Anatomic Dissection via Subfrontal Exposure of the Chiasmatic Cistern. A, Subfrontal exposure of the chiasmatic cistern. The frontal lobe has been elevated to expose the chiasmatic cistern. The arachnoid trabecula in the chiasmatic cistern has been removed to expose the diencephalic leaf of Liliequist’s membrane, which extends from the outer arachnoidal membrane covering the dorsum sellae and attaches to the floor of the third ventricle behind the pituitary stalk. The superior hypophyseal artery ascends along the membrane. B, Another specimen, anterior view. The optic chiasm has been elevated, and a segment of the right carotid artery has been removed to expose the diencephalic leaf of Liliequist’s membrane. C, Anterolateral view of the diencephalic membrane, which separates the chiasmatic and the interpeduncular cisterns. D, The right carotid artery has been elevated. Some trabeculae from Liliequist’s membrane extend laterally to attach to the optic nerve. (Images courtesy of AL Rhoton, Jr.)