Cerebellum

Cerebellum. (or) What are functional divisions of cerebellum? Give the functions of each division.
Answer:

Cerebellum lies dorsal to the brain stem.
On either side it is connected to brain stem by.
1. Inferior cerebellar peduncle to the medulla.
2. Middle cerebellar peduncle to the pons and.
3. Superior cerebellar peduncle to the midrain.

Structure:

Cerebellum consist of.

1. A small medial portion called vermis.

The part of vermis on the upper surface of cerebellum is called superior vermis.
The part of vermis on the under surface of cerebellum is called inferior vermis.
Vermis is formed by nine parts.

Fissures present over vermis:

2. Two large laterally placed cerebellar hemispheres.

It has two portions.
1. Larger portion called lobules ansiformis.
2. Smaller portion called lobules paramedianus.

Functional division:

Vestibulocerebellum.
- It receives impulses from vestibular apparatus
- Now, from vestibular apparatus afferent pass to vestibulocerebellum through vestibulocerebellar tract.
- Efferent return back to vestibular nuclei
- From these nuclei signals are send to spinal cord via vertibulospinal and reticulospinal tracts.
Spino cerebellum.
- It regulates tone, posture and equilibrium by receiving impulses from proprioceptors in muscles, tendons, joints, tactile receptors, visual receptors and auditory receptors.
- It also receives the cortical impulses via pontic nuclei.
- It regulates postural reflexes by modifying muscle tone.
- It helps in adjustment of posture and equilibrium in response to visual and auditory pathway.

2. Control of muscle tone and stretch reflexes.

Cerebellum forms an important site of a x y systems.
The gamma motor neurons reflexly modify the activity of alpha motor neurons and thus regulate the muscle tone.

3. Control of movements.

Involuntary movements.
Cerebellum coordinates the subconscious movements.
Voluntary movements.
Cerebellum guides and controls all movements accompanied by a conscious awareness of an individuals.

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