A, Anterior view of the pituitary gland. The gland is located below the optic nerves and chiasm and between the cavernous segments of the internal carotid arteries. The right optic nerve has been elevated to expose the pituitary stalk. The superior hypophyseal arteries arise from the medial side of the supraclinoid portion of the internal carotid artery and pass medially to the pituitary stalk and optic chiasm. B, Superior view of pituitary gland. In this case, the diaphragm was largely absent, so that the subarachnoid space extended across and was separated from the top of the anterior lobe only by arachnoid membrane. The right half of the dorsum sellae has been removed to expose the posterior lobe, which was hidden under the dorsum. The inferior hypophyseal artery travels medially from the intracavernous carotid to the posterior lobe. C, C and D, superior and inferior surfaces of a gland in which the anterior and posterior lobes form a relatively ovoid structure. The pars tuberalis wraps partially around the stalk. D, C and D, superior and inferior surfaces of a gland in which the anterior and posterior lobes form a relatively ovoid structure. The pars tuberalis wraps partially around the stalk. E, The anterior and posterior lobes have been separated. The stalk joins the anterosuperior surface of the posterior lobe and is partially surrounded by the pars tuberalis. F, F and G, superior and inferior surfaces of another gland. The posterior lobe is multinodular and the right half of the posterior lobe seems larger than the left half. G, F and G, superior and inferior surfaces of another gland. The posterior lobe is multinodular and the right half of the posterior lobe seems larger than the left half. H, Inferior surface of another pituitary. The anterior and posterior lobes form separate distinct nodules. The posterior lobe forms a nodule attached to the posterior edge of the anterior lobe. (Images courtesy of AL Rhoton, Jr.)