The most posterior portion of the corpus callosum is called the Splenium. The portions of the Corpus Callosum includes the Rostrum, Genu, Truncus, Isthums, and the Splenium. Genu is the most anterior portion of the Corpus Callosum while the Splenium is the most posterior portion, Truncus is the most body of the Corpus Callosum and the Rostrum is inferior to the Genu.