Inferior view of the pineal region posterior to the midbrain. The superior colliculus and pineal gland are visible with retraction of the precentral cerebellar vein (also known as the vein of the cerebellomesencephalic fissure). Also visualized are the deep veins of the cerebrum: the basal veins of Rosenthal join the internal cerebral veins. Together, these veins form the vein of Galen. Medial posterior choroidal arteries are visualized here and usually arise from the proximal P2 segment of the posterior cerebral artery. (Image courtesy of AL Rhoton, Jr.)