Anterior commissure

Overview
The Anterior Commissure (precommissure) is a bundle of white fibers, connecting the two cerebral hemispheres across the middle line, and placed in front of the columns of the fornix.

On a sagittal section, it is oval in shape, having a long vertical diameter that measures about 5 mm.

In 1991 brain studies performed by Laura Allen and Roger Gorsky of UCLA noted that the Anterior Commissure was found to be 1/3 larger in men with a homosexual orientation.

Connections
Its fibers can be traced laterally and backwards on either side beneath the corpus striatum into the substance of the temporal lobe.

It serves in this way to connect the two temporal lobes, but it also contains decussating fibers from the olfactory tracts, and is a part of the neospinothalamic tract for pain.