The Cerebellum

Question 1

Where is the Cerebellum located?

Answer 1

The cerebellum is located posterior the pons and inferior to the occipital and temporal lobes.

Question 2

Name the 3 functional lobes of the Cerebellum

Answer 2

Cerebrocerebellum
Vestibulocerebellum
Spinocerebellum

Question 3

What are the inputs to all 3 lobes?

Answer 3

Cerebrocerebellum - Cerebral cortex via the Pons
Vestibulocerebellum - Vestibular hair cells and vestibular nuclei.
Spinocerebellum - spinocerebellar tract

Question 4

What are the outputs to all 3 lobes?

Answer 4

Cerebrocerebellum - Cerebral cortex via the thalamus
Vestibulocerebellum - the vestibular nuclei, affecting the vestibulospinal tracts to target alpha/gamma motor neurones to affect movement and tone
Spinocerebellum - the reticular formation and the rubrospinal tract to target alpha/gamma motor neurones to affect movements and tone.

Question 5

What is the function of the Cerebrocerebellum?

Answer 5

To plan and coordinate movements of the body with the corticospinal tract. It also helps to control the rhythm and timing of these movements.

Question 6

What is the function of the Vestibulocerebellum?

Answer 6

To control movements of the eyes, but also to maintain balance, posture and equilibrium of the body by influencing the gamma motor neuron for muscle tone.

Question 7

What is the function of the Spinocerebellum?

Answer 7

To control ongoing gross limb movements through activation of the reticulospinal tracts via the reticular formation, and the rubrospinal tracts via the rubrospinal tract.

Question 8

What is the overall function of the Cerebellum?

Answer 8

To plan and coordinate movement, to prevent unwanted movement and to be involved in the planning stages of movement by affecting the pre and supplementary motor cortices.

Question 9

The cerebellum has no direct access to motor neurone pools, how does it therefore exerts its influence on skeletal muscle?

Answer 9

The reticular formation and the medial and lateral reticulospinal tracts.
The red nucleus and the rubrospinal tract
The primary motor cortex (PMC) and the Corticospinal tract (CST)
The vestibular nuclei and the medial and lateral vestibulospinal tracts.

Question 10

What is the name of the feedback loop for the role of the cerebellum as comparator?

Answer 10

The cortico-pontine-cerebellar-thalamico loop.

Question 11

Describe the role of the cerebellum as comparator

Answer 11

• A raw command of movement is sent from the primary motor cortex via the corticospinal tracts to the muscle – this is the intended movement
• A copy of this command is sent to the cerebrocerebellum via the Pons.
• The movement occurs, however the intended movement was to press the B key on a piano, but the person presses the A key by mistake when looking at their music.
• Somatosensation of what movement actually occurred, namely proprioception, is sent via the spinocerebellar tract to the Spinocerebellum.
• The cerebellum therefore has the intended movement and feedback from what actually occurred.
• It therefore compares the degree of error between these two movements and creates a new and updated plan of what should happen to correct the error. This is sent from the cerebrocerebellum to the cerebral cortex to target the corticospinal tract.
• The cerebellum is therefore very important in skill acquisition, so that the movements eventually become automatic.