6o 4 A N A 1 
lungs in expiration through the trachea into the larynx, 
and through the glottis into the mouth, it produces voice, 
fpeech, and tinging. The ftrength of the voice is propor¬ 
tional to the quantity of air blown out, together with the 
narrownefs of the glottis; and, therefore, a large pair of 
lungs eafily dilatable, an ample cartilaginous and elaftic 
larynx and wind-pipe, a free echo of the noftrils, and a 
powerful expiration, all conduce to this effeft. Singing 
is when the voice, modulated through various degrees of 
acutenefs and gravity, is expelled through the larynx, 
while it is trembling and fufpended between two contrary 
powers; and herein lies the principal difference between 
the chanting of fimple notes and the exprcffion of words. 
Speech is performed by the larynx at red, or held in the 
fame place, with tones of voice differing but little in acute¬ 
nefs and gravity; but then the voice is varioufly changed 
or modulated by the organs of tire mouth. Singing has a 
Variation in the tone or cadence of the voice, together 
with a modulation of it by the organs of the mouth at the 
lame time. 
The pharynx is a mufcular and glandular bag; the 
outer furface of which is clofely joined to tire inner fur- 
face of all the fpace which is at the bottom of the mouth, 
behind the pofterior nares, uvula, and larynx, and which 
reaches from the cuneiform procefs of the os occipitis all 
the way to the cefophagus, which is a continuation of 
the pharynx. 
The falival glands furnifh that fluid by which the mouth 
and tongue are continually moidened in their natural date; 
and they may be enumerated in the following manner : 
glandulae parotides, glandulae maxillares, glandulae fub- 
linguales, glandulae molares, planduhe buccales, glandu¬ 
le labiales, glandule lingualcs, amygdalae, glandule pa¬ 
latine, glandule uvulares, glandule arytenoidea, glan¬ 
dule thyroidea. All the intide of tire cheeks, near the 
mouth, is entirely full of fmall glandulous bodies, called 
glandules hucca/cs, which open by final 1 holes or orifices 
through the inner membrane of the mouth. The mem¬ 
brane which covers the inlide of the lips, which is a con¬ 
tinuation of that on the cheeks, is likewife.perforated by 
a great number of fmall holes, which anfwer to tire fame 
number of fmall glands, called glandulos labiales. We 
might likewife reckon among the falival glands thofe of 
the fuperior portion of the pharynx, and alfo the follicles 
of the membrana pituitaria of tire nares, and of the linufes 
■which communicate with them. 
Such hard and tough foods as confid of long parallel 
fibres, or are covered with a bony (hell or cartilaginous 
{kin, generally require madication to divide them into lefs 
cohering parts, that they may more eafily yield their nou- 
rifhment to the diffolving powers of the domach. The 
more diligently they are fubdivided in the mouth, the more 
relifhing and agreeable they become to the domach; and 
the nearer they approach to the nature of a fluid, the more 
eafily are they digefled or aflimilated. Mod animals, there¬ 
fore, are provided with teetli extremely hard ; and, as the 
materials of our food are various in their texture and firm- 
liefs, nature has accordingly furniftted us with teeth va- 
rioufly figured. The office of the incifores is only, in the 
fofter foods, to cut thofe which are tougher than the red 
into fmaller portions; fuch as the fibres and membranes of 
animals and vegetables, with the brittle feeds and kernels 
of fruits. The canine teeth lacerate tough aliments, and 
hold fad fuch as require long trituration by the grinders. 
By the motion of the jaw in madication, the falival glands 
are comprefled, fo as to diicharge their juices into the 
mouth in great plenty ; and the food being ground be¬ 
tween the teeth, and intermixed with the watery faliva 
and air, is broken down into a foft juicy pulp, replete with 
.eladic air; the food afterwards undergoes a farther diffo- 
lution from the warmth of the parts caufing the air to ex¬ 
pand, and, by its eladicity, bin d afunder the particles of 
the food, between which it is included and confined. In 
this aft of madication, the oily, aqueous, and faline, parts 
.of the food are intermixed the one with the other; the 
O M Y. 
fmell and tade of different ingredients are loft in one, 
which, by the dilution of the faline parts with faliva, ren¬ 
ders the food flavourable ; but fuch particles as are more 
volatile and penetrating, being direftly abforbed by the 
bibulous veffels of the tongue and cheeks, enter draight 
into the blood-vdfels and nerves, fo as to caufe an imme¬ 
diate recruit of the whole faculties. 
OF THE THORAX. 
By the thorax vve commonly underdand all that part of 
the body which anfwers to the extent of the herrtum, ribs, 
and vertebrae of the back, both outwardly and inwardly. 
It is divided into the anterior part, called commonly the 
breajl ; the poderior part, called the bac/t ; and the lateral 
parts, called the right and left fidcs. The external parts of 
the thorax, befides the Ikin and membrana adipofa, are 
principally the mamma;; and the mufcles which cover the 
ribs, and fill the (paces between them. The internal parrs 
are contained in tire large cavity of that portion of the trunk 
which the ancients called the middle venter, but the moderns 
name it limply the cavity of the breajl. This cavity is lined 
by a membrane named pleura, which forms the mediafti- 
num ; and contains the heart and lungs, with the veffels, 
&c. which go in or from them: through it, likewife, the 
cefophagus paffes to tire ffomach ; and part of the nerves 
are contained in it which go the contents of the abdomen. 
The name of mamnice, or breafs, is given to two emi¬ 
nences, more or lefs round, iituated in the anterior, and a 
little towards tire lateral parts of tire thorax. Their fize 
and figure vary in the different fexes and different ages. 
The body of the mamma is partly glandular, and partly 
confiffs of fat ; or it is a gland of the conglomerate kind, 
furrounded on all fides with cellular fubftance and fat. 
The glandular part is divided into little maffes, feparated 
alfo by fat, and again fubdivided into fmall granulae, from 
which the laftiferous dufts arife. The cellulous pelli- 
culae fupport a great many blood-veflels, lymphatics, and 
ferous or laftiferous dufts, together with fmall glandular 
moleculse. 
The areola, or coloured circle or difk round the papilla 
or nipple, is formed by the fkin ; the inner furface of 
which fuftains a great number of fmall glandular moleculae, 
of that kind which Morgagni calls glandulaeJcbacece. Tlicfe 
tubercles are perforated by fmall holes, through which a 
kind of febaceous matter, more or lefs liquid, is poured 
out, to defend the areola and nipple. The texture of the 
nipple is fpongy, elaftic, and liable to divers changes of 
conliftence, being fometimes harder, fometimes more flac¬ 
cid. It feems to confift chiefly of ligamentary fafciculi, 
gently folded, or curled ; among which, thofe near the 
circumference of the nipple feem to have a tranfverfe or 
annular difpofition, which, however, is not uniform. This 
difpofition or direftion feems to be owing to the elaffic 
folds; and, from this fimple ffrufture, it is eafy to explain 
how infants, in fucking, and women in drawing the teats 
of cows, bring out the milk. For the excretory tubes, 
being wrinkled in the fame manner as the fafciculi, do, by 
thefe wrinkles or folds, as by fo many valves, hinder the 
milk contained in the dufts from flowing out; but, when 
the nipple is drawn and elongated, the tubes lofe their 
folds, and the paffage becomes ftraight. Thofe who un¬ 
derhand the principles of the air-pump, will more readily 
conceive the manner in which the child draws out the milk. 
The pleura is a membrane which adheres to the inner fur¬ 
face of the ribs, fternum, and convex fide of the diaphragm. 
It is of a very firm texture, and is fupplied with blood-vef¬ 
fels and nerves, in all which it relembles the peritonaeum. 
Each fide of the thorax has its particular pleura, entirely 
diftinft from the other, and making, 'as it were, two great 
bladders, fituated laterally with refpeft to each other in the 
great cavity of the bread, in fuch a manner as to form a 
double feptum or partition, running between the vertebrae 
and the fternum. This particular duplicature is termed 
m diaflinum ; the two laminae .of which are clofely united 
together; but, in the middle, and towards the lower part 
