[TA] entrance to the cerebral aqueduct; point at which the caudal part of the third ventricle is continuous with the cerebral aqueduct of the midbrain; located on the midline immediately anterior (ventral) to the posterior commissure. SYN: apertura aqueductus mesencephali [TA], apertura aqueductus cerebri*, opening of cerebral aqueduct*, aditus ad aqueductum cerebri.
