A spinal fluid-filled space in the center of the brain in communication with the lateral ventricles.
One of the four ventricles in brain that produce cerebrospinal fluid. This one is located in the lower forebrain and midbrain. It surrounds the massa intermedia.
The third ventricle (ventriculus tertius) is one of four connected fluid-filled cavities within the human brain. It is a median cleft between the two thalami, and is filled with cerebrospinal fluid (CSF).