Explanation

All the ventricles of brain and central canal of spinal cord contain lymph-like extracellular fluid called cerebrospinal fluid (CSF). The total amount of CSF present in and around central nervous system is 80-150 mL. CSF contains glucose, proteins, lactic acid, urea, $Na^{+},\ K^{+},\ {Ca}^{2 +},{Mg}^{2 +},\ Cl^{-},HCO_{3}^{-}$ and some WBCs.