Anterior brainstem and associated neurovasculature. The caudal midbrain, pons, and proximal medulla are in view along with lateral portions of the cerebellum. The vertebral arteries join near the pontomedullary junction to form the basilar artery. The posterior inferior cerebellar arteries are the largest branches of the vertebral arteries and are one of three pairs of vessels supplying the cerebellum. The posterior inferior cerebellar artery is seen wrapping around the lower lateral surface of the medulla to the posterior inferior surface of the cerebellum. Two other cerebellar arteries, the anterior inferior and superior cerebellar arteries, arise respectively from caudal and rostral portions of the basilar artery and course to their destinations on the cerebellum. Between these branches arise several smaller pontine arteries that course transversely on the pons. The trochlear nerve emerges from the dorsal surface of the midbrain while the oculomotor nerve emerges from its anterior surface. The latter nerve passes between the superior cerebellar and terminal posterior cerebral arteries, which supply the occipital and posteromedial temporal lobes. The trigeminal nerve emerges from the anterolateral surface of the pons. It expands into the sensory trigeminal or Gasserian ganglion from which arise the three divisions of this nerve, V1 or ophthalmic nerve; V2, or maxillary nerve; and V3, mandibular nerve. The facial and vestibulocochlear nerves emerge along the lateral aspect of the pontomedullary junction. Anterior and medial at this junction arise the abducens nerves. Lower cranial nerves (glossopharyngeal, vagus, and spinal accessory) are outlined as a group. (Image courtesy of PA Rubino)