18 



Bones of the Skull. 



r 



Facies parietalis x Angulus 



occipitalis 



- Margo sagittalis 



Foramen parietale 



Tuber parietale 

 , Linea temporalis inferior 



i i 



, Linea temporalis superior 



Margo occipitalis yg 



Angulus frontalis 



Margo frontalis 



Angulus mastoideus 



Margo squamosus 



Angulus sphenoidalis 



19. Right parietal bone, os parietale, from without. 



The OS parietale (parietal bone) (see also Figs. 20, 55, 56, 6166) is paired and 

 helps to form the roof and lateral wall of the skull. It is a quadrangular, flat, saucer-shaped 

 bone with an external, convex fades parietalis and an internal, concave fades cerebralis. 



The bone has four margins, and four angles. The posterior convex margin, mar go 

 occipitalis, is deeply serrated and unites with the margo lambdoideus oss. occip. to form the 

 sutura lambdoidea. The inferior margin, margo squamosus, is concave and bevelled from 

 without ; it is attached to the margo parietal, oss. temper, (sutura squamosa). The anterior, 

 slightly concave margin, margo frontalis, is serrated and unites with the margo parietal, oss. 

 front, to form the sutura coronalis, and the upper straight, markedly serrated margin, margo 

 sagittalis, forms with the same margin of the opposite parietal bone the sutura sagittalis. 

 The anterior superior angle, angulus frontalis, lies in the middle of the sutura coronalis and 

 adjoins the frontal bone; the posterior superior angulus occipitalis, adjoins the upper extre- 

 mity of the squama occipitalis. The posterior inferior angle, angulus mastoideus, is inserted 

 in the incisura parietal, oss. tempor. and forms there with the upper margin of the pars 

 mastoid. oss. tempor., the sutura parietomastoidea. The anterior inferior angle, angulus 

 sphenoidalis , is bevelled from without, attached to the angul. pariet. of the ala magna oss. 

 sphenoid, and forms with this the sutura sphenoparielalis. 



