CHAP, in.] SKELETON OF THE HEAD AND TRUNK. 63 



corpnal^ suture, and below with the temporal bone by a suture (sq) 

 which is called squamous, because the margins of the bone it joins 

 are so bevilled off that the temporal lies on the parietal like a scale. 

 From the hinder margin of the parietal a plate of bone extends for- 

 wards at an acute angle, with a strongly concave free margin. This 

 plate divides one part of the brain from another, and is an ossifica- 



A B 



Fig. 33. RIGHT PARIETAL BONE. 



A. Internal surface. 



B. External surface. 

 e. Parietal eminence. 



/. Surface for articulation with frontal. 

 sq. Surface for temporal bone. 

 t. Tentorium. 



tion of a membrane called the tentorium, and described with the 

 brain structures (t). The parietal is always a single bone. 



25. The remaining bones of the roof of the skull are the 

 FRONTALS, which lie side by side in front of the parietals, and roof 

 over the hinder part of the face as well as the front part of the 

 cranium. The suture which divides them is termed the " frontal 



Fig. 34. THE FRONTAL. 



A. External aspect. 



B. Internal caspect. 



/. Surface joining the other frontal. 

 fu. Outer wall of nasal fossa. 

 m. Nasal process. 



op. Orbital part of lateral plate. 

 tp. Temporal part of lateral plate, 

 p. Pre-orbital process. 

 po. Post-orbital process. 



suture," and is the direct continuation forwards of the sagittal suture. 

 The frontals together form a considerable, rather convex triangular 

 expansion above, the outermost part of which is the post-orbital 

 process (po) of the hinder part of the orbit ; while behind this the 

 frontal forms part of the temporal fossa. 



But the greater part of each frontal is its lateral part (0p), ffhiph 

 descends from the outer margin, almost at right angles with its 



