Endoscopic endonasal middle clinoidectomy. A prominent left middle clinoid has been removed. Note the indentation created by the middle clinoid at the medial roof of the cavernous sinus. Middle clinoid removal improves access to the parasellar region, as required for pituitary adenomas invading into the cavernous sinus. Note the different location of the MOCR and middle clinoid. (Image courtesy of JC Fernandez-Miranda)