THE SKULL. 



11 



THE SKULL. 



The skull is formed of twenty-two bones ; of these, 

 eight enter into the formation of the cranium and four- 

 teen into the construction of the face. The bones of the 

 cranium are arranged singly and in pairs. The single 

 bones are the frontal, ethmoid, sphenoid, and occipital; 

 those in pairs, the parietal and the temporal. 



THE FRONTAL BONE. 



The frontal bone is located at the anterior part of 



FIG. 2. FRONTAL BONE, OUTER SURFACE. 



the cranium and forms the forehead. It consists of a 

 vertical and horizontal portion. The vertical portion is 

 convex from side to side and from above downward ; 

 midway between its superior and inferior border, on each 

 side of the median line, are two rounded elevations, 

 known as the frontal eminences, the bases of which, in 

 well-marked specimens, are about the size of a silver 

 half-dollar ; below these, directed horizontally outward, 

 are the rounded superciliary ridges which mark the 



