Moreover, to provide sufficient exposure and maneuverability, the posterior nasal septum and middle turbinate were removed so that the classic intrasphenoid landmarks could be identified (A) involving the planum sphenoidale: OC, optic canal; mOCR, medial optico-carotid recesses; ICA, internal carotid artery; ST, sella turcica; and clivus.
Source: wiktionary