Cerebrospinal fluid (CSF) is a clear, colorless body fluid found in the brain and spinal cord. It is produced by the specialised ependymal cells in the choroid plexuses of the ventricles of the brain, and absorbed in the arachnoid granulations. There is about 125mL of CSF at any one time, and about 500mL is generated every day. CSF acts as a cushion or buffer for the brain, providing basic mechanical and immunological protection to the brain inside the skull. CSF also serves a vital function in cerebral autoregulation of cerebral blood flow.