Ventricles of brain

The ventricles are hollow spaces in the human brain. They contain cerebrospinal fluid (CSF). There are four ventricles in a human brain.
This is the ventricular system: it continues as the central canal of the spinal cord. The ventricles are interconnected: this allows the flow of cerebrospinal fluid. 
The ventricle lining is an epithelium-like membrane. The CSF is produced by cells of this lining.