DIAGRAM: GASTROINTESTINAL: GI: ARTERY: VERTEBRAL ARTERY AND BASILAR ARTERY, NORMAL, DRAWING INDICATING POSITION IN POSTERIOR FOSSA AND RELATIONS WITH CRANIAL NERVES; SUPERIOR CEREBELLAR ARTERY, POSTERIOR CEREBRAL ARTERY, ANTERIOR INFERIOR CEREBELLAR ARTERY, POSTERIOR INFERIOR CEREBELLAR ARTERY