Cerebrospinal Fluid.
Cerebro spinal fluid is clear colourless fluid which surrounds and bathes the brain and spinal cord.
It is a filtrate of blood and is produced in hollow spaces at the centre of the brain called ventricles.
Containing the cerebrospinal fluid is a tough waterproof sack made up of three membranous layers called the meninges which surround the brain and spinal cord.
Cerebrospinal fluid acts as a "cushion" or buffer for the brain. It providing also a basic mechanical and immunological protection to the brain inside the skull.