Anterolateral view of pontomesencephalic junction. The midbrain, pons, and portion of right cerebellum are in view. The basilar artery, formed by union of the right and left vertebral arteries, ascends on the pons midline beginning at the pontomedullary junction. The anterior inferior cerebellar arteries arise from it proximally followed by smaller transverse running pontine arteries. Distally, the superior cerebellar arteries arise and the basilar artery terminates with the posterior cerebral vessels. Near this junction, the posterior cerebral artery receives the posterior communicating artery from the internal carotid. At the interpeduncular fossa the oculomotor nerves emerge from the midbrain and pass between the superior cerebellar and posterior cerebral arteries. The trochlear nerves originate on the dorsal surface of the midbrain and wrap around the cerebral peduncles coursing forward toward the cavernous sinus. The trigeminal nerves emerge from the anterolateral aspect of the pons. The abducens nerves emerge at the pontomedullary junction near the midline, while the facial and vestibulocochlear nerves emerge from the anterolateral aspect. The labyrinthine artery, a branch of the anterior inferior cerebellar artery, can be seen coursing with this right nerve bundle toward the internal auditory meatus. (Image courtesy of PA Rubino)