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Systems: Neurology AB > Motor Control 1 > Flashcards

Flashcards in Motor Control 1 Deck (64)
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1
Q

What are the 3 levels of motor control?

A
  • High
  • Middle
  • Low
2
Q

What is the function of high motor control?

A

Strategy

3
Q

What is the function of middle motor control?

A

Tactics

4
Q

What is the function of low motor control?

A

Execution

5
Q

What structures are responsible for high motor function?

A
  • Association neocortex

- Basal ganglia

6
Q

What structures are responsible for middle motor control?

A
  • Motor cortex

- Cerebellum

7
Q

What structures are responsible for low motor control?

A
  • Brain stem

- Spinal cord

8
Q

Strategy

A

The goal and the movement strategy to best achieve this goal

9
Q

Tactics

A

The sequence of spatiotemporal muscle contractions to achieve a goal smoothly and accurately

10
Q

Execution

A

Activation of motor neuron and interneuron pools to generate goal-directed movement

11
Q

By what pathways is the brain connected to the spinal cord?

A
  • Lateral pathways

- Ventromedial pathways

12
Q

What do lateral pathways control?

A

Voluntary movements of distal muscles- under direct cortical control

13
Q

What do ventromedial pathways control?

A

Posture and locomotion under brain stem control

14
Q

What is the longest lateral pathway?

A

Corticospinal tract (~1 million axons)

15
Q

Where does the corticospinal tracts originate?

A
  • 2/3 originates in areas 4 and 6 of the frontal motor cortex
  • The rest is somatosensory
16
Q

Where does the corticospinal tract decussate?

A

At medulla/spinal cord junction

17
Q

Where do the corticospinal tract axons synapse?

A

Ventral horn motor neurones and interneuonres in order to control muscles

18
Q

What type of pathway is the rubrospinal tract?

A

Lateral pathway

19
Q

Where does the rubrospinal pathway originate?

A
  • Rednucleus of the midbrain

- Inputs from the same cortical areas as the CST

20
Q

What would lesions in the CST and RST result in?

A
  • Fine movement of arms and hands would be lost

- Can’t move shoulders, elbows, wrist and fingers independently

21
Q

What would lesions in the CST alone cause?

A
  • Fine movement of arms and hands would be lost
  • Can’t move shoulders, elbows, wrist and fingers independently
  • The functions would reappear after a few months as the RST takes over
22
Q

What lateral pathways control voluntary movements?

A
  • Corticospinal tract

- Rubrospinal tract

23
Q

What 2 ventromedial pathways control posture and locomotion?

A
  • Vestibulospinal tract

- Tectospinal tract

24
Q

What does the vestibulospinal tract do?

A

Stabilises the neck

25
Q

What does the tectospinal tract do?

A

Ensures eyes remains stable as body moves

26
Q

What ventromedial pathways control trunk and antigravity muscles?

A

Pontine and medullary reticulospinal tracts

27
Q

Where do the pontine and medullary reticulospinal tracts originate?

A

Brain stem

28
Q

What do the pontine and medullary reticulospinal tracts reflexly do?

A

Maintain balance and body position

29
Q

What do the pontine and medullary reticulospinal tracts do?

A

Innervate trunk and antigravity muscles in the limbs

30
Q

What do the pontine and medullary reticulospinal tracts use?

A

Sensory information about balance, body position and vision

31
Q

What do voluntary movements such as throwing require input from?

A

Motor cortex via lateral pathways

32
Q

What does the motor cortex directly activate?

A

Spinal motorneurones and frees them from reflex control by communicating via nuclei of ventromedial pathways

33
Q

What do the primary motor cortex and pre-motor cortex areas plan and control?

A

Precise voluntary movements

34
Q

What do upper motor neurones in the cortex and brainstem target?

A

Lower motor neurones in the spinal cord

35
Q

What do some UMN and LMN do?

A

Form circuits that control reflexes such as the stretch and withdrawal reflexes

36
Q

What is the distribution of the LMN?

A

Somatotropic

37
Q

Describe the somatotropic distribution of LMN.

A

Medial ones control axial and proximal limb muscles, lateral ones innervate distal limb muscles

38
Q

What do white matter tracts differ in?

A

Origin and function

39
Q

What do medial descending tracts from the brainstem control?

A

Posture and balance and orienting mechanisms

40
Q

What do lateral descending tracts from the cortex control?

A

Precise skilled voluntary movements

41
Q

Where is the primary motor cortex?

A

Precentral gyrus

42
Q

What lies rostrally to the primary motor cortex?

A

A mosaic of premotor areas

43
Q

What do we need to know to plan movement in the cerebral cortex?

A
  • Where the body is in space
  • Where it wants to go
  • Select a plan to get there
44
Q

What is the somatotropic organisation in the primary motor cortex?

A

Motor homunculus area 4

45
Q

How can epileptic seizures march across the body?

A

Can begin with abnormal finger movements, then hand, then arm, shoulder, finally face.

46
Q

What can Penfield electrical stimulation be used for in epileptics?

A

To decide areas of the brain to be spared surgically

47
Q

What do area 6 neurones do?

A

Drive complex movements on either side of the body

48
Q

What is area 4?

A

Primary motor cortex

49
Q

What are the 2 somatotopically organised motor maps in area 6?

A
  • Premotor area PMA

- Supplementary motor are SMA

50
Q

What does the SMA innervate?

A

Distal motor units directly

51
Q

What does the PMA connect?

A

Reticulospinal neurones innervating proximal motor units

52
Q

Why is the somatotopic motor map not precise?

A

-It does not represent upper motor neurones causing individual muscle movements

53
Q

What does microstimulation in a specific area of primary motor cortex elicit during purposeful movements on contralateral arm?

A

-Coordinated movements of hand and mouth
OR
-Movements that bring hands into central space to inspect/manipulate objects

54
Q

What is a mental image of body in space generated by?

A

Somatosensory, proprioceptive and visual inputs to posterior parietal cortex (areas 5 and 7).

55
Q

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

A

Prefrontal and parietal cortex

56
Q

What junction is located in area 6?

A

Junction where signals what actions are desired are converted into how the actions will be carried out.

57
Q

What does PET show during practised voluntary finger movements?

A

Blood flow increases in somatosensory, posterior parietal areas + prefrontal cortex, areas 6 and 4

58
Q

What area is active if you think about movements?

A

6

59
Q

When does area 4 become active?

A

By doing an action by activating the neurones of the CST and RST

60
Q

What fires before a movement?

A

Decision making neurones in cortical PMA

61
Q

What are decision making neurones in command centres?

A

Neurones in the premotor area (PMA) that fire action potentials one second before a movement occurs

62
Q

When do PMA mirror neurones fire?

A

When self or others perform specific actions

63
Q

What may mirror neurones underpin?

A

Emotions and empathy

64
Q

When may mirror neurones be dysfunctional?

A

In autism