Endoscopic view of anterior exposure of pons and medulla and surrounding structures. Extensive bony removal of the clivus, body of sphenoid, and portions of petrous bone reveals the pons and rostral medulla and associated vasculature and cranial nerves. The basilar artery in the center of the image overlies the pons and is formed by union of the vertebral arteries at the pontomedullary junction. The trigeminal nerve (CNV) can be seen emerging from the upper lateral pons while the abducens nerve (CNVI) arises from the ventral pons at the pontomedullary junction. The acousticofacial bundle (CNVII and CNVIII) leave at the lateral pontomedullary junction coursing toward the internal auditory meatus. The glossopharyngeal (CNIX) and vagus (CNX) nerves emerge from the lateral medulla. The hypoglossal nerve (CNXII) is shown leaving the medulla in the groove between the olive and pyramid of this structure. (Image courtesy of AL Rhoton, Jr.)