The term interpeduncular cistern (cisip) refers to the narrow cerebrospinal fluid (CSF) filled space between the pia mater (pia) and arachnoid (arac), which separates the surface of the brain from the dura mater (dura) and cranium ventrally, the midbrain (MBR) dorsally, the mammillary body (mmb) rostrally, the pons (PON) caudally, and the ventromedial surfaces of the limbic lobe (LLB) and temporal lobe (TLB) laterally. It is found in the human ( Rai-2022 ), macaque ( Martin-2000 ), rat ( Bedussi-2017 ) and mouse ( Hof-2000 ). Updated 11 Dec 2025.