Midline inferior view after sectioning of the floor of the third ventricle. Retractors divide the midbrain and floor of third ventricle in the midsagittal plane to reveal an inferior view of the third ventricle. The anterior and posterior commissures are visible, as is the massa intermedia (interthalamic adhesion). The optic chiasm is superior to the pituitary infundibulum, which is split and retracted here to reveal the anterior commissure and lamina terminalis. The optic tracts are visible from the chiasm to the lateral geniculate body. The right anterior choroidal artery can be seen entering the choroidal fissure and supplying the choroid of the lateral ventricle. (Image courtesy of AL Rhoton, Jr.)