Posterior commissure

The posterior commissure (also referred epithalamic commissure, in animal anatomy as caudal commissure ) is a cross- track ( commissure ) of the brain in the region of the transition from the intermediate to the midbrain on the roof of the " water line " ( mesencephalic aqueduct ). This cross connection plays a role, especially for two-sided pupillary light reflex, since it connects the nuclei pretectales both halves of the brain together.