10 



HUMAN ANATOMY. 



Its muscular attachments are three pairs, corrugator super- 

 cilii, orbicularis palpebrarum, and temporal. 



It is developed from membrane by two ossific centres, one 

 for each lateral half. 



PARIETALS. These are two quadrilateral bones forming the 

 superior and lateral walls of the cranium. Each bone consists 

 of two surfaces, four borders, and four angles. 



The external surface is convex and presents the parietal emi- 

 nence a little above the middle, marking the original centre of 

 ossification, the temporal ridge, crossing about the centre for at- 

 tachment of the temporal fascia, and the parietal foramen, near 

 the superior border or sagittal suture, for passage of a vein to 

 the longitudinal sinus. 



FIG. 4. 



1, 2. 3, 4, superior, inferior, anterior, and posterior borders; 5, su- 

 perior longitudinal sinus; 6, parietal foramen; 7, anterior inferior 

 angle. 



The internal surface is concave, and presents furrows for 

 the branches of the meningeal arteries, depressions for cerebral 

 convolutions, and Pacchionian bodies; 



A half groove along the superior border for longitudinal 

 sinus, and 



A groove near the posterior inferior angle for the lateral 

 sinus. 



The superior border articulates with its fellow of the oppo- 

 site side, forming the sagittal suture; 



The inferior border articulates from before backward with 

 the sphenoid, squamous, and mastoid portions of temporal bones; 



The anterior border forms with the frontal bone the coronal 

 suture, and 



