QS Study

Cerebrospinal fluid (CSF):

It is a clear, colorless modified tissue fluid, formed by ultra filtration of plasma in the CNS. The cerebrospinal fluid (CSF) is found in the arachnoid spaces of the brain and cord. It acts as a cushion or buffer for the brain, providing basic mechanical and immunological protection to the brain inside the skull. The CSF is contained within a system of fluid-filled cavities called ventricles.

Physical characteristics

  • Appearance – Clear & colorless.
  • Volume – 130 ml.
  • Rate of production: 0.5 ml/min.
  • Pressure: 60-150 mm of water.
  • Sp-gravity: 1.007, PH – 7.34-7.35
  • The color of the fluid — normal is clear and colorless.
  • Turbidity – Cloudy or turbid CSF may indicate the presence of white or red blood cells, microorganisms, or an increase in protein levels.

Composition –

  • Protein: 15-45 mg /100 ml.
  • Glucose: 50-85 mg/100 ml.
  • of cells: 0-3 lymphocytes/mm3.
  • Clear, colorless, transparent fluid.
  • Alkaline in nature
  • Specific gravity 1.005
  • Water – 99.13%
  • Solids – 0.87 %
  • CI– = 114.0 mEq whereas plasma has 100 mEq

Cerebrospinal Fluid (CSF) Formation 1

Fig: Cerebrospinal Fluid (CSF) Formation


It is formed mainly in the choroid plexuses of the lateral, third and fourth ventricles; some originates from the ependymal cells lining the ventricles and from the brain substance through the perivascular spaces. Today it is generally believed that CSF formation is an active energy-consuming metabolic process which occurs mainly in brain ventricles, in choroid plexuses. The choroid plexus consists of projections of vessels and pia mater that protrude into the ventricular cavities as frond-like villi containing capillaries in loose connective stroma.

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