5 2.8 ,A N A T 
but the moderns name it limply the cavity of the breaf. 
The cavity is lined by a membrane named pleura, and di¬ 
vided into two lateral cavities by a membranous feptum 
rained mediajlinwn, which is a production or duplicature 
of the pleura. Thefe parts are the heart, pericardium, 
trunk of the aorta, beginning of the carotid and fubcla- 
vian arteries, the fuperior portion of the defcending aorta, 
the intercoftal arteries, the vena cava fuperior, vena azy¬ 
gos, termination of the fubclavian veins, a portion of the 
afpera arteria, and of the oefophagus; the duCtus ladle us 
or thoracicus, the lungs, pulmonary artery, pulmonary 
veins, &c. The cavity of the thorax is terminated down¬ 
ward by the diaphragm, which parts it from the abdoingn. 
The abdomen begins immediately under the thorax, and 
terminates at the bottom of thd pelvis of the ofla innomi- 
nata. Its circumference or outer furface is divided into 
regions; of which there are three anterior, viz. the epi¬ 
gastric or fuperior region, the umbilical or middle region, 
and the hypogaftric or lower region. There is but one 
pofterior .region, named regio lumbar is. The epigajlric re¬ 
gion begins immediately under the appendix enliformis at 
a fmall fuperficial depreftion called the pit of the fomach, 
and in adult fubjeCts ends above the navel at a tranfverfe 
line’fuppofed to be drawn between the laft falfe ribs on 
each fide. This region is iub-divided into three parts, 
epigajlrium, already named; and two lateral regions, term¬ 
ed hypochondria. The epigaftrium takes in all that fpace 
which lies between the falfe ribs of both fides, and the 
hypochondria are the places covered by the falfe ribs. The 
•umbilical region begins in adults above the navel, at the 
tranfverfe line already mentioned; and ends below the na¬ 
vel at another tranfverfe line, fuppofed to be drawn paral¬ 
lel to the former, between the two criftas of the ofTa ilium. 
This region is likewife divided into three parts; one mid¬ 
dle, which is properly the regio umbilicalis; and two la¬ 
teral, called ilia or the fan/is-, and they comprehend the 
fpace between the falle ribs and upper part of the os ilium 
on each fide. The hypogajlric region is extended down¬ 
ward from the inferior limit of the umbilical region, and 
is divided into three parts ; one middle, called pubis ; and 
two lateral, called inguina or the groins. The lumbar re¬ 
gion is the pofterior part of the abdomen, and comprehends 
all that fpace which reaches from the lowed: ribs on each 
fide, and the lad vertebra of the back, to the os facrum 
and neighbouring parts of the olfa ilium. The lateral 
parts of this region are termed the lows, but the middle 
part has no proper name in men. Ladly, the bottom of 
the abdomen, which anfwers to the pelvis of the Ikeleton, 
is terminated anteriorly by the pudenda or parts of gene¬ 
ration; and poderiorly by the chines or buttocks, and 
anus. The buttocks are feparated by a folfa, which leads 
to-the anus, and each buttock is terminated downward by 
a large fold which didinguifhes it from the red of tire 
thigh. The fpace between the anus and parts of genera¬ 
tion is called perinatum ; and is divided into two equal la¬ 
teral parts by a very diftinct line, which is longer in males 
than in females. The cavity of the abdomen, formed by 
the parts already mentioned, and covered by the fkin and 
membrana adipofa, is lined on the infide by a particular 
membrane, called peritonceum. It is feparated from the ca¬ 
vity of the thorax by tire diaphragm, and terminated be¬ 
low by the .mufeuli levatores ani. This cavity contains 
the domach and,the intedin.es; which are commonly di¬ 
vided into three fmall portions, named duodenum, jejunum, 
and ileum ; aiid three large, called ccecum, colon, and reftum. 
It contains likewife the mefentery, mefocolon, omentum, 
liver, gall-bladder, fplpen, pancreas, glands of the mefen¬ 
tery, vafa laCtea, receptaculum chyli, kidneys, renal glands, 
ureters, bladder, and the internal parts of generation in 
both fexes. 
T,he whole arm is divided, as in tire Ikeleton, into the 
fhoulder, the arm properly fo called, the fore-arm, and 
the hand. To thefe we muft add the fhoulder, the axilla 
or arm-pit, the elbow, tiie fold of the arm, and the hollow 
of the hand. What is called the fhoulder, is formed by 
0 M Y. 
the flefliy belly of the rrinfculus deltoides; and the axilla 
by the correfponding edges of the pectoralis major and 
latiflimus dorfi. The elbow anfwers to the olecranum ;' 
the fold of the arm is on the fore-fide of the articulation 
of the os humeri, with the bonqs of the fore-arm, and’ 
the hollow of the hand is in the middle of the palm. 
The lower extremities of the whole body are divided in¬ 
to the thigh, leg, and foot. The thigh begins anteriorly 
on one fide of the fold of the groin ; and pofteriorly, a lit¬ 
tle above the lower half of the buttock. It terminated' 
anteriorly at the patella on the knee, and pofteriorly at the 
poples or ham. It is formed chiefly by the mufcles which 
furround the os feinoris. The leg has but very few muf¬ 
cles on the fore-part, but a great many large .ones behind ; 
where the ga ft roc no mi i and foleus form a kind of'belly, 
called the calf of the leg. The leg begins anteriorly at the 
knee below the patella, and pofteriorly at the poples ; and 
it terminates below at the ancles. The convex part of the 
foot, near its articulation with the leg, is termed the neck of 
the foot ; and the under part, which is the bafts of the 
whole lower extremity, the foie of the foot. The flefliy 
parts are more confiderable on the foot than on the hand. 
Thus the human fyftem is made up of a variety of parts 
formed of matter apparently under very different kinds of 
modification ; and thefe conftitute a whole, the different 
parts of which are fufceptible of various degrees of iin- 
preffions from powers, to tiie aCtion of which they are 
fubjeCted. This entirely arifes from the mode of their 
organization. The bones, from the nature of their fabric, 
are perhaps lefs fufceptible of the action of powers applied 
to them, than any other part of the fyftem ; they appear 
defigned to form the bafts of the body ; they fupport the. 
foft parts ; they defend and contain the more delicate and 
noble organs. Though liable to difeafe, they are not fub- 
jeCt to injury like the other parts ; and even after death, 
that rapid and fpontaneous decompofition does not take 
place in them which we perceive in the reft of the fyftem. 
They may be expofed for ages, without lofing their ori¬ 
ginal form; and they feem to bear a confiderable analogy 
to inorganifed matter. 
Anatomical refearch, however, fully proves, that bone 
is as truly organifed matter as any other part of the 
body. This indeed is a conclulion which we might have 
drawn a priori, from the confideration, that inorganifed 
matter could not pofiibly form a part of an animated fyf¬ 
tem. The anatomift proves the truth of the affertion. 
He fhews that the bones are fupplied with blood-vefl'els, 
as well as the flefliy parts. He exhibits their ftruCfcure, 
and points out their periods of growth and decay, which 
can only be effected by the action of depoftting and ab- 
forbing veflels ; and in fiiort, fully proves, that they are 
as truly organifed matter as the reft of the body. But 
their organifation is fo conftituted, as tp be exaftly fitted 
for the purpofe they are deftined to ferve. In fad, we 
obferve, that bones are formed of a fyftem of veflels, ia- 
the infterftices of which, a feemingly earthy matter, mixed 
with mucus, is depofited. This earthy matter, which 
gives hardnefs and ftrength to the bones, is in reality in¬ 
organifed and dead matter, a true phofphate of lime, 
liable to no alteration when feparated from the body, ex¬ 
cepting by the operation of the laws of chemical attraction. 
The bones are alfo fupplied with nerves. They may be 
obferved, in fmall threads, entering into the fubftance of 
the bones. Small nerves may alfo be feen entering into 
each bone, along with its nutritious veflels; and in fome 
cafes we obferve them palling through large holes in bones, 
as the nerves which go into the jaws to fupply the teeth. 
But, notwithftanding that anatomifts can demonftrate the 
exiftence of nerves in the bones, yet the fact has been 
doubted, becaufe the bones feem infenfible to pain. It 
is true, tiie periofteum may be feraped from a bone, a 
bone may be cut through, as in amputation, or in tiie 
operation of trepanning, or cauftics may be applied to 
bone; and the patient, in all thefe. cafes, fcarcely feels 
pain. It mu ft, however, be admitted, that bone, even in 
