THE CEREBRAL VEINS 



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of (1) the frontal diploic vein (y. diploica frontalis), which opens into the supra- 

 orbital vein by an aperture in the supraorbital notch; (2) the anterior temporal 

 diploic vein (v. diploica temporalis anterior), which is confined chiefly to the 

 frontal bone, and opens into one of the deep temporal veins through an aper- 

 ture in the greater wing of the sphenoid; (3) the posterior temporal vein (v. diploica 

 temporalis posterior), which is situated in the parietal bone, and terminates in the 

 lateral sinus through an aperture at the postero-inferior angle of the parietal bone 

 or through the mastoid foramen; and (4) the occipital diploic vein (v. diploica 

 occipitalis), the largest of the four, which is confined to the occipital bone, and 

 opens into the lateral sinus or the torcular Herophili. 

 The emissary veins are considered on page 730. 



FIG. 501. Veins of the diploe as displayed by the removal of the outer table of the skull. 



The meningeal or dural veins (vv. meningeae) chiefly correspond with the 

 middle meningeal artery and its branches, as its two venae comites. The veins 

 accompany the middle meningeal artery, are united to the sphenoparietal sinus, 

 pass through the foramen spinosum, and join the pterygoid plexus. The other 

 dural veins correspond somewhat to the anterior and posterior meningeal distribu- 

 tion and empty into the neighboring sinuses. 



The Cerebral Veins (Venae Cerebri). 



The cerebral veins possess no valves, and their walls, owing to the absence of 

 muscle tissue, are extremely thin. They pierce the arachnoid membrane and the 

 inner or meningeal layer of the dura and open into the cranial venous sinuses. 

 They may be divided into two sets, cerebral and cerebellar. 



The cerebral veins consist of (a) the superficial veins, which are placed on the 

 surface of the brain, and (6) the deep veins, which lie in its interior. 



The superficial cerebral veins (venae cerebri externae) ramify upon the surface 

 of the brain, being lodged in the fissures between the convolutions, a few running 

 across the convolutions. They receive tributaries from the substance of the brain 

 and terminate in the sinuses. They are divisible into two sets, superior and 

 inferior. 



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