Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/165

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tiort of ligaments. The external lateral fide, or that next the fecond bone is unequally concave, and cartilaginous to- ward the fuperior and pofterior edges. The largeft portion of this fide is articulated with the fecond bone. The reft to- ward the anterior edge is joined laterally to the fecond bone of the metatarfus. The backfide is the !eaft ; it is cartilaginous and almo I triangular, fuited to the firft of the three triangular furfaces of the os fcaphoides. The anterior fide is cartilagi- nous, laro-e, and- fetni lunar, the convex edge being turned toward the other foot, and by this the firft »s curfeifoi me is ar- ticulated with the firft bone of the metatarfus. The angle is turned upwards, and the obliquity of it occasions the anterior fide to be the higheft, and the poftcrior lower!-. The fecond cs cur. if) me has the bafis upward, and the angle downward, and refemhles a wedge more than the firft : (his baiis is fhort and rough, for the infertions of ligaments. The backfide is cartilaginous, and perfectly triangular, fuited to its articula- tion, with the middle furface of the convex fide of the osfca- phoides The anterior fide is alfo cartilaginous, a little more oblong and articulated with the bafts' of the fecond metatarfal bone. The two lateral fides have, toward their fuperior and pofterior edges, oblong cartilaginous furfaces, by which they arc articulated with the firft and third offa cUneiformta ; the reft of thefe two fides is a little deprefted, and there, by fmall interfaces, void fpaces are left between the bones : this is every way the ftraiteft bone of the three, its angles hid be- tween the two other bones of the fame name, and does not reach fo low as theirs, which makes this part of the foot a lit* tie hollow The third os cuneiforms has likewife its bafis up- ward, and its angle downward. The bafis is longer than that of the fecond, almoft flat or very little convex, and rough for the infertion of ligaments j the angle runs down lower than that of the fecond bone. The backfide is car- tilaginous and triangular, that is of the fame figure with the third fuii'ace of the convex fide of the os fcaphoides : the anterior fide is, likewife, cartilaginous and triangular, but alittleoblong,being articulated with the bafis of the third bone of the metatarfus. The internal lateral fide is broad, with two cartilaginous furfaces, one toward the pofterior edge, the other toward the anterior ; the firft is for its lateral arti- culation with the fecond os cumifsrme ; the fecond for its lateral articulation with the bafis or the fecond metatarfal bone. The external lateral fide is likewife broad, and toward its pofte- rior edge has a large cartilaginous furface for its articulation with the os cuboides towards its anterior edgc.There is a fort of void fpace for the paffage of vefle!s,and fometimes a little cartilagi- nous corner for its lateral articulation with the fourth bone of the metatarfas. WrnJIovfs Anatomy, p. 100.

Ctvti'agcs of the O'- femoris. No part of the os femarh is covered, except the uniform convexity of the head, and the articular portion of the lower extremity. The trochanters have no true cartilage, what appears like it being only the remains of tendinous infertions; the cartilaginous fubftance, which to a certain age unites the apophyfes to the body of the bone, does not belong to thefe, becaufe it is only found in the time of youth, and in adults is converted into a bone. The carti- laginous matter, by which the head of the os femoris is ce- mented, deferves, however, to be obferved here, becaufe that apophyfis has been fcparated by violent falls. The con- vexity of the head of the cs fepiorh, all the way to its fymphy- its with the neck,is covered with a very fmooth, fhining carti- lage. A little below the middle of this convexity, and fome- thing toward the back part, there is a depreffion in the fhape of a crefcent, the cartilage being here interrupted by the in- fertion of the internal articular ligament of the head of the os femoris. The cartilage which covers the lower extremity of this bone is exactly fitted to the femf-oval convexity of the inferior furface of each condyle, and to the pulley formed by their union. WinjtovS* Anatomy, p. 126.

Ligaments of the Osfcmms. The os femoris is connected by its upper extremity to the os innominatum, and by the lower to the bones of the leg, by means of feveral ligaments. The li- gaments of the upper extremity are two in number, one which furrounds the whole articulation thereof, with the co- tyloide cavity, and one contained in the articulation. The firft is termed the orbicular ligament of the head of the os fe- moris ; the other the internal ligament ; and to thefe may be, though but improperly, added a third, which is of the nature of a capfular ligament. The orbicular ligament is themoft confiderable, the largeft, and the ftrongeft, of all the articular ligaments of the human body ; it is fixed quite round the bor- der of the cotyloide cavity, and is made up of feveral forts of fibres, and is much ifronger and thicker hi fome parts than in others ; the other, or internal ligament of the head of the os femoris, rcfemblcs a flat cord, and is compofed of a bundle of flat fibres, clofely interwoven. The ligaments of the lower extremity of the os femoris, by which this bone is connected with the leg, are fix in number, one pofterior, two lateral, two middle, or crucial, ahd the capfular. The crucial liga- ments lie within the joint, and are fixed by one end to the back part of the notch, or opening, which parts the two con- dyles : thefe are furrounded by the capfular ligament, but all the reft lie on the outfide thereof, being clofely joined to it. Of the two lateral ligaments, one is internal, and broad, being

fixed to the tuberosity of the internal condyle ; the other is ex-^ ternal, and narrow, and is fixed to the tuberufity of the exter- na! condyle. The pofterior ligament is broad and thin, and being fixed a little above the convexity of the external con- dyle, it thence defcends obliquely behind the great notch, and internal condyle. The capfular ligament is, as it were, glued to the three former, and is fixed^quite round the inferior ex- tremity of the osfermrh ; at a fmall diftance above the anteri- or, lateral, and pofterior parts of the cartilage, and above the pofterior part of the great notch ; and from the cartilage and notch, through the fmall fpace upward already mentioned, it covers the bone, and afterwards is inverted' downward, to form the capfula for the mucilaginous liquor of the joint. Wtnjlows Anatomy, p, 126. Osfrom-is. This is fituated in the anterior part of the skull, and forms that part of the face which is called the forehead, from whence it has its name. Its figure is fymmetrical, refembling a large fhell almoft round. Tho' this has always been looked upon as .one bone, it is to be obferved that it is fometimes found divided into two equal parts by a continuation of the fagittal future ; and this divifion is equally common to both fexes. Confidered as one bone it may be divided into an up- per part, which belongs to the crown of the head, a lower part which belongs to the bafis of the skull, an anterior part which is the forehead, and two lateral parts at which the temples begin, Its two fides are the one external, which is in its greateft part convex, and forms the forehead ; the other internal, which is concave in proportion. On the outfide are obferved the following eminences : Two fuperciliary arches, which form the upper edge of each orbit, or die fu- percilia; three riiings not always equally apparent, one be- tween the two arches, and the other two above them ; winch may be called the knobs of the forehead : five apophvfis, one at the extremities of each arch, one between the orbits, which fuftain the ofla nafi, and which in fome fubjects makes a part of the bony feptum of the nofe. This laft may be called the nafal apophyfis, the other four the angular apo- phyfes. The external cavities are thefe two orbitary por- tions or vaults forming the upper portions of the orbits : a remarkable depreffion in each of thefe vaults above the ex- ternal angle, which contains the lachrymal gland : a fmall depreffion above the internal angle, to which is fixed the car- tilaginous pully of the great oblique mufcle of the eye; two portions of the temporal foflse ; two little crifhe which form the anterior extremity of the great femicircular plane of the temples, on each fide, at the edge of the fuperciliary arches, near the external angle; two fuperciliary foramina, which are fometimes double, and fometimes only notches ; and, laftly, two holes or portions of holes, called the internal orbitary holes.

On the infide of this bone we fee a fliarp perpendicular emi- nence, called the frontal or coronal fpine, directly oppofite to the middle rifing on the outfide already mentioned ; above this fpine, a portion of the groove for the longitudinal finus, which when the fpine is wanting, runs down lower; below the fpine a confiderable opening, called the ethmoidal open- ing, becaufe it contains the os ethmoides ; the fides of this are always more or lefs cellular. Between this opening and the coronal fpine, a blind opening, which in fome fubjects is wholly in the os froxti's, in others, common to that bone and to the os ethmoides, and which feems to open into the fron- tal finufes near the nofe. The anterior foflie of the bafis of the skull, which receive the anterior lobes of the brain, and which, by juting out forwards, form the rifings on the outfide, before taken notice of : toward the lower part they are uneven, anfwering the inequalities of the lobes, and they are alfo a little raifed, to make room for the orbits, fulci or furrows of the arteries of the dura mater, and fometimes other indeterminate depreffions. Tho' this bone is in general compofed of two tables, ^and a diploe, yet the orbitary vaults are very thin, and without any diploe. About the middle of the lower part of the bone, where the middle rifing is com- monly fituated, the two tables are parted, to form two ca- vities called the frontal, or fuperciliary finufes, and the fe- parated portions are here each of them compofed in fome nieafure of two tables, or at leaft have two furfaces, which make in all four furfaces of each of the two tables. The frontal finufes are extended on the edge of the fupercilia- ry on each fide, more or lefs, all the way to the fuperciliary perforations ; below they are open, and communicate with the cells of the os cribrofum. They are commonly parted by a bony feptum, which is often more or lefs uneven ; fometimes alfo it is perforated, and fometimes part of it, fometimes the whole is wanting.

In different fubjects thefe finufes are obferved to vary ex- tremely both in extent and form ; in fome they are very (mail, and often very irregular, and their difpofition cellulous ; fome- times alfo they are entirely wanting, and in fuch fubjects the cavity of the nofe is larger than ordinary ; cue of them does not open into the nofe but only communicates with the other.

The os frontis is articulated by future with feven other bones, the ofla parietal ia, os ethmoides, os fphenoides, offa lacry- malia, ofla nafi, maxillaria, and the offa malarum. It con-