Page:Encyclopædia Britannica, first edition - Volume I, A-B.pdf/356

 O M Y. Part VI. go2 A N A 1 arytenoid cartilages forward, and confequently loofen other by fome fibres, and meet at the linea alba. Their may be to draw the middle portion or great cavity of the glottis, and render it capable of the fmalleii quaver- ufe the pharynx upward. ings of the voice. The arytenoidasi bring the arytenoid cartilages clofe The ftylo-pharyngaei are inferted interiorly by one extogether, and prefs them againft each other ; and when tremity in the apophyfis, or epiphyfis ftyloides. From mufcle runs down obliquely along the lateral the cartilages are in this fituation, they may at the fame thenceofeach the pharynx, covering and crofling the other' time be inclined either forward by the thyro-arytenoidaei, part It extends gradually in breadth as it defcend.Sy or backward by the crico-arytenoidsei pofteriores'. By mufcles. this means the glottis, when fhut, may be either relaxed and forms two principal portions, .one fuperior which is; and one inferior which is broad. The narrow or tenfe ; and in this laft cafe it is intirely flint, as when narrow, portion is fpread among the mufcular fibres above the we hold in oar breath inflraining. The general ufe of the epiglottis is to cover the glottis thyroid cartilage, and the broad portion is inferred in the like a pent-houft, and thereby hinder any thing from' fide of that cartilage; and thus the ftylo-pharyngseus is falling into it when we eat or drink; it ferves likewife partly a true ftylo-thyroidaeus. Thefe mufcles may draw to hinder the air which we infpire from rulhing dirtdlly the pharynx laterally upward, efpecially by their thyUpon the glottis, but by fplitting it, as it were, obliges roid portions. it to enter by the fides, or in an oblique courfe. The The peryflraphylo-pharyngsei are two fmall rnufcles ininufcles of the epiglottis do not appear to be abfolutely ferred between the uvula and lower extremity of the inneceflary for that cartilage; for in deglutition, it may be ternal ala of the apophyfis pterygoides, and run obliquefufSciently deprefled by the bafis of the tongue; and it ly backward on the fides of the pharynx. The glolfomay raife itfelf again by its own elafticity. The thyro- pharyngsei are fibres which run along the lateral edges of epiglottici and aryteno-epiglottici may ferye to (hut any the tongue, from which they are parted'backward, and lateral openings that might remain when the epiglottis is run down on the fides of the pharynx under the fiylodeprefied by the bafis of the tongue; and the hyo-epi- pharyngxi. glottici may pull it a little forward in ftrong refpirations, The hyo-pharyngxi in general are thofe on each fide which are inferted in the os hyoides; and they may be as in fighing, yawning, 6 c. reckoned three pairs, the bafio-pharyngxi, kerato-pharyngxi minores, and kerato-pharyngxi majores; thefe The PHARYNX. denominations being taken from their infertions in the The pharynx is a mufcular and glandular bag, the out- bafis, and in the fmall and great cornua of the os hyer furface of which is clofely joined to the inner furface oides. of all that fpace which is at the bottom of the mouth, The mylo-pharyngxi is a mufcular portion diftinfl from behind the poflerior nares, uvula, and larynx, and which the genio-gloflus, inferted in the fide of the pharynx. reaches from the great or anterior apophyfis of the os T he fyndefmo-pharyngxi are fafciculi of mufcular ficccipitis all the way to the cefophagus, which is the con- bres very diftindtly inferted by one 'end along the liga* ments by which the fuperior cornua of the cartilago thytinuation of the pharynx. Though almoft all the mufcular or fleftiy portions of roides are connected to the extremities of the great corwhich the pharynx is compofed, concur in the formation nua of the os hyoides. From thence they run backof one continued bag or receptacle, they are neverthelefs ward and meet at the linea alba. very diftinguifhable from each other, not only by their The thyro-pharyngxi are very broad, and each mufcle different infertions, from which they' have been denomi- is inferted along the outfide of the ala of the cartilago nated, but alfo by the different dire&ions of their fibres. thyroides, between the edge of that cartilage and the The greateft part of them may be looked upon as diga- oblique line in which the thyro-hyoidxi are fixed Fromftric mufcles, the middle tendons of which lie backward thence they run up obliquely backward, and meet under in one longitudinal line, which in fome fubjedts appears the linea alba. plainly like alinea alba. The crico-pharyngxi are inferted each in the lower The cephalo-pharyngaei are inferted in the lower fide part of the fide of the cricoid cartilage. They feem to of the apophyfis bafiliaris, or great apophyfis of the os be appendices of the thyro-pharyngxi, (hewing no other ©capitis, about the middle of the pofterior part. From marks of diflinftion but thefe infertions, and a fmall difthence they feparate laterally, and fometimes join the fty- ference in direction, becaufe as they run backward they fo-pharyngsei. The linea alba of the pharynx begins by defcend a little. the middle adhefion of thefe. mufcles. The lowed of thefe mufcular fibres make a complete The petro-phnryngaei' are inferted in the lower part of circle backward, between the two fides of the bafis of the extremity of the apophyfis petrofa; the fpheno-pha- the cartilago cricoides. This circle is the beginning of ryngaei, partly in the os fphenoides, directly abcjve the the cefophagus, and has been thought by fome to form a internal ala of the apophyfis pterygoides, and partly in diftinift mufcle, called xfophagaus. the neighbouring cartilaginous portion, of the Euflachian The particular ufes of all thefe mufcles are very diffitube ; and. the pterygo-pharyngxi, in the edge of the cult to be determined. It is certain that thofe of the fame aia of the apbphyfis pterygoides. Thefe three muf- middle and lower portions of the pharynx ferve chiefljr d.ea on, each fide run obliquely backward, covering each for deglutition. Tht