Cerebrospinal fluid (CSF):
Secreted by choroid plexus (95%), interstitial space and ependyma (5%). Produced at rate of 500ml/day with total volume around 150ml. Found in and around brain (50%) and spinal cord (50%) cushions and give buoyancy to CNS – also provides nourishment and is responsible for chemical stability of the environment for the brain and lymphatic drainage. Flows uninterrupted throughout the CNS
Clear colourless watery fluid that circulates through ventricles and subarachnoid space – returned to dural venous sinuses by arachnoid villi.
Similar in composition to blood plasma – has less protein and more vitamin C
• projects into ventricles (mainly 3rd and 4th); composed of ependymal cells that line a network of capillaries on folded surfaces
• forms CSF at a rate of about 0.5ml/min (total volume about 130ml) – replaced 3-4x/day