Ligament
Tentorium cerebelli
A dural partition above the cerebellum
High-yield
The tentorial notch permits passage of the midbrain and has close relationships with CN III and major vessels. Displacement through this opening can compress neural structures, with findings that vary as the process progresses.
Overview
The tentorium is an arched fold of meningeal dura between cerebellum and the overlying occipital/inferior temporal regions. Its attached margins meet skull-base and occipital landmarks. An anterior opening surrounds the midbrain. Transverse and superior petrosal sinuses follow attached margins; the straight sinus lies at its junction with the falx cerebri.
Reference facts
- Attachments
- Attached to the occipital transverse-sinus grooves and petrous superior borders. Attached margins reach posterior clinoid processes; the free margins continue toward anterior clinoid attachments.
- Function
- Supports and separates supratentorial cerebral structures from the cerebellar compartment while leaving the tentorial opening around the midbrain.
- Clinical point
- Herniation across its free margin can compress CN III, cerebral peduncles and adjacent vessels; no single pupil or weakness pattern occurs in every case.
Clinical correlation
Uncal displacement may impair CN III on the mass side, producing a poorly reactive enlarged pupil. Motor-pathway compression often causes opposite-sided weakness. If the opposite cerebral peduncle is compressed against the tentorial edge, weakness can instead occur on the mass side (Kernohan–Woltman phenomenon).
Frequently asked questions
Where does the tentorium cerebelli attach?
Attached to the occipital transverse-sinus grooves and petrous superior borders. Attached margins reach posterior clinoid processes; the free margins continue toward anterior clinoid attachments.
What does the tentorium cerebelli do?
Supports and separates supratentorial cerebral structures from the cerebellar compartment while leaving the tentorial opening around the midbrain.
Why does the tentorium cerebelli matter clinically?
Herniation across its free margin can compress CN III, cerebral peduncles and adjacent vessels; no single pupil or weakness pattern occurs in every case.