950 
in the u lip a projection in the centre, from 
which . meted gently arching upwards, 
proceeds laterally, while, in the lower, the 
centre exhibits a depression, and the line from 
it proceeds in a contrary direction, so that 
when the mouth is closed these borders are 
pot pen evenly to each other: they are of a 
colour, turned outwardly, and marked 
from before backwards by slight wrinkles pro- 
duced by the contraction of the orbicular 
muscle; their chief interest to the anatomist 
is in showing the continuity of the skin with 
mucous membrane. Besides the tegu- 
Mentary coverings of skin and mucous mem- 
brane, these organs contain within their thick- 
ness the orbicularis muscle, with which are 
blended the insertions of the greater number 
of the muscles of the face (see Face), whose 
varied actions render these features so pecu- 
liarly expressive of the passions: numerous 
glands, vessels, and nerves, and an areolar 
tissue complete their structure. The labial 
glands constitute a thick lamina between the 
muscular and mucous layers, producing slight 
elevations upon the surface of the latter; they 
resemble the salivary glands in appearance, 
are of small but varying size, placed close to 
each other but perfectly distinct, each posses- 
sing a separate excretory duct, which opens 
upon the free surface of the mucous mem- 
brane. The lips are most abundantly supplied 
with vessels and nerves; the coronary arteries, 
from the facial, course along their free borders 
directly beneath the mucous membrane; they 
also receive numerous twigs from the buccal, 
infra-orbital, and mental branches of the in- 
ternal maxillary and submental branch of the 
facial ; the veins accompany the arterial branches; 
the lymphatics terminate in the glands at the 
base of the jaw, as evidenced by the frequent 
enlargement of the latter from the irritation of 
cancerous or other sores about the lips: the 
nerves are derived from the portio dura and 
fifth pair. 
Use_The lips are of great importance, more 
particularly the lower, in retaining the saliva 
within the cavity of the mouth, and are actively 
engaged in the acts of sucking and blowing ; 
the utterance of many articulate sounds de- 
pends chiefly upon their action, and when 
viewed as organs of expression they are parti- 
cularly adapted by their extreme mobility to 
indicate the passing thought. 
The cheeks (bucce) form the lateral exten- 
sible walls of the buccal cavity; examined 
from the interior of the mouth they will be 
found limited above and below by the reflexion 
of their investing mucous membrane upon the 
external surfaces of the superior and inferior 
maxillary bones: their superficial surface is 
bounded behind by the external ear and the 
posterior border of the lower jaw, below by 
the horizontal ramus of the same bone ; supe- 
riorly they may be arbitrarily separated from 
the temple by the zygoma, and from the orbit 
by the lower margin of its cavity, and are con- 
tinued anteriorly into the sides of the nose and 
lips; they therefore present somewhat of a 
quadrilateral outline, and in the young and 
PHARYNX. 
but in the emaciated 
mouth. The skin of the cheek is smooth, thin, 
and delicate in front and above, and remark- 
able for its extreme vascularity, as seen in the 
act of blushing; it is covered behind and 
below in the adult male with hair, and in the 
aged its surface is more or less furrowed with 
wrinkles: the subcutaneous cellular tissue is 
dense and loaded with a variable yer 4 
fat, a particularly abundant mass of which is 
lodged between the buccinator and masseter 
muscles. The muscular structure of the cheeks 
has been already described in the article Facer. 
Between the muscles and mucous membrane — 
are irregularly dispersed a considerable num- — 
ber of buccal glands; they are of small size, 
similar to those of the lips, and like them open 
upon the mucous surface by separate duets: 
these openings are not likely to be mistaken 
for that of the parotid duct, which is marked — 
by a very distinct prominence, is of larger size” 
and situated opposite the interval between the 
second and ‘hed stan teeth in the upper jaw: 
there is an aggregation of several of these 
buccal glands, imbedded in the fat between 
the buccinator and masseter muscles, form-— 
ing a larger glandular mass which opens into 
the mouth opposite the last molar tooth, and 
has been called the molar gland. The cheeks 
receive a rich supply of vessels from the facial, 
transverse facial, and internal maxillary arteries; 
the veins correspond to these branches am 
empty themselves into the internal and external 
jugular veins. The lymphatics probably ter- 
minate in the glands of the neck. As wit 
other parts of the face, the cheeks derive the 
nervous filaments from the portio dura am 
fifth pair. “ff 
Use.—While the tongue guides the fooc 
outwardly to the teeth, the cheeks act int 
taining it between them during mastication 
they are employed during the act of sucking 
and when distended by air or fluids they ate” 
actively engaged in forcibly expelling them, 
exemplified in playing upon wind instrume! 
or in squirting liquids from the mouth. 
The palatine arch and gums.—The palat 
arch or hard palate forms the greater part 
the superior boundary of the buceal cay 
it has a parabolic figure, bounded laterally ¢ 
in front by the teeth, and is continued pos 
riorly into the velum palati without exhibit 
any line of demarcation; it presents mesia 
a whitish ridge, more prominent before 
behind, which commences from a small € 
nence situated immediately behind the ine 
teeth and corresponding with the lower ori! 
of the anterior palatine canal; the ridge #l 
extends backwards and is traceable as fa 
the uvula; from it are passing laterally a ¥ 
able number of transverse rugee, apparent 0} 
at the anterior part of the palate, its buc 
surface being, in the greater part of its exte 
rfectly smooth. The palatine arch is frame 
y the palate processes of the superior maxih 
lary and palate bones,* and invested on ' 
" * 
*\) oa 
healthy form a rounded Fars eee 
in towards 
‘ 
aa 
en 
* See FACE. 
