fourth ventricle (in red).

Fourth ventricle:

ventricle found nearest to the back of the brain. The fourth ventricle is tent-shaped, with the peak of the tent protruding into the cerebellum and the floor of the tent being formed by the pons and medulla. It connects to the third ventricle via the cerebral aqueduct and also connects to the central canal of the spinal cord. Like the rest of the ventricular system, the fourth ventricle contains cerebrospinal fluid.

Read more: Know your brain - Ventricles

Watch this 2-Minute Neuroscience video to learn more about the ventricles.