JAW. 61 



of the glenoid and condyloid articular cavities, and of the 

 intermediate fibrous cartilage. 0. C. 265. 



"Just under the beginning of the zygomatic process of each 

 temporal bone, before the external meatus auditorius, an oblong 

 cavity may be observed ; in direction, length, and breadth, in some 

 measure corresponding with the condyle of the lower jaw. Before, 

 and adjoining to, this cavity, there is an oblong eminence placed 

 in the same direction, convex upon the top in the direction of its 

 shorter axis, which runs from behind forwards ; and a little con- 

 cave in the direction of its longer axis, which runs from within 

 outwards. It is a little broader at its outer extremity, as the 

 outer corresponding end of the condyle describes a larger circle in 

 its motion than the inner. The surface of the cavity and eminence 

 is covered with one continued smooth cartilaginous crust, which 

 is somewhat ligamentous, for by putrefaction it peels off, like a 

 membrane, with the common periosteum. Both the cavity and 

 eminence serve for the motion of the condyle of the lower jaw. 

 The surface of the cavity is directed downward ; that of the 

 eminence downward and backward, in such a manner, that a trans- 

 verse section of botli would represent the italic letter f. Though 

 the eminence may, on a first view of it, appear to project consider- 

 ably below the cavity, yet a line drawn from the bottom of the 

 cavity to the most depending part of the eminence is almost hori- 

 zontal, and therefore nearly parallel with the line made by the 

 grinding surfaces of the teeth in the upper jaw ; and when we 

 consider the articulation farther, we shall find that these two lines 

 are so nearly parallel, that the condyle moves almost directly 

 forwards in passing from the cavity to the eminence ; and the 

 parallelism of the motion is also preserved by the shape of an 

 intermediate cartilage. 



" In this joint there is a moveable cartilage, which, though 

 common to both condyle and cavity, ought to be considered rather 

 as an appendage of the former than of the latter, being more closely 

 connected with it, so as to accompany it in its motion along the 

 common surface of both the cavity and eminence. This cartilage 

 is nearly of the same dimensions with the condyle, which it covers; 

 is hollowed on its inferior surface to receive the condyle : on its 

 upper surface it is more unequal, being moulded to the cavity and 

 eminence of the articulating surface of the temporal bone, though 

 it is considerably less, and is therefore capable of being moved 

 with the condyle from one part of that surface to another. Its 



