Vasculature of the posterior brainstem.  The temporal lobe and tentorium cerebelli have been retracted superiorly and the cerebellum has been retracted inferiorly to expose the vessels located on the posterior aspect of the brainstem. The posterior cerebral artery is visible on the inferior surface of the temporal lobe, and the superior cerebellar artery supplying the superior aspect of the cerebellum.  From this view, numerous veins can be seen coalescing at the posterior aspect of the midbrain. The paired internal cerebral veins course posteriorly along the roof of the third ventricle and unite with the basal veins of Rosenthal to form the great cerebral vein of Galen in the quadrigeminal cistern. At the apex of the tentorium cerebelli, the great cerebral vein joins the inferior sagittal sinus to form the straight sinus. (Image courtesy of AL Rhoton, Jr.)