Cerebrospinal fluid

Dr Daniel J Bell and Dr Craig Hacking et al.

Cerebrospinal fluid (CSF) is the clear liquid that surrounds and bathes the brain and spinal cord.

CSF is produced by the epithelium of the choroid plexus within the ventricular system and flows in the direction from the lateral ventricles to the third ventricle, then fourth ventricle and then around the brain and spinal cord. The majority of CSF is absorbed into the venous system by the arachnoid villi, which protrude into the dural venous system around the brain, particularly the superior sagittal sinus and transverse sinuses.

Normal volume ranges differ depending on the source but are generally in the 150-250 mL range with approximately 700 mL produced daily, hence the entire CSF volume is replaced 3-4 times per day.

There are numerous functions of CSF which include:

  • protection of the brain and spinal cord against rapid acceleration and deceleration
  • providing buoyancy to the brain
  • maintenance of intracranial pressure (see Monro-Kellie doctrine)
  • supplies nutrients
  • removes metabolites (see glymphatic system)

Radiographic features


CSF has a density close to water, around 0-10 Hounsfield units


CSF is high signal on T2 and ADC sequences and suppresses on FLAIR and DIR sequences. It is low signal on almost all other sequences and does not enhance.

Anatomy: Brain
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Article information

rID: 58893
Section: Anatomy
Synonyms or Alternate Spellings:
  • Cerebrospinal fluid (CSF)

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