Motor Control 1

Question 1

Look

Answer 1

Question 2

What are lateral pathways responsible for?

Answer 2

Lateral pathways control voluntary movements of distal muscles – under direct cortical control

Question 3

What are ventromedial pathways responsible for?

Answer 3

Control posture and locomotion under brainstem control

Question 4

What pathways come under lateral spinal tract?

Answer 4

Corticospinal

Rubrospinal

Question 5

What pathways come under ventromedial pathways?

Answer 5

Tectospinal

Vestibulospinal

Pontine reticulospinal

Medullary Reticulospinal

Question 6

Where does 2/3rds of the CST originate?

Answer 6

In areas 4 and 6 of the frontal motor cortex, the rest is somatosensory

Question 7

Where does the CST decussate?

Answer 7

Decussates at the medulla - spinal cord junction

Question 8

Where do CST axons synapse?

Answer 8

Ventral horn motor neurones and interneurones

Question 9

Where does the rubrospinal tract start?

Answer 9

Starts in the red nucleus of midbrain - inputs from same cortical areas as CST

Question 10

What is the result of a lesion in the CST and RST?

Answer 10

• Fine movements of arms and hands lost. Can’t move shoulders, elbows, wrist and fingers independently.

Question 11

What is the result of a lesion in the CST alone?

Answer 11

•same deficits, but after few months functions reappear. Been taken over by RST, because if now lesion RST – lose restored functions.

Question 12

What are the two ventromedial pathways that control posture and locomotion?

Answer 12

Vestibulospinal and tectospinal

Question 13

What is the VST responsible for?

Answer 13

Stabilizes head and neck

Question 14

What is the TST responsible for?

Answer 14

Ensures eyes remain stable as body moves

Question 15

Where do pontine and medullary reticulospinal tracts originate?

Answer 15

Brainstem

Question 16

What is the function of the pontine and medullary reticulospinal tracts?

Answer 16

Use sensory information about balance, body position and vision

Reflexly maintain balance and body position

Innervate trunk and antigravity muscles in limbs

Question 17

What is the relationship between the motor cortex and the ventromedial pathways?

Answer 17

During an action like throwing, the motor cortex directly activates the spinal motoneurones and frees them from reflex control by communicating via the nuclei of ventromedial pathways.

Question 18

What do the primary motor cortex and pre-motor areas fo?

Answer 18

Plan and control precise voluntary movements

Question 19

Describe the distribution of lower motor neurones

Answer 19

Somatotopic

Medial lower motor neurones - control axial and proximal limb muscles

Lateral lower motor neurones - control distal limb muscles

Question 20

What is the function of the medial and lateral tracts?

Answer 20

Medial tracts are from the brainstem - control posture balance and orienting mechanisms

Lateral tracts are from the cortex - they control precise skilled voluntary movements

Question 21

Summary

Answer 21

Question 22

What are the following landmarks on the brain?

Answer 22

Question 23

What makes up Broddman area 6?

Answer 23

The pre-motor area and the supplementary motor area

Question 24

What is the function of area 6?

Answer 24

Drives complex movements on either side of the body

Question 25

What is the result of weak electrical stimulation of area 4?

Answer 25

Twitch of contralateral muscles - demonstrates somatotopic organistaion of precentral gyrus

Question 26

What is the function of the supplementary motor area?

Answer 26

Innervates distal motor units directly

Question 27

What is the function of the PMA?

Answer 27

•PMA connects reticulospinal neurones innervating proximal motor units

Question 28

What are the two effects of microstimulation of the primary motor cortex?

Answer 28

(A) coordinated movements of hand and mouth

or

(B) movements that bring hands into central space to inspect/manipulate objects

Question 29

How is a mental image of the body in space generated?

Answer 29

Generated by somatosensory, proprioceptive and visual inputs into the posterior parietal cortex (areas 5 and 7)

Question 30

Damage to what area causes neglect of one side of the body?

Answer 30

Damage to areas 5 and 7, responsible for creating an image of the body in space

Question 31

Where are decisions made about what actions/movements to take and their likely outcome?

Answer 31

Prefrontal cortex and parietal cortex

•axons from both converge on area 6. This is the junction where signals encoding what actions are desired are converted into how the actions will be carried out.

Question 32

What is the difference between areas 4 and 6?

Answer 32

• if you only think about movements - area 6 is active but area 4 is not: area 4 is for “doing it” by activating the neurones of the CST and RST

Question 33

When are the three occasions neurones fire from area 6?

Answer 33

When movement is made

When movement is imagined

When others make the same specific movement