134 



OSTEOLOGY 



arched direction are two curved lines, the superior and inferior temporal lines; the 

 former gives attachment to the temporal fascia, and the latter indicates the upper 

 limit of the muscular origin of the Temporalis. Above these lines the bone is 

 covered by the galea aponeurotica; below them it forms part of the temporal 

 fossa, and affords attachment to the Temporalis muscle. At the back part and 

 close to the upper or sagittal border is the parietal foramen, which transmits a 

 vein to the superior sagittal sinus, and sometimes a small branch of the occipital 

 artery; it is not constantly present, and its size varies considerably. 



The internal surface (Fig. 133) is concave; it presents depressions corresponding 

 to the cerebral convolutions, and numerous furrows for the ramifications of the 

 middle meningeal vessel; 1 the latter run upward and backward from the sphenoidal 

 angle, and from the central and posterior part of the squamous border. Along 

 the upper margin is a shallow groove, which, together with that on the opposite 



Occipital 

 angle 



Mastoid 

 angle 



Frontal 

 angle 



Sphenoidal angle. 



FIG. 133. Left parietal bone. Inner surface. 



parietal, forms a channel, the sagittal sulcus, for the superior sagittal sinus; the 

 edges of the sulcus afford attachment to the falx cerebri. Near the groove are 

 several depressions, best marked in the skulls of old persons, for the arachnoid 

 granulations (Pacchionian bodies'). In the groove is the internal opening of the 

 parietal foramen when that aperture exists. 



Borders. The sagittal border, the longest and thickest, is dentated and articu- 

 lates with its fellow of the opposite side, forming the sagittal suture. The squamous 

 border is divided into three parts: of these, the anterior is thin and pointed, bevelled 

 at the expense of the outer surface, and overlapped by the tip of the great wing 

 of the sphenoid; the middle portion is arched, bevelled at the expense of the outer 

 surface, and overlapped by the squama of the temporal; the posterior part is thick 

 and serrated for articulation with the mastoid portion of the temporal. The 



1 Journal of Anatomy and Physiology, 1912, vol xlvi 



