BONES OF THE HEAD 



61 



and sides' of the skull. Each is roughly quadrilateral, 

 and presents two surfaces external and internal, four 

 borders and four angles. This bone articulates, at 

 the anterior border, with the frontal bone; posterior 

 border, with the occipital bone; internal border, with 

 opposite bone; inferior border, great wing of sphenoid; 

 squamous portion of temporal, and the mastoid por- 

 tion of the temporal. 



FIG. 26 



UGULAR PROCESS 



ARROW IN ANTERIOR 

 CONDYLAR FORAMEN 



The occipital bone, viewed from below. (Spalteholz.) 



The Frontal Bone. This forms the forehead, and 

 also enters into the roofs of the orbital and nasal 

 cavities. Its anterior surface is convex and the con- 

 vexity is greatest on either side, where the rounded 

 frontal eminences are to be seen, separated by a slight 

 depression below from the superciliary ridges. The 

 latter ridges are just above the orbits and afford pro- 

 tection to them from injury. In the middle line be- 

 tween the two ridges is a smooth surface the glabella. 



