The term posterior basal cistern refers to one of two subdivisions of the basal cistern; the other is the anterior basal cistern. The medial part of these two cisterns is referred to as the suprasellar cistern. The posterior basal cistern is a cerebrospinal fluid filled subarachnoid space between the ventral surface of the brain and the cranium that extends from the Foramen magnum to the Dorsum sellae. It includes the Cisterna pontocerebellaris, the interpeduncular cistern, and the superior cistern ( Schiebler-1999; Kretschmann-2004 ).