Anterior Perspective of Cerebellum with Brainstem Partially Removed. The pons and rostral medulla have been removed to expose the diamond-shaped fourth ventricle.  Choroid plexus is  suspended from the roof of the ventricle and extends laterally through the foramina of Luschka into the pontocerebellar angle immediately caudal to the flocculus.  Note the intimate apposition of the inferior, middle and superior cerebellar peduncles; these massive fiber bundles connect the cerebellum to the medulla, pons and midbrain, respectively .  The perfusion zones of the superior cerebellar artery, anterior inferior cerebellar artery (AICA), and posterior inferior cerebellar artery (PICA) are demonstrated. Note the regional associations between the AICA/PICA and the cranial nerve rootlets. (Image courtesy of AL Rhoton, Jr.)