THE PAKIETAL BONES. 



119 



The cerebral surface is concave from before backwards and from above down- 

 wards. It is moulded over the surface of portions of the frontal, parietal, occipital, 

 and temporal lobes of the cerebrum, and displays impressions corresponding to the 

 arrangement of the gyri of those portions of the brain. It also presents a series 

 of well-marked grooves for the lodgment of the veins which accompany the 

 branches of the middle rneningeal artery (F. Wood Jones) ; these radiate from the 

 sphenoidal angle of the bone, the best marked running upwards at some little 

 distance behind and parallel to its anterior border. Close to the superior margin 

 there is a series of depressions for arachnoideal granulations, and there also the bone is 

 channelled so as to form a groove (sulcus sagittalis), which is completed by articulation 

 with its fellow of the opposite side. Within the groove lies the superior sagittal 

 venous sinus, and to its edges the falx cerebri is attached. Close to the mastoid 

 angle there is also a curved groove, the transverse sulcus, in which the highest 

 portion or bend of the transverse venous sinus is lodged. 



Parietal tuberosity 



Parietal 

 foramen 



Frontal angle 



Superior temporal line 



Inferior temporal line 



Sphenoidal 

 angle 



For articulation with the 

 great wing of the sphenoid 



For articulation with 

 the squamous part of 

 the temporal 



Mastoid angle v For articulation with the mastoid part of the temporal 



FIG. 131. THE RIGHT PARIETAL BONE (Parietal Surface). 



The anterior, superior, and posterior borders are deeply serrated. The anterior 

 border articulates with the frontal bone, forming with it the coronal suture. In 

 the superior part of this suture the frontal bone overlaps the parietal, while the 

 parietal overlies the frontal below. The posterior border is united with the 

 occipital bone to form the lambdoid suture. The superior border articulates with 

 its fellow of the opposite side by means of the sagittal suture ; in the interval 

 jtween the two parietal foramina this suture is usually simple in its outline, 

 "he frontal angle is almost rectangular, and corresponds to the site of the anterior 

 fontanelle. The occipital angle, usually more or less rounded, corresponds in 

 sition to the posterior fontanelle. The inferior border (margo squamosus) is 

 irved, and shorter than the others ; it lies between the sphenoidal and mastoid 

 ingles. Sharp and bevelled at the expense of its outer table, it displays a fluted 

 mgement, and articulates with the squama temporalis of the temporal bone, 

 sphenoidal angle, pointed and prominent, articulates with the great wing 

 )f the sphenoid. It is wedged into the angle formed by the union of that bone 

 ith the frontal, and is bevelled at the expense of its inner table anteriorly, 



8 a 



