DEGLUFITION. 
aéts in conjunction with the oppofite mufcle. By depref- 
fing the os hyoides, and fixing it in its depreffed fitvation, it 
will affiit, as well as the oe fucceeding mulcles, in wae 
down the lower jaw. the os hyoides is then a fixed 
point, - bea the ities extending from its nee on 
to the jaw 
Sterno-hy ey aa “This is a broad, thin, and flat mufcle, fitu- 
ated on the front of the neck, jut under the platy{ma my- 
i i f the cheft to the en 
of the larynx. It has a broad tendinous origin from the 
outer part of the pofterior furface of the firft bone of the 
fternum, from the contiguous cartilage of the firft rib, from 
the joint of the clavicle and fternum, and from the clavicle 
itfelf. It grows rather narrower as it afcends, covers the 
furface of the trachea, a gone to the mufcle of 
The two together completely cover the 
front of the larynx, and are Sintered into the middle of the 
lower edge of the bafis of the os hyoides, in the fpace left 
€ e attachme mo-hyoidei, It is 
between th 
covered by the platy{ma myoides, and fterno-cleido-mattoi- 
deus; and lies upon the fternc-thyroideus, hyo-thyroideus, 
crico-thyroideus, thyroid gland, and fuperior thyroid vef- 
fels. draws down the os hyoides and parts nasoutaie to 
it, as the tongue, larynx, lower jaw even, 
panes the connexions of the os hyoides, bend die head 
forwa 
The Fern seas is a tue of fimilar fhape and fitu- 
ation ta the fo which it lies. 
the { ; from which part it afcends in front of t 
trachea, and thyroid gland, and is foon marked tranf. 
verfe tendinous line. Its edge at firft ern that of the 
oppofite mufcle in front of the trachea; it grows narrower 
as it pailes upwards, and at the fame time feparetes from the 
other: it terminates by a tendinous infertion into the ob- 
lique ridge of the ala of the thyroid cartilage. 
is every where covered by the fterno- hyoideus; and it lies upon 
the fubclavian, and internal jugular veins, the carotid artery, 
the trachea, the thyroid gland and its veffels, and the crico- 
i 
with the preceding mufcles, for which reafon we defcribe it 
here, although it is not attached to the os hyoi 
The hyo-thyrcideus is a mufcle of a flattened an sifing & 
from the oblique ridge of the thyroid ala, and afcending ina 
ftraight direCtion to the under edge of the cornua of the 
hyoides, in which it isinferted. It is covered by the deans 
hyoideus, and omo-hyoideus externally, and it lies on the 
thyroid cartilage. It will mutually approximate the os hy- 
oides and larynx; elevating the latter, or deprefling the for- 
mer, according as the 
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roduce “a parts connected to the’os hyoides, 
efcent of that bone cannot take place with- 
out ue eee ding aeons of the larynx, and thefe are one 
of the means by which ee baa io the voice is altered in 
eng or rae ve arynx is fo intimately 
connected with the bee aoe it yateee ev aged motion of 
the latter ; and its afcent and defcent in the neck, in the 
procefs of deglutition, are effected through the aon of the 
hyoideal mufcles. fee that the os linguale is a very 
moveable part ; that its connexions in the neck leave it a 
free power of — and that it ia numerous mufcles, 
oc of moving it in every direétio 
Th 
Its furface- 
urs therefore in producing the fame effeQ& je 
tongue ecco the lower oar of the mouth; is- 
bounded in front and at the. fides by the teeth and alveolar 
wen Its 
mits of 
aller ia ont; here it 
mente ates ar a rounded end, rather Ge on its upper 
and lower afpects, and named the apex. At the back part 
it bacsmes broader, thicker, and more convex, and is clofely 
attached below to the furrounding parts : this is called the 
bafis or root of th 
ace are free nia all kinds of attachment. er 
ortions of the n, which ate in contact with ee inner 
furface of the ie teeth, and the inner alveo-ar plate of 
the lower jaw, are flattened in their form, and are uncon- 
neéted in their Regina. The inferior furface of the cae 
cannot be very clearly defined, 
under furface, in the fpace left between the two lateral die 
vilions of the lower jawbone, with feveral see arifing 
rom the jaw, ftyloid procefs and os hyoides, ~ continued 
into the fubftance of the organ, which they hav 
of moving in every dirc@ion, in the cavit Ns 
t is the intermixture of thefe mufcles with. the lingual 
nerves and veflels, and with a large mafs of a very peculiar 
mufcular fibre, called the a na mulcle, that forms ne 
fubftance of the tongue. aw 
its a 
e tongue is connected to the epiglottis by three folds 
of membrane, 
e membrane of the sana Nes covering the inner 
* continued to the upper convex part of te organ, Tn th 
mer fituation it is f{mooth like the lining of the cheeks ; 
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becomes connected to t Ei ior and late: a - aa € 
tongue, along the fide of which it as far as the very 
apex of the organ, mixed with the fibres of the aaleitae, 
The parts in conta& with it are the digaftricus, fabmaxillary 
gland, and nerve of the ninth pair externally ; the fuperior 
conftri¢tor of the pharynx and the lingualis internally. 
Hyo-gloffus, (bafio- Te cerato-gloflus, and chondros 
glofius ot Albinus). a isis a broad and thin mufcle, arif- 
ing extenfively from the os shu. to the bafis, cornu, and 
corniculum of which it is attached, afcending ina ftraight 
dire€tion, and terminating in the fide of the tongue. The 
parts in conta& with it are, vanes sak digaftricus, ftylo- 
hyoideus, mylo- ia. nerve of the ninth pair. and fub- 
lingual giand; internally, the lingual pee gloffopharyns 
geal nerve, and genio- picts mufele, 
Genios 
