The area beneath and behind the posterior limb of the anterior commissure has been dissected away to reveal the extension of the stria terminalis in the region of the amygdaloid nucleus. The complex relations of fibers and gray matter in this area, known as the substantia innominata, do not lend themselves to display by gross dissection. However, a system of fibers (3) is seen passing laterally toward the temporal lobe in this area beneath the lentiform nucleus. These fibers approach the region from the upper surface (stratum zonale) of the thalamus and follow an arching course roughly parallel to the stria terminalis. They have been described as the thalamotemporal tract.