The CSF has different functions amongst which:

• Hydromechanical protection (shock absorption) with 2 mechanisms:
  • Shock absorption, cushioning the brain against the skull.
  • CSF allow the brain and spinal cord to reduce the effective weight of the brain from the normal 1.500 grams to less than 50 grams. The reduction in weight lessens the force applied to the brain parenchyma and cerebral vessels during mechanical impact.
• To maintain the electrolytic environment on the central nervous system (CNS):
  • Chemical buffer to maintain constant ionic environment.
• Influencing the systemic acid-base balance.
• Being a medium for:
  • Nutrients to neuronal and glial cells.
  • Hormone transport.
  • Transport of neurotransmitters.
  • Transport of releasing factors.
  • Transport of neuropeptides.
  • Oxygen and carbon dioxide transport.
  • Electrolytes transport.
  • Anesthetic gases such as ether or nitrous acid.
• Functioning as a lymphatic system by removing waste products of cellular metabolism towards the venous system.
• Maintaining a stable intrinsic CNS temperature.
• Immune function (CSF contains immunoglobulins and mononuclear cells).

Glucose concentration is lower than that of blood and it is the major source of energy for the brain.

The protein content is some 100 times less than that of plasma.

Higher protein concentration (by lumbar puncture) is a sign for brain infection or tumor.

The pH of the CSF is 7.4.