Ventricles:

Ventricles (in purple).

Ventricles (in purple).

cavities of the brain that contain cerebrospinal fluid. The ventricular system consists of four such cavities: two lateral ventricles, the third ventricle, and the fourth ventricle.

Read more: Know your brain - Ventricles

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