| XXX | (161) | XXX |
161 A N A T O M Y. Part I. circumference of the orbit.—From the proper orbiface is convex and fmooth ; backward, it is unequal and nal concave, for lodging part of the crotaphyte mufcles. tar procefs, a very rough triangular furface is extended The four angles of each of thefe bones have been downwards and outwards, to be connected to the cheekreckoned procefi'es by fome. The vone at the exter- bone ; and therefore may be called the malar procefs, the loweft: protuberant part of which fome fhare of nal canthus of the orbit, called the fuperitr orbitar pro- from cefs, is the longed and thickert. The fecond termi- the mafleter mufcle takes its rife. Behind the orbitar a large tuberofity or bulge of the bone appears, nates near the middle of the lower edge of the orbit in a procefs, (harp point, and is named the inferiorrbitar procefs. which is efleemed the'fourth procefs. On the interThe third, placed near the lower part of the cheek, nal part of this we often meet with a ridge, almoft of and thence called maxillary^ is the ihorted, and neared the fame height with that in the nafal procefs, which tranfverfely, and is covered by a fimilar ridge of to a right angle. The fourth, which is called zygo- runs matic, becaufe it is extended backwards to the zygoma the palate-bone, on which the back-part of the upper of the temporal bone, ends in a point, and has one fide edge of the os fpongiofum inferius refls. The convex dreight, and the other flopping.—Between the two or- back-part of this tuberofity is rough for the origin of bitar angles there is a concave arch, which makes about part of the external pterygoid mufcle, and more intera third of the external circumference of the orbit, from nally is fcabrous, where the palate and fphenoid bones which a fifth procefs is extended backwards within the are joined to it. That fpongy protuberance at the mbit, to form near one third of that cavity ; and hence lower circumference of this bone, where the fockets for it may be called the internal orbitar procefs.—From the teeth are formed, is reckoned the fifth.—The fixth the lower edge of each of the ofla malarum, which is is the horizontal plate, which forms! the greater part of between the maxillary and zygomatic procefles, the muf- the bafe of the noftrils, and roof of the mouth; its upfler mufcle takes its origin; and from the exterior part per furface, which belongs to the noftrils, is very fmooth, of the zygomatic procefs, the mu/culus dijlorfor oris but the other below is arched and rough, for the ftrongriles ; in both which places the furface of the bone is er adhefion of the membrane of the mouth, which is ftretched upon it, and in chewing, fpeaking, drr. might orough. Oh the external furface of each cheek bone, one or therwife be liable to be fe pa rated.—^The feventh'rifes more fmall holes are commonly found, for the tranfmif- like a fpine from the inner edge of the laft, and forms a fion of fmall nerves or blood-veflels from, and fometimes fmall part of the partition of the noftrils. into the orbit. On the internal furface are the holes The depreffions in each maxillary bone are, 1. Afinufor the paflage of the nutritious vefiels of thefe bones. ofity behind the orbitar procefs, made by the temporal A notch on the outfide of the internal orbitar pro- mufcle. 2. A pit immediately before the fame procefs,. cefs of each of thefe bones aflifls to form the great flit where the origin of the muflculus elevator labiorum comcommon to this bone and to the fphenoid, maxillary, munis, and elevator labii fuperioris, with a branch of the fifth pair of nerves, are lodged fecurely. 3. The and palate-bones. The lubdance of thefe bones is, in proportion to their hollow arch of the palate. 4. The femicircular great notch, or entry to the lower part of the noftrils, bebulk, thick, hard, and folid, with fome cancelli. Each of the olfa malarum is joined, by its fuperior and twixt the root of the nafal procefs and fpine of the painternal orbitar procelfes, to the os frontis, and to the late-plate. 5. Sockets for the teeth: The number of orbitar procefs of the fphenoid bone, by the tranfverfe thefe fockets is uncertain. 6. The lacrymal fofla in the future. By the edge between the internal and infe- nafal procefs, which aflifts the os unguis to form a pafrior orbitar procefles, to the maxillary bone", by the in- fage for the lacrymal dudh Immediately on the outternal orbitar future.—By the fide between the maxilla- fide of this, there is a fmall depreffion, from which the ry and inferior orbitar procefs, again to the maxillary inferior or lefler oblique mufcle of the eye has its origin. bone, by the external orbitar future.—By the zygoma- 7. The canal on the upper part of the great tuberofity tic procefs, to the os temporum, by the zygomatic fu- within the orbit, which is almoft a complete hole ; in ture. this a branch of the fuperior maxillary nerve pafles'. Ossa Maxillafua Superiora, are the largeft Befides thefe, the fuperior furface of the great bulge is bones, and conflitute the far greater part of the upper concave, to. receive the under part of the eye.—Immedijaw. ately above the tranfverfe ridge in the nafal procefs, a The procefles of each os maxiilare may be reckoned fmall hollow is formed by the os fpongiofum. feven.—The firll is the long nafal one at its upper and The holes of this bone are two proper and two comfore-part, which is broad below,-and turns fmaller, as it mon, which are always to be found, befides feveral orifes upwards, to make the fide of the nofe. At the thers, whofe magnitude, number, 6c. are uncertain. root of this, a tranfverfe ridge may be obferved within The firft of the proper is the external orbitar, immedidie noftrils, which fupports the fore-part of the upper ately below the orbit, by which the infra-orbitar branch edge of the os fpongiofum inferius.—The fecond is pro- of the fecond branch of the fifth pair of nerves, and a duced backwards and outwards, from the root of the fmall artery, come out, after having palfed in the canal, nafal proeds, to form the lower fide of,the orbit ; and the bottom of .the orbit, deferibed Numb. 7. of the "therefore may be galled orbitar.—The edge of this orbi- atdepreflions.—The fecond is xhe. foramen incifivusn, juft tar procefs, and the ridge of the nafal one, which s cpn- behind, the fore-teeth, at its under part, is one S tir.ued from it, make a confiderable portion of the exter- irregular hole common towhich, both the maxillary bones when Vol. I. No. 7. 3 Si they
