x 
: ei 
dy‘e, and iato the articular cartilage of the jaw. It is cover- 
ed externally by the temporal mufcle, and internal max: lary 
artery ; internally by the oe ain and the in- 
ferior maxillary nerve, ard above by the zygomatic foffa. 
The right and left mufcles ating in conjunction will carry 
the two Satie direatly forwards under the articular emi- 
mnence. Ifthe right fhould a& feparately, it will carry for- 
wards the condyle of its own fide, and thereby move the 
chin towards the oppofite fite, and vice oe It always 
acts upon the cartilage, as well as upon the condyle. 
Digaftricus or biwenter maxille inferioris (conti oracuillien) 
is placed at the fide of the upper part of the neck 5 poflrfles 
au elongated form; and gonfifts, as its names imply, of two 
portions of mufele joi ined > am‘ddletendon, Itar.fis by a 
mixtureof tendinous and flethy fibres from the groove within 
the maftoid procefs, and geen obliquely forwards and in- 
wards. This 18, which is called the pofteror beily of the 
mufcle, grows at firlt a duaily thicker i i 
again decreafes, and is contracted into a roundifh tad es 
chord, which paffes through the fibres of the fty'o-hyoideus, 
or behind that mufcle, and running about half an inch above 
the os hyoides, 1s conneéted to that bone by a thin aponeu- 
rotic expanfion. Afterwards it is reficcted upwards and 
forwards at an obtufe angie, and {preads out into the antenor 
fAi:fhy belly, which is about an aes in length, —— to 
the lower edge of the front of the approxima to the 
e mutcle, and is ixferted i ae (eae fofla at 
the fide of the fymphvfis. 
e trachelo-mattoideus, fplenius, and poe cleido-mattoi 
deus m ver di 
’ 
fome branches of the ecieeial caida artery, and the nerves 
of the ninth pair. The anterior part ie placed between the 
mylohyoideus and latiffimus colli, The fubmaxillary gland, 
placed between the two divifions of the mufcle, is bounded 
below by the middle tendon. 
‘The contraétion of this mufcle opensthe mouth by draw- 
ing the frovt of the lower jaw towards the mafoid procefs ; 
and the {welling both of its anterior aa potterior portions 
can a aoe nly ‘perceived byt when we open the 
The o of the age does not feem to be 
ith the motions of the os hyotdes, Tince its 
tendon paffes above that bone, to which it is only conneéted 
by a flender aponeurofis, and cor feqnently the curve de- 
alas by the courfe of the mufele is flight; now it is only 
n proportion to the degree of that curvature that the digaf- 
pale taken altogether can have the power of elevating the 
os hyordes. Thea nterior portion draws the os 
when the eer axillary bone ie pr evented from defcending,y 
is very obvious ; and Soemmerring ftates that the circumftance 
may be Aye y particularly in infants when fucking.—(De t 
Corp. Hum. Fabr, t. 3.p. 10 
Latifimus colli (platifma myoides, thoraco-facien).——-T his 
mufcle confifts of a very thin layer of mufcular fibres, fitu- 
ated under the fkin of the nee the whole fide of which is 
covered by it, and extending over a confiderable part both of 
ft. The weaknefs of it 8 fibres is compen- 
ipou Ss me 
cer on, among oe eee menbqaes at the upper part of 
cheft, at one or two inches below the clavicle. Thefe 
t of 
part of their inner edge, where 
lower jaw: they are not quite in conraét b The pof- 
tericr cdge reprefents an obudie line defeending from the 
angle of the jaw towards the middle of the fhoulder. When 
the fibres oe ies at the balis of the lower jaw, they ters 
minate in tw The inter portion is fixed to the fym- 
ph: fis of ae er and to its lower edge, jult under the ort. 
gin cf the depreffor anguli oris; a few obres however pafs 
over tte bene to the integuments of the chin. The outer di- 
vifion afcends over the jaw, and turns, when it has arrived on 
the face, by a gentle > {weep, inwards and forwards, to the 
preffor anguli oris throughout 
external furface of this auucle’ is lial ie connected to ag 
{kin by an adipous membrane, not much charged with fa 
On the oppofite afpect, it is in contact, on the chelt, with 
the‘pectoralis major, deltoid, and clavicte. On the neck, it’ 
covers the gresteit part of the fterno-cleido-maltoideus, a part 
ia the omo-hyoideus, the iterno-hyoideus, digaftricus, and 
mylo-hyoideus ; the external jugular vein ; the carotid and 
- fuperior thyroideal arteries; the fub-maxillary, and a part 
of the paruti glands. In the face it lies upon the maffeter, 
buccinator, and preffor ie i orts mufcles, and the exter- 
maxillary artery aud facial vein ies 
It draws down the fkin of the lateral and lower part of 
the face, or penstoutcely is in deprefiing the a lip, 
and corner © mout neern- 
ed in acorns “the forvowftl ond indignant ‘palfione. It 
alfo acts very principa'ly in depreffing the lower jaw. In all 
its contractions the Heer mult be thrown more or lefs 
into tranfverfe wrinkles, and this effe@ refembles that pro- 
duced by the panniculus carnofus of animals; but we cannot 
regard this corrugation as the primary ufe of the mufcle. 
Other mufcles affit in depreffing the lower jaw, as thofe 
which pafs from that bone to the o 
preffors of the os hyvides, all w 
fubfequent part of the prefent article. e 
we have jult confidered as bein 
and ay acting w very conliderable mechanical 
muft confider alfo that the office of the laft- 
ufcles requires no great exertion; that wh 
the elevators are relaxed, the weight -of the jaw itfelf affitts 
in the depreffion ; and uel that the depreffors - 
the jaw hold the Tame relation to the elevators, as the e 
tenfors do to the flexors in the trunk and limbs; where ail 
the great efforts are made in the dire€tion of flexion, and e 
tenfor baa are required only for the purpofe of reftoring 
the pa 
The as is the mouth is the {pace included between the 
lips and cheeks on the front and fides ; the palatine eli and 
the foft palate co and behind ; the tongue and membrane 
of the mouth below 
1 
mmunicates 
