DEGLUTITION. 
a esob and Farwa rds, the other upwards and backwards. 
the zr of thefe it is united to the f{ynchondrolis, 
ae saree the bafis and cornu of the os h 
is uae in its Situation, 
are fixed to it; and its upper extremity receives t 
of the tylo- my oraest igainen, coe polterior — of 
cornu of the os es terminates in a fomew ound. 
tubercle, to een Hic hyo- eae eal amet is ey 
The bafis of this bone contains much of the cancellous tex- 
ture; but that is lefs abundant in the cornua, Its offifica- 
ticn commences by five aan one for the bafis, one for 
e for each connie Thefe 
ony pieces are feparated at “Get y much cartilage, which 
is Sie dep! offified, except at the iss of junGion, where 
mina of eae remains ine 
—— of the numerous mufcles which fix thé os 
and tongue, 
motions sof both thofe eae. Properly fpeaking, it has no 
functions of its owns Its motions are not relative to itfelf, 
but are defigned merely to produce motion of the see or 
Jarynx. It is only connected to the tongue by means of 
pst lcal fibres; but it -is fixed to the bafis cramii 7 a liga- 
ment which we proceed to defcribe. 
The ftylo Deal ligament arifes from the flyloid pro- 
cefs of the temporal bone, defcends obliquely forwards and 
inwarde, and is fixed to a leffer cornua of the os hyoides. 
It is of different thickne {fs in different inva, < alten 
rb 
eeeding beyo 
cae without carrying with it the 
all reftrain ce by the tongue, ae that alfo is move- 
able. 
Mufeles moving the os hyoides.—Vhe digaftricus or biven- 
ter maxille, which we have already defcribed, mult be env- 
merated sie thefe; fee its defcription in a preceding part 
of 8 arti 
ee mandibule eee healt —This is a very 
Beal and rather thin mufcle; flattened on its furfaces, and 
extending tran{verfely acrofs the {pace left between the two 
It has a tendinvts origin, from 
which com- 
mences juft under e 
liquely downwards and forwards to the fymphyfis. 
are continued to the fame point on the oppofite fide in an 
arched direction, the mufcle ia concave on its fuperior, 
= see on ee inferior afp 
e middi of the msl, in a ftraight line from the 
of the os hyoides, t 
mufcle “differ much in length ; 
eae and are inferted into the upper edge of the bafe of the 
os hyoides, juft behind the digaftricus; the fucceeding fibres 
become ia ie ively fhorter and fhorter to the adie edge 
of the mufele, where their length is = infiguif e 
Seal rae en of this mafcle is in tat on Scie fide 
with the antevior portion of the deals. with the fubs : 
6 
maxillary gland and latiffimus colli. Internally it covers the 
genio-hyot ides, genio- Sain hyog!oflus, fublingual gland, 
Whartonian duct, and nerve of the ninth pair. 
It elevates the os hyoides, and at the fame time raifes all 
the parts in front of that bone, which are contained in the 
concavity of . fibres. Hence it muft prefs the tongue 
the palate, and comprefs the fublingual glands, 
When the os ‘hyoides is fixed, it may deprefs the lower 
jaw. 
Genio-hyoideus.—This mufcle, baa is ane immediately: 
behind the middle tendinous line cf the jan erfus mandi- 
bul, is of a rounded form, and extends the inferior 
tubercle of the inner furface of the chin, sbiquely down- 
wards and backwards, to the middle of the bafis of the os hy- 
oides. It lies very ene to its fellow of the oppolite fide, to 
which it is connecte ne and aie Keri’ threads, fo 
that ona {uperficial infpeGtio on they v appear to form - 
one mulcle. It is covered on its a Oe oF inferior afpe& 
by the tranfverfus mandibule, and lies in contact, by its op- 
courfe it draws up the 
protruding the tongue fromthe mouth. When the os sees 
hee fixed ay the powers that deprefs it, it will draw down 
the low 
Syl is _This a flender elongated mufcle, hav- 
ing a tendinous origin cod the ftyloid procefs, defcending 
obliquely forwards and inwards, reir increa afing i in aha 
as it defcends, and inferted into the bafis or the end of 
the cornu of the o i ea 
tricu es. 
on the infide a the fame ne ti 
the os hyoides upwards and backw w 
med ; and therefore contributes to ay ee the tongue when 
as been ap shat rom the mouth; both mutcles a@ing 
fogciier ep elevate it nearly in a Le ight direQion, If 
it 1s employed in ne with the o-hyoideus and tran{- 
verfus eae bue. the larynx will be me dire&tly, as the 
oppofition of the powers tending to carry it forwards and 
backwards prevents it from moving in either of thefe 
ways. 
Om o-hyoideus ‘(coraco-hyoideus, iis: -hyoideus, hpi 
to-hyoideus),—-It arifes by tendon from the mi or eee 
of the fcapula, A et the notch at the root of t 
racoid procefs, and ane from the facie fecha 
over that notch. Forming a thin, flat, and narrow mufcle, 
it afcends alon 
° 
that bone, by an aponeurofis. 3 between oe fherno- 
cleido-maftoideus, and the veffels of Te neck, and is con- 
trated at that part into a thin and narrow tendon. After. 
wards it erie = the fame flefhy form which it poffefled 
before, and e from under the fterno-cleido-matfoi-. 
deus, earre more diredly in the front ofthe n eck, and con- 
em t poffeffes in the em- 
bryo a nearly equal breadth . broughost, without any middle 
tendinous por It vered by the deumionus eos 
fterno- cleido- maftoideus, clavicle and trapezius and lie 
upor car d artery, re on 
nal jugular ¢ vein, s-sdae thyroideal veffele, and hyothyroi- 
deus mufcle. The fter se hae lies along the front edge 
i i It fome 
