A, Tentorial surface. The tentorial surface is drained by the superior hemispheric and superior vermian veins, which are divided into an anterior and a posterior group. The anterior group and the veins from the cerebellomesencephalic fissure empty pre-dominantly into the vein of Galen and its tributaries. The posterior group drains the posterior part of the tentorial surface and empties into the tentorial sinuses, which are tributaries of the straight, transverse, or superior petrosal sinus, or the torcula. Some of the inferior hemispheric veins from the suboccipital surface pass forward under the transverse sinus and cross the posterior part of the tentorial surface to empty into the tentorial sinuses. B, Suboccipital surface. The suboccipital surface is drained by the inferior hemispheric and inferior vermian veins, which ascend toward the transverse sinus, but then turn forward below the sinus and commonly empty into the tentorial sinuses. Some of the inferior hemispheric veins from the suboccipital surface empty into the inferior vermian veins, which in turn empty into the tentorial sinuses. C, Petrosal surface and anterior surface of the brainstem. The anterior hemispheric veins, which drain the petrosal surface, and the veins from the brainstem commonly unite to form the superior petrosal veins that empty into the superior petrosal sinus. (Images courtesy of AL Rhoton, Jr.)