Final answer:
CSF fills the ventricles and then moves into the subarachnoid space, providing a cushion and removing wastes from the CNS.
Step-by-step explanation:
Cerebrospinal fluid (CSF) is crucial for protecting and supporting the central nervous system (CNS). Produced by the choroid plexus within the ventricles, CSF flows through the ventricular system, and after reaching the fourth ventricle, it moves into the subarachnoid space through openings known as apertures. This space is filled with CSF, which not only removes metabolic wastes from the nervous tissue but also acts as a protective liquid cushion for the brain and spinal cord.
The CSF eventually gets reabsorbed into the bloodstream at structures called arachnoid granulations, ensuring that there is a continuous flow and turnover of this vital fluid. Therefore, to answer the student's question, CSF fills the ventricles and leaves the ventricles to go into the subarachnoid space.