Anterior and superior view of olfactory tracts. Frontal lobes have been reflected posteriorly to view the anterior cranial fossa. The olfactory tracts extend posteriorly from the olfactory bulbs overlying the cribriform plates. Optic nerves exit the orbit through optic canals and cross over at the optic chiasm. Middle and anterior cerebral arteries can be seen branching from the internal carotid arteries. Middle cerebral arteries traverse the lateral sulcus while anterior cerebral arteries pass between the cerebral hemispheres. The A1 or precommunicating segment of the anterior cerebral artery extends from its origin from the ICA to the anterior communicating artery, a short vessel which connects to the contralateral cerebral artery. The A2 or postcommunicating segment of the anterior cerebral artery continues distal to the origin of the anterior communicating artery into the interhemispheric fissure and around the genu of the corpus callosum. The superior hypophyseal artery, a branch of the ICA, can be seen coursing toward the pituitary stalk and gland. It supplies the optic nerve, chiasm, and anterior pituitary. (Image courtesy of AL Rhoton, Jr.)