The suprasellar cistern (also known as the chiasmatic cistern or pentagon of basal cisterns) is a cerebrospinal fluid-filled cistern located above the sella turcica, under the hypothalamus and between the uncus of the temporal lobes. It contains the proximal part of Sylvian fissure (sometimes separately termed the Sylvian cistern), the optic chiasm, the infundibular stalk and the cerebrovascular circle of Willis. It has the shape of a pentagon at the level of the optic chiasma, and of a six-point star at the level of cerebral peduncles frequently likened to the star of David. It is continuous posteriorly with the interpeduncular cistern.
It is important to review on MRI and CT since obliteration may occur when there is uncal herniation and in cases of severe intracranial hypertension. It can also be filled with blood from subarachnoid hemorrhage.