A, The insert shows the approach along the inferolateral margin of the cerebellum. The cerebellum has been elevated to expose the right cerebellopontine angle. The facial nerve exit zone from the brainstem is seen along the lower margin of the vestibulocochlear nerve. The AICA passes between the facial and vestibulocochlear nerve. A large tortuous PICA loops upward anterior to the facial and vestibulocochlear nerves and behind the trigeminal nerve, before turning downward to reach the medulla. The flocculus and the choroid plexus protruding from the foramen Luschka often hide the junction of the facial and vestibulocochlear nerves with brainstem. In this case, the flocculus has been gently elevated to expose the junction of these nerves with the brainstem. B, Enlarged view. Exposing the facial nerve exit zone from the brainstem is facilitated by directing the exposure along the inferolateral margin of the cerebellum in the area above the glossopharyngeal nerve and below the lower edge of the flocculus. C, The vestibulocochlear nerve has been depressed. This exposes the distal segment of the facial nerve, but does not provide access to the junction of the facial nerve with the brainstem, which should be visualized in dealing with hemifacial spasm. D, The vestibulocochlear nerve has been gently elevated. This exposes both the rostral and caudal margins of the facial nerve at the brainstem. A rootlet of the nervus intermedius is also exposed. The vein of the middle cerebellar peduncle passes between the facial and vestibulocochlear nerve. (Images courtesy of AL Rhoton, Jr.)