The rather thin boi 

 pyramid between the hiai 

 the petrosquann 

 men tympani. 



Near the ap< ••. oi i 

 shape, usualh but a sligl 

 and lodges the semilunar I i 



The superior border of :i 

 other, shows upon ii 

 margins, the superior pet* 

 it contains a sinus ■ »f the dura mal 



'J'Ik' posterior ( erebral 

 a portion of the posterior i erebral 

 than the posterior border, it exhil 

 foramen (Fig. ; f ", which leads i 

 the facial and auditory ner 



Above and somewhat i 

 petrous portion, there is a depression, I 

 directed toward the apex of the pyramid, 

 distinctly developed and wry large in tin 

 Below and external to it, and at about th 

 slit-like orifice, the external apertui 

 nally and below, and accommodat 

 ear.* In the vicinity of the anterior ; 

 groove, the inferior petrosal . 

 of the occipital bone, forms .1 channel ii 

 of the dura mater see alsi ; 



The posterior border of the p> 1. 

 lateral portions) by the pctro 

 notch (Fig. 56 , com sponding to the 

 ally an intra jugular pt 



The anterior border is 

 b) the sphenopelt 



with the lateral surface ^i the Ixxh 

 the actual apex of the pyramid, I 

 57 I, whi< li leads into thi 

 portion of the temporal bone and I 



Externa] to the internal ( 

 into the middle car beneath the 

 because it contains both the tens 



* A gr ov< 





