Cerebrospinal fluid is the clear, nutrient-rich fluid that circulates through the subarachnoid space, the brain and spinal cord. The fluid, referred to as CSF, is produced in the ventricles of the brain and fills the brain cavities as well as the spinal canal where the fluid bathes the nerves. CSF provides the brain and spinal cord with chemical nutrients, removes cellular waste and functions as a cushion to prevent injury.
The fluid also contains active neurotransmitters and hormones, acting as a messaging medium for the central nervous system and a regulator for temperature changes around the brain. In a spinal tap procedure, a thin needle is inserted into the spine between two vertebrae of the lower back and CSF is withdrawn to test for cerebrospinal infections and neurological disorders including meningitis and multiple sclerosis.