A, The vertebral and basilar arteries and their branches course superficial to the veins. The veins on the anterior surface of the pons and medulla and the petrosal surface drain predominantly into the superior petrosal veins, which empty into the superior petrosal sinuses. B, The arteries have been removed. The median anterior pontomesencephalic and median anterior medullary veins ascend on the front of the brainstem. The transverse pontine and transverse medullary veins run transversely across the pons and medulla surfaces. The anterior hemispheric veins drain the petrosal surface and commonly empty into the vein of the cerebellopontine fissure, which ascends to join the superior petrosal veins. The vein of the pontomedullary sulcus passes across the pontomedullary junction. C, Enlarged view of the right petrosal surface. The anterior hemispheric veins drain the petrosal surface and pass forward to empty into the vein of the cerebellopontine fissure or a superior petrosal vein. The vein of the cerebellopontine fissure arises at the lateral apex of the cerebellopontine fissure and crosses the middle cerebellar peduncle, where it is joined by a large transverse pontine vein. D, Enlarged view of the left petrosal surface. The vein of the cerebellopontine fissure arises from the union of the anterior hemispheric veins at the apex of the cerebellopontine fissure and ascends to be joined by a superior hemispheric vein from the lateral part of the tentorial surface before emptying into the superior petrosal sinus. E, The cerebellum has been removed to expose the veins of the superior, inferior, and middle cerebellar peduncles. The vein of the superior cerebellar peduncle ascends to join the vein of the cerebellomesencephalic fissure. The vein of the inferior cerebellar peduncle crosses the peduncle at the inferolateral margin of the fourth ventricle and passes around the lateral recess to join the veins in the cerebellopontine angle. The veins of the cerebellopontine fissure and middle cerebellar peduncle and a transverse pontine vein join to form a superior petrosal vein. The vein of the cerebellomedullary fissure empties into the vein of the middle cerebellar peduncle. F, Posterior view of the right cerebellopontine angle. The vein of the cerebellomedullary fissure passes laterally across the lateral recess and empties into the vein of the middle cerebellar peduncle. The latter vein and the vein of the cerebellopontine fissure join to form a large superior petrosal vein. A large anterior hemispheric vein ascends along the petrosal surface. (Images courtesy of AL Rhoton, Jr.)