III.] 



THE CRANIAL SKELETON. 



75 



the brain and spinal marrow are connected and become 

 continuous through this occipital foramen. 



If the skull be turned base upwards, a strong bluntly 

 pointed prominence will be seen to project from each outer 

 margin on a line passing from right to left through the occi- 

 pital condyles. The prominence is called,, from its shape, the 

 mastoid ' process. 



FIG. 83. Side view of Man's Skull the lower jaw being slightly removed, and 

 the line of ligamentous attachment of the hyoid represented by a dotted line. 



a, greater wing of the sphenoid bone ; a, opening of external auditory meatus ; 

 bh, body of the hyoid ; c, an occipital condyle ; c ' , corniculum of hyoid ; cr, 

 coronoid process ; cy, condyle of the lower jaw ; f, frontal bone ; j, malar ; 



/, lachrymal ; rn, mastoid process ; m.r, maxillary bone ; , nasal bone ; 

 occipital bone ; p, parietal ; pt, internal pterygoid process ; s, squamous part 

 of the temporal bone ; st, styloid process (connected by a dotted line with 



corniculum of hyoid) ; ty, greater cornu of hyoid ; z, zygomatic process of 

 temporal bone. 



The under surface of the face (formed by the bones of the 

 roof of the mouth) lies at a different level from that of the 

 base of the skull proper. Connecting these two surface? 

 there are on each side a pair of vertical bony plates ter- 



* From /biao-TO, a nipple. 



