It is partially bounded by the leaves of the Liliequist membrane, one of the arachnoid membranes, which separate it from its direct cranial and caudal relations¹.

superiorly the diencephalic leaf, separates this space from the suprasellar cistern above
inferiorly the mesecephalic leaf, separates it from the prepontine cistern below
laterally, the margin is the medial borders of the cerebral peduncles, therefore, this space communicates with the crural cisterns and ambient cisterns laterally

The interpeduncular cistern also has limiting borders.

posteriorly it is the posterior perforated substance
anteriorly it is the origin of the leaflets of the Liliequist membrane

This cistern contains a number of structures including the proximal portion of the oculomotor nerves (CN III), the distal basilar artery, the origin of the posterior cerebral arteries (and thalamoperforating arteries) as well as the origin of the superior cerebellar arteries. Depending on the posterior limit of the diencephalic membrane this space can also be said to communicate with the suprasellar cistern contents (the mammillary bodies) ⁴.

Related pathology

subarachnoid hemorrhage - as the interpeduncular cistern is a dependent space in the supine position, small volume subarachnoid hemorrhage may be detected here