The posterior end of the corpus callosum is the thickest part, and is termed the splenium (Greek splenion = a bandage).
It overlaps the tela chorioidea of the third ventricle and the mid-brain, and ends in a thick, convex, free border.
A sagittal section of the splenium shows that the posterior end of the corpus callosum is acutely bent forward, the upper and lower parts being applied to each other.