THE BONES OF THE HEAD 



63 



temporal muscle, and the portion between it and the inferior border, 

 which is vertically striated and called the planum iemporale, 

 forms a part of the temporal fossa, and gives origin to fibres of the 

 temporal muscle. Near the superior border, about an inch in front 

 of the postero-superior angle, is the parietal foramen, for an emissary 

 vein which passes between the intracranial superior longitudingil 

 sinus and one of the tributaries of the extracranial occipital vein. 



The internal surface is concave, its deepest part, opposite the 

 parietal eminence, being known as the parietal fossa. This siu-face 

 presents a number of digitate impressions for the convolutions of 



Superior Border 



Parietal Foramen 



Anterior Border 



Posterior Border 



Superior Temporal 

 Ridge 



Inferior Border 



Inferior Temporal Ridge 



Fig. 42. — The Right Parietal Bone (External View). 



the parietal and part of the frontal lobes of the cerebrum, and a 

 system of branching meningeal grooves for the divisions of the 

 middle meningeal artery. These commence as two grooves, each 

 of which soon becomes arborescent. The anterior, the larger of 

 the two, commences on the inner surface of the antero-inferior 

 angle, where it may be bridged over into a short canal, and the 

 posterior starts from the centre of the inferior border. Superiorly, 

 close to the superior border, there is a half groove which, ^^dth 

 that of the opposite bone, lodges the superior longitudinal venous 

 sinus. Along the course of this groove, but external to it, are 

 several depressions, best marked in old persons, which lodge the 



