The cerebral veins are divisible into external (superficial cerebral veins) and internal (internal cerebral veins) groups according to the outer surfaces or the inner parts of the hemispheres they drain into. The cerebral veins are divisible into external (superficial cerebral veins) and internal (internal cerebral veins) groups according to the outer surfaces or the inner parts of the hemispheres they drain into. The external veins are the superior cerebral veins, inferior cerebral veins, and superficial middle veins. This article incorporates text in the public domain from page 652 of the 20th edition of Gray's Anatomy (1918)