Page:Encyclopædia Britannica, first edition - Volume I, A-B.pdf/348

 Part VL 294 ANA T O M Y. ^eited in the moveable cartilage which forms the ala of It is proper here to obferve the whole extent of the maxillary finus. Below, there is but a very thin par^iie oares. '1 he oblique or lateral mufcle is a thin fleihy plane, tition between it and the dentes molares, the roots of lying on the fide of the former. The lateral mufcle is which do, in fome fubjefts, perforate that feptum. Afixed by its upper extremity to the apophyfis nafalis of bove, there is only a very thin tranfparent lamina bethe .os inaxiilare, below its aniculation with the os fron- tween the orbit and the finus. Backward, above the tutis,. and fometimes a little lower than the middle of the berofity of the os maxillare, the fides of the finus are yiner edge of the orbit. From thence it runs toward very thin, efpecially at the place which lies before the the,ala naxium, and is inferted in the moveable cartilage, root of the apophyfis pterygoides, through which the innear the os maxilhire, being covered laterally by a por- ferior maxillary nerve fends down a ramus to the foramen palatinum pofterius, commonly called gujiatorium. tion of the neighbouring mufcle of the upper lip. . The ttanfverfe or inferior mufcle, called alfo myrti- Inward, or toward the conch® narium, the bony part formeSy is inferred by one end in the os maxillare, near of the finus is likewife very thin. the lower edge of the orbit, much about the place which The lachrymal facculus is an oblong membranous bag, anfwers to the extremity of the.focket of the dens cani- into which the ferous fluid is difeharged from the eye nus on the fame fide. From thence it runs almofttranf- through the punfta lachrymalia; and from which the fame verfely upward, and is fixed in the lateral cartilages of the fluid pafTes to the lower part of the internal nares. It is noie, over which it fometimes runs to the ai® of the fituated in a bony groove and canal, formed partly by the apophyfis nafalis of the os maxillare and os unguis, great cartilage, to be inferted there. The fail two pairs .of thefe mufcles raife and dilate partly by the fame os maxillaxe and lower part of the os the al® of the nares when they aft; and at the fame, unguis, and partly by this lower portion of the os unguis dme.raifedie upper lip, by reafon of their conneftion with and a fmall fuperior portion of the concha narium in. the mufcles of that part. They likewife wrinkle the ferior. This bony lachrymal duft runs down for a little way ikin on the fides of the nofe. . The membrana piufitaria is that which lines the whole obliquely backward, toward the lower and lateral part of internal nares, the ediular convolutions, the conch®, the internal nares on each fide, where its lower extremithe fides of the feptum narium, and, by an uninterrupted ty opens on one fide of the fious maxillaris ander the continuation, the iuner furface of the finus frontales and inferior concha. The upper part of this duft is only an m-ixillyres, and of the duftus lacrymales, palatini, and fphe- half canal or groove; the lower is a complete canal, narthan the former. noidales. It is likewife continued down from the nares to rower The facculus lachrymalis may be divided into a fuperior the pharynx, feptum palati, &c. It is termed pituitaria, becaufe, through the greateft or orbitary portion, and an inferior or nafal portion. orbitary portion fills the whole bony groove, being part of its latge extent, it ferves to feparate from the The rite rial blood a mucilaginous lynipha, called/>;7z/h<a by fituated immediately behind the middle tendon of the orbicularis. The nafal portion lies in the the ancients, which in the natural Hate is pretty liquid ; mufculus bony canal of the nofe, being narrov/er and Ihorter than but it is fubjeft to very great changes, becoming fome- the I'mes, glutinous or fnotty, fometimes limpid, 6t nei- former. otbitary portion is difpofed at its upper extremither is it. feparaied in equal quantities through the whole ty,The much in the manner of an iateftinum c®cum and rnembra&e. When we carefully examine this membrane, it appears at the lower extremity is continued with the portior nafalis. Towards the internal angle of the eye, behind to be of a different llrufture in different parts. Near the tendon, of the orbicular mufcle, it is perforated by the edge of the external nares it is very thin, appearing a fmall to be the Ikin and epidermis in a degenerated Hate. All dufts. fliort canal formed by the union of the lachrymal the other, parts of it in general are fpungy, and of different thickneffes. The thickefl pans are thofe on the The nafal portion having reached the lower part of . ieptum narium, on the whole lower portion of the, inter- the bony duft under the inferior concha, ter mi mites in a fmall, flat, membranous bag, the bottom of which, is nal nares, and on the conch®. On the fide next the periofteum and penchendrium it perforated by a round opening. The fubftance of this facculus is fomething fpongy or is plentifully flored with, fmall glands, the excretory cellulous, and pretty thick, being ftrongly united by its dufts of which are very long near the feptum narium, convex fide to the periofteum of the bony canal. and their orifices very vifible. The frontal, maxillary and fphenoidal finufes open in- The duftus inciforii, or nafo:palatini of Steno, are canals whidv go from the bottom of the internal nato the internal narys, but in different manners. The two crofs the arch of the palate, and open behind the f rontal finufes ©pen from above downward, anfwering tp res or largeft dentes inciforii. Their two orifices may the in bndibula of the os ethmeides. The fpheaoidales firft feen in the fkekton at the lower part of the open forwards, oppofite to the pufter'ror orifices of the benafaldiftinftly fbfl®, on the anterior and lateral? fides of the crifta: nares; and the maxillares open a little higher, between ma:iillares; and we may likewife perceive their oblique the two conch®. 1'he opening of the finus maxillaris in fome fubjeft's paflage through the maxillary bones, and laftly their inis fing’e, in others double; it lies exaftly between the ferior orifices 4a a ftnail cavity or foiTula, called fora? men palaiinum ante) ins. two conch®, about the middle of their depth.