delta fornicis

com·mis·sur·a for·'ni·cis

[TA]
the triangular subcallosal plate of commissural fibers resulting from the converging of the right and left fornix bundles that exchange numerous fibers and that curve back in the contralateral fornix to end in the hippocampus of the opposite side.

delta fornicis

(dĕl′tă for′nĭ-sĭs) [L.]
A triangular surface on the lower side of the fornix.