Tonsil of cerebellum
Tonsilla cerebelli
A rounded lobule on the underside of each cerebellar hemisphere, lying beside the uvula just above the foramen magnum and the medulla.
At a glance
- English
- Tonsil of cerebellum
- Latin (TA2)
- Tonsilla cerebelli
- System
- Brain and spinal cord
- Region
- Head
- Side
- Paired, left and right
About the tonsil of cerebellum
The tonsil of the cerebellum is a rounded, almond-like lobule on the inferior surface of each hemisphere, close to the midline. It is lobule IX of the hemisphere in the numbered scheme, the lateral counterpart of the uvula of the vermis, to which it is joined. The two tonsils lie side by side in the lower part of the vallecula, the midline hollow on the underside of the cerebellum.
Lateral to each tonsil lies the biventral lobule, from which it is separated by a fissure; medially lies the uvula. The tonsils hang down towards the foramen magnum and rest just behind and beside the medulla oblongata, over the roof of the lower fourth ventricle. They sit in the cerebellomedullary cistern, the cisterna magna, and are wrapped by loops of the posterior inferior cerebellar artery, which supplies them.
In function the tonsil is grouped with the posterior lobe of the hemisphere and in many accounts is linked with the vestibular and eye movement systems, but it is better known for what happens when it moves out of place.
Its position just above the foramen magnum is what makes it clinically important. When pressure inside the skull rises, for example from a mass in the posterior cranial fossa or severe brain swelling, the tonsils can be forced down through the foramen magnum. This tonsillar herniation, known as coning, compresses the medulla and its centres for breathing and circulation and is a medical emergency; for the same reason, a lumbar puncture is avoided when such a pressure rise is suspected. In Chiari malformation type I the tonsils lie lower than normal, below the foramen magnum, and can block the flow of cerebrospinal fluid, causing headache and sometimes a fluid cavity in the spinal cord.
Function and supply
- Function
- Part of the posterior lobe of the cerebellar hemisphere, often linked with vestibular and eye movement control.
- Blood supply
- The posterior inferior cerebellar artery, whose tonsillar loops wrap around it.
Anthromica
See the tonsil of cerebellum where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
