The Fornix is a massive, curvilinear, cable-like tract providing one of the two major reciprocal links between forebrain and midbrain (the medial forebrain bundle, from which it arose, is the other). It is a key connection of the limbic system and historically is a major component of the limbic sulcal circuit of James W. Papez. The Alveus is a thin layer of nerve fibers which covers the hippocampus.

fornix and alveus