A, The falx cerebelli, which fits into the posterior cerebellar incisura in which the vermis is partially buried, has been preserved. The inferior hemispheric veins drain the hemispheric portion of the suboccipital surface. A large left inferior hemispheric vein ascends toward a tentorial sinus. A large right inferior hemispheric vein descends medially to join an inferior vermian vein, which ascends to empty into the sinuses in the tentorium. The occipital sinus courses within the falx cerebelli and joins the torcula above and the sigmoid sinus below. B, The falx cerebelli has been removed to expose the inferior vermian veins, which ascend and pass below the transverse sinus to empty into the tentorial sinuses. The retrotonsillar veins and other veins around the superior pole of the tonsils ascend to join the inferior vermian veins. C, The branches of the PICA supplying the left hemisphere have been removed, but those on the right have been preserved. The inferior vermian and hemispheric veins on both halves of the suboccipital surface ascend and pass below the transverse sinus to empty into the sinuses in the tentorium. D, Enlarged view of the inferior vermian veins that ascend to empty into sinuses in the tentorium. E, Another cerebellum. A large right inferior hemispheric vein joins an inferior vermian vein that crosses the upper edge of the suboccipital surface and courses for a short distance on the tentorial surface before emptying into a tentorial sinus. F, Enlarged view of another cerebellum. The large right inferior vermian vein passes forward to join the sinuses in the tentorium. A superior hemispheric vein from the tentorial surface descends to join a tentorial sinus. In the midline, a superior and inferior vermian join to empty into a tentorial sinus. (Images courtesy of AL Rhoton, Jr.)