Walsh & Hoyt: Papilledema: General Considerations

The craniospinal cavity is an almost rigid bony enclosure completely filled by tissue, CSF, and circulating blood. Within this enclosure, CSF is constantly produced at the rate 500 ml/day, or 0.35 ml/minute. Almost all of the production is by the choroid plexus within the lateral ventricles, although the choroid plexuses of the 3rd and 4th ventricles and the ependymal lining of the ventricular system also contribute a small amount. The secretion of CSF is related to sodium transport in the brush border of the choroid plexus epithelium, and is dependent on sodium-potassium-activated ATPase as well as the enzyme carbonic anhydrase.