Venous Drainage of the Central Core. A, The temporal operculum was removed in this lateral view, and the superficial sylvian vein can be seen draining into the sphenoparietal sinuses at the sphenoid bone. The insular veins drain into the deep sylvian vein, which later empties into the anterior part of the basal vein of Rosenthal, and the posterior thalamic vein drains into the posterior part of the basal vein of Rosenthal at its course along the perimesencephalic cisterns. B, The superior and medial aspects of the central core are drained by a ventricular group of veins that pass through the choroidal fissure to join the internal cerebral veins located inside the velum interpositum cistern at the roof of the third ventricle. The internal cerebral veins exit this cistern posteriorly over the pineal gland and are joined by the basal veins to form the great vein. C, In this superior view of an axial cut of the brain, the ventricular veins drain mainly into the thalamostriate veins, which join the anterior septal veins to form the internal cerebral veins. Both fornices were cut and retracted to show the internal cerebral veins at the velum interpositum cistern, located between the third ventricle inferiorly and the fornices superiorly. (Images courtesy of E de Oliveira)