BONES OP THE CRANIUM. 181 



surface is smooth and convex, in the centre of which is the 

 parietal protuberance. On either side of this protuberance, 

 and extending in an arched direction transversely across 

 the hone is the temporal FlG - 37 - 



ridge; helow this ridge the 

 temporal muscle is attach- 

 ed, above the aponeurosis 

 of the occipito-frontalis. 

 The inner or cerebral sur- 

 face is marked by the mid- 

 dle artery of the dura ma- 

 ter, and the convolutions of 

 the brain. The trunk of 

 this artery is seen in the 

 anterior inferior angle of 

 the bone, lodged in a groove, and branching upwards and 

 backwards. 



The circumference presents four edges and. four angles, the 

 anterior edge is serrated and unites with the frontal bone in 

 the coronal suture. The posterior is very irregular and 

 joins the occipital in the lambdoid suture. The superior is 

 the longest and meets its fellow on the middle line in the 

 sagittal suture. The inferior is the shortest, is thin, and 

 unites with the temporal by the squamous suture. 



Of the angles, the anterior superior is nearly straight ; 

 this, in the infant is wanting, the anterior fontanelle or open- 

 ing taking its place. This opening is four-cornered, and 

 is made so by a similar deficiency in the superior project- 

 ing points of the frontal bone. The anterior inferior angle 

 is long and curved, and unites with the sphenoid bone. 

 The posterior superior is rounded, and by its deficiency 

 forms the posterior fontanelle. The posterior inferior is 

 very irregular and unites with the mastoid portion of the 

 temporal. 



FIG. 37 represents internal surface of left Parietal Bone, a Sagittal suture, 

 6 Line for squamous suture, c Coronal suture, d Lambdoidal suture. 

 Groove for superior longitudinal sinus. / Parietal foramen, g Inferior ante- 

 rior angle and groove for middle artery of dura mater, h Inferior poste- 

 rior angle. ^ 



