Lateral surface of pons and medulla. The left aspect of the cerebellum has been retracted to show the caudal brainstem. The posterior inferior cerebellar artery, a branch of the vertebral artery, is seen wrapping around the lower lateral surface of the medulla to the posterior inferior surface of the cerebellum. The basilar artery is in lateral view on the anterior pons. It gives rise to the two other cerebellar arteries, the anterior inferior and superior cerebellar arteries, to their respective surfaces on the cerebellum. Rostrally, the trigeminal nerve emerges from the anterolateral aspect of the pons while the facial and vestibulocochlear nerves emerge along the lateral aspect of the pontomedullary junction. Anteriorly at this junction arise the abducens nerve which is crossed anteriorly by the anterior inferior cerebellar artery. The facial and vestibulocochlear nerves enter the internal auditory meatus. The main trunk of the facial nerve is seen coursing along the medial wall of the middle ear cavity with its ossicles before bending downward toward the stylomastoid foramen. The rootlets of the glossopharyngeal, vagus, and cranial roots of the accessory nerves emerge from the lateral medulla. These and the spinal root of the accessory nerve course toward the intracranial opening of the jugular foramen as does the inferior petrosal sinus. The rootlets of the hypoglossal nerve emerge from the medulla more anteriorly and converge into the definitive nerve that enters the hypoglossal canal located between the jugular foramen and edge of foramen magnum. (Image courtesy of AL Rhoton, Jr.)