basal cistern

This allows the cerebrospinal fluid to flow directly to the basal cisterns, thereby shortcutting any obstruction.

The interpeduncular cistern (basal cistern or Fossa interpeduncularis) is a wide cavity where the arachnoid extends across between the two temporal lobes.

An alternative treatment for obstructive hydrocephalus in selected patients is the endoscopic third ventriculostomy (ETV), whereby a surgically created opening in the floor of the third ventricle allows the CSF to flow directly to the basal cisterns, thereby shortcutting any obstruction, as in aqueductal stenosis.