PHARYNX. 
part of the pharynx its free surface presents 
numerous slight elevations occasioned by the 
glands which are situated beneath it; these in- 
deed are scattered over the whole pharynx, but 
are especially abundant at its upper part, where 
they form a compact lamina between its mus- 
culo-membranous tunic and the mucous mem- 
brane, opening upon the surface of the latter 
by slender ducts. 
5. Vessels and nerves. —The bloodvessels 
distributed to the pharynx are derived from 
several sources, but chiefly from an especial 
trunk, viz. the ascending or inferior pharyngeal 
artery ; this vessel arises from the posterior part 
of the external carotid, often its first branch, 
near the bifurcation of the common carotid ; it 
ascends to the base of the skull, lying close by 
the side of the pharynx and upon the rectus 
capitis anticus major muscle, sending off nu- 
merous small branches, which, intermingling 
with the pharyngeal plexus of nerves, are dis- 
tributed to the constrictors and stylo-pharyn- 
geus, to the velum, arches of the palate and 
tonsil, ending in minute ramifications on the 
mucous membrane ; the next most regular sup- 
ply is from the inferior palatine and tonsillitic 
ranches of the facial artery ; the internal max- 
illary, lingual and superior thyroid vessels con- 
tribute an irregular supply of small and unim- 
portant twigs. The veins form a considerable 
plexus, the pharyngeal venous plexus, which is 
produced chiefly by the frequent anastomoses 
of the pharyngeal vein with the small branches 
that accompany the inferior palatine and tonsil- 
litic arteries, and with some of the commencing 
twigs of the internal maxillary vein; the pha- 
ryngeal vein, which receives the blood from 
this plexus, opens, either singly or in conjunc- 
tion with the lingual, into the internal jugular 
vein ; of the lymphatics, but little is known; 
they probably enter the chain of glands which 
Jie along the outer side of the carotid sheath. 
An intricate plexus of nerves, the pharyngeal 
plexus, is situated upon the sides of the pha- 
rynx, the branches being particularly numerous 
upon the middle constrictor muscle near its 
origin; it is of some length, and subject to 
variety in the number of its filaments in diffe- 
rent subjects ; it interlaces with the ramifica- 
tions of the arterial twigs from the ascending 
pharyngeal, and derives its branches from the 
three portions of the eighth pair of nerves and 
from the superior cervical ganglion of the sym- 
pathetic; the glosso-pharyngeal nerve sends 
downwards two or more branches to the plexus; 
one of these I have seen to join the superior 
laryngeal nerve ; they are given off just before 
the nerve winds round the lower border of the 
stylo-pharyngeus muscle; subsequently one or 
two branches penetrate this muscle to be distri- 
buted to the pharyngeal mucous membrane ; 
the pneumo-gastric detaches one or two pharyn- 
geal branches; the larger one appears in a great 
measure formed by a branch from the spinal 
accessory nerve ; these join with the filaments 
from the glosso-pharyngeal ; the superior laryn- 
geal nerve by its external branch also contri- 
butes a few filaments ; lastly, from the superior: 
cervical ganglion of the sympathetic, twigs are 
949 
> 
derived, which, communicating with those 
already mentioned, complete this intricate 
plexus ; the branches from it are distributed to 
the pharyngeal walls, to the soft palate, and 
stylo-pharyngeus muscles. The digastric branch 
of the facial nerve and the lingual or its de- 
scending branch are described as sometimes 
communicating with this plexus: for the more 
minute anatomy of these nerves see Par 
Vacum, Gtosso-PHARYNGEAL NERVE, AND 
Sprnat Accessory. 
Mouth, (Gr. croua; Lat. os; Fr. bouche.)\— 
The mouth is an oval cavity, symmetrical, and 
situated at the lower part of the face, below 
the nasal fossee, between the jaws, and in front 
of the pharynx, with which it communicates by 
a posterior opening, called the isthmus fau- 
cium, and has also a dilatable aperture ante- 
riorly guarded by the lips: it is liable to con- 
siderable alterations of form and size, from 
complete closure to a state of extreme exten-. 
sion, when it represents a quadrangular py- 
ramid with the base in front: the greatest 
change occurs in its vertical diameter from the 
movements of the lower jaw; in it are per- 
formed the various functions of mastication, 
tasting, partly that of deglutition, and it is 
subservient also to the production of articulate 
sounds. The mouth or buccal cavity is bounded 
both laterally and anteriorly by the alveolar 
borders of the upper and lower maxillary bones 
and teeth, the lips completing the boundary 
in front and the cheeks laterally: above it is 
roofed in by the arched palate and more pos- 
teriorly by the velum palati; inferiorly the 
tongue forms its floor. In the examination of 
these boundaries the reader is referred to the 
articles Face and Trers for the description 
of the maxillary bones and teeth. 
The lips (labia) are two moveable curtains 
placed in front of the mouth, presenting be- 
tween them when applied to each other a 
transverse slit convertible by their separation 
into a more or less considerable opening, which 
constitutes the anterior aperture of the buccal 
cavity : the lips are united at the lateral limits 
of this fissure to form the commissures or 
angles; the anterior surface of the upper lip, 
which usually projects a little beyond the lower, 
is covered with hair in the adult male, and 
exhibits in the median line a vertical groove 
continued to its free border from the septum 
of the nose: two ridges bound this furrow on 
either side, and from thence the upper lip 
passes off laterally to the cheek, insensibly in 
the young and plump face, but otherwise a 
line of demarcation is produced by an oblique 
fold of the skin which descends from the side 
of the nose to near the commissure of the lips 
on either side of the face: the anterior surface 
of the lower lip descends more or less abruptly 
backwards to the chin, divided from it by a 
transverse groove: it is covered with hair usu- 
ally at the centre only, and slightly bulging 
near its free border shelves off gradually to the 
sides of the face: the free borders are the 
thickest parts of the lips, their large develope- 
ment forming a characteristic feature in the 
Negro; in their outline they differ, presenting 
