Posterosuperior view of right cerebellopontine angle. The facial (CN VII) and vestibulocochlear (CN VIII) nerves can be seen entering the internal acoustic meatus. The anterior inferior cerebellar artery (AICA) arises from the basilar artery and passes between CN VII and VIII. The labyrinthine artery most commonly branches from AICA and accompanies CN VIII to the inner ear. The subarcuate artery, also a branch of AICA, supplies the bony labyrinth, facial canal, and mastoid antrum. The posterior inferior cerebellar artery (PICA) arises from the vertebral artery and passes between vagus (CN X) and spinal accessory (CN XI) nerves before they enter the jugular foramen. The superior petrosal vein (vein of Dandy) is an important venous drainage system in the posterior fossa. It drains the anterior cerebellum and brainstem and forms usually by union of the pontine trigeminal vein, vein of the cerebellopontine fissure, and the vein of the middle cerebellar peduncle. The posterior inferior cerebellar artery (PICA) arises from the vertebral artery and often passes between vagus (CN X) and spinal accessory (CN XI) nerves before they enter the jugular foramen. The trigeminal nerve (CN V) emerges from the lateral pons and has three branches that provide principle sensory innervation to the face. Part of the choroid plexus of the fourth ventricle can be seen.  (Image courtesy of AL Rhoton, Jr.)