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^4 AHA T valve to hinder what we fwailow-j and efpecially what we drink, from returning by the nares. The ufes of the different mufcles of the feptnm are not as yet fufficiently known, nor the different motions of which it is capable. The TONGUE. The tongue is divided into the bafis and point; the upper and under Tides ; and the lateral portions or edges. The bafis is the poflerior and thickeft part; the point, the anterior and thinneft part. The upper fide is not quite flat, but a little convex, and divided into two lateral halves, by a (hallow depreffed line, called linea lingnie mediana. The edges are thinner than the other parts, and a little rounded as well as the point. The lower fide reaches only from the middle of the length of the tongue to the point. The tongue is principally compofed of very foft flelhy fibres, intermixed with a particular medullary fubftance, and difpofed in various manners. Many of thefe fibres are confined to the tongue without going any farther, the red form feparate mufcles which go out from it in different ways, and are inferted in other parts. All the upper fide of the tongue is covered by a thick membrane of a papillary texture, upon which lies another very fine membrane like a kind of epidermis, which is likewife continued over the lower fide, but without papillse. Three forts of papillss may be didinguilhed in the upper fide of the tongue, capitatae, feroi-lenticulares,, and villofac. Thofe of the fird kind are the larged, refembling little mufltrooms with (hcrt dems, or buttons without a neck. They lie on the bafis of the tongue in final! fuperficial foffulse. They referable finall conglomerate glands feated on a very narrow bafis, and each of them has fometimes a fmall depreffion in the middle of their upper or convex fide. They occupy the whole furface of the bafis of the tongue. They are glandular papillae, or fmall lalival or mucilaginous glands. We oftentimes obferve, about the middle of this part of the tongue, a particular hole of different depths, the inner furface of which is entirely glandular, and filled with finall papillae, like thofe of the fird kind. It is called, foramen at cum Morgagnii, as being fird defcribed by that anthor. Since that time M. Vaterus has difcovered a kind of falival dufts belonging to it ; and M. Heider found two of thefe duds very didindly, the orifices of which were in the bottom of the foramen caecum near each other. He obferved the duds to run backward, divaricating a little from each other, and that one of them terminated in a fmall oblong veficle fituated on the fide of the fmall cornu of the os hyoides. The papillae of the fecond kind, or (emi-lenticulares, are fmall orbicular eminences, only a little convex, their circular edge not being feparate from the furface of .the tongue. When we examine them in a (bund tongue, with a good microfcope, we find their convex (ides full of fmall holes or pores, like the end of a thimble. They lie chiefly in the middle and anterior portions of the tongue, and are fometimes mod vifible on the edges,
O M Y. Part VI. where they appear to be very fmooth and poliflied, even to the. iraked eye. The papillae of the third kind, or villofe, aire the fmalleft and moft numerous. They fill the whole furface of the upper fide of the tongue, and even the interftices between the other papillae. The fleftiy fibres of which the tongue is compofed, and which go no further than the tongue, may be termed •mufculi lingua interiores; and they are the fame which Spigelius named mufculi linguales. The fibres thefe mufcles confift of are of three general kinds, longitudinal, tranfverfe, and vertical; and each of thefe fituations admits of different .degrees of obliquity. The longitudinal fibres point to the bafis and apex of the tongue, and feem partly to be expanfions of the mufculi llylo-glotli, hyo-glolli, and genio-glofli; of which hereafter. The vertical fibres feem likewife to be in part produced by the fame genio-glofli, and the tranfverfe by the mylo-gloffi. The mufculi exteriores are four in number, and make a part of the body of the tongue. The mylo-glolli are fmall fle(hy planes, fituated tranfverfcly, one on each fide, between the ramus of the lower jaw, and the bafis of the tongue. Their infertion in the jaw is immediately above the pofteiiorhalf of the mylo-hyoidteus, between the prominent oblique line on the infide of the bone, and the dentes molares. From thence they run toward the bafis of the tongue, and are loft there on one fide of the gloffo-pharyngxi. The ftylo-glofii are two long fmall mufcles which run down from the ftyloid apophyfes, or epiphyfes, and form two portions of the lateral parts of the tongue. Each mufcle is fixed in the outfide of the apophyfis ftyloides by a long tendon. The ftylo-hyoidaeus is the lowed, and the ftylo-pharyngseus is in the middle, but more backward. As it runs down almoft oppofite to the infide of the angle of the lower jaw, it fends off a pretty broad and (hort lateral aponeurotic ligament, which being fixed in that angle ferves for a frsenum, or ligamentum fufpenforium, to the mufcle in this part of its courfe. From thence it pafl'es on to the fide of the bafis of the tongue, where it firft of all adheres clofely to the lateral portion of the hyo-gloffus, and then forms, together with that mufcle, a large portion of the fide of the tongue. The hyo-gloffi are each inferted in three parts of the os hyoides that lie near each other, in the bafis, in the root of the great cornu, and in the fymphyfis between thefe two ; and on this account the hyo-gloffus has been divided by fome into two or three diftind mufcles, called bafio-glojj'us, cerato-glojfus, and cbondro-glojfus. It is fituated on the infide, and a little lower than the ftylo-gloflus, with which it forms the lateral part of the tongue. The portion inferted in the bafis of the os hyoides lies more anteriorly, and is larger than the other two; that which is inferted in the fymphyfis is the leaft, and that inferted in the great cornu the moft pofterior. This mufcle is partly fuftained by the mylo-hyoidsus, as by.a girth ; and the anterior portion is diftinguiftied frqm the reft by the paffage of the nerves of the fifth pair, and of the arteries which accompany them. The genio-gloffi are fituated clofe to each other onlower the
