Endoscopic view of right anterior medioinferior perspective of the basilar artery and pons area. The clivus and most of the sphenoid bone have been removed to reveal the basilar artery (formed by right and left vertebral arteries uniting at the pontomedullary junction) ascending on the pons midline. From the basilar artery arise the anterior inferior cerebellar arteries, several pontine arteries (not labeled), and the superior cerebellar arteries before terminating with the posterior cerebral arteries. Near the pontomedullary junction arise the abducens nerve and from the pons more anterolaterally the large trigeminal nerve. The pituitary gland (unlabeled) occupies a midline position between the cavernous internal carotids as it rests on the sella turcica. Within the cavernous sinus, the abducens nerve courses along the lateral surface of the ICA while the trochlear and oculomotor nerves course within the lateral wall of the sinus.The oculomotor nerves emerge from the midbrain between the superior cerebellar and posterior cerebral arteries while the trochlear nerve can be seen coursing laterally after emerging from the dorsal surface of the midbrain. The posterior cerebral artery is shown receiving the posterior communicating artery from the internal carotid. The sigmoid sinus is visible as it approaches the jugular foramen. (Image courtesy of AL Rhoton, Jr.)