Ciliary hairs in the cerebral ventricle. Coloured scanning electron micrograph (SEM) of the wall of a cerebral ventricle. The cerebral ventricles are four communicating cavities within the brain that are continuous with the central canal of the spinal cord. They are filled with cerebrospinal fluid (CSF) which has a number of functions. As well as buffering the brain from shock, CSF also transports hormones around the brain and absorbs its waste products, before being absorbed into the bloodstream. This circulation is facilitated by the movement of the ciliary hairs on the ventricle walls.