Endoscopic anterior view of the sellar, suprasellar, infrasellar, and parasellar regions. The pituitary gland rests within the sella turcica and is enclosed by dura mater containing intercavernous sinuses that communicate laterally with the cavernous sinuses via the diaphragma sellae. The lacerum, cavernous, and clinoid segments of the internal carotid artery are visible. The petrous carotid terminates in the lacerum segment shortly after turning superiorly out of the carotid canal. The cavernous carotid is a continuation of the lacerum segment and has a posterior genu in the posterior cavernous sinus and an anterior genu immediately prior to entering the proximal dural ring to become the clinoidal segment. At the distal dural ring, the clinoid segment continues as the supraclinoid or ophthalmic segment, which gives rise to the ophthalmic artery. The carotid sympathetic plexus is visible as a perivascular plexus on the surface of the internal carotid artery. McConnell’s capsular arteries typically arise from the cavernous segment and are divided into anterior and inferior capsular arteries, which supply the sella dura mater and the anterior pituitary capsule. The abducens (CNVI) nerve can be seen leaving the pons to course towards the cavernous sinus. The basilar artery courses near the midline of the ventral pons and gives rise to pontine arteries that radiate laterally on the pons. In the suprasellar region, the optic chiasm can be seen in close proximity with the ophthalmic artery. This artery, a branch off the supraclinoid segment of the internal carotid artery, courses with the optic nerve through the optic canal to the orbit. The anterior cerebral arteries, terminal branches of the internal carotid arteries, are visible at the top of the image entering the interhemispheric fissure. (Image courtesy of AL Rhoton, Jr.)