The suprasellar cistern (also known as pentagon of basal cisterns) is a cerebrospinal-fluid filled space located above the sella turcica, under the hypothalamus. It contains the optic chiasm, the infundibulum and the circle of Willis. It has the shape of a pentagon at the level of the optic chiasm, and the shape of a six-point star at the level of cerebral peduncles, frequently likened to the star of David.

Cerebrospinal fluid (CSF) pathway studies have revealed that the CSF secreted from the choroid plexus of the ventricles after egressing from the fourth ventricle reaches the basal suprasellar cistern and ultimately the sylvian cisterns.

It is an important intra-cranial cistern to review on MRI and CT, since it can be obliterated in uncal herniation and in cases of severe intracranial hypertension. It can also be filled with blood from subarachnoid hemorrhage.