Anatomy: Posterior Fossa, Hindbrain & Craniocervical Junction
Tentorium cerebelli
The tentorium cerebelli is a tough membrane separating the cerebellum from the cerebrum, whose position relates to posterior fossa size in Chiari malformation.
In short: Tentorium cerebelli
- It is a tough membrane between the cerebellum and the cerebrum.
- It forms the roof of the posterior fossa.
- Its position and attachment relate to posterior fossa size.
- A low tentorium can contribute to a small posterior fossa.
What it is
The tentorium cerebelli is a tough, tent-like membrane (a fold of the dura mater) that separates the cerebellum below from the cerebral hemispheres above. It forms the roof of the posterior fossa, and its position relates to the size of that compartment in Chiari malformation.
Understanding Tentorium cerebelli
The tentorium stretches across the back of the skull, forming the top of the posterior fossa where the cerebellum sits. Its level of attachment helps determine the size of the posterior fossa: a low-lying tentorium can contribute to a smaller posterior fossa, which is associated with Chiari I (since less room for the cerebellum can push the tonsils downward). The tentorium has an opening (the tentorial incisura or notch) through which the brainstem passes. Understanding the tentorium clarifies a structure that helps define the posterior fossa's size — a key factor in the development of Chiari I — and adds to the picture of the compartment that holds the cerebellum.
Why it matters
Understanding the tentorium cerebelli helps families see how the roof of the posterior fossa relates to that compartment's size, and how a low tentorium can contribute to the crowding seen in Chiari I.
Common questions
What is the tentorium cerebelli?
A tough membrane separating the cerebellum from the cerebrum.
What does it form?
The roof of the posterior fossa.
How does it relate to Chiari?
Its position relates to posterior fossa size; a low tentorium can contribute to a small fossa.
Bottom line
The tentorium cerebelli is the membrane forming the roof of the posterior fossa, whose position relates to that compartment's size in Chiari malformation.
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