22 - Neural Control of Movement

Question 1

What is the difference in the function of upper and lower motor neurones?

Answer 1

Lower motor neurones produce muscle contractions via motor units
Upper motor neurones produce voluntary movements

Question 2

What is the main function of the cerebellum?

Answer 2

Coordinate muscle movements and select correct sequences

Question 3

What is the main function of the basal ganglia?

Answer 3

Initiation and maintenance of movements containing the motor programs

Question 4

What are the 3 motor pathways that upper motor neurons contribute to?

Answer 4

• Corticospinal tract
• Rubrospinal tract
• Vestibulospinal and reticulospinal tract

Question 5

Where are the cell bodies of upper motor neurons found?

Answer 5

Cerebral cortex and brainstem

Question 6

What are 5 functions of upper motor neurones?

Answer 6

• Inhibition
• Reflex modulation - modulate intensity
• Efference copy
• Activation of other brainstem UMN (reticular formation, red nucleus)

Question 7

What are the corticospinal, rubrospinal and vestibulospinal and reticulospinal tracts?

Answer 7

- Corticospinal 
From the cerebral cortex to the spinal cord
Precise movements
- Rubrospinal 
From the brainstem to the spinal cord
Gross movements
Facilitates flexor movements
- Vestibulospinal and reticulospinal 
From the brainstem to the spinal cord
Posture and balance - mainly trunk muscles

Question 8

Draw a diagram representing the organisation and location of UMN pathways

Answer 8

• Look at google docs

Question 9

What is the role of the motor cortex?

Answer 9

To know where the body is in space, where it intends to go and the selection of a plan of how to get there

Question 10

Label the picture A-D

- Look at google docs

Answer 10

A - pre-frontal cortex
B - frontal eye fields
C - Pre-motor cortex and supplementary cortex
D - Primary motor cortex

Question 11

What are the decision, planning and action cortex?

Answer 11

Decision - Posterior parietal cortex (areas 5 and 7)
Planning - Association motor cortex (area 6)
Action - Primary motor cortex (area 4)

Question 12

What are the divisions of the cerebellum? What does each division do?

Answer 12

- Vestibulo-cerebellum 
Balance and posture
Eye movements
- Spino-cerebellum 
Locomotion
Voluntary movements of arms and legs
- Cerebro-cerebellum 
Skilled motor tasks
Speech, hand-eye coordination, cognitive eye movements

Question 13

What is the brake theory?

Answer 13

To keep still - put the brake on all movements (except reflexes to maintain posture)
To move - apply brake to some postural reflexes and release brake on voluntary movement
Basal ganglia - take the brake off in both situations

Question 14

What are the 5 nuclei of the basal ganglia?

Answer 14

Caudate

• Putamen
• Globus pallidus
• Substantia nigra
• Subthalamic nuclei

Question 15

What is muscle tone?

Answer 15

Tension in the muscle due to partial state of contraction

Question 16

How is muscle tone maintained?

Answer 16

Reflexively - stretch and GTO reflexes and gamma motor neurones
Also adjusted by descending motor pathways

Question 17

How is tone and posture related?

Answer 17

• Most of the body weight is anterior to the vertebral column
• Deep muscles of the back are therefore important in maintaining postural stance
• Antigravity muscles are more developed and have greater tone

Question 18

What occurs if there is damage to the cerebellum?

Answer 18

• Ataxia: Complete lack of integration of the sequences of movements(complete incoordination) and hypotonia

Question 19

What happens if there is damage to the basal ganglia?

Answer 19

Slowing or unwanted movements (hyper/hypokinesia)

Question 20

What happens if there is damage to the association motor cortex?

Answer 20

Apraxia: unable to execute familiar learned movements in absence of sensorimotor dysfunction

Question 21

What happens if there is damage to the descending pathways?

Answer 21

Spasticity and hypertonia due to lack of inhibition from UMN

Question 22

What is the definition of Spasticity, rigidity and flaccidity?

Answer 22

Spasticity - Increased muscle tone due to the loss of inhibition of gamma motor neurones
Rigidity - Increases muscle tone due to the loss of inhibition of alpha motor neurones
Flaccidity (hypotonia) - Decreased muscle tone to the nerve or LMNs damage