Fourth ventricle

Dr Craig Hacking and Dr Jeremy Jones et al.

The fourth ventricle is one of the components of the ventricular system in the brain, along with the lateral and third ventricles. It extends from the cerebral aqueduct (of Sylvius) to the obex and is filled with CSF.

CSF enters the ventricle via the cerebral aqueduct and leaves via one of four routes:

It is characteristically diamond-shaped in cross-section and located within the pons or upper part of the medulla oblongata. The roof, located dorsally is formed by the superior medullary velum and inferior medullary velum overlying the cerebellum. The floor, located ventrally, is formed by the rhomboid fossa, a diamond-shaped depression on the dorsal surface of the pons and upper half of the medulla. The sidewalls are formed by the veli and cerebellar peduncles.

The obex is the most caudal tip of the fourth ventricle.

Related pathology

See also

Anatomy: Brain
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Article information

rID: 5849
Section: Anatomy
Synonyms or Alternate Spellings:
  • 4th ventricle

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