tentorium cerebelli

The tentorium cerebelli is a fold of the dura mater, the tough outer membrane covering the brain, that separates the cerebellum from the occipital lobes of the cerebrum above it.

This tent-shaped structure stretches horizontally across the back of the skull, forming a roof over the posterior cranial fossa.

The opening in its center, called the tentorial notch, allows the brainstem to pass through.

Neurosurgeons and radiologists reference the tentorium when describing lesions as supratentorial or infratentorial.