176 MAMMALIAN ANATOMY 



two upper cover the cerebrum and the two lower support the cere- 

 bellum. 



The basilar process is very little wider than it is thick. On its 

 lower surface is a median projection, the pharyngeal tubercle, for the 

 attachment of the median part of the pharynx. Its lateral surface is 

 roughened for articulation with the petrous of the temporal. The 

 quadrate anterior surface joins the sphenoid. The jugular notches 

 are prolongations of the grooves for the lateral sinuses, and the anterior 

 condyloid foramina pierce arching plates, sometimes called the jugular 

 tubercles, which are impressed transversely by grooves for cranial 



nerves. 



THE PARIETAL BONES. 



General Description. The Pari'etals are two thin, curved plates 

 which are united by their upper edges to form the back part of the 

 vault of the cranium (Fig. 115). They are joined in front to the 



FIG. 115. 



POSITION OF LEFT PARIETAL BONE. SIDE VIEW. 



frontals, below to the sphenoid and the temporals, and behind to the 

 occipital and the interparietal. 



Each parietal is nearly square, a little longer than high, and 

 presents on examination two surfaces, four borders, four angles, and 

 an internal plate-like tento'rium l or tentorial process. 



The outer surface (Fig. 116) is strongly convex, except for a 

 narrow strip along the posterior border which is flat or even slightly 

 concave from before backward. The highest point of the convexity 

 is somewhat behind and above the centre of the bone, and is known as 

 the parietal eminence. Below this eminence a faint curved temporal 



1 A tent. 



