62 



OSTEOLOGY 



The orbital arch ends in extremities called the internal 

 and external angular processes. The frontal sinuses 

 (hollow spaces) which communicate with the nasal 

 cavities contain air, and are lodged in the frontal 

 bone just above the orbital arches. The frontal bone 

 articulates with twelve bones the parietals, the 

 sphenoid, the malars, the nasals, the superior maxillae, 

 lacrymals, and ethmoid. 



FIG. 27 



Left parietal bone, external surface. (After Gray.) 



The Temporal Bones. These are paired, assist in 

 forming the sides and base of the skull, and contain 

 the organ of hearing. They present three parts 

 squamous, petromastoid, and tympanic. 



