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Question 1

•electrical stimulation of the cerebellum causes?

Removal of the cerebellum causes ?

The main function of the cerebellum is?

Answer 1

1does not cause any motor movement.

2paralysis of no muscles although it causes the body movements to become abnormal.

The main function of the cerebellum is to coordinate motor activities initiated by other motor areas in the brain. important for rapid muscular
activities

Question 2

Longitudinal Functional Divisions of the Anterior and Posterior Lobes

Answer 2

Vermis: Control movements in axial body, neck, shoulders, and hips
•Intermediate zone: Control muscles in the distal portions of the upper and lower limbs
•Lateral zone. : overall planning of sequential movements

Question 3

•Three deep cerebellar nuclei?

All deep nuclei Receive impulses from two sources?

Answer 3

1.The dentate
2.Interposed
3.Fastigial

1.the cerebellar cortex
2.the deep sensory afferent tracts to the cerebellum

Question 4

Neuronal Circuit of the Cerebellum
•Afferent Pathways from Other Parts of the Brain.

Answer 4

1.Corticopontocerebellar pathway
2.Olivocerebellar tract
3.Vestibulocerebellar fibers
4.Reticulocerebellar
fibers

Question 5

Afferent connections of the cerebellum

Answer 5

1-From motor cortex: Corticopontocerebellar pathway (cerebral motor ,premotor cortex and cerebellar somatosensory cortex) passes by way of pontile nuclei and Pontocerbellar tract mainly to lateral division of cerebral hemisphere on the opposite side of the brain from the cerebral area
2-From inferior olive: •The inferior olive receive impulses from: Cerebral Cortex, Basal ganglia, Reticular formation &Spinal cord and then projects them to all parts of the cerebellum.

3-Vestibulocerebellar fibers:
•From the vestibular nucleus.

4-Reticulocerebellar fibers:
•From reticular formation.

5-Dorsal and ventral spino-cerebellar tracts:
•These tracts carry impulses from Muscle spindle, Golgi tendon organ & large tactile receptors of the skin and joints.
•They inform the cerebellum about the state of muscle contraction, degree of tension of the muscles , position of different parts of the body.

Question 6

Efferent Connections of the cerebellum:

Answer 6

Efferent signals are discharged from the deep
cerebellar nuclei to:
1- Motor cortex: 2-To basal ganglia:
3-To the red nucleus:
4-To the reticular formation: 5-To the vestibular nuclei:

Question 7

Functional Unit of the Cerebellum

Answer 7

Balance Between Excitation and Inhibition at the Deep Cerebellar Nuclei.
1.Direct stimulation of the deep nuclear cells by both the climbing and the mossy fibers excites them
2.Signals arriving from the Purkinje cells inhibit them.

•Other Inhibitory Cells in the Cerebellum.
3.Basket cells and Stellate cells.
4.These cells in turn send their axons and cause lateral inhibition of adjacent Purkinje cells

Question 8

Output Signals from the Cerebellum

Turn-On (At the beginning of Movement)

Answer 8

Turn-On (At the beginning of Movement): Cortex initiates contraction and at the same time send
1-excitatory impulses to deep nuclei(Via Mossy Fibers)
2. Cerebellum sends excitatory signals back into the
mm
cerebral cortical motor system to enforce contraction

Question 9

Output Signals from the Cerebellum
Turn-Off (At the End of Movement)

Answer 9

Turn-Off (At the End of Movement)

1.Mossy fibers have a second branch → signals to granule cells (via parallel Fibers) → Purkinje cells
2.Purkinje cell is excited, → strong inhibitory signal to the deep nuclear cell that had turned on the movement → turn off the movement

Question 10

Functions of the Cerebellum

Answer 10

A. Control of body posture & equilibrium:
•Through flocculonodular lobe of cerebellum.
•Impulse from vestibular apparatus either directly or through vestibular nucleus.
•It discharges to vestibular nucleus though Fastigial nucleus.
•If flocculonodular lobes are removed → disturbance of equilibrium.

B. Control of muscle tone:
•Cerebellum send impulses to RF → reticulospinal tract → spinal cord → regulate γ-motor afferents.
•Paleocerebellum→ ↓ stretch reflex,
neocerebellum→ ↑ stretch reflex.

C. Coordination of voluntary movements:

D. Coordination of involuntary movements: Cerebellum also receives feedback information from spinal cord & periphery.
Cerebellum prevent kinetic tremors in involuntary movements.

E. Extramotor predictive function:

Question 11

C. Coordination of voluntary movements:

Answer 11

1- servo-comparator Function

2- Prevent overshoot of Movements and to “Damp” movements.

3-Cerebellar Control of Ballistic Movements.

4-Planning and timing of Sequential Movements

5-Timing function