Cerebral aqueduct (of Sylvius)

Last revised by Craig Hacking on 12 Mar 2018

The cerebral aqueduct (of Sylvius) is the structure within the brainstem that connects the third ventricle to the fourth. It is located within the midbrain, surrounded by periaqueductal grey matter (PAG) with the tectum of midbrain located posteriorly and the tegmentum anteriorly.

It is filled with CSF and its obstruction leads to obstructive hydrocephalus with dilatation of the lateral and third ventricles only. 

Related pathology

See also

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Cases and figures

  • Figure 1: ventricular system
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  • Figure 2: brain (sagittal section)
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  • Figure 3: midbrain (level of superior colliculi)
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