E, Enlarged view of the area below the left anterior perforated substance. The olfactory, anterior cerebral, posterior fronto-orbital, and deep sylvian veins join to form the basal vein. The inferior ventricular vein joins the basal vein at the posterior edge of the cerebral peduncle. F, Inferior view of the cerebral hemispheres with the parahippocampal gyri removed to expose the temporal horns and atria. The left fimbria and posterior cerebral artery have been preserved. The left inferior ventricular vein passes above the choroid plexus and through the choroidal fissure located between the fimbria and thalamus. The lateral atrial veins also pass through the choroidal fissure. The lower lip of the calcarine sulcus has been removed on both sides to expose the anterior calcarine veins and calcarine artery and the upper lip of the fissure formed by the cuneus. G, The left fimbria, posterior cerebral artery, and choroid plexus have been removed to expose the inferior ventricular vein crossing the roof of the temporal horn. The anterior calcarine veins, which empty into the vein of Galen, are exposed below the cuneus. H, The floor of the third ventricle has been removed to expose the fornix coursing above the foramen of Monro. The massa intermedia and posterior commissure are exposed. The basal veins pass around the midbrain to join the vein of Galen. Small hypothalamic veins join the anterior end of the basal vein. (Images courtesy of AL Rhoton, Jr.)