Subarachnoid spaces and cisterns as seen in a median section of the brain

The superior cistern (located dorsal to the midbrain) together with the subarachnoid space at the sides of the midbrain are referred to clinically as the cisterna ambiens. The superior cistern is important because it contains internal cerebral veins, which join caudally to form the great cerebral vein (of Galen). It also contains the posterior cerebral and superior cerebellar arteries. The choroid plexuses in the roof of the third and fourth ventricles are shown in red.