Anterior Interhemispheric Transcallosal Approach – Francisco Salomao, M.D. The cerebral hemisphere is gently and gradually retracted away from the falx. Exposure of the corpus callosum: The right frontal lobe is retracted away from the falx. The pericallosal arteries are identified and mobilized. The corpus callosum may be incised between the pericallosal arteries or on either side of the pair for a length of 2–3 cm. The lateral ventricle is then entered. Entry into the lateral ventricle: Lateral ventricle landmarks. Choroidal plexus and veins (septal and thalamostriate) run toward the foramen of Monro. (Courtesy of Dr. Cassius V. C. Reis, Federal University of Minas Gerais, Belo Horizonte, Brazil) View of interior of lateral ventricle: The foramen of Monro is blocked by a tumor.