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 223 Part II. ANA T O M Y. as w'ell as in thofe of the fcapula, is very particu" des, having firfl: font ofF a fmall lateral portion, which is oides, lar, and very different from what we find in all the other fixed a little higher to the root of the cornu. bones of the human body. All thefe bones have folid fulcra, on which they are either moved or kept fixed by STYLO-HYOIDiEU S. the proper mufcles, after the manner of a lever or otherwhereas the os hyoides is merely fufpended, haThis is a fmall flefhy mufcle, lying obliquely between wife; ving nothing to fix it but thefe very mufcles which move the apophyfis ftyloides and os hyoides. manners. It is fixed laterally, by one extremity, to the root or it inThedifferent mylo-hyoktaeus reprefents a moveable Hodr or bed, bafis of the apophyfis llyloides, and, by the other, to which fuflains the tongue with its mufclcs and glands, the os hyoides, at the place where the bafis and cornu and forms the bottom cavity of the mouth. When unite, and likewife to the cornu itfelf, from whence it the two portions of thisof the mufcle adl together, they draw has been called Jiylo-cerato-hyoicLeus. the os hyoides a little forward, and fix it in that fituaraifing the whole tongue at the fame time, and OMOPLATO HYOID.EUS fivs OMO-HY- tion, compreffing the glandulas fub-lingualcs. If one lateral OIDAiUS vulgo COR ACO-HY 01D ALU S. portion ads more thah the other, it puts the os hyoides and in a condition to ferve as a This is a very long fmall mufcle, much narrower in an obliqueforfituation, the motions of the tongue. than the fterno-hyoidteus, and fituated obliquely on the fixedThepoint pull the os hyoides much more forfide of the neck or throat, between the d'capula and os ward thangeniothehyoidei mylo-hyoideus ; and as they are very narhyoides. . It is commonly fixed, by the lower extremity, to the row, and dofely united together, there feems to be very fuperior cofta of the fcapula, between the fmall notch little occafion for one of them to ad without the other. The ftylo-hyoidasi move the os’ hyoides upward and and the angle, and fometimes very near the angle. From thence it pafies over the coracoid apophyfis, ad- backward in a middle diredion, between thofe in which hering fometimes to it by a kind of aponeurofis, or mem- they fie; .and they draw it more upward and backward branous ligament, and from this adhelion the name of co~ when they ad freely; that is, without-being checked or racQ-hyoidanis was given it by fome who had not difco- confined by other msfcles, in the manner which we fhall fee hereafter. When one ads more than the other, the vered its main infertion. It is likewife often fixed to the clavicula by ligamen- bone is moved obliquely. tary or flefhy fibres ; and has fometimes been been infert- The omorhyoidan, or coraco-hyoidsei, ad as the ftyloed in the whole middle portion of that bone, being infe- byoidafi, in a middle diredion between the oblique directions in which they lie, and. draw, the os hyoides downparably united with the fferno-hyoidseus. Having paffed the clavicle, it is bent forward, and ward and backward, when they are not counterbalanced runs between the flerno-maftoidseus and internal jugular by the flylo-hyoidad. When one ads more than the ovein, the frnall middle tendon being fituated in this place. ther, the bone is drawn obliquely to the right or left From thence it runs up to its infertiop in the inferior la- hand. teral part of the bafis of the os hyoides, near the cornu, When thefe mufcles and the ftylo-byoidsei ad togeand infertion of the fierno-hyoidatus, which it covers a ther, the os hyoides is drawn backward by a dired molittle. tion compounded of four oblique motions. This compound motion is direded more upward or more laterally, to the degree, of adion of the ftylo-hyoidcei, Sterno-Hyoidjeus five Sterno-Cleido-Hyoid^us. oraccording omo-hyoidad, or of any one mufcle of each pair; and This is a long, thin, flat mufcle, broader at the lower in all thefe motions the four mufcles are counterbalanced the genio-hyoidaei. than at the upper part, and fituated, together with its byThe flerno-hyoidaei draw the os hyoides diredly downfellow, on the fqre-fide of the throat.7 It is fixed, by its lower extremity, in the fuperior and ward, and ferve to counteibalance the different motions lateral part of "the inner or poiterior fide of the flerpum, of the ftylq-hyoidaei, omo-hyoidai, and genio-hyoideei. in the pofterior part of the flernal extremity of the cla- They may, in fome cafes, be aflifted by the ilerno-thyvicula, in the tranfverfe ligament which coftnedfs thefe roidad, and thyro-hyoidaei, as we fliall fee hereafter. two bones, and in the inner or back-fide of the cartilage According to the method commonly obferved in comof the firfl: rib. All thefe other infertions are more con- plete treatifes of myology, the following mufcles remain fiderable than that in the fternum, which is fometimes fiill to be deferibed, viz. The mufeies of the forehead, occiput, palpebras, eye, external ear, nofe, lips, tongue, fcarce perceivable. From thence it runs up on the fore-fide of the afpera uvula, du&us Euflacbianus, pharynx, larynx, parts of arteria, joined to its fellow by a membrane, which forms generation, anus, and bladder; and to thefe we ought' a fort of ilinea alba, and is inferted laterally in the lower even to add the heart, as Mr Cowper has done in the late edge of the bafis of the os hyoides. edition of his Myotomy. But the defeription of thefe will be better undei flood when we treat of the parts to Uses of the Mufelej winch move the Os Uyoides. which they belong. See Part VI. The mechanifm obfervedin the motions of the os hyE X P L A-