| XXX | (158) | XXX |
Part I. 158 A N A T O M Y. lower edge of the nafal perpendicular plate is received of the body of the fphenoid bone, where the pterygoid into the furrow of the vomer. -Its pofterior edge is proceffes are riling from it, and are extended over 'the joined to the fore-part of the proceffus azygos of the lower part of the aperture of the linus, as far as to joinfphenoid bone. Its upper edge joins the nafal procefs the ethmoid bone, while their body hangs down into the of the frontal and nafal bones, and its anterior one is nares.—Befides thefe pairs of procefles, there is a lharp connected to the middle cartilage of the nofe. ridge which dands out from the middle of its bafe : BeFrom all which the ufes of this bone are evident, viz. caufe it wants a fellow, it may be called proceffus azygos. to fuftain the anterior lobes, of the brain; to give paffage The lower part of this procefs, where it is received into to the olfadory nerves, and attachment to the falx ; to the: vomer, is thick, and often not quite perpendicular, •enlarge the organ of fmelling, by allowing the membrane but inclining more to one fide than the other. The_ foreof the nofe a great extent; to ftraiten the pafiage of the part of this procefs, where it joins the nafal plate of the air through the nofe, by leaving only a narrow winding os ethmoides, is thin and dreight. canal, on the fenfible membranous Tides of which the fub- The depreflions, finuofities, and foffae, on the exterflances conveyed along with the air mud ftrike, to form nal furface of this fphenoid bone, may be reckoned up part of the orbit of the eyes and feptum narium; -while to a great number, viz. two on the temporal apophyfes all its parts are fo light as not to be in hazard of fepara- where the crotaphite mufcles lodge,—;Two on the orbitar ting by their weight; and they are fo thin, as to form a ‘prbceffes, to make; Way for the globes of the eyes.Two between the temporal and fpinous procefi’es, for relarge furface, without occupying much fpace. Os Sphenoides, or wedge-like bone, fo called be- ceiving the temporal bones. Two between the plates caufe of its fituation in the middle of the bones of the of the pterygoid proceffes, where the mnfculi pterygoidei cranium and face, is of an irregular figure, and bears interni and ptery-daphylini interni are placed. Two ibme faint refemblance to a bat with its wings extended. between the pterygoid and orbitar proceffes, for forming When we view the external furface of the os fphenoi- the holes common to this and to the cheek and maxillary des, two or three remarkable proceiles from each fide of bones. Two on the lower ends of the aliform proit may be obferved; which are all of them again fubdivi- ceffes, which the palate-bones enter into.—"■—Two at the ded. The firft pair is the two large lateral proceffes roots of the temporal and pterygoid proceffes, wher - the or wings; the upper part of each of which is called the larged fiiare of the external pterygoid mufcles have their Temporal procefi, bccaufe they join with the temporal rife. Two at the fides of the proceffus azygos, for bones in farming the temples, and the feat for fome forming part of the nofe, <bc. ihare of the crotaphite mufcles. That part of the wings What was deferibed under the name of temporal and which jutts out towards the inftde, fomewhat lower than fpinous proceffes on the outfide of the fltull, are likewife the temporal apophyfes, and is Ifnooth and hollowed, feen on its infide, where they are Concave, for receiving where it makes up part of the orbit, is thence named or- part of the brain ; and commonly three apophyfes on the hitcur procejifes. Behind the edge feparating thefe two internal furface of the Iphenoid bone are only mentioned. procefles, there is often a fmafl groove, made by a Two rifing broad from the fore-part of its body, branch of the fuperior maxillary nerve, in its padage to become fmaller, as they are extended obliquely backthe temporal mufcle. The lowed and back-part of each wards,. The third ftanding on a long tranfverfe bafe, wing, which runs out fharp to meet the offa petrofa, has near the back-part of the body of this bone, rifes nearly been ftyled the fpinoas procefs : from near the point of ere<fl, and of an equal breadth, terminating often in a which a fharp pointed procefs is frequently produced little knob on each fide. The three are called clinoid, downwards, which fome call Jlyliform, that affords ori- from fome refemblance which they were thought to have gin to the ptery-flaphylinus externus mufcle. From this to the fupporters <Sf a bed. From the roots of the ilyloid procefs a very fmall groove is extended along the anterior clinoid proceffes, the bone is extended on each edge of the bone to the hollow at the root of the inter- fide outwards and forwards, till it ends in a lharp point, nal plate of the following proceffes, which forms part of which may have the name of the trasifoerfe fpinohs prothe Euflachian tube.—The fecond pair of external pro- ceffes. Between, but a little farther back than the ceffes of the cuneiform bone is the two which Hand out two anterior clinoid proceffes, we fee a protuberance conalmoft perpendicular to the bafe of the fkull. Each of fiderably fmaller than the pofterior clinoid procefs, but them has two plates, and a middle folia facing backwards, of its lhape.—Another procefs from between the tranfand are named pterygoid ox aliform proceffes. The ex- verfe proceffes, often forces itfelf forwards into the os ternal plates are broadeft, and the internal are longed. ethmoides. From each fide of the external plates, the pterygoid Within the lltul), thefe are two finuofities in the inmufcles take their rife. At the root of each internal ternal part of each wing of the fphenoid bone, for replate, a fmall hollow may be remarked, where the muf- ceiving the. middle part of the brain. —One between culus ptery-daphylinus internus, or circumflexus palati, the tranfverfe fpinous proceffes, for lodging the part of rifes, and fome fhare of the cartilaginous end of the Eu- the brain where the crura medullas oblongata; are.—Imdachian tube reds; and, at the lower end of the fame mediately before the third .or middle clinoid procefs, a plate, is a hook-like riling or procefs, round which the fingle pit generally may be remarked, from which a foffa tendon of the lad named mufcle plays, as on a pulley. goes out on each fide to the holes through which the op• To thefe another pair may be added, to wit, the tic nerves pafs. The pit is formed by the conjoined oplittle triangular thin procefs, which comes from each fide tic nerves ; and in the foils thefe nerves are lodged, as they
