# Cerebrospinal Fluid --- **Cerebrospinal fluid**, or **CSF** is a clear, viscous fluid that surrounds and protects the tissues of the [[central nervous system]]. It protects the brain in several important ways. It's viscous nature prevents friction from motion, as well as cushioning which prevents the brain from rattling about and hitting the inside of the skull from minor jostling. CSF also allows the [[brain]] to float. The brain is very delicate, and even though it only weighs 3 pounds, if there were no CSF to float in it would crush itself under it's own weight. CSF is constantly being produced by the [[choroid plexus#Ependymal Cells|ependymal cells]] of the [[choroid plexus]] which line the [[brain ventricles|ventricles]], and is constantly being drained out. If it cannot drain out appropriately, this leads to [[hydrocephalus]], which can be very dangerous. ## Testing If Something is CSF or Not If there is some fluid and you suspect it's CSF you can test it for glucose, and it will be positive. It also separates into concentric rings, apparently ## Problems with CSF - [[hydrocephalus]] ___