Within the brain are five fluid filled cavities,
the walls of which are lined with ependymal cells. Roughly
400 cc's of cerebrospinal fluid (CSF) are produced daily
by the choroid plexus (small vascular structures which project
into the ventricles). The CSF passes from the lateral
ventricles, through the foramen of Monro, to the third ventricle.
From there, it passes through the aqueduct of Sylvius (in
the brainstem) to enter the fourth ventricle. From the
fourth ventrticle, the CSF leaves through the foramen of Luschka
and the foramen of Magendie, to percolate around the brain
and pass around the spinal cord.