Chap. 5 -3 Temporal Bones. gg 



bone is convex. On their inner concave furface we 

 obferve a number of deep furrows, difpofed like the 

 branches of trees, which receive the blood-veffels of 

 the dura mater. On the infide of the upper edge of 

 the ofTa parietalia, there is a large fmtiofity, where the 

 upper part of the falx is fattened, and the fuperior 

 longitudinal finus is lodged. The o(Ta parietalia are 

 the moft equal and fmooth, and are among the thinneft 

 bones of the cranium ; and yet the divifion of their 

 fubftancc into two tables and a diploe is no where fo 

 remarkable. Thefe bones are joined before to the os 

 fronds by the coronal future j at their long inferior 

 angles, to the fphenoid bone, by part of the future of 

 this name j at their lower- edge, to theofla temporum, 

 by the fquamous future ; behind to the os occipitis, 

 by the larnbdoidal future ; and above to one another, 

 by the fagittal future. In a child born at the full time, 

 none of the (ides of this bone are completed, and the 

 brain is in general not completely furrounded by a bony 

 cafe, till fix or feven years of age. 



The ofia temporum are equal and fmboth above, 

 where they terminate in a thin femicircular edge, which, 

 is laid over the inferior part of each of the offa parie- 

 talia, as the fcales of fifli are placed over each other, 

 forming a junclure, which is on this account called 

 fquamous. Behind this, the upper part of the tempo- 

 ral bone is thicker, and more unequal. Towards the 

 bafe of the (kuli, the temporal bone is very irregular 

 and unequal, and becomes contracted into an oblong 

 very hard fubftance ; and being extende,cl forwards and 

 in wards,, becomes fmajler, and is called the os petro- 

 fum, which contains the internal parts of the organ of 

 hearing. This bone .has three remarkable proceffes. 

 The firft placed at the lower and pofterior part of the 

 bone, is from its refcmblance to a nipple called maf- 

 H a tgides 



