Is the median cavity in the brain bounded by the thalamus and the hypothalamus on either side, and anteriorly by the optic chasm.
One of four connected fluid-filled cavities comprising the ventricular system within the human brain.
It is a median cleft between the two thalami, and is filled with cerebrospinal fluid.
It communicates with the lateral ventricles anteriorly by the interventricular foramina of Monro, and communicates with the fourth ventricle posteriorly by the cerebral aqueduct of Sylvius.