ORGANIC STRUCTURE.

combines with the nitric acid^ and forms an infolu-
ble compound. When a folution of uree in water
is boiled, there is difengaged a very large quantity
of ammonia, which arifes from the decompolitioii
of that fubllance.

Urine, by the precipitation of the fubftances it
holds in folution, is fufceptible of forming calcu-
lous concretions. Urinary calculi are found in
the kidneys, along the ureters, in the bladder, and
even in the canal of the urethra.

The introdu61ion of a foreign body into the
bladder often determines the formation of a cal-
culus, to which it ferves as a nucleus.

The different human calculi are formed of the
following fubftances: phofphate of lime, ammoniaco-
viagnefian phofphate, uric ac'idy urate of ammonia^
oxalate of lime, carhonate of lime, and flex : thefe
matters are pure or mixed, and almofS: always dif-
pofed in ftrata.

Calculi ofphofphate of lime, of ammoniaco-mag-
i)elianphofphate,andofcarbonateof lime, are white;
thofe of phofphate of lime are never cryftallized,
and form a magma with fulphuric acid ; thofe of
ammoniaco-magnefian phofphate are alwaj^s cryf-
tallized in brilliant laminse, and diflblve com-
pletely in fulphuric acid ; thofe of carbonate of
lime cryftallize generally in clofe filaments ; they
diflblve entirely in the nitric and muriatic acids,with
which they efFervefce : the laft Ikind are very rare.

Calculi

SYSTEM OF CIRCULATIOX. 34g

Calculi of urate of amrnonia are of a yellowilli
gray colour; ibey diliblve completely in potafh,
with a difengagement of ammonia ; thofe formed
by pure uric acid are more or lefs yellow, and dif-
folve alfo in potalli, but without a difengagement
of ammonia.

Calculi of oxalate of lime are always more or lefs
black and tuberculous; and hence they have been
called muraux, on account of. their fuppofcd re-
femblance to a mulberry : by calcination they
give quick-lime, or carbonate of lime.

Calculi which exhibit filex affecl alfo the mul-
berry form J they are foluble in acids, give no lime,
and are not altered by calcination. Silex has
never been found but in two calculi, and even
then it was covered, firft by oxalate of lime, and
then by uric acid.

Calculi formed only of phofphate of lime, or
ammoniaco-magnelian phofphate, are rarely found;
thefe two falts are almoft always mixed.

Calculi of pure uric acid are very often found;
and fome of urate of ammonia equally pure ; but
the uric acid, for the moft part, is accompanied
by urate of ammonia.

It is not uncommon to find calculi of pure ox-
alate of lime; but this fait in general ferves as a
nucleus to the other calculi.

When a calculus is compofed of phofphate of
lime, ammoniaco-magnelian phofphate, uric acid,

urate

350 ORGANIC STRUCTtJJlSi

urate of ammonia, and oxalate of linne, thefe mat-
ters are almoft always difpofed in the following
order : oxalate of lime in the centre, next urate
of ammonia, then uric acid, and in the laft place
phofphate of lime mixed with, and fometimes co-»
vered by, am moniaco-magnefian phofphate,

Thefe refults of the analyfis of urine and human
calculi are a very ihort extract from the mofl in-
genious feries of experiments ever made on ani-
mal fubftances. This labour, for which -we arc
indebted to Fourcroy, Vauquelin, and Thenar,
while it conveys ufeful information to the medical
pra6lilioner in regard to the nature of urinary
calculi, will furnifh hints for difcovering the pro-
per means to prevent the > ravage occafioned by
calculous afFe61ions. None however but phyli-
cians who are good chemifts will be really deli-
rous to take advantage of thefe means, or can pro-
perly employ them.

347. The blood, after having diftributed itfelf to
all the organs by means of numerous arterial rami-
fications, and their indefinite divifions, and after
having every where conveyed the materials necef-
fary for the different fecretions, and for eifedling
the continual changes which take place in every
part of the organization, returns by two orders of
vefTels, the veins and the lymphatics.

The veins bring back the greater part of thebloody
and in particular that which has undergone the leafl:

change.

SYSTEM 0? CIRCULATIOX% 351

change, and which Hill retains its red colour. The
means of the communication which exifts between
the extremities of the arteries and the firft radicles
of the veins cannot be obferved ; they are con-
cealed from us on account of their infinite mi-
nutenefs,' and have hitherto eluded our microfco-
pic refearches. I-t is known, however, that under
certain circumftances the blood feems to pafs di-
redlly from the arteries into the veins, without
undergoing any remarkable changes.

The fides of the veins are much thinner than
thofe of the arteries. Their fi:ru6lure, examined
in the large trunks, is compofed of three tunics,
the middle one of which appears to be vafcular.
The venous veflfels are alfo more numerous, larger,
and more extenfible, than the arterial : it is efi.i-
mated that the capacity of the veins is to that of
the arteries as nine to four. The interior of the
veins exhibits membranous folds in the form of
valves; thefe valvulous folds, which oppofe the
return of the blood, are for the moft part difpofed
in pairs, and are not found in the fmall veins nor
in the large trunks : the veins which convey the
blood from the vifcera contained in the large
cavities, and thofe which are fituated at a confi-
derable depth between the mufcles, are alfo un-
provided with them. The veins in their progrefs
follow a dire6lion contrary to that of the arteries,
and are not very flexuous. Their anaftomofes are

alfo

052 ORGANIC STRUCTURE,

alfo lefs frequent : it is to be obferved, ttiat m
uniting they decreafe in fize ; the blood, which is
then more confined, mull circulate with greater
velocity.

The veins which bring back the blood from the
inferior limbs and from all the parts of the abdomen
unite into a large venous trunk, which afcends to-
wards the heart (vena cava afcendens). Thofe
which bring back the blood from the head, from
the fuperior limbs, and from the thorax, unite alfo
into a large trunk, which defcends towards that
organ (vena cava defcendens.) Thefe two large
veins open into a finus, auricle, with the fmall
vein which conveys back the blood from the
beart.

348. The lymphatic vefiels are exceedingly thin
and tranfparent; their fides feem to be formed of
two laminse, which, notwithllanding their thin-
nefs, are remarkably "ftrong. Their radiculae arife
at the furface of the membranes, and open into all
the cellules or cavities by pores or villolities,
which feem to poffefs a power of fu6lion. The
lymphatics abforb the aqueous fluids difperfed
throughout all the tilTues, and the ferous re(i-
duums produced by the changes which are con-
tinually efFedled in every part of the organization,
Thefe vefTels are highly contractile, and exhibit
frequent anaftomofes ; in general they accompany
the veins ; like them, are difpofed-in two ftrata,

one

SYStEM OF CIRCULATION. 353

one fuperficial and the other profound, and are
furnifhed with valves which prevent the return
of their fluid.

The lymphatic vefTels are exceedingly nume-
rous: by their inextricable interfe6lions they pro-
duce plexus, and feem even to form the whole
tifllie of the white organs.

The lymphatics^ after a certain paflage, meet
with fmall glands, which they enter. The ferous
fluids and the chyle which they carry thither are
there aflimilatedj and, having undergone a fort of
digeflion^ iffue from thefe fmall glands by larger
and lefs numerous veflTels. The lymphatics con-
tinue to advance towards the thorax, traverfing the
glands which they meet with ; and the lymph in
thefe glandulous organs acquires new chara6iers of
animalization.

The lymphatic glands are fmall and very nume-
rous; they vary in their form and conflftence;
they are obferved more evidently towards the bend
of the large articulations, in the abdomen, the
neck, and around the organs of fecretion.

In proportion as the lymphatics unite, and the
rami form branches, their abfolute capacity de-
creafes, the fluid is more confined, and mufl cir-
culate with more rapidity.

The refult of the fucceffive union of all the
lymphatics is two trunks, which difcharge them-
felves into a vein fltuated under the clavicle. Of

VOL. I, 2 A thefe

354 -ORGANIC STRUCTURE,

tbefe two trunks, the largePf^ the mOil exten-'
live, and fometimes the only one apparent, arlies
in the abdomenj on the left fide of the vertebral
column, towards the middle of the lumbar region,
where it exhibits fometimes a fort of dilatation
(refervoir of the chyle), and receives the lymphatic
velTelsofthe inferior limbs, thofe of the organs
contained in the pelvian and abdominal cavities,
and thofe of the fides of thefe cavities. This lym-
phatic trunk traverfes the diaphragm with the
aorta, and penetrates into the thorax (thoracic
du<51:) : it afcends on the fides of the bodies of the
vertebrae, in the fubftance of the pofterior medi«.
aflinum ; and when it reaches the cervical region
it bends to the left, and opens into the fub-clavian
vein of that fide. This thoracic dud receives, in
different points of its extent, the lymphatics which
proceed from the right fide of the head, the neck,
and the bread, and frcm the thoracic limb of that
lide. When the left thoracic du61 exifts alone, it
receives the lymphatics of the right fide.

The right lymphatic trunk is obferved on the
fide of the laft vertebra of the neck. This fmall
trunk (the brachio-cephalic) receives the lympha-
tics which return from the right fide of the head,
the neck, and. the breafi, and thofe of the right
thoracic limb : it opens into the fub-clavian vein
of that fide.

349. The arterial bicod, in diftributing itfelf to

SYSTEM OP eiRCULATlON. 355

tfevery part, and traverfing every point of the orga-
nization, undergoes a fort of alteration : it lofes
ibme fubftances eflential to its compofition, and
becomes charged with feveral foreign matters. It
is in this flate that it returns by the veins and the
lymphatic veflels.

The lymphatics^ in their progrefs, traverfe the
numerous lymphatic glands already mentioned.
The lymph and the chyle experience in thefe
glands a peculiar affimilation, and undergo im-
portant changes, before they unite with the venous
blood.

The venous blood, in its partial paflage through
the liver, begins to be diveftcd of its foreign fub-
ftances, and is completely freed from them in the
lungs : it there acquires thofe materials which were
taken from it, and refumes the qualities of arterial
blood, to ferve for a new circulation.

We fhall here defcribe the different organs
through which the venous blood pafles before it
penetrates to the aorta.

350. The veins which bring back the blood
from the principal .vifcera of the abdomen unite
into a large trunk which proceeds into the liver.

The liver is a gland of conliderable fize, and of
a dark red colour, lituated in the right hypochon-
dre, the epigaftric region, and a part of the left
hypochondre ; below the diaphragm, to which it
is contiguous fuperiorly, and above the ftomach
2, A a « aad

356 ORGANIC STRUCTURE*

and the inteftines : it is more voluminous towards
the right tide j is fmooth and convex at the top and
before, concave and unequal at the bottom and
behind. At the lower part and before it exhibits
a fharp edge, in the middle of which is a flight
depreffion that divides it into two lobes, of which
that on the right is larger. This gland has alfo
a fmall lobe at the bottom and behind (lobulus
Spigelii).

The liver is covered throughout its whole ex-
tent by the peritonaeum : this membrane is refledled
from diiFcrent points of its furface, and its double
fold forms feveral ligaments, by which it is fixed to
the neighbouring parts. One, which is very large^
arifes from above the middle of the convexity of the
liver, ^nd proceeds to the navel and the centre of the
diaphragm (fufpenfor ligament). It receives before,,
the umbilical vein, v/hich is ob{lru61ed after birtb,
and becomes ligamentous. The peritonaeum pro-
duces on the iides two expaniions, which form two
lateral ligaments. It adheres alfo behind the dia-
phragm by the cellular tifTue (coronary ligament.)

The hepatic organ receives its blood from a
fmall artery (right branch of the cogliac) and a very
large vein (fub-hepatic or vena portse). The blood
of the fmall artery feems deflined for the particu-
lar nourifhment of the liver i the ligature of this
veffel in animals does not interrupt the fecretion
of the bile.

SYSTEM OP CIRCULATION, 357

Tbefub-hepatic vein or vena porta is formed by
two trunks (the fplenic and merenteric)^ which
bring back the blood from the ftomach, the
epiploon^ Jhe inteftines, the mefentery, the pan-
creas, and the fpleen. This large vein proceeds
into the liver towards the middle of its depreffion,
tranfverje fc'ijfure, which is obferved on its concave
face, where it forms a large finus, and then dif-
tributes itfelf to the right and the left ; it then
divides and fubdividesitfelf indefinitely in the fub-
ftance of that vifcus. The divilions of this vein
accompany thofe of the artery, the nerves of the
liver, and the duds which bring back the bile.

The fub-hepatic vein is enveloped from its
origin by a prolongation of the peritonseum ; this
prolongation accompanies the three orders of vef-
lels, as well as the nerves, and forms of th<2m a
fort of common capfule (^capfida GUjfonii), from
which proceed very fine membranous partitions
interpofed between thefe parts. The fub-hepatic
vein, with its divifions, dilcharges the office of an
artery to the liver, fince it furnifhes it with almofl
all the blood it receives : it is obferved that the
fides of* this vein are thick, and that it has no
valves in the infide.

The nerves of the liver (branches of the pneu-

mogaflric and trifplanchnic) unite and form a

plexus (the hepatic), which accompanies the bili^

a A 3 ^ry

358 ORGANIC STRUCTUKE.

ary da^ls, and the veffels which carry the blood
thither.

The blood is diftributed throughout the whole
fubftance of the hepatic organ, where it frees it-
felf from the albuminous and oily matters, which it
contains in excefs. The combination of thefe
fubftances with a fmall quantity of foda forms a
faponaceous liquor, which excretes from every
point of the liver, through particular du(^s, and
is conveyed into the duodenum, where it becomes
one of the mofl powerful agents of digefdon.

The venous blood, after being freed from the
materials of the bile, returns by veins and lympha-
tic veflels.

The veins (fub-hepatic) bring back the blood
from every part of the liver, purfuing a direcStion
perpendicular to the veflels which carry it thi-
ther : their fides are thin, and without valves.
From the union of their numerous rami arife
three branches, which proceed from the three
lobes of that gland : thefe three veins form a
trunk, which proceeds into the vena cava,

The lymphatic veflels of the liver are very nu-»
merous in the fubflance of that vifcus, and parti-^
cularly at its furface. Thofe of the gaftric flde
unite into fome trunks, which proceed into
glands fituated near the hepatic dudls : thofe of
the diaphragmatic iide unite along the fufpenfor

ligament

SYSTEM OP CIRCULATION. 35g

ligament of the liver, traverfe the diaphragm, and
proceed into the large chyliferous du6l (the
thoracic).

351. The venous blood, after undergoing fome
changes on its partial pafTage through the liver,
and after receiving all the fluids brought by the
lymphatic and chyliferous veflels, unites into two
large veins, which proceed into a flnus called
ihe^mis of the vena cav£ (pulmonary or right
auricle.)

This linus is lituated at the upper part of the
heart, on the right, and fomewhat behind ; it is
fhaped like the fegment of a fpbere, and exhibits
a fmall appendix.

Its interior furface is furrowed by carneous pil-
lars, which adhere to its fides.

At the top and before is the oripics of the fu-
perior vena cava ; that of the inferior vena cava is
lituated below and behind ; it is larger than the
former, and furnifhed with a valve fhaped like a
crefcent, which prevents the blood from flowing
back : in general this valve is incomplete, and
feems to be in part torn or pierced : it is more ap-
parent in the foetus, and dircfls ail the blood of
the inferior vena cava towards the foramen ovale.
Before this valve is the aperture of the vein of the
heart (the coronary), v;hich is alfo furnifhed with
a valvular fold.

The fin us of the venas cavae correfponds wilhin

to that of the pulmonary veins, from u-hich it is

2 A 4 f^paratcd

360 ORGANIC STRUCTUREo

feparated by a carneous partition: on this parti-
tion is obferved a fmall oval fofTa, which in the
foetus is a hole of the fame form ; the greateft di-
ameter of this hole is four or five lines, and it is
furnifhed with a femilunar valv6, which correfponds
to the linus of the pulmonary veins.

After birth^ this valve is prefled clofeiy to the
aperture by the blood which arrives in greater
abundance in that linus from the lungs ; it adheres
to it, and the foramen ovale is foon completely
obftru61ed : it has however been found open at an
advanced age.

The finus of the vense cavae communicates with
ihe pulmonary ventricle by a round aperture. Its
tendinous circumference is furnifhed with a valve^
produced by a membrane cut into three tri-
angular portions of unequal fize, which termi-
nate in a point (valvulas tricufpides, triglochines).
To thefe membranous portions are attached, by
their free edge, tendinous or carneous filaments,
which proceed from the fides of the ventricle. The
a6lion of this valve is to prevent the blood from
flowing back into the auricle during the contrac-
tion of the ventricle.

The pulmonary ventricle has the form of a folid
triangle I its interior face exhibits a great number
of carneous pillars, adherent or free, and of dif-
ferent fizes. The greater part of thefe pillars are
dire6]ed from the bafe to the apex, and others
crofs the latter in an oblique diredion.

The

SYSTEM OP CIRCULATION. 3<)I

The pulmonary orifice of the ventricle Is fur-
Bitlied in its circumference with three femilu-
nar valves (figmoid). Thefe valves, when dilated,
have been con^pared to three pigeon-bafkets the
convex faces of which touch each other: they ex-
a6lly clofe the aperture, and prevent the reflux of
the blood from the pulmonary artery into the ven-
tricle.

The pulmonary artery, after a fhort pailagc, di-
vides itfelf into two branches, which proceed to
the two lungs. In the foetus, thele two branches
are very fmall ; bat the pulmonary artery has
a dire6l communication with the aorta by a
canal. The blood which arrives from the ven-
tricle, being able to penetrate only in fmall
quantity into the lungs comprefled and not yet
dilated by refpiration, proceeds dire61Iy into the
aorta by this arterial canal\ but, after birth, the
pulmonary arteries expand ; the whole blood palles
into them ; and the arterial canal, which flovvly be-.^
comes obftrudted, firft towards the aorta, is changed
into a ligament during the firft years of life.

352. The LUNGS are placed in the two cavi-
ties of the breaft, the form of which they nearly
retain ; they are convex and fmooth on the out-
fide, and excavated towards the heart, which they
embrace. They are broad ; are flat and have
fharp edges below, and are narrower and rounded
at the top and behind.

The

36*2 ORGANIC STRUCTURE.

The right lung is compofed of three lobes, and
the left of two. They are of a dark red colour ia
the fcstus; of a purple red in infancy ; become
of an afh white colour in adults, and are inter-
fperfed with blaeifh fpots, which with age increafe
in number and inteniity.

In the foetus, the lungs are clofe, compa6l, and
heavier than water; but, when they have been
diftended by air during refpiration, they retain a
great part of that air after death : they continue
light, fpongy, and float in water.

The cellules of the lungs (the bronchial) are ex-
ceedingly fmall : the lad membranous ramifica-
tions of the bronchia? terminate in theinfide of them.

The bronchial ramifications of the two lungs
arife from two trunks, produced by the tracheal
artery at its termination : the fuperior aperture of
the tracheal artery is the larynx.

The larynx is a cartilaginous dilatation fltuated
at the bottom of the pharynx, and before the cefo-
phagus. The principal cartilage which enters into,
the formation of it islituated below theos hyoides;
it has been compared to a buckler, on which ac-
count it is called the thyroid. It is broad and round
before, and in the middle exhibits a vertical line :
it is incomplete behind, and its lateral faces ter-
minate at the top and bottom in angles or horns^
which are prolonged backwards: the fuperior ones
are thinner and longer.

fj- Below

SYSTEM OP CIRCULATIOJT. 303

Below the thyroid cartilage is another annular
cartilage (the cricoid), narrow before and broad
behind, which is articulated with the inferior horns
of the thyroid.

Above the poilerior edge of the cricoid cartilage,
in the fpace left by the thyroid behind, there are
two fmall triangular cartilages, twifted fomewhat
round, fo as to reprefent the portion of a funnel
(arytsenoid) : the broad bafes of them reft upon
and are articulated with the cricoid ; their fummit,
which is thin and narrow, is dire^ed inwards.

In the laft place, the larynx above its fuperlor
aperture (glottis) exhibits a cartilage (epiglottis),
which is thin, broad and round ; its bafe is united
before to the os hyoides, and on the fides to the
thyroid and arytaenoid cartilages, by lax liga-
ments ; its fummit falls down behind on the aper-
ture of the glottis, during the paiTage of the ali-
ments. At the entrance of that aperture it forms
a fort of pipe, which makes the air vibrate on its
paflage, and produces found.

All thefe cartilages are united by ligaments,
which concur to form a very flexible cavity : thefe
ligaments produce, by their folds in the interior of
the larynx, two deep excavations {lateral ven-
tricles).

The cartilaginous pieces which form the larynx
are moved by means of feveral pairs of fmall muf-
fles. One extends from the fuperior edge of the

cricoid

3^4 ORGANIC STRUCTURE.

cricoid cartilage to the inferior edge of the thyroid,
on the lateral parts of thefe cartilages : erico-thy-
ro'ulian.

Another is inferted in the pofterior part of the
cricoid cartilage, and is fixed at the bafe of the
arytenoid cartilages : crko'arytamid'mn,
' From above the lides of the cricoid cartilasfe.
and behind the thyroid, arifes a mufcle which is
inferted before the arytenoid cartilages : lateral
crlco-arytisnoidian.

From the interior face of the thyroid cartilage
arifes a fmall mufcle, which proceeds backwards
and upwards, towards the arytsenoid cartilage:
thyro-arytaenoidian.

In the laft place, a fmall lingle mufcle covers the
two arytaenoidal cartilages behind : arytatioidian.

The combined a6lion of thefe mufcles can
lengthen or fhorten, dilate or contra6l the capacity
of the larynx, and produce a variation iri the aper^
ture of the glottis.

Befidcs thefe fmall mufcles, which tend to move
the different pieces of the larynx, there are two
others^ which can lower or raife the whole of it,
Of thefe mufcles, one is inferted in the interior
face of the firft piece of thx fternum, below the
fiylo-hyoidian, and proceeds to the oblique line
obferved on the thyroid cartilage. This mufcle
tends to lower the larynx : Jlerno-thyroidian^

Another, of a fmaller lize, is attached on the

- 6 . thyroid

SYSTEM bf CIRdUtATION. $Qq

thyroid cartilage, above the preceding, and pro-
ceeds to the OS hyoides. This mufcle can raife
the larynx, when the os hyoides is fixed : hyo-thy"
. roidian»

The larynx which is lined with a liiucdus mem-
brane is furrounded by feveral glands : the prin-
cipal of thefe glands, which is broad and fiar, is
fituated before the thyroid cartilage, by the name
of which it is diftinguifhed j before the cricoid
and the upper part of the trachea. The particular
ufe of the produ6l of its fecretion is not known.
A feries of fmall glands is obferved alfo before the
arytssnoid cartilages, and a fmall glandulous body
on the epiglottis.

The larynx is continued inferiorly with the tra-
chea, which defcends before the oefophaguSj to
the height of the fecond dorfal vertebra.

This conduit is compofed of cartilaginous rings
united by looie intermediate ligaments t their
number varies between fixteen and twenty. They
are incomplete behind, and the vacuity is filled up
by a longitudinal ligament*

The firudture of the trachea is fuch, that it3
length and diameter can be eafily varied : the
cavity of it is lined, like the larynx, by a mucous
membrane furnifhed with fmall glands.

Inferiorly, the trachea is divided into two trunks,
which are the commencement of the bronchia s

the

366 ORGAHIC STRUCTURE,

the (horter one proceeds to the right long, and
the oiher to the left.

< In penetraiing into the lungs, the bronchiae are
divided into rami, and labdividcd into ramifica-
tions, exceedingly delicate in every point- of that
organ. .

The texture of the bronchis is the fame as that
of the trachea ; but in proportion as the diameter
of thefe conduits decreafes, the rings of them be-?
come irregular, and at length difappear. The
bFoncb.ial conduits are then membranous, and ter- "
niinate in the numerous cells of the lungs.
Thefe cells have not a dired communication with
each other, but only by the cpnduits of the
bronchise. , ,

Ip the interior part of the lungs, along the
bronchial ramifications, are obferved a g'reat num-
ber of fmall glands, fituated chiefly at the angles
of their divifions (bronchial glands.)

353. The two divifions of the puhnonary artery,
at their entrance into the lungs, fubdivide thera-
felves into three parts on the right, and into two
on the left. Thefe arteries aceompany the bron-
chia?., and foKovv them by fubdividing in the fame
manner. Their lafl ra.mufculi penetrate into the
bronchial cells, expand over the fides of them, and
there anaftomofe dire611y with the capillary extra-
pi", ties of the veins.

■ • The

SYSTEM OF CIRCULATION-. 36f

The pulmonary veins follow alfo the divlfions of
the bronchise, and bring back the blood from every
part of the lungs : the ramufculi unite to for;:i
rami ; the rami to form branches ; and the branches
produce large veins for each lung, which pour the
blood into the fin us : Jinus of tbe pulmonary veins
(left auricle or aorta).

354. This linns (auricle) is ftoaller than the
preceding ; it is fituated at the pofterior and left
part of the heart, Tn the ftate of dilatation it af-
fe(5ls a cubic form, with an indented prolongation
at the top and on the outfide : auricular appendix*
The interior face of it is fmooth : it exhibits, be-
hind, the orifice of the four pulmonary veins; in the
infide, it corrcfponds to the iinus of the vens cavae,
and in the foetus exhibits the foramen ovale : at
the top and on the outfide is found the cavity of
the appendix. Before, the lin'us communicates
with the aortic ventricle by an aperture, the cir-
cumference of which is tendinous. This aperture
is furnifhed behind with a membranous valve,
cut into two fharp-pointed portions {valvules mi-
trales"), to which are attached tendinous and flefhy
fibres inferted in the fides of the ventricle. This
valve prevents the blood from flowing back whea
the ventricle contrads.

The left or aortic ventricle is fituated before the
finus of that fide ; and on the left fide of the pul-
monary ventricle it is fmaller, and of a form ana-
logous

36s ORGANIC ST^UCtU'RE^

logous to that of the latter ; but its fides are much
thicker : its interior face is furnifhed with earneous
pillars, like the right ventricle.

At the top and on the right is found the orifice
of the aortic artery, which is furnifhed with a triple
valve (figmoid)j fimilar to that which is found at
the entrance of the pulmonary artery.

2SS' ^^^ heart and the lungs are contained in
the cavity of the thorax. The interior fides of this
cavity are lined with a membrane, which is refleft-
ed on each lung, and forms a particular covering
to them, called the j)Ieura.

To have a proper idea of the difpofitioh of this
membrane, it will be necefi^ary to follow it in its
different folds.

The pleura, after covering the fides of the thorax
and the diaphragm, is reflected, before, along the
middle of the llernum, with that of the oppofite
fide, and forms the two laminae of the anterior
mediaftinum, between which the heart is lodged.
When it arrives behind that organ, and before the
pulmonary veflels, it is reflected on it felf, and covers
the interior face of the lungs, and then their exterior
face. When it reaches the bafe of that organ, it is
united to that of theoppofitefide,and again feparates
to produce the pofterior mediaflinum. The pleura
then continues on the lateral parts of the vertebral
column with that which lines the fides of the
thorax.

Ill

SYSTEM OF CIRCULATION. SGQ

In the anterior mediaftinum are found the heart
and the thymus gJand; in the pofterior, the aorta,
the cefophagus, the thoracic canal, and the prse-
lumbo-rhoracic vein.

356. The thymus, of which we have not yet
Ipoken (in the calf it is diftinguiflied by the name
o^fweetbread), is a voluminous gland, which in the
foetus is foft and reddifh ; in children it decreafes
and becomes yellow ; with age it continues to lofe
fome of its bulk, aiTumes more confiftence, and
becomes of a dark yellow colour ; in old age it
difappears almoft entirely. In children it fecretes
a milky humour, the excretory du6ts of which are
not yet known. We are ftill ignorant with re-
fpe6l to the ufe of this organ.

357. The pleura feems to be formed of only one
membrane ; it adheres by a cellular tiffue to the
fides of the thorax, and to the furface of the lungs,
which it covers. Its interior furface is applied to
itfelf without adhefion, by the contadl of the lungs
with the fides of the thorax. This furface is
fmooth, and fecretes abundance of ferous matter,
with which it is continually lubricated.

358. The heart is enveloped alfo by a peculiar
membrane, called the pericardium, thick, and of a
compa6l texture. It is formed of two folds, the
exterior of which, after enveloping thfe heart, is
continued on the large veflels : it adheres at the.

VOL. I. as bottom

370 ORGANIC STRUCTURE.

bottom to the diaphragtrij and in the reft of its ex-
tent to the mediaftinum. The interior fold, when
it reaches the large vefTels, is refle(5led on the
heart, and is thus placed in conta6l with itfelf : its
fmooth furface fecretes abundance of ferous matter,
which continually moillens the heart and pericar-
dium.

359. The blood is a red vifcous fluid of a fa-
line favour. On the firft view it appears to-be
compofed of a limpid fluid, having floating in it
red moleculas, refpe61ing the nature of which a
great deal has been written. The red globules of
the blood have been feen under a lenticular form,
and pierced with a hole in the middle, &c. It has
been judged that they are fcarcely the eight hun-
dredth part of a line in diameter.

The temperature of the blood is nearly forty
degreesof the centigrade thermometer (104° Fahr.).
That contained in the arteries is of a bright red
colour, and appears to be warmer than that of the
veins.

The blood when newly drawn from a vein ex-
hales an aqueous, odorous, and putrefcible vapour;
that of the veins feems to difengage azote, and that
of the arteries oxygen.

Chemical analyfis of the blood (hows that it
con fills of three principal fubftances, Jihrous mat-
ter ^ albumerif and colouring matter. There are

found

SrSTEM OP CIRCULATION. 371

found in it alfo different falts which are pure foda,
phofphate of lime, phofphates of foda and of am-
monia, and muriates of foda and of ammonia.

To analyfe the blood, it muft firft be left at refl;
it then feparates into two partSj one folid, called
the crajjame?itum) or cake ; and the other liquid^
called thejenim or ly?nph.

The craffamentum is more or lefs red ; it con-
tains fibrous matter, colouring matter, and albumen .

If a pound of craiTamentum, wrapped up in apiece
of linen, be fufpended under the cock of a ciftern,
fo as to be fubje6ted to a continual ftream of water,
it is obferved that the water gradually carries off
the colouring matter, and a part of the albumen ;
land at the end of twelve or fifteen hours nothing
remains but the white fibrous matter.

To feparate the colouring matter from the albu-
men, which is found mixed with the former in the
water, the water mufi; be boiled ; the albumen then
coagulates, and carries with it the colouring mat-
ter. This matter is then obtained by calcination^
mixed only with a fmall quantity of the phofphate
of lime. The colouring matter, after this procefs,
gives only phofphate of iron with excefs of oxide.
The waters employed for wafhing lofe their colour
by boiling; they retain only a yellowifh white
tinge, and hold nothing in folution but a very
fmall quantity of the foluble falts which^ as already
faid, are found in blood.

2 B 2 The

372 ORGANIC STRyCTURE.

The ferum, which is of a yellowifh white coioufy
h vifcous and perfedlly limpid ; it turns fyrup of
violets green, in confequence of the cauflic foda
which it contains. When nitrate of filver is poured
into ferum, it produces an abundant flaky precipi-
tate, which difTolves only in part in pure nitric
acid : this proves that the precipitate is partly
owing to muriate of filver which has been formed.
Serum, when mixed with lime water or a folublc
calcareous fait, fuffers to be precipitated phofphate
of lime. In the laft place, ferum, when heated,
forms itfelf into a mafs by the concretion of the
albumen.

Serum then is compofed of water holding in fb-
lution : albumen, foda, phofphates of foda and of
ammonia, muriates of foda and of ammonia. This
liquor is perfe611y analogous to the white of
an egg.

Though the lymph has not yet been well analyfed,
it is however known that it has a great analogy, to
the blood, and none to milk : it feparates fponta-
neoufly into a ferous part and a fmall curd : the
latter contains fibrous matter.

360. The blood, in returning froiu every part
of the lungs, is collected by four veins which pour
it into a finus \finus of the pulmonary veins (left or
aortic auricle).

From this finus it pafies into the left ventricle^
aiid is propelled thence into the aorta.

Thff

SYSTEM OP CIRCULATION. 373

The aorta in its pafTage furnifhes a very great
number of arterial branches, the fubdivilions of
which are diftributed to every part.

On its ifTuing from the heart, it gives out, on
(he right and left, the fmall cardiac artery (coro-
nary)^ which is reflected on that organ, and is dif-
tributed to the ventricle and finus belonging to
its fide. Thefe two arteries penetrate the whole
fubflance of the heart, and anaftomofe in feveral
places.

At the fummit of its curve, the aorta furniOies
two large branches on each lide : it furnifhes them
dire6lly from the left fide ; but from the right tide
gives out in general only one large branch, which
is divided.

Of thefe two branches, one is diftributed to the
liead, the cephalic ^ and the other to the thoracic
member : the hrachial.

361. The cephalic {primitive carotid artery)
afcends obliquely without, on the tides of the tra-
cheal artery, and at the height of the larynx is di-
vided into two branches.

Of thefe two branches, one is diftributed to the
neck, the face, and the exterior part of the cra-
nium, the maxillo-facial 'y the other, traverfing the
temporal bone, proceeds to the brain : anterior
cerebral.

362. The maxillo-facial {exterior carotid
^rtery) afcends on the fides of the neck as far
as the neck of the condyle of the maxillary

2 B 3 bone-.

374 ORGANIC STRUCTURE.

bone ; and in its paflage farniflies eight principal
branches.

The firfb arifes near the origin of the maxillo-
facial, and defcends, within and before, towards
the fuinmit of the thyroid gland, on which it ex-
pands : a ramus penetrates the larynx, the laryn-
pan, between the os hyoides and the cricoid carti-
lage, another proceeds into the interval which fe-
parates the cricoid and thyroid cartilages. This
artery, in its paflage, diilributes itfelf to the neigh-
bouring parts, and exhibits frequent anaftomofes:
the Juper'ior thyroidian *.

The fecond ifllies above the preceding ; it pro-
ceeds inwards, towards the os hyoides, paiTes be-
tween the hyo-gloffian and the genio-gloflian
mufcles, diftributing itfelf to the mufcles attached
to that bone ; where it divides : one part paffes
between the genio-gloffian and the mylo-hyoi-
dian mufcles, and proceeds to the root of the
tongue, where it advances in a ferpentine direc-
tion, below and on the lides of that organ, as far
as the point of it. The other is directed towards
the back of the tongue, and expands at the root of
it : the Tmgual. This artery furniflies the Jub-Tin-
gual, i\\Q /up er -Tmgual, and a hyo'idian ramus.

The third is obferved below the lingual. It is
final!, afcends on the lides, and a little behind the

* We fliall not mention the numerous varieties obferved in
the origin and diftribution of the arteries, we Ihall exhibit only
the moft conftant ftate,

pharynx^

SYSTEM OF CIRCULATION, 3^5

pharynx, and proceeds to the pharynx and the gut-
tural conduit of the ear, diflributing itfelf to the
neighbouring parts: a ramus penetrates into the
craniunrij through the pofterior foramen lacerum,
and conltitutes the poflerior meningian : inferior
pharyngian.

The fourth arifes above the lingual. It afcends
along the fuperior part of the pharynx, and pafles
over the maxillary gland, near the angle of the
jaw. In its palTage, it furnillies the mufculo-pa-
latine, the tonfillary, and the fub-maxillary. It
proceeds before, along the interior face of that
bone, is then refle6led outwards, afcends on its ex-
terior face, near the anterior edge of the zygomato-
maxillian, and proceeds to the commifTura of the
lips, after giving out the inferior labial. In that
place this artery farnithes two rami, which expand
in the thicknefs of the lips ; it then afcends along
the cheek, on the fides of the nofe, at the famnjit
of which it terminates, anaftomoling with the fub-
orbitar : the labial.

The labial, in this long paflage, furnifhes the
mujculo'^alatine, ihQ fub-maxillary ^ the iotifillary, the
inferior labial jihe, two labial coronary, and fome rami.

The fifth iffucs from the maxillo-facial, almoft
oppofitc to the lingual. It afcends obliquely be-
hind, under the fterno-, cervicO', and trachelo-maf-
toidian mufcles -, pafles between the maftoid apO'
phylis and the tranfverfe apophyfis of the atlas,

2 B 4 and

376 ORGANIC STRUCTURE.

and afcends under the integuments as far as the
occiput, where it expands in numerous rami : the
occipital.

The fixtb, which is very fmall, arifes in the fub-^
fiance of the parotid gland. It proceeds back-
wards, above that gland, as far as the maftoid apo-
phylis, where it furnifhes a ramus, which pene-
trates into the ear by the Itylor-mafloidian foramen
(aquedu6l of Fallopius), and diftributes itfelf in
the inlide of that organ. This artery then divides
on the fides of the maftoid apophyfis : a branch
proceeds before the ear, and another on the occi-
put : pojierior auricular. This artery gives the
Jiylo' majio'idiariy the tympa?iic, and fome mufcular
and cutaneous rami.

The maxillo-facial, at its termination behind
the neck of the condyle of the jaw, divides into
two branches, which are the laft furnifhed by this
artery.

The feventh continues in the dire61ion of the
maxillo-facial. At its origin it gives out a branch,
which proceeds, before, on the parotid gland, the
zygomato-maxillian, the falival du6l of Steno,
and as far as the palpebralian mufcle. The body
of this artery then continues under the parotid
gland, pafles betvreen the meatus auditorius,
where it throws out a ramus to the anterior part
of the ear and the condyle of the jaw : it then af-?
cends behind the zygomatic arch^, above the tem-

poro-i

SYSTEM OF CIRCULATION. ^Jf

poro-maxilHan mufcle, in the fabflance of vv^hich it
fends out a branch, and terminates in two rami, one
of which expands on the forehead, and the other on
the fides of the head : the temporal. This artery
furnifhes the anterior auricular, the Jub-%ygomatic,
and iho. fuperjicial temporals.

In the laft place, the eighth rifes towards the
middle of the branch of the jaw-bone. It afcends
along that bone, and the fmall pterygo-maxillian,
and proceeds to the fummit of the zygomatic fofia,
towards the fpheno-maxillary fifiTure : the maxiUo-
huccal.

In its pafTage, this artery furnifhes feveral
branches :

a. The firft proceeds within, under the fmall
pterygo-maxillian mufcle, and penetrates into the
cranium through the fpheno-fpinous foramen, where
it gives out fome ramufculi, and divides into two
rami, which expand on the meninx, and are lodged
in the furrows obferved on the fides of the interior
part of the cranium : middle meningiaii.

h. Another defcends anteriorly between the
great pterygo-maxillian and the branch of the jaw ;
and proceeds in the dentary canal : the maxillo-den-
tary. Before it enters this canal, this artery furnifhes
a ramus to the mylo-hyoidian and the membrane
of the mouth. It then pailes through the dentary
canal, giving out ramufculi which enter the alveoli

of

378 . ORGANIC STRUCTURE.

of the dentes molares. When it reaches the hole
of the chin, it furnifhes another fmall twig, which
penetrates into ihe alveoli of the canine and inci-
for teeth: it then itTues from that hole, and diltri-
butes itfelf to the mufcles of the lower lip, anafto-
mofing with the labial.

c. A branch pailes under the fmall pterygo-
maxillian mufcle, to which it diftributes itfelf, as
well as to the great pterygo-maxillian : the pery-

zotdian.

d. Two branches are diftributed chiefly in the
bottom of the temporal foflae : the profound tem-
porals. One arifes below the zygomatic arch,
palles before the fmall pterygo-maxillian mufcle,
and gives out rami, which expand on the temporo-
inaxillian. The other proceeds in the furrows of
the temporal foffa, below the temporo-maxillian.
It generally gives out a ramus which pafles before
the condyle of the jaw, and is diftributed to the
zygomato-maxillian • the majfeter'ine. Thefe ar-
teries anaftomofe with the fuperficial temporals.

e. The maxillo-buccal, before it penetrates to
the bottom of the zygomatic foffa, furniflies
alto a branch which defcends anteriorly on
the maxillary bone: y«/>ifr-m^^i//,2;_)'. It furnifhos
ramufculi which penetrate into the maxillary
iinufes, and to the roots of the upper dentes mo-
lares: it then lofes itfelf in the bucco-labian muf-
cle.

ifM

SYSTEM OF CIRCULATION. 3*g

cle, the membrane of the mouth, the neighbouring
integuments, and anadomofes with the labial and
the fiib-orbitar,

f. The maxillo-buccal, when it reaches the bot-
tom of the zygomatic fofla^ gives out a branch,
which penetrates into the fab-orbitar canal: tljs
fub-orbitar. Before it ifTues from this canal, it fur-
nifhes a ramus, which pafies through the dentary
canal, and diftributes itfelf to the canine tooth and
the incifbrs. It then ifTues through the inferior
orbitar hole, and diftributes itfelf to the mufcles of
the nofe and the lips, prcfenting frequent anafto-
mofes. In its paflage it fends out ramufculi, which
penetrate into the orbit and the maxillary (inus.

g. It then fends out two rami, one of which
pafles through the pterygoidian canal, and the
other through the pterygo-palatine foramen.
Both thefe rami are diftributed to the fummit of
the pharynx and the guttural conduit of the ear :
fuperior pharyngian.

b. In the laft place, the maxillo-buccal furnifhes
two rami, one of which defcends along the pofte-
rior palatine canal, and diflributes itfelf to the
palate : the other pafles through the fpheno-pala-
tine foramen, penetrates into the nafal foilse, and
divides into feveral ramufculi, which are diftri-
buted on the fides of that cavity : ■palatine and
^terygo-falathie.

363. The anterior, cerebral, mUrlor caro-
tid,

380 ORGANIC STRUCTURE.

tid^ Is larger in infancy than the maxillo-facial :
in adult age it becomes equal to it.

This artery afcends on the fides of the larynx
and of the vertebral canal ; it proceeds as far as the
bafe of the cranium, making feveral infledlions,
without giving any rami, and penetrates i^ito the
cranium through the winding canal near the pe-
trous portion of the os temporale. When it
reaches that cavity, it pafles on the fide of the body
of the OS fphenoides ; is then reflected upwards,
turns round in the notch of the anterior cliqoid
apophyfis, and traverfes the meninx.

The anterior cerebral, immediately after traver-
iing "this membrane, gives out a branch, which
enters the optic hole, and is diflributed to the orbit:
the orhitar.

The ophthalmic artery penetrates into the orbit,
below and on the exterior fide of the ocular nerve,
around which it turns ; it pafi!es below the fuperior
mufcle of the eye, and proceeds towards the in-
terior fide of that cavity.

In this fhort pafiage it furnifhes feveral branches,
namely :

a. The lacrymal, which advances along the
exterior fide of the orbit, is diftributed to the ex-
terior mufcle of the eye, the orbito-palpebralian,
the lacrymal gland, and the upper eye- lid. A
ramus even traverfes the os jogale, and expands
on the cheek.

6 ■ h. The

SYSTEM OF CIRCULA.T10K". 3S1

h. The/uh-irian branches, which pierce the fcle-^
rotica in different places : they proceed between
that membrane and the choroid, as far as the
ciliar ring fligamentum clUare), where they are
fub-divided into a great number of capillary vef-
fels, which form anaflomotic circles, exceedingly
delicate, around the large and fmall circumference
of the iris.

c. The two ethmoidal branches, which advance
inwards, pafs over the lobe of the eye, penetrate
into the two interior orbitar holes, enter the cra-
nium, and are refied^ed in the ethmoidal cells,
through the crebriform plate of the os ethmoides.

d. The central of the retina, which penetrates
into the optic nerve before it enters the orbit.
This artery advances into the centre of that nerve,
as far as the retina, on which it expands.

e. The nmfcular, which gives out two rami :
one of thefe, which is larger and conftant, is diftri-
buted to the inferior and lateral mufcles of the
eye ; the other proceeds into the fuperior, the int^->
rior, and the great oblique mufcles of the eye.

f. The two falpeh-alian: thefe are dire(5ted to-
wards the interior angle of the orbit, from which
they are diftributed to both eyelids, furnifhing ra-
raufculi to the neighbouring parts.

g. In the laft place, the orbitar furniflies alfo
fome rami, which are diliributed to the eye-
brows, the forehead (the frontal), and to the nofe

(the

382 ORGANIC STRUCTO'RE.

(the nafal), and terminates by anafl-omofing witli
the labial.

The anterior cerebral artery, after having pierced
the dura mater, and furnifhed theorbitar, proceeds
backwards under the brain, and then gives out
a connnunicating branch, which anaflomofes with
the pofterior cerebral. This fmall and pretty long
branch furnifhes, in its paflage, ramufculi to the
furrounding parts, and then fends out a ramus
which is diflributed to the choroid plexus.

The anterior cerebral artery is then divided into
two branches. The fmaller proceeds before : the
anterior lobar-, the other proceeds on the lide, be-
tween the anterior and middle lobes of the brain :
nuddle lobar.

The anterior lobar is refledled forwards, below
the mefolobe, and by a fhort tranfverfe branch
conimunicates near its origin with its fellow. This
artery, when it reaches the anterior part of the
mefolobe, afcends before the brain, and is refle6ted
on its farface. In this whole pailage it furnifhes
numerous ramifications, which expand on the
meningine, between all the anfradiuofities of the
brain, from which they penetrate into the interior
parts of that organ.

The middle lobar takes a lateral dire(5lion below
the brain. It pafles between its anterior and mid-
dle lobes,. and divides into feverai branches, which
continue to advance between thefe parts, furnifh-

ing

SYSTEM OF CIRCULATION. 3S3

ing numerous rami to the choroid plexus, the
meningine, and the neighbouring parts of the
brain. Thefe branches are then fubdivided, and
expand over the meningine, in the numerous folds
which it forms on the lateral parts of the encepha-
tic organ, and lofe themfelves in the interior of
that organ.

364. The brachial artery extends from
the aorta to the bending of the arm.

To facilitate the defcription of this artery, its ex-
tent is divided into three parts : ift, that which is
under the clavicle (fub-clavian) ; 2d, that which
is under the arm-pit (axillary) ; 3d, that which
correfponds to the arm (humeral).

^6^. The sue-clavian furniflies, in general,
lix branches :

The ift proceeds to the brain, the ^ojierior cere-
hral (vertebral) ; it rifes along the neck, accom-
panying the inferior thyroidian, then enters the
canal produced by the holes of the tranfverfe apo-
phyfes of the vertebra of the neck, and proceeds
as far as the great occipital foramen, making feveral
inflexions, efpecially at the top. In this paflage^
it fends out feveral rami to the vertebral canal and
to the neighbouring mufcles.

When it enters the cranium, it proceeds ante-
riorly on the fides of the rachidian prolongation,
and gives out a great number of fmall rami, one
of which is diftributed to the pofterior part of the

meninx:

384 ORGANIC STllUCTtJlt,E*

meninx : the occiplto-nienmg'mn : two others de-
fcend, one before and the other behind that pro*
longation. The anterior extends as far as its
extremity ; the pofterior terminates towards the
lumbar region : anterior ami fojierior median of the
rachis (anterior and poiterior fpinals).

The pofterior cerebral artery then fends out a
large ramus, which is diftributed on the inferior
face of the cerebellum : inferior great cerehelhus.

The two pofterior cerebral arteries then unite
and form a trunk, which advances over the whole
length of the mefencephalon : the me/encephalic
(bafiliar) ; this trunk furnifhestwo fmall rami, one
behind, inferior fmall cerehellous ; and the other
before, near its termination : fmall fuperior cere-
hellous, Thev diftribute themfelves to the bafe of
the mefencephalon and of the cerebellum.

The mefencephalic trunk then divides into two
branches, the pojlerior lobar ^ which proceed on the
iides. Each firft furnifhes a communicating rartlus,
which proceeds to the anterior cerebral artery and
fome other fmall rami. This artery then divides,
and expands over the pofterior lobes of the brain,
diftributing itfelf in its numerous anfradluolities.

It is to be obfervcd, thac the brain receives a
large quantity of blood, fince the calibre of the
four cerebral trunks has been eflimated at a lixth
part of that of the aorta. This blood circulates in
thefe veffels, forming at the bafe of the cranium

an

SYSTEM OF CIK-CULATION. 3S5

an anaftomotic circle, in fuch a manner that it
would be poffible to tie any one of the cerebral
arteries without the circulation of the blood in the
brain being interrupted.

The fecond defcends into the breaft, proceeds
over the cartilages of the ribSj near the fternum,
between the pleura and the inter-coftian muf-
cles. Between each inter- cotl:al fpace it gives out
two rami, which traverle the inter-coftian muf-
cles, thofe above the breaft, and lofe themfelves
in the mammella?. It dillributes itfelf alfo to the
thymus gland, themediaftinum and the diaphragm.
This artery then defcends towards the bottom of
the breaft, furnifhes a ramus to the itcrnal appen-
dix, and fome others which are loft in the fub-
fiance of the mufcles of the abdomen, analto-
moling with the ep'igajiric and ih^fub-Jienial (inte-
rior mammillary). This artery furnifhes medlajiinei,
Juh-mammillary ^ inter-cojial, 2iudf up 67' -diaphragmatic
rami, and often a thymic and a bronchial ramus.

The third arifes oppolite to the fub-fternal, and
afcends before and on the fides of the neck, far-
nifliing a ramus to the mufcles of that part: af-
cending cervical. It then patfes under the cephalic,
proceeds to the thyroid gland, and penetrates its
fubftance. It there anaftomofes with rami of
that of the oppofite fide, and of the fuperior thy-
roidian. This artery diftributes itfelf alfo to the

VOL. I. a c oefophagus^

360 ORGANIC STRUCTURE,

cefophagu?, the larynx, and as far as the bottorti
of the pharynx: inferior thyroidian.

The fourth arifeSj for the moll part, on the ex-
terior fide of the thyroidian. It proceeds upwards
on the lides of the neck, pailes between the tranf-
verfe apophyfis of the laft cervical vertebra, and
that of the firll: of the back, and afcends obliquely
towards the occiput, furnifhing rami to the muf-
cles over which it pafles : Irachelo-cervical (pofte-
fior cervical.)

The fifth, trachelo-fcapular, often forms two
branches at its origin : one of thefe proceeds out-
wards and downwards, under the clavicle, and
gives out feveral rami to the neighbouring
parts. When it reaches the fuperior edge of tfce
fcapula, it pafles under the fuperior fuper-fcapulo-
trochiterian, gHdes under the acromion apophyfis^
and lofes itfelf in the inferior fuper-fcapulo-tro-
chiterian mufcle '. fuperior fcapular.

The other, which' is larger, takes an oblique direc*
tion upwards and outwards, under the fterno-maf-
toidian mufcle, where it, gives out a ramus which
Jofes itfelf on the fides of the neck. It then divides
into two branches : the firft proceeds upwards, and
diftributes itfelf between the dorfo-fuper-acromian
and the trachclo-fcapulian mufcle : the fecond pro-
reeds towards the fuperior e,^gG of the fcapula,
paffing under the dorfo-fcapulian mufcle ; it then

defcends

SYSTEM OF CIRCULATIOTST. 38f

^iefcends along the pofterior edge of that bone,
and divides itfelf, near its inferior angle, into feve-
ral rami, which lofe themfelves in the fub-fcapulo-
trochinian, the dorfo-fcapulian, and the cofto-fca-»
pulian mufcles: the tranfverfe cervical.

The lixth ifTues from below the exterior extre-
mity of the fub-clavian. It dcfcends before the
neck of the firft rib, often of the fecond, and
lomeUmes of the third, and furnifhes feveral rami*
Some of thefe are dire6led backwards, pafs over
the fides of the vertebrae, and lofe themfelves ia
the mufcles of the neck and the back. The reft
proceed outwards, along the inferior edge of the
ribs, betweeo the inter-coftal mufcles : fome rami
are diftributed to the oefophagus and the bron-
chiae : fuperior inter-cqfiaL

366. The axillary is a continuation of the
fub-clavian. It proceeds outwards, forming an
arc in the hollow of the arm-pit : it extends from
the firft rib to the point where the large dorfal
mufcle is attached.

In this pafTage it furnifhes five principal
branches, the diftribution of which is pretty con-
ftant ; but they vary a great deal with refpe6l to
their origin, as feveral of thefe branches often arife
from a common trunk.

The firft arifes before and in the middle of the

axillary. It then immediately divides itfelf int<^

2 c 2 feveral

388 ORGANIC STRUCTURE.

feveral rami, which proceed to and expand be-
tween the flerno-hiimerian and the cofto-coracoi-'
dian mufcles : Jierno-thoracic (fuperior thoracic.)

The fecond iffiies clofe to the preceding. It
defcends below the fterno-humerian mufcle, and
divides into feveral rami, which are diftributed to
the coHo-fcapulian mufcle, the inter-coftians^ and
the mammilla: cojio-lhoracic (inferior thoracic).

The third arifes near the preceding ones. It
pafles over the cofto-coracoidian mufcle, and fur-
nifhes feveral rami, which are loft in the fterno-
humerian and cofto-clavian mufcles; it then conti-
nues between the fterno-humerian and the fub-
acromio-humerian mufcles, and in this paflage fur-
nifhes a ramus, which expands on the articulation
of the humerus with the fcapula : the fufer-fca-
pular (acromial).

The fourth defcends polteriorly, below the
point where the fub-fcapulo-trochinian mufcle is
attached, and furnifhes fome fmall rami to that
mufcle, and to the cellular tiffue of the arm-pit i
it then divides into two branches : the inferior
branch, which is fmaller, inferior fcapular, follows
the inferior edge of the fub-fcapulo-trochinian
mufcle, and lofes itfelf in the cofto-fcapulianj the
lumbo-hurnerian, and the fcapulo-humerian.

The other, which is ftronger, exterior fcapular ,
is dire6led backwards, between the fcapulo-hume-
rian and the inferior fuper-fcapulo-trochiterian

mufcles.

SYSTEM OF CIRCULATION. SgQ

mufcles, and divides into two rami. One of thefe
raoii pafles over the anterior edge of the fcapula,
and lofes itfelf in the inferior fuper-fcapulo-trochi-
terian mufcJe, and another fmaller is diftributed
to the fub-fcapulo-trochinian : fuh-fcapular (com-
mon fcapular).

The fifth ilTues from below the head of the nu-
merus. It is often divided, at its origin, into two
branches : one, the anterior circumflex, pailes
under the coraco-humerian, and the fliort portion
of the fcapulo-olecranian mufcle, and expands be-
fore and around the articulation of the fhoulder.
The other, which is much larger,' the pofteiior
circumflex, palles behind the humerus, between the
fcapulo-humerian mufcle and the inferior fuper-
fcapulo-trochiterian, below the fub-acromio-hu-
merian ; gives out a great number of rami, and
lofes itfelf in turning round before and below the
head of that bone -. fcapulo-humeral.

367. The humeral artery is a continua-
tion of the axillary ; it extends from the middle of
the hollow of the arm-pit, as far as the middle of
the bending of the arm. In this paflage it fur-
ni(hes above, towards the upper third of the hu-
merus, a very large branch, the exterior coUateraJ,
which proceeds outwards, betvveen the humero-
cubitian and the fcapulo-olecranian mufcle, and
divides itfelf into two branches. One of thefe
branches diftributes itfelf in the fubftance of the
a c 3 fcapulo"

^gO ORGANIC STRUCTURE.

fcapulo-olecranian ; the other, which is ftrongef,
turns round behind the middle of the humerus^
and defcends along the exterior fide of the arm,
between the humero-fuper- radian, and the exte-
rior portion of the fcapulo-olecranian : it terminates
around the articulation, anaftomofing with the
radial recurrent.

Below this collateral branch arifes another, the
inierior collateral, which defcends along the inte-
rior iide of the arm, before the fcapulo-olecranian
mufcle, and as far as the articulation.

The humeral artery then continues before the
arm, along the interior edge of the fcapulo-ole-
cranian mufcle, and before the humero-cubitian,
giving out to them frequent rami : the mujculat
of the arm.

In the laft place, the humeral artery gives out
near the articulation of the elbow two xami, one
of which proceeding towards the epicondyle dif-
tributes itfelf to the neighbouring meifcleSj and
anaftomofes with the interior collateral and the
cubital recurrent. The other proceeds towards
the epitrochlea, and is diftfibuted in the fame
manner as the interior : collaterals of the articula-
tion of the elhow. ^

At the bending of the arm the humeral artery
divides into two branches, one of which follows
the radial edge of the fore-arm, and the other its

<^hital edge.

368. The

SYSTEM OF CIRCULATION. 3gf

368. The radial artery extends along the
anterior and exterior face of the fore- arm, as far
as the extremity of a part of the fingers. Near its
origin it furnifhes a branch, which is refledled
■ towards the epicondyle, recurrent of the epicondyk^
and is diftributed to the mufcles attached to that
part, anaftomofing with the exterior collateral of
the arm. In its paflage along the exterior edge of
the fore-arm, the radial artery fnrniflies feveral
rami to the neighbouring mufcles : inufcular of the
fore- arm.

Near the articulation of the wrift, this artery
divides into two branches, after giving out a fmall
ramus before that articulation. One of thefe
branches, the radio-palmaris, pafles before the an-
nular ligament of the carpus, gives out a ramus
to the mufcles of the thumb, and proceeds to-
wards the palm of the hand. It there furniilies
an artery, which anailomofes with the cubital
arch, and then terminates in two rami: one of
thefe lofes itfelf on the radial fide of the thumb;
the other defcends into the interval between the
thumb and the index finger, and expands along
the correfponding edges of thefe two fingers.

The other branch, furniOied by the radial artery
at its termination, proceeds to the exterior fide of
the articulation, the radio-fuper-palmaris ; it gives
out a ramus which proceeds in a tranfverfe direc-
tion on the carpus, dorfal of the carpus, and an-^

a c 4 other

ORGANIC STEUCTURg.

ther which proceeds to the radial fide of tbe
thumb.

The radial artery, wLen it reaches the interval
between the two firft bones of the metacarpus,
feparates into three branches. One of thefe
branches glides in the fubftance of the metacarpo-
phalangian mufcle of the thumb ; pafTes along the
tirft bone of the metacarpus, and divides into two
branches, which are diftributed on the fides of the
thumb. The fecmd pafles over the firft dorfal
inter-ofTeous mufcle, along tbe radial edge of the
fecond bone of the metacarpus. The thirds which
is much larger, advances between the carpjan ex-
tremities of the two firft bones of the metacarpus ?
it turns round in the palm of the hand, and unites
itfelf to a branch of the cubital to form the pro-
found palmary arch. This arch furniihes, if!:,
rami which are reflc6led before the carpus, to the
ligaments of that part and to the mufcles of the
thumb ; ad, four rami which pafs before the in-^
ter-oiieous mufcles, to vi^hich they diftribute them-
felves as well as to the lumbricals, and terminate
towards the heads of the bones of the metacar'
pus, anaftomofing with the digital arteries ; 3d,
three rami, which pierce tbe lecond, third, an4
fourth dorfal intei'-offeous mufcles ; diftribute
themfelves to the fuper-palmary face, and each
j:iivide into two ramufculi, which lofe thenrifelve^
on the tides of the laft four fingers.

0^6.^, The

SYSTEM OF CIRCULATION. 3g3

369. The cubital artery, which is larger
than the radial, defcends before, along the cubital
edge of the fore arm, as far as the fingers. Near
jts origin it gives out two branches, one of which
pafles before the epitrochlea, diftributes itfelf to the
neighbouring- parts, and anaftomofes with the col-
laterals of the cubitus. The other, which is
larger, pafles behind the epitrochlea, fends out fe-
veral rami to the neighbouring mufcles, and anafto-
mofes with the inter-mufcular of the arm : th&
recurrent of the epitrochlea.

The cubital then penetrates under the mufcles
attached to the epitrochlea, and furnifhes two
branches. One of thefe branches palTes between
the inter-ofleous ligament and the mufcles by
which it is covered : the anterior inter-ojjeous : it
furnifhes a ramus which glides between the two
layers of the mufcles, and fome others which are
diftributed to the mufcles and to the periofteum,
Inferiorly, this artery traverfes the inter-offeous
ligament, and terminates on the convexity of the
hand, where it anaftomofes with the dorfal of the
carpus.

The other, the pojierior inter -ojfeous, traverfes at
the top the inter-ofleous ligament, and gives out a
branch, the olecranian recurrent, which is refle6led
between the olecranon and the epicondyle, in the
fubftance of the epicondylo-cubitian mufcle. It
diilributes itfelf to the neighbouring mufcles, and

anaflomofcs

3Q4 ORGANIC STRUCTURE,

anaftomofes with the exterior collateral artery.
Thepofterior inter-ofleous then continues between
the two layers of the mufcles of the fuper-palmary
face of the fore-arm, to which it fends out a great
number of rami, and terminates near the vvrilt,
anaflomofing with the anterior inter-offeous.

After fumifhing thcfe rami, the cubital artery pe-
netrates, at the top, under the common epitrochlo-
phalanginian mufcle, and ifTues towards the mid-
dle of the fore-arm, from which it then proceeds
as far as the wrift : the cuhko-fuper-palmaris. At
this place it gives out feveral rami, one of whicli,
diHributes itfelf over the hand, anaftomofing with
the dorfal of the carpus. Another tranfverfe
branch palTes before the articulation, and anafio-
mofes with a limilar one furnifhed by the radial
artery. A third branch pafTes under the tendons
of the common epitrochlo-phalanginian mufcle^
and of the common cubito-phalangettian, and
concurs to the formation cf the profound palmary
arch.

In the ]aft place, the cubital artery defcends
into the palm of the hand, the cuh'ito-p.ahnar'is,
under the palmary sponeurofis, and forms a tranf-
verfe arch from which arife four principal rami,
fometimes five, and even fix. The firft paffes
over the mufcles of the palmary face of the little
finger, and ternlinates along its cubital edge ; the
fecond proceeds in the interval between the fourth

. and

SYSTEM OF ClRtULATIOK, SQS

and fifth bones of the metacarpus, and feparateS^
into two rami, which terminate along the oppolite
edges of thefe two fingers ; the third and fourth
proceed, in like manner, to the fummi^ of the
other two intervals between the following fin-
gers, and lofe themfelves along their oppofite
edges.

When the cubital furnifhes one or two rami
more, they terminate alfo on the fides of the index
finger and the thumb. The fuperficial palmary
arch is then formed entirely by the cubital, but
for the moft part the latter rami -proceed from the
radial.

The two rami, which proceed on the fides of
each finger, anaflomofe with each other towards
the nail-like extremity.

370. The aorta, after furnifhing, towards its
curvature, the cephalic and brachial arteries^ is re-
iledled dire6i:ly downwards, and defcends, a little
to the left, before the bodies of the dorfal verte-
brae, between the lamina of the pofterior medi-
aflinum on the right fide, and a little behind the
oefophagus. It advances as far as the lower part
of the brcafi:, traverfes the diaphragm between
its two pillars, and penetrates into the abdomen,
where it advances as far as the fourth lumbar
vertebra.

The.

^g§ ORGANIC STIltJCTUREe,

The iborack aorta^ during its pailage, furniilies
feveral fmall branches.

I ft. It gives out one at the top, which expands
on the pofterior part of the pericardium : ^ofterlor
fsncardian.

ad. It furniflies, at the top and on each fide, a
branch which follows the diftribution of the bron-
chia? in the rnterior of the lungs : tie hronchiaL
The right branch, which in general is the largeft,
arifes often from the trunk of the iirft inter-coftal :
it turns round on the cefophagus, gives out to it
fome rami, and proceeds to the origin of the bron-
©hiae, where it feparates into feveral rami, which
sre diftriboted on the aerian canals, and "penetrate
with them into th@ interior of the lungs. The
left, which is often double, gives out mmi to the
csfophagus and the pericardiumj and like the right
diftributes itfeif in the lungs.

3d. Before the aorta are obferved three or four
iiiiali branches^ diftributed along the csfophagus,
and. which fend out fome rami to the pofterior
mediailinum : the cefophagian.

4tb. The aorta fends out two or three rami^
which expand on the pofterior mediaftinum : the
pofierlor mediqfi'me,

5th. Behind, and on the fides of the aorta, there
arife from nine to twelve branches, which proceed
on the lateral parts of the bodies of the vertebras,
and are continued between the ribs; the inter- c.ojial.

Thefe

SYSTEM OF eiRCULATiOl<f. ^gj

Thefe branches, when they arrive between the
heads of the ribs, feparate into two rami : fome
proceed backwards, and are diilributed in the
rachidian canal, and to the mufcles of the back ;
the reft continue along the inferior edge of the
ribs, and proceed to the inter-coftian mufcles and
thofe of the thorax, exhibiting frequent anaiio-
mofes.

371. The aorta penetrates into the abdomeis,
through the aperture left between the two pillars of
the diaphragm, and proceeds as far as towards the
fourth vertebra of the loins, where it bifurcates.

The abdominal aorta, in its paflage, furnifhes
branches which are diftributed to the diaphragm^
the ftomachjthe liver, and the fpleen, the intefiinesj
the fuper- renal capfules, to the kidnevs, and the
loins.

ift. At the top, the abdominal aorta funiifhes,
on the right and left, a branch which expands
under the diaphragm : the fuh -diaphragmatic (ia-
ferlor diaphragmatic).

Each of thefe afcends before that mufcle, give?
out fome rami to its pillars, to the liver (on the
right fide), and to the fuper-renal capfule. It
then divides into two rami, one of which proceeds
towards the middle of the diaphragm, and the
other on the fides of that partition : they both
exhibit frequent anaftomofes. '

2d. Before, it fends out a large trunk, which
correfponds to the back part of the ftomach : the

OPISTO-

39s ORGANIC STRl7CTtJK.E«

opisTo-GASTRic, and which divides into three
branches. One of thefe proceeds to the ftomach
(the gaflric), another to the liver (the hepatic), and
the third to the fpleen (the fplenic).

The gcijiric artery proceeds towards the oefopha-
gian ©rijfice of the fiomach, gives out different rami
which furround that orifice, and others which af-
cend along the cefophagus : it then feparates into
feveral branches, which follow the fmall curvature
of the tlomach, and expand on the two fides of that
organ, anaftomofing with each other, and with the
gaftro- epiploic artery, right and left.

For the mofl part, it furnifhes a branch whicK
pafles before the trunk of the vena port^,. pene-
trates into the left extremity of the tranfverfe ful-
cus of the liver, and is diflributed in its left lobe :
left lobar (left gaflro- hepatic).

The hematic artery is larger than the preceding.
Before it proceeds into the liver, it gives out dif-
ferent rami, one of which proceeds to the pylorus,
and the fmall curvature of the fl:omach, the gajlro-
pyloric ; others are diflributed to the pancreas, th^
pancreatic, and to the commencement of the duo-
denum, duodenal. A large ramus pafles under the
pylorus, proceeds in the fubflance of the great epi-
ploon, advances towards the great curvature of the
ilomach, the right gajlro-epiploic, and expands on
the fides of that vifcas, exhibiting frequent anailo-
mofes.

The hepatic, after furnifbing thefe arteries, pro-
ceeds

SVST"EM op CmCULATIOKTo SQf^

^ceeds to the right lobe cf the liver, right lobar i
and fends out a ramus, which divides itfelf on the
iides of the gall-bladder, the cyftlc ; continues to-
wards the right extremity of the tranfverfe fulcus,
and lofes itfelf in the fubftance of the liver.

The hepatic artery furnifhes fometimes the left
lobar.

Thtfplenic artery is larger in adults than the
hepatic -, the contrary rs the cafe in children : it
proceeds to the left, in a furrow of the pancreas,
and gives out feveral rami to that vifcus, thefpleno-^
pancreatic ; it then fends out feveral rami which
expand on the large cul-de-fac of the llomach i
the fpletiO'gaJiric, Before it proceeds to the fpleen,
this artery gives out alfo a branch which advances
to the left, below the ftomach, enters the laminae
of the large epiploon, ths left gajlro-eplploic, and
furniflies rami, fome of which proceed to the left
extremity of the pancreas, and others to the epi-*
ploon : left epiploic. This branch then expands on
the large curvature of the ftomach, where it ter-
minates, analtomofing with the right gaftror
epiploic.

The fplenic artery then proceeds to the fpleen,
and feparates into five or fix branches, which pene-
trate through the fcilTure, and diftributethemfelves
in its fubftance.

3d. Before the abdominal aorta, and belov/ the
opifto-gaiirric, arifes a large artery which diftributes
iffelf to the mefentery and the inteflines ; thefupe-

rior

400 ORGANIC STRUCTURE,

rior me/enteric. This artery defcends obliquely,
on the left, behind the pancreas, pnfTes under the
tranfverfe mefo-colon, returns to the right, and
thus forms a curve between the laminae of the
mefentery.

In this paflage, it gives out, fuperiorly, fome
rami to the pancreas, iha pancreatic ; and others to
the commencement of the duodenum, the duode-
7ial. It then furnifhes a large trunk, which ex-
pands in the duplicature of the mefo-colon, the
mefo-colicj and divides into two branches, one of
which proceeds along the afcending part of the
colon, and the other along its tranfverfe part.
Both thefe branches anaftomofe with their colla-
terals, and with each other.

This mefenteric artery then furnifhes another
branch, which proceeds tranfverfely under the
liver, towards the right portion of the colon: the
right colic. It proceeds in the duplicature of the
mefo-colon, and divides itfelf into feveral rami,
which expand on the afcending portion of that in-
teftine, anaflomofing with the collaterals.

Lower down, and towards its termination, the
fuperior mefenteric furnifhes a branch which de-
fcends on the right, and proceeds to the coecum,
the ileum and the colon : the ileo-colic^ This
branch advances behind the right lamina of the
mefentery, and furnifhes two rami, oneofvi'hich
anafloraofes with the right colic, and the other
proceeds along a portion of the ileum. This

branch

■>&

StSTEM OP eiRC0LATION'. 401

branch then continues towards the coeeum, and
furnifhes a ramus to its appendix : the ccecal.

From the convexity of the fuperior mefenteric
artery arife, on the left, a great number of rami
(from twelve to fifteen). Each of thefe feparates
into two, which proceed in the folds of the mefen-
tery, as far as the jejunum and the ileum. Alt
thefe rami anailomofe vs^ith the neighbouring ones,
and form arches, whence arife other rami which
unite with their collaterals to form fmaller arches:
this arrangement is repeated four and even five
times. When thefe arches reach the inteftines,
they give birth to two right layers of ramufculi^,
which expand in the. fubftance of the fides of the
inteftines, where they form a vafcular reticulation,
which covers the whole furface of them.

All the veflels diftributed on the inteftines ex-
hibit, in general, a fimilar arrangement.

4th. The abdominal aorta gives out inferlorly,
dole to its bifurcation, an artery which is diftri-
buted to the mefo-colon and to the mefo-redlum :
inferior mefenteric. This artery, near its origin,
fends out a trunk which foon divides into two
branches : ihefirji proceeds towards the tranfverfe
portion of the colon, and furnifhes two rami, one
of which afcends before the kidney, and proceeds
towards the tranfverfe portion of the colon, where
it terminates by uniting with a branch of the fu-
perior mefenteric, and forms there a remarkable

VOL. J. 2D anafiomofis:

402 ORGANIC STRUCTURE.

anaftomofis : that of IlioJan, The other follows
the dire6lion of the defcending portion of the
colon, and terminates by anaftomofing inferiorly
with the neighbouring rami : left great colic (fiipe-
rior and middle colic).

The/econdj which is not fo large, proceeds to-
wards the defcending portion of the colon, and
divides itfelf into two rami which anaftomofe with
their collaterals : thefmaU left colic. A third is dif-
tributed to thecommencement of thefigmoid flexure
of the colon, and anaftomofes with its neighbours.

In the lafl place, the inferior mefenteric artery,
after giving out fome rami to the iliac part of the
colon, defcends on the right, penetrates into the
lefler pelvis, diftributes itfelf behind the re^lum,
and anailomofes with feveral of the neighbouring
rami : artery of the reBum.

5th. The abdominal aorta, immediately after
furnifhing the fuperior mefenteric, gives out, on
each fide, a branch which divides into feveral rami.
Some of thefe proceed to the pillars of the dia-
phragm, and others to the fuper-renal capfules,
and the neighbouring adipofe tifllie : the fu-per-
r^«<2/ (middle capfular).

6th. Below the latter arife one, two, and fome-
times three, on each fide of the aorta, which pro-
ceed tranfverfally towards the kidneys, ths renal,
furnifhing fome ramufculi to the fuper-renal cap-
fules, the neighbouring adipofe tifTue, and the

ureter.

SYSTEM OF CIRdULATION.' 40*3

ureter. When thefe branches reach the kidneys^
they divide into feveral rami, which lofe themlelves
in the finuofities of that vilcus.

7th. Below the renal rami there arlfe, in-generalj
on each fide of the aorta, two Jong flender arteries,
which proceed downwards in an obHque dire(?tion,
along the pfoas, giving out fome fmall rami to the
neighbouring parts. Each then iflues from the
abdomen, through the inguinal ring, defcends
along the tefticular cord, and proceeds to the epi-
didymis and the tefticles: the teji'icuJar (fpermatic).

In the female, this artery penetrates into the
lefler pelvis, and diftributes itfelf to the ovariurh,
giving out fome rami to the broad ligaments, the
conduits of the ovaria, and the lateral parts of the
matrix: artery of the ovarium,

Sth. The lateral and pofterlor parts of the ab-
dominal aorta give birth, on each fide, to four or
five arteries, which proceed tranfverfely on the
bodies of the firft four of the lumbar vertebrse.
Thefe arteries furnifh fome ramufculi to the neigh-
bouring parts, and then divide into two rami.
Some of thefe proceed backwards between the
tranfverfe apophyfes, give out rami which pene-
trate into their rachidian canal, and lofe themfelves
in the mufcles of the back. The reft pafs behind
the praelumbo-trochantinian mufcles, fend out
rami to the pillars of the diaphragm, and to the
ilio-tranueifian; are refle6ied on the mufcles of
a D 2 th«

ORGAl^IC STRUCTURE.

the abdomen, and terminate by anaftomofing with
rami of the laft inter-coflals, of the fub-ftcrnal and
fub-pubian : the lumhar.

9th. Behind the abdominal aorta, and near its
bifurcation, is an odd artery, which defcends on
the middle of the body of the laft lumbar vertebra,
before the middle part of the facrum, and as far
as the coccyx : middle facral. In this palTage it
furnifhes on each fide a ramus, which proceeds
in a crofs dired^ion on the body of the laft verte-
bra, and anaftomofes with the neighbouring parts.
It then continues and gives out feveral rami on
the fides of the facrum.

372. The abdominal aorta, when it reaches to-
wards the fourth lumbar vertebra, divides into
two branches : pelvi-crurales (iliac). Thefe
two branches proceed downwards, and on the fides,
near to the articulation of the facrum with the
bones of the ilium, where they again bifurcate, and
farnifh two other branches: one of thefe penetrates
into the pelvis, the pelvian ; and the other pro-
ceeds to the abdominal limb : the crural.

In the foetus, the peiyi- crural feparates alfo into
two branches, one of which proceeds to the abdo-
minal limb, and the other^ which is much larger,
penetrates into the pelvis. The latter gives birth
to two branches furniOied in general by the pel-
vian, but in that cafe they are only very delicate
rami % the body of the artery runs along the

fides

SYSTEM OF CIRCULATION. 405

iides of the bladder, and then proceeds to the um-
bilicus. ^

373. The PELViAN ARTERY penetrates into
the lefler pelvis, and gives birth to eight principal
branches, or arterial bundles, which extend over
its fides, and are diftribut^d to the different organs
it contains,

ill. At the top and behind, a branch which af-
cernds on the fide, and divides itfelf into two rami ;
the firfi: proceeds on the lateral parts of the bodies
of the laft lumbar vertebrae, and is diftributed on
the praelumbo- and iliaco-trochantinian mufcles,
and enters into the rachidian canal. The fecond
afcends outwardly, and diilributes itlelf in the iliac
fofla : U'mco-mufcidar.

2d. Several branches which proceed on the fides
of the facrum, furnifh rami to that bone, and
others which proceed, through the facral holes,
into the vertebral canal : lateral facral,

3d. An artery which proceeds before, and on
the fides of the pelvis, as far as the interior fub-
pubio-trochantinian mufcle: the fuh-^ubio-femoraL
In this paflage it fends fome rami to the prae-
jumbo- and, ilio-trochantinian mufcles, pafi!es
through the fub-pubian hole, traverfing the inte-
rior (ub-pubio-trochantinian, and gives two rami,
one on the right and the other on the left, which
diftribute themfelves upwards and inwards to the
muf2les of th^ thigh.

4th, Before, an artery very large in the foetus,
203 and

400 ORGANIC STRUCTURE.

and in a great part obliterated in adults. In the
latter^ it furnifhes feme rami, which are diflributed
on the fides of the bladder, to the matrix, the va-
gina, &c.: the umViUcal.

5th. Above the latter, fome branches which
proceed to the bladder, the re6lum and the uterus.
One of thefe branches pafles between the bladder
and the .redlum, and diftributes itfelf to thefe or-
gans, to the proftate gland and the feminal veifels.
In the'female, this artery gives out a confiderable
branch which penetrates the broad ligament, runs
along the fides of the matrix, and the Fallopian
tube, proceeds to the ovarium, and anaftomofes
with the artery of that part. Another ramus is
diflributed to the vagina : the veftco-projiatic (ute-
rine and vaginal veficals).

6th. The pelvian artery, near its termination,
gives out a large branch, which diftributes itfelf to
the mufcles of the nates, fejfiere (pofierior iliac),
Thisbranch furnifhes, in the lefi^r pelvis, fome rami
totheredium, and to the facro-trochanterian muf-
cle : it then iflTues from this cavity^ pafi^ing by the
fummit of the ifchiatic notch, and foon fepafates
into feveral branches, which expand between the
great and the lefler trochanterian and the facro-
femorian mufcles.

7th. Below the preceding arifes another artery,
which gives fome rami to the re6tum, the bladder,
and the uterus. It then iffues from the pelvis
gbove the facro trochanterian mufck, towards the

lower

SYSTEM OF eiRCULATlON. 40/

lower part of the ifchiatic notch, and divides itfelf
into fcveral rami, which expand under the facro-
femorian mufcle, towards the coccyx, the tubero-
fity of the ifchium, and to the pofterior mufcles of
the thigh : the ifchiatic.

8th. In the laft place, the pelvian artery gives a
branch, which arifes generally from a trunk com-
mon to the preceding. It iflues from the pelvis,
between the pubio-flib-umbilian and the ifchio-
coccygian mufcles, advances on the interior face
of the ifchiatic tuberolity, and terminates at the
organs of generation .- the fuh-^elvian (interior
pudical).

In the pelvis, it furnifhes rami to the bladder,
and often a large ramus to the middle part of the
re6lum. On the outiide of this cavity, it gives rarhi
to the facro-trochanterian and the facro-femorian
mufcles ; it then furnifhes two branches : one of
thefc, which is fuperficial, pafles over the tube-
rolity of the ifchium, and proceeds to the fcrotum :
the perinaaJ : the other penetrates to agreater depth
between the tuberofity of the ifchium and the
canal of the urethra, and gives rami to the mufcles
of the anus and of the perinasum : ifchio-ferimeal
(tranfverfe of the perinaeum). When it reaches
the lower part of the fymphyfis of the pubis, this
branch divides itfelf into two other rami, one of
which pafles under the root of the cavernous body,
proceeds over the back of the penis, and termi-
2 D 4 nates

408 ORGANIC STRUCTURE,

nates in the fubftance of the glans : the other
lofes itfelf in the cavernous body.

In the female, the perinaeal artery lofcs itfelf in
the large labia ; and the profound one proceeds to
the clitoris : the ifehio-clitorian,

374. The crural artery arifes before the
jun6i:ion of the facrum with the hip-bone; it pro-
ceeds towards the ilium, palles under the crural
arch, defcends firll on the interior lide of the fe-
mur, and then behind that bone, and terminates at
the ham, where it feparates into two branches^
which are diftributed to the leg and to the foot.

The crural artery, in order to facilitate the de-
fcription of it, is divided into three portions: one
correfponds to the pelvis, near the iliac fofTse (the
iliac) ; another correfponds to the groin (the in-
guinal); and the third extends along the thigh (the
femoral).

The ILIAC PORTION farniflies interiorly a.
branch which proceeds on the pubis, Juh-pubum
(epigaftric), and is reiled^ed under the fides of the
abdomen, chiefly along the fierno-pubian, forming
feveral anaftomofes. It gives out a ramus, which
accompanies the tefticular cord as far as the tefli-
cles, and terminates below the flernum, anafto-
mofing with the fub-fternal.

The other artery, furnifhed by the iliac portion,
afcends interiorly as far as the anterior angle of
the ilium, turns round on the edge of that bone,

and

SYSTEM OF CIRCULATION. 4Qg

ihnd expands in feveral rami in the mufcles of the
abdomen, and in the ilio-trochantinian, producing
fome anaftomofes : circuvijiex of the Ilium (anterior
iliac).

The INGUINAL PORTION fumiihes exteriorly
fome branches, which are ramified in the inguinal
glands, the mufcles and neighbouring integu?
ments : the inguinal (tegumentous of the abdo-^
men.)

Interiorly, this portion gives out two or three
fmall branches, which are diflributed to the region
of the pubis, to the fcrotum (thefcrotalj, or to the
vulva, the vulvar (exterior pudical).

The FEMORAL PORTION givcs to the upper part
of the thigh a large branch, which penetrates be-
tween the triceps addudlor and the tri-femoro-
rotulian mufcle, and is diftributed behind the
thigh : the inter-mujcular or profound of the thigh.
This artery furnifhes, near its origin, two large
rami, one of which proceeds inwards between the
fub-pubio-femorian and the tendon of the pras-
lumbo-trochantinian mufcle, and terminates in fe-
veral ramufculi, which are diftributed to the muf-
cles of the fuperior and interior part of the thigh,
around the articulation, and to the exterior parts
of generation : the fuh-trochantinian (the interior
circumflex).

The other defcends exteriorlvj pafTcs between
the ilio-pra;tibian and the ilio-rqtulian mufcles,

and

410 ORGANIC STRUCTURE.

and divides itfelf into two rami, the firft of which
is refle6led around the articulation, and lofes itfelf
in the mufcles of the pofterior part of the thigh :
the fecond defcends before the thigh, and expands
between the ilio- and the trifemoro-rotulian : the
Jub-trochantenan (exterior circumflex).

The profound artery then defcends, and gives
out a great number of rami, which are diftributed
interiorly and pofterioily to the mufcles of the
thigh : it furnifhes alfo a ramufculus, which peme-
trates into the thigh.

The femoral artery^ after fending out the pro-
found one, defcends below the ilio-prstibian muf-
cle, furni(hing in its paflage a great number of
rami to the neighbouring mufcles : the mufcular.
Towards the lower third of the thigh, it traverfes
the tendon of the third addu6lor, proceeds to the
pofterior part of the thigh, and defcends along the
ham behind the articulation, where it afTumes the
name of the poplitean. In this fhort pafiage it
furnifhes four branches, two on each fide, the one
above the other : the poplitean articular (the fupe-
rlor and inferior articular).

Of the two fupcrior, one (the interior) afcends
within, pafTes above the interior condyle of the
femur, and diflributes itfelf to the articulation of
the knee. In this paflage, it gives rami to the neigh-
bouring mufcles, to the interior lateral ligament,
the articular capfule, and upon the rotula. The

other

SYSTEM OP CIRCULATION. 41!

other (the exterior)^ which is more profound, af-
ccnds on the exterior cond}']e of the femur, and
diilributes itfelf to the articulation, fending out
rami, which terminate, like the preceding, at the
iimilar parts of the opposite lide.

Below thefe branches, the poplitean artery pro-
<iuces feveral more rami, which proceed to the
periofteum of the femur, and behind the articular
capfule.

Of the two inferior branches furnifhed by the
poplitean, the exterior arifes below the poplito-ti-
bian mufcle, defcends on the outfide, and pafles
under the exterior lateral ligament of the articula-
tion between the femur and the tibia. It furniOies
rami to the poplito-tibian, to the tendons of the
neighbouring mufcles, and to the articulation, and
divides into two rami, one of which pafles behind
and the other before the rotula.

The interior arifes a little lower down ; it is co-
vered by the bifemoro-calcanian mufcle, defcends
under the condyle of the tibia, and terminates on
the interior fide of the articulation and on the ro-
tula, like the preceding. The four rami which
terminate on the rotula form between them an
anaftomotic circle.

The poplitean artery, when it reaches below the
condyles of the tibia, divides itfelf into two
branches. One, which is profound, traverfes fu-
periorly the inter-oileous ligament, and defcends

before

412 ORGANIC STRUCTURE.

before the leg as far as the foot : anterior ilUal.
The other defcends along the pofterior part of the
leg, as far as the fole of the (ooi -. pojierior tibial.

37^. The anterior tibial pafTes between
the tibia and the perone ; traverfcs at the top the
inter-ofieous ligament ; defcends before the leg,
between the tibio-fuper-tarfian and the common
peronaso-fuper-phalangettian inufcle of the toes^
and expands on the foot.

After having pierced the inter-oileous ligament,
this artery gives out a ramus which is refledled
before the articulation, recurrent of the knee, and
then furnifhes a great number to the anterior
mufcles of the leg. When it arrives towards the,
loner third of the tibia, it ifTues from below the
mufcles, pafles before that bone, and defcendsbelow
the annular ligament, where it gives out a ramus,
on each fide of the articulation of the foot : ths
vialUolar,

When it reaches the \.2iY^\i^, fuper'tarjian, it di-
vides itfelf into two branches, one of which pro-
ceeds outwards on the common calcaneo-fuper-
},>halangettian mufcle, and forms a curvature. The
concavity of this curvature furnifhes fome rami to
the articulation of the bones of the tarfus. From
its convexity three rami proceed^ which advance
towards the bones of the metatarfus : when they
approach the heads of thefe bones, they divide
themfelves into two ramufculi which expand on

the

SYSTEM OF CIRCULATION. 413

the fides of the toes. The other, which is larger,
Droceeds on the tarfus, as far as the os cuboides,
where it gives out a branch which pafles over the
firfl inter-ofleous mufcle, and advances towards the
anterior extremity of the firft bone of the meta-
tarfuSj where it divides itielf into two ramufculi,
which lofe themfelves on the fides of the firft and
fecond toes.

The trunk of the anterior tibial penetrates be-
tween the heads of the firfl: and fecond bone of the
Ti\&\2iXzx{x\.'^,fuper~metaiarfian, and divides itfelf into
two branches : one of thefe branches anaftomofes
with the exterior plantaris^ and concurs towards
the formation of the plantar arch : the other dil^
tributes itfelf under the great toe.

376. The posterior tibial, at its origin,
fends out a very large branch, which defcends be-
hind the perone : the •peroneal. This artery is co-
vered by the tibio-calcanian,and the peronso-fub-,
phalangettian mufcle of the great toe ; it fends out a
great number of rami, which are diftriljuted to ^he
mufcles of the poflerior and exterior part of the
leg. The peronfeal then defcends between the
extremities of the tibia and of the perone, and di-
vides itfelf into two branches, one of which pafies
under the calcanian tendon, diftributes itfelf
around the articulation, and terminates on the ex-
terior fide of the foot by feveral aaafloraofes. The

other

414 ORGANIC STRUCTURE.

other pierces the inter-offeous ligament, defcendls
before the articulation of the tibia and the perone,
and terminates in feveral rami, which proceed over
the foot, anaftomoting with the fuper-tarfian and
the exterior malleolar.

The pofl:erior tibial then defcends behind the
tibia, under the tibio-calcanian mufcle, as far as
the lower part of the leg, where it becomes fuper-
ficial.

In its paflage, it fends out a great number of ra-
mi to the mufcles of the pofterior part of the leg,
and a ramus which penetrates into the tibia : the
medullary of the tibia. When it reaches the inte-
rior fide of the calcaneum, it divides itfelf into two
branches : one of thefe branches follows the interior
edge of the foot, the interior ■plantaris ; fends out
rami to the mufcles of the great toe, and terminates
on its interior fide, anaftomofing with fuper-meta-
tarfian rami. The other, the exterior plantaris.
which is larger, penetrates between the mufcles of
the fole of the foot, to which it diflributes itfelf.
When it approaches the fifth bone of the metatar-
fus, it is refledted inwards, and forms a curvature,
the convexity of which is turned forwards. This
curvature fends out fome rami, which proceed
backwards, and diftribute themfelves in the muf~
cles, on the bones of the metatarfus. It furnifhes
three rami which afcend through the metatarfo-

inter-

«

SYSTEM OP CIRCULATION. 415

inter-phalangian mufcles. It then fends out four
larger rami, in the interval of the bones of the
metatarfus ; thefe rami, when they arrive between
the heads of thefe bones, divide into two ramuf-
culi, which expand on the fides of the toes.

All the rami which proceed on the tides of
the toes anaftomofe at their extremities.

TABLE
/

[ 41§ 1

TABLE OF THE HEART AND
ARTERIES.

S77. The blood, which returns from every part of the body, is
conveyed to the heart by two large veins, the vexa cava; these veins
pour it into a sinus, sitms of the 'vena cava, (right or pulmonary au-
ricle,) through two orifices, one at the top, the other at the bottom :
the latter is furnished with a valve, or portion of valve, in the form
of a crescent.

From this sinus the blood passes into the right or pulmonary ven-
tricle, through a circular aperture furnished with a tricuspid valve.
It issues from this ventricle by an orifice provided with a triple semi-
lunar valve (sigmoid), and proceeds into the pulmonary artery.

The pulmonary artery, which contains venous blood, divides it-
self, after a short passage, into two trunks which proceed to the two
lungs. The right trunk divides into three branches, and the left
into two, each of which is divided and subdivided indefinitely, and.
terminates in exceedingly fine ramusculi, which proceed ,on the
sides of the last bronchial cells, into which the air penetrates during
respiration. These arteriolae, it is probable, anastomose with the
veins which bring the blood from every part of the lungs.

The small veins unite to form venous rami, which produce
branches, and the union of branches forms two large trunlts for each
lung.

The four pulmonary veins contain attcrial blood j they proceed
into a sinus, sinus of the pulmonarj/ veins (left or aortic auricle),
which is smaller than the preceding, and the sides of which are
thicker.

From this sinus the blood passes into the left or aortic ventricle,
through a round aperture furnished with a two-pointed valve (val-
vula mitralis). This valve is smaller and thicker than the preced-
ing j it drives the blood into the aorta, whence it is distributed to all
the parts, by means of numerous arteries which are divided and sub-
<livided indefinitely.

Tlie aorta, on issuing from the heart, proceeds in an oblique
direction to the right; returns to the left, and forms a curvature,
which terminates at the height of the third dorsal vertebra ; it then

descends^

4

TABLE OP THE HEART AND ARTERIES. 41/

decends to the left, along the bodies of the dorsal vertebrae, passes
between the pillars of the diaphragm, penetrates into the abdomen,
and terminates at the height of the fourth lumbar vertebra, where it
divides into two branches.

THE AORTA GIVES,

At its origin.
Two arteries, -which are reflected on the heart,

NEW NAMES. OLD NAMES. "^ .

The cardiac Csroaary.

Froni each side of its curvature^
Two large trunks*, one of which is distributed to the head.

The cephalic. ..... . Primitivt carctU.

and the other to the thoracic limb.

The brachial Sub-daviar,

Along the thorax.
Several branches, which proceed

To the pericardium^

The posterior peiicardian. .... The same.

To the hroncMaf

The bronchia!. .... The same.

To the cBSophaguSf

The cKophasian. . . • . . . The same.

To the mediastinunit

Posterior mediastine. . . • . . The same.

Between the ribs.

The intercostal. . . , . . . Inferior or aortic intercostal.

In the abdomen branches which are distributed

To the abdominal face i)f the diaphragm,

Tlie sub-diaphrasmatic Inferior iiaphragmatic.

To the stomach, the liver, and the spleen.

The opiito-gastric. ...... Caliac trunk.

To the mesentery and the intestines.

Slip, and infer, mesenteric Thesame.

To the super-renal capsule.

The iDper-renal. . . . . . . Midile capsular.

* They proceed immediately from the left side; but on the rijht, the aorta, in jensraJ, furnishei
rily one tninlc, which is divided.

VOL. I. 2 E 2V

419 ORGANIC STRUCTURE,

3'o the kidneys.

vzvf SAsras.

' OLD NAMES.

The renal.

. Tht same.

To the testicle or the ovarium

The testicular.

, , The spirmatlsr

Artery of the ovarium.

To the lumbar region.

The lumbar. . i

..... The same.

.To the sacrumy

Middle tacrsl. r

• . . . • The same.

The aorta, at its termination, divides into two branches, whicl
are distributed to the pelvis and to the abdominal limb.

The pelvi-erunl. .... . . Primitive cr commsn iliac.

THE AORTA AT ITS ORIGIN FURNISHES,

L The CARDIAC arteries, one of which is inferior or right, and
the btlier superior or left.

II. The CEPHALIC TRUNK, which divides into two branches at
the height of the larynx; one of these branches is distributed to the
exterior part of the head,

The maxillo-facia!. . . . ... Exterior cantii.

The other penetrates into the interior of the craniuitr.

The anterior cerebtal. . . ... Interior carotid.

A. The MAxiLLO-FACiAL givcs eight prthcipal branches :
1st. One is distributed to the thyroid gland, to the lai7nx, and
to the OS hyoidcs,

Superior thyi'oidian ... ... The sanie.

> It furnishes the laryngian and several rami.
£d. One proceeds to the tongue and to its different muscles^

The lingual. . . . . . The same.

It gives the sub-lingual and a hyoidian ramus.
Sd. One furnished to the pharynx and the velum palati,

Inferior pharynsian. . .... the same.

It sends out the posterior meningian.

4th. One is distributed to the maxillary gland, ^to the jaws, t»
the commissurcE of the lips, and as far as the tip of the nose,

, The labial. ■ . , . , E.vJcrfsr maxiltan'.

It

TABLE OP THE HEART AND ARTERIES. 4I9

It o-ives out, the muscuh-palatine, the sub-maxillary, the tonsillar}/,
the inferior labial, the two coronary labial, and soine rami.

5th. A branch which proceeds to the occiput,

NEW NAMES. OLD NAMES.

The occipital • The same.

- It furnishes muscular and cutaneous rami.
6th. One expands behind the ear, within that organ and on the
occiput,

Poiterior auricular. ... . The same.

It gives out the stylo-mastoidian, the tympanic, some muscidar and
cutaneous rami.

7 th. One distributes itself on the sides of the head to the parotid
gland, before the ear, to the cheek, and to the integuments of the
upper part of the head,

The temporal Tfe samt.

It gives the anterior auricular, the sub-zygomatic (trSinsvevse of the
face), and the superjicial temporals.

8th. One proceeds to the meninx, to the teeth, to the muscles of
the jaw, to the cheek, to the pharynx, to the velum palati, and to
the nasal fossae,

The maxillo-buccaL . . . . ■ . Interior maxUlaryi

It gives the middle ?nenijigian, the maxiilo-dentary (inferior deo-
tary), the pterygoidian, the profound temporals, the zygomato-max-
illary (ihasseterine), the super-maxillary (buccal), the sub-orbitar,
the superior pharyngian, the palatine, and the spheno-palatine.

B. The ANTERIOR CEREBRAL penetrates into the cranium, and
at its entrance gives a branch which proceeds in the orbit, distri-
buting itself to the lacrymal gland, to the eye and to its muscles, to
the eye-lids and in the nose,

Theorbitary. .... . Ophthalmic,

Which gives the lacrymal, the sub-irian (ciliary), Me ethmoidals,
the central of the retina, the muscular, the palpebral, the frontal,
and the nasal.
The anterior cerebral is afterwards distributed in the anterior and

middle lobes of the brain :

It furnishes.

The communicitiBj, . . . . The same,

2 E 9 Which

420 ORGANIC STRUCTURE.

Which gives sotne rami to the choroid plexus, choroidian,

NEW NAMES. OLD NAMES.

The sntcrior lobai". . • - : • Artery cf the corpus callosum.

The middle lobar.

III. The BRACHIAL TRUNK, v/hich in its passage along the
thoracic liiT:b is dhnded into sub-claviar, axillarv\ and humeral.

A. The suB-CLAViA" furnishes six branches :

lst> One is distiibiited to the posterior part of the brain, to the
cerebcUuui, and to the rachidian prolongation,

The posterior cercbial. . .... The vertebral.

It ftcr'tiishes.

The occipito-meningian. .... Pcsterlor ^>entn^'-:in.

The anterior snd potteiior median of the rachis . A-nierKr an', po^terhr si :nal,

Tlici .feri.^r ^arge ceiebeilous. . . I'lferior ',f tk- ctnlnl.m.

The raeencephalic. . • . . Th' bi i'ltjry,

Thr pos'erior lobar Tiir posterior or in/ert-.r cf the cerebrum.

Thp 'tife'ior sTiail cerebeliou:. . ". . . Inferior c,,' the cerebnium.

Th= siljclior iCrcieUou:. . . . Superior cf the cerebellum.

5;d, Cne Is dj' tritutcd be^o^v the stcnum, to the thymus, to the
medi"iciiui!r., tc the d;?,phrLgm, and to the parietes of the abdoilien.

The sub-sternil. . ... Int-rl-r j.-.in.viUlcry,

It i^ives '7i7ediastiiv', siib-inaniini.la,'',', inier-costal, super-dia-
phragniaiic (superior di?-phr^.2■lr.a^ic) rnmi,

'V'^ii-^^fur.ihf! a ''hijmic and Ircnchial rnrnus.

,'' ' ~. . ; :c;.cj- .; CO he thj'roid ^Liua ^na to the muscles of the

iic- :,

Iiifeiior thyroidiaii The snme.

It furnishes the ascending cervical and several ravti,
4th. One proceeds on the sides of the neck,

The trachelo-cervical. . . . . . Puterhr profoufj c-rv:ca!.

5th. One is distributed to the muscles of the lateral parts of the
neck and of the shoulder,

Trachelo-scapular. . .... Tramversecei'vkctl.

It furnishes.

The superior scnpnLiry.

6th. One proceeds beneath the first rib, and gives some rami to
the oesophagus,

Superior inter-costa!. . . ... The same,

B. The

TABLE OP THE HEART AND ARTERIES. 421

B. The AXILLARY furnishes five principal branches :

1st. One branch is distributed to the pectoral muscles, /

NEW NAMES. OLD NAMES.

Tilt sterr.o-thoracic. . . . . . The sv^^yioi thor.ick.

2d. Another to the costo-scapulian and the inter-costian muscles,
and to the breast,

The costo-(horacic. • . . . . Thf in fir hr thoracic.

3d. One proceeds on the summit of the shoulder.

The supcr-scapularj'. . . " . . . Acrcmial.

4th. One proceeds to the muscles of the interior side of the
scapula.

Sub-scapular. . . . . . . . Common scapular.

5th. One is distributed around the articulation of the shoulder
with the arm,

The scapulo-humera!. . . . : . Anterior and^fjstirior circumpx.

C. The HUMERAL ARTEnY (brachial) furnishes three principal
branches before it divides at the bend of the arm :

1st. One branch penetrates profoundl}' into the muscles oi the
arm.

The inter-muscular or profound.

It furnishts.

The interior and exterior collateral.

2d- Ssveral rami are distributed to the muscles of the anterior
part of the arm.

Muscular of the arm.

Sd. Two rami proceed on the sides of tii? articulation of the
elbow ;

Collaterals of the articulation of the elbow.

The humeral artery, when it reaches the bead of the arm, di-
vides into two branches.

The radial and the cubitaL

A. The RADIAL furnishes four principal branches :
1st. One which is reflected towards the epicondyle.

Recurrent of the epicondyle Radial recurrent,

2d. Rami which proceed to the radial side of the fore-arm,

Ths mujcularolthefoie-arm. , , , .

2 E 3 3d. A branch

422 ORGAKIC STRUCTURE,

Sd. A branch which is distributed in the palm of the hand to the
last fingerSj and which concui-s towards the formation of the super-
ficial paimar arch,

NEW NAMES. OLD NAMES.

The radio-palmar, . . . . . The palmar raiial.

4tb. A branch which descends on the back of the hand, sends out
a ramus to its pahnar surface, and concurs towards the formation of
the profound palmar arch,

Kadio-super- palmar. ..-.-. Dorsal Radial.

B. The CUBITAL furnishes four principal branches :
1st. Two are reflected towards the epitrochlea where they are
distributed,

Eecunent of the epitrochlea. .... Anterior arid posterior cubital recurrent,

2d. Two are directed on the faces of the inter-osseous ligament.

Anterior inter-osseous.
The intcr-osscous,

I

Posterior inter-osseous.

The posterior inter-osseous furnishes a branch which is reflected
towards the olecranon,

Olecranian recurrent. ..... Posterior radial recurrent.

Sd. One is distributed to the back of the hand,

Cubito super-palmar. .... . Cubital dorsal.

4th. One proceeds in the palm of the hand to the first three fin-
gers, and forms in a great measure the superficial palmar arch,

Tlie cubiio-palmar The palmar.

THE AORTA GIVES IN THE THORAX:

I'st. A branch, which is distributed to the posterior part of the
pericardium,

Posterior pericardian.

2d. Two arteries, which proceed to the bronchiae and are rami-
fied with them in the lungs.

The bronchic. ... ... Bronchial.

Sd. Some rami, which are distributed to the cesophagus.

The teophagian The samp.

4th. Some small arteries, which expand on the posterior part of

the media^iinum,

Posterior mediastirie. ... . . The somt. ^

5th. From

TABLE OF THE HEART AND ARTERIES, 423

Slh. From nine to twelve branches, which divide between the
heads of the ribs into two rami, one of which is distributed to tiie
muscles of the back and the other to the inter-costal muscles,

Aew names.

^e inter-coscal. . . «

OLD NAMES.
• Inferior or aortic intercostal!.

THE AORTA FURNISHES IN THE ABDOMEN,

I. Two branches, which are distributed to the two sides of the ab-
dominal surface of the diaphragm, and give some rami to the super-
renal capsules and to the liver,

^ub-diaphragmatic. . . . • . Inferior diaphragmatic.

II. A large trunk situated beneath the stomach,

THE OFISTRO-GASTRIC Cdliac.

Which divides into three branches i
1st. One is distributed to the stomach.

The gastric. - . . - Stomachic cormtrj.

It furnishes sometimes

The left lobar of the li-!er. . . . Li/t gastro-hepatic

2d. The other proceeds to the liver.

The hepatic.

It gives rami .

To the pyloruSt

The jastro-pyloric . . . , Pyloric.

To the pancreas and the duodenum^

The pdncrtatico-dmdenal.

To the stomach and the epiploon,

Rijht gastro-epiploic Jhe same.

To the gall bladder ,

The cystic,

3d. The last proceeds to the spleen.

The splenic. ..... The same.

And gives branches

To the pancreas.

The spleno-pancreatic.

To the stomach.

The sf Icna-eaiiric . -» <> » . < Short vaiclH

,424 OJKJANIC STRUCTUHE.

To the left side of the great epiploon,

KEW NAMES. OJ.D i'AMES.

LcfE saicro-epiplcic.

III. A large branch, v^^hich is distributed to the mesentery of the
^mall intestines, to these intestines and to the coecum.

The superior mesenteric. . . , , The same.

It gives rami

To the pancreas,

'Ihe pancreatic.

To the duodenum.

The duodenal.

To tht nieso-colon,

The meso-colic.

To the right colon.

The right colic.

To the coecum, the ilium, and the colon.

The ilip-colic.

^ To the co?cum.

The cffical.

IV. A branch, which arises near the bifurcation of the aorta, and
is distributed to the mesentery and the large intestines,

The inferior meienteric. . . . . The sam -.

It furnishes,

The left great colic. . . . . ) Superhr left colic.

2, Mi We left cUic.

The small left eolic f

Ai tery of rlic rectum. . . . . . ^mfi^'O'-m colic.

V. Two branches, which are distributed to the super-renal cap-
sules and to the cellular tissue of the kidney.

The super-renal. . . , Middle capsular.

VI. Two large branches, which proceed to the kidneys.

The renal. t jlie same.

They furnish super-renal, adipose, and ureteric rami,

VII. Two small arteries, which proceed to the testicles or to the
ovarium.

The testicular. . . , . Thssftymatlc.

Ai tery oi the ovarium.

VIII. Four

' TABLE 'OP THE HEART AND ARTERIES. 425

VIII. Four or five arteries, -which are distributed to the muscles
of the loins and to the parietes of the abdomen,

NEW NAMES. OLD NAMES.

The lumbar !« ■same.

IX. An odd branch, which arises betwiftn the two divisions of the
aorta and descends on the sacrum.

The middle sacral.

THE AORTA AT ITS TERMINATION DIVIDES INTO TVl'O
TRUNKS:

THE TELVI-CRURAL.

. The primitivi iliac.

The pelvi-crural artery, which arises at the height of the fourth
lumbar vetebra, descends outwardly, and after a short passage di-
vides into two branches 3 one of which is distributed in the pelvis.

THE PELVIAN.

. Interior or hypogastric iliac.

The other issues from the pelvis through the crural arch, and de-
scends along the thigh,

TIIE CRURAL The same.

A. The PELVIAN divides into eight principal branches or ar-
terial bundles :

1st. A branch is distributed in the muscules of the iliac fossa.

The iliaco-musailar Ilio-lumhar.

2d. Several proceed on the sides of the sacrum,

The lateral sacral Tiic same.

3d. One issues from the pelvis through the sub-pubian holf, and
is distributed to the three adductors.

The iub-pubio-femoral. ..... O^Jturr.trix.

4th. Another, considerable in the foetus and almost obliterated in
adults, is distributed to the bladder, to the utei us, and to the vulvo-
uterine eonduit.

The umbilical. . - The santf.

5th. One proceeds to the bladder, to the prostate gland, ^ to thd
rectum, to the uterus, and to the vaginal conduit.

The vesico-pvostatic.

Vter'ine and vaginal vesical.

6th. Brancli

426 ORGANIC STRUCTURE^ "

6th. Branches which proceed to the muscles of the nates,

NEW NAMES. OLD NAMES.

The fessieres - • ^ posterior iliac,

7th. A branch passes under the sacro-feniorlan muscle, acconi"
panics the sciatic nerve, and loses itself in the muscles of tfae pos-
terior part of the thigh,

- The ischiatit:>

Sth. The last is distributed to the organs of generation,

Ilie sub-pelviin^ ..... The interior puiicaL

The latter furnisheSj

the perineal, . ... ... Transverse of the perinautn.

The ischio-penian Dorsal oftheyari.

Theischio-clicorian. . . ... Artery oj tht clitoris .

B. The CRURAL divides into three portions: the iliac, inguinal,
and femoral.

I. The ILIAC PORTION furnishes two branches, one of which is-
reflected on the sides of the abdomen, and loses itself in the
muscles.

The supcr-pubian. . ^ - ^ . Spgajtriic^

The other follows the direction of the ridge of the ilium, and loses
itself in the muscles of the abdomen, ,

circumflex of the ilium. Anteritr iliac.

II. The INGUINAL PORTION fumishes branches, which are ra-
mified to the glands of the groin and to the neighbouring cellular

tissue.

The inguinal. . Tegumentous of the abdomen.

And some branches, which proceed to the scrotum or to the

vulva.

The scrotal. ...

The vulvar.

.1

Exterior fuiical.

III. The FEMORAL PORTION gives:

lEt. A large branch, which is distributed profoundly in the mus-
cles of the thigh,

Ifitcr-muEcalar or profound. . ■ • . Prof lund artery.

The

TABLE OF THE HEART AND ARTERIES. 427

The latter , furnishes from its upper part two branches, one of
•which proceeds inwards and turns round on the articulation of the
femur, '

KEWNAMESf. OLB NAMES.

Sub-lrochantinian._. . . - . . Inttrhr circumfia:

The other loses itself on the exterior side of the articulation,

Sub-trochantinian. ..... Exterior circumflex.

2d. Branches along the thigh.

The muscular.

3d. Four branches, two on each side, and one above the other,
■which are distributed to the articulation of the knee.

Popliteal articular, . , , . . . Superior and inferior articular.

The femoral, when it reaches the ham, divides itself into tvvo
branches :

The anterior and posterior tibial.

a. The anterior tibial divides itself into four branches ;

1st. One small one is reflected towards the knee,

'Recurrent of the knee.

9d. Two proceed towards the sides of the articulation of the
foot.

The malleolar. . . . .

Sd. A branch is directed on the tarsus, and distributes itself to
the muscles and bones of that part,

The super-tarsian. .... Arttry of the tarsus.

4th. The last forms a curvature on the convexity of the foot,

The auper-metatarsian. .... Artery of the metatarsus.

I. The POSTERIOR TIBIAL gives first two branches:
1st. One descends behind the perone, and is distributed io the
muscles of the posterior part of the leg.

The peroneal. . ... thtferoneal.

9d. The other, which is very small, pcnenetrates into the
medullary canal of the tibia through its nourishing foramen,

Mrd'illiry of tli« tibia, . , » ^'ckriihlnt ^tficsiiia.

o At

428 ORGANIC STRUCTURE,

At the lower part of the leg the posterior tibial divides itself into
two branches :

1st. One follows the interior edge of the foot and terminates on
the great toe,

NEW NAMES. OLD NAMES.

Interior plantar. .... The same.

The other penetrates below the sole of the foot and forms the
plantar arch, from which rami proceed to the muscles of the sole
of the foot and to the toes,

txteiior plantar. . ... The same.

END OP THE FIRST VOLUME,

W.i;ks and Taylor, Vsmtea, Chaatet^-Lar.e.

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