Fig. 2.

Sagittal schematic of CSF flow in the mature cerebroventricular system. CSF is produced primarily by the choroid plexus, which is located in each ventricle in the brain. CSF flows from the lateral ventricles, via the foramen of Monro, to the third ventricle, and then through the cerebral aqueduct/aqueduct of Sylvius to the fourth ventricle. Upon leaving the fourth ventricle, the CSF flows down the spinal cord and fills the subarachnoid space surrounding the brain. It is ultimately resorbed into the venous circulation by arachnoid villi