The body of fornix joins the hippocampus and mammillary bodies, structures in the base of the brain that are involved in memory formation and recall. It is part of the limbic system.

The body of fornix is just one segment of four components that comprise the fornix of the brain. The other elements are the fimbria, crus, and column.

The fornix is C-shaped and is the main structure of the hippocampal formation. It is a bunch of nerve cell fibers protruding from the under surface of the corpus callosum, the nerve fibers that join the two halves of the brain. From there, the body of fornix extends to the interventricular foramen, an opening at the center of the brain. Next to the foramen, the body of fornix forms the anterior (front) columns of the fornix in the lower borders of the septum pellucidum, which is a membrane located at the midline of the brain.

In CT imaging studies, the body of fornix is seen hanging from the slender, superior (upper) part of the septum pellucidum. It is situated above the tela choroidea (connective tissue) and ependymal roof (membrane lining) of the third ventricle, a fluid-filled cavity in the brain.