Lecture 11 - Contributions of Cerebellum to Motor Function

Question 1

What is the function of the cerebellum?

L11 S5

Answer 1

• helps sequence motor activities but does not initiate movement
• compares actual movements to intended movements
• functions with spinal cord to enhance stretch reflex
• functions with brain stem to make postural movements
• functions with cerebral cortex to provide accessory motor functions

Question 2

What are the anatomical divisions of the cerebellum?

L11 S6;9-10

Answer 2

Medial to lateral:

• vermis (divides hemispheres)
• intermediate zone
• lateral zone

Anterior to posterior:

• anterior lobe
• posterior lobe
• flocculonodular lobe

Question 3

What are the functions of the vermis, intermediate zone, and lateral zone?

L11 S11-13

Answer 3

Vermis:
-control functions for muscle movement of axial body, neck, shoulder, and hips

Intermediate zone:
-control functions for muscle movements of distal extremities

Lateral zone:
-planing of sequential motor movements with cerebral cortex

Question 4

What are the different nuclei located in the cerebellum?

L11 S14

Answer 4

Denate nuclei

Emboliform nuclei

Globose nuclei

Fastigial nuclei

Question 5

What are the different layers of the cerbellar cortex and what cells does each layer consist of?

L11 S16

Answer 5

Granular layer:

• innermost
• granule cells and Golgi type II cells

Purkinje cell layer:

• middle
• Purkinje cells

Molecular layer:

• outer
• stellate cells, basket cells, Purkinje cells, Golgi type II cells

Question 6

What are the different cell types of the cerebellar cortex and what are their functions?

L11 S17-18

Answer 6

Granular cells:

• forms parallel fibers
• excitatory

Golgi cells:

• from parallel fibers to granular cells
• inhibitory

Basket cells:

• from parallel fibers to Purkinje axon hillock
• inhibitory

Stellate cells:

• fromm parallel fibers to Purkinje dendrite
• inhibitory
• only output from cerebellar cortex

Question 7

What are the cerebellar afferent fibers and efferent fibers?

L11 S19-20

Answer 7

Climbing fibers:

• afferent
• from medullary olives
• synapse with Purkinje cells and “conditions” them
• provide complex spikes
• role in motor learning

Mossy fibers:

• afferent
• from brainstem and spinal cord
• synapse with Purkinje cells and granule cells
• provide simple spikes

Purkinje cell axons:

• efferent
• always inhibitory

Question 8

What are the different functional organizations of the cerebellum?

L11 S25-30

Answer 8

Vestibulocerebellum:

• flocculonodular lobes and vermis
• functions in balance and eye movements
• responsible for pendular movements

Spinocerebellum:

• vermis and intermediate zones
• controls rate, force, and range of movement
• receives information regarding intended and actual movement

Cerebrocerebellum:

• lateral zones
• coordination of skilled movement and speech
• plans future movements