Anterior midline view of the pituitary gland and adjacent structures. Extensive bone removal in the anterior midline of the head has exposed several structures. The pituitary gland and stalk can be seen in the center of the image. Superior and anterior to this are the optic chiasm and optic nerves to their bony canals. Along the lateral surface of the sphenoid body (removed) are the cavernous segments of the internal carotid arteries coursing within the cavernous sinus. The supraclinoid or ophthalmic portion of the internal carotid artery gives rise to the ophthalmic artery, which accompany the optic nerves into the orbit, and the superior hypophyseal artery to the pituitary gland, pituitary stalk, and optic chiasm and nerve. The clivus has also been resected to show the pons and the overlying basilar artery, which forms by union of the vertebral arteries at the pontomedullary junction. (Image courtesy of AL Rhoton, Jr.)