The tentorium cerebelli, the second largest dural infolding, is a wide crescentic septum that separates the occipital lobes of the cerebral hemispheres from the cerebellum. The tentorium cerebelli attaches rostrally to the clinoid processes of the sphenoid, rostrolaterally to the petrous part of the temporal bone, and posterolaterally to the internal surface of the occipital bone and part of the parietal bone.

The falx cerebri attaches to the tentorium cerebelli and holds it up, giving it a tent-like appearance (Latin tentorium, tent). The tentorium cerebelli divides the cranial cavity into supratentorial and infratentorial compartments. The supratentorial compartment is divided into right and left halves by the falx cerebri. The concave anteromedial border of the tentorium cerebelli is free, producing a gap called the tentorial notch through which the brainstem (midbrain, pons, and medulla oblongata) extends from the posterior into the middle cranial fossa.