Crus of fornix

The crus of the fornix is the posterior continuation of the fimbria of the hippocampus. As the fimbria collects additional fibres and enlarges, it becomes the crus of the fornix.

Each crus curves superiorly and anteriorly beneath the splenium of the corpus callosum. Some fibres cross to the opposite side through the forniceal commissure (also called the dorsal hippocampal commissure). The right and left crura then continue anteriorly near the midline to form the body of the fornix.