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Neuro 4 > Motor control (and brian motor control) > Flashcards

Motor control (and brian motor control) Flashcards

1
Q

What is the “final common pathway”?

A

The main pathway coming down from the primary motor cortex in the brain (alpha motorneurons). Controls voluntary movements.

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2
Q

What are higher order reflexes?

A

spinal reflexes that have been tweaked by the input from the brainstem nuclei (to control posture and balance)

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3
Q

Where fo brainstem nucli recieve input from?

A

Cerebellum, cerebral cortex and basal ganglia

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4
Q

Where is your “muscle memory”?

A

From cerebellum

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5
Q

What are the 4 systems controlling oevement and what di they do? (.30)

A

Cerebral cortex (descending control pathways)
-what you want to do

cerebellum
-“while you’re doing that, this is how you’re going to do it”

basal ganglia
-recognise previous experiences, “this is the best way to achieve what you want to do”

spinal reflexes
(local spinal chord/brain stem circuits)

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6
Q

Medial white matter in spinal chord has axons from where?

A

axons from brainstem

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7
Q

What is the spacial map of body musculature in hte spinal chord?

A

in anterior horn, have more medial muscles more medially and more lateral muscles more laterally eg fingers are more distal to biceps

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8
Q

What sensory information enters in at:
-spinal chord
-brianstem
-cortex

A

Spinal chord
-proprioception, tactile localisation, touch, pain

Brainstem
-vestibular system -> information re balance

Cortex
-movements in response to other senses and factors eg smell, emotions, intellectual etc

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9
Q

Stretch reflex: example, uses information from m……

A

eg platelar tendon reflex

Information from muscle spindles

Monosynaptic

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10
Q

Wha tis reciprocal inhibition?

A

An inhibitory interneuron that is also synapsed on say the stretch reflex, and causes releaxation of the antagonist to allow the movement to occur

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11
Q

Where does the 3rd lot of information go to?

A

In platelar tendon reflex:
1. contracts muscle (monosynaptic stretch reflex)
2. Lateral inhibition (antagonist relaxation )
3. Information up to the brain - tha;amus and somatosensory cortex

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12
Q

Inverse stretch reflex is due to what? What does it do? What nerve?

A

Golgi tendon organs
It prevents muscles being torn off, so if muscle load is too high then it does the opposite of the stretch reflex (relaxes the agonist and stimulates the antagonist
1B afferent nerves

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13
Q

What nerves are 1a?

A

The stretch reflex

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14
Q

What are the 3 actions of the inverse stretch?

A

1 = to agonist - inhibitory
2 = to antagonist - excitatory
3 = to the brain

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15
Q

What is the purpose of hte flexor/withdrawal reflex?

A

To protect us from pain eg protect us from standing on a pin

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16
Q

What is the circuitry of flexor reflex?

A

It is for pain - the A omega nociceptive axons are triggered by pain, branch a lot, activating interneurons at several spinal levels, activating alpha neurons which control ALL flexor muscles of the affected limb

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17
Q

What is the crossed extensor reflex?

A

When the pain stimulus from 1 side, causing flexion of he ipsilateral side (activation of flexor agonist and inhibition of flexor antagonists), then also travels to the contralateral side and causes extension of the contralateral limb.

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18
Q

What is faster - flexor and crossed extensor relex or stretch reflex?

A

Stretch reflex, not as many interneurons

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19
Q

Can the GTO over ridbe overridden by teh CNS?

A

YES

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20
Q

How do membrane potentials work?

A

Depends on the stimulus affecting the dendrite - the stronger the stimulus and the closer it is to the axon hillock, then the more likely it is to send off an action potential

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21
Q

What is th e jendrassik manouver and what is it used for? How does it work?

A

it is used to enhance reflexes, ask the patient to pull apart from their grip and they will start focussing on that rather than the knee jerk. It works beacuse the high activity in the upper motor neurones helps to overcome the descending inhibition

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22
Q

What is anticipating pain?

A

It is saying that if you are expecting something ot be painful, it most likely will be more painful because the electrical activity centers are readying themselves and can increase strength of the withdrawal reflex when the painful stimulus arrives

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23
Q

primary motor cortex no.

A

4

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24
Q

What aris the functinal heirarchy? Where are they located?

A

It is the orfder in which we cna decide what to do and then initiate movements:
-High (strategy - figuring out the goal and how to achieve) - Association neocortex and bsaal ganglion
-Middle (Tactics - hw we are going to do that smoothly and not fall over) - motor cortex and cerebellum
-low (execution - actually firing the action potentials and genarating the movement)

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25
Q

What are the lateral pathways for?

A

fine motor control and distal muscles - direct cortical control

26
Q

What do the veneteromedial pathways control?

A

POsture and locomotion (brainstem control)

27
Q

What is the Corticospinal tract made up of?

A

Motorneurons initated in the motor cortex

28
Q

Rubrospinal gets info form?

A

Red nucleus in the brainstem - receives input from the same corticospinal areas as the Corticospinal tract but it focusses more on the less distal muscles (more core based)

29
Q

What do CST and RST do?

A

Control voluntary movement

30
Q

What happens if there is a lesion in the CST and the RST? What about nly in ht eCST?

A

If there is a lesion in both you will end up with loss of fine movements of arms and hands - unable to move shoulders, elbows, writ and fingers independently.

If onlyin the CST, then the same deficits are seen but functions will reappear in a few months as they are taken over by RST (primitavly we think there wwas only the RST as not nearly as much fine motor movements were needed

31
Q

Where does the CST/RST dessucate?

A

CST dessucates in the medulla
RST dessucates pretty much immediatly sa it exits the midbrain

32
Q

What do the pathways inhibit/excite?

A

Excite pools of agonist muscles and inhibit the antagonists

33
Q

What are the vestibulospinal and tectospinal tracts?

A

they run down the front of the spinal chord.

Vestibulospinal stabilize head and neck

tectospinal ensures eyes remain stable as the body moves

34
Q

What does the pontine and medullary reticulospinal tract do? What is interesting abou tit?

A

Straight down form brainstem. Trunk /antigravity muscles in limbs. Uses sensory information from balance, body position and vision to reflexly maintain balance and postition

35
Q

Medial and lateral tracts control what?

A

Medial tracts = posture, balance and orienting mechanisms
Lateral = control of precise, skilled movements

36
Q

premotor and supplementary motor areas are where? What area are they?

A

Premotor area is area 6 =anterolateral to the primary motorcortex

Supplementary cortex is area 6, aterioror toth eprimary motor cortex

37
Q

SMA vs PMA? What areas are they?

A

Supplementary motor area = innervates distal motor units directly

Premotor area = connects with reticulospinal neurones innnervating proximal motor units

38
Q

How do we get an idea of where we are in space?

A

Through connections with the somatosensory, proprioceptive and visual inputs (areas 5 and 7). they converge into area 6 = signals encoding desired actions are converted into how it carry it out

39
Q

Where are decsions taken?

A

Prefrontal and paietal cortex

40
Q

What is activated if we think about doing something but don’t actually do it?

A

Just area 6, (Supplementary motor area and the premotor area).

41
Q

What is the function of area 4?

A

Area 4 is for DOING actions, like legit sending the impulse to tell muscle to contract

42
Q

What is the function of area 6 (PMA and SMA)?

A

To converge our body’s current position (from areas 5 and 7) with input from basal ganglia as to how we are going t carry out movement

43
Q

Where are decision making neuronses in the motor cortex?

A

In the perfrontal and parietal cortex

44
Q

Where are the mirror neurones in hte motor cortex and what are their funcitons?

A

So basically if we see someone doing something that we know/ could figure out how to do then it fires up premotor cortex 6. It is a way in which we can learn to do things by seeing them, and also can potentially understand the actions/goals of others.

45
Q

What are in control of the feedback and the feedforward mechanisms?

A

Feed forward mechanism is via area 6 premotor - getting ready to produce movement. Receives information brainstem reticular formation nuclei

Feedback is via vestibular nuclei to spinal chord to correct postural instability.

46
Q

Major input to area 6 from wherefrom where?

A

From ventral lateral nucleeus in the dorsal thalamus

47
Q

Which basal ganglia are involved in the modulation of movements?

A

Caudate, putamen (input), -> globus pallidus -> Ventral lateral nucleus -> Area 6

48
Q

What is a glutamatergic neuros?

A

Excititory

49
Q

When does the putamen fire in relation to limb/trunk movements?

A

before

50
Q

WHen does the caudate fire in response to eye movements?

A

before

51
Q

What is the motor loop - cortex - basal ganglia - cortex?

A

Cortex -> putamen ->globus pallidus -> ventral lateral nucleus -> Supplementary motor area

52
Q

What is the chain of neurones in the disinhibitory circuit?

A

Cortical excitiation -> excites putamen -> inhibits globus pallidus -> reduces inhibition on ventral lateral nucleus ->fires to the supplementary motor area

53
Q

What is the difference direct/indirect pathway?

A

Direct pathway = as above -> stimulatory

Indirect pathway = antagonises direct route: via subthalamic nuclei, suppresses inapropriate action

54
Q

Why are there “direct” and “indirect loops through the basal ganglua?

A

Direct - elects specific motor action

indirect - suppresses inappropriate actions

55
Q

What does the dopamine from the basal ganglia do?

A

Just keeps everthing flowing, and allows the direct and especially the indirect pathways to continue to function.

56
Q

What effect pde dopamine have on the direct and indirect pathways?

A

Allows them to function smoothly. So without dopamine, the specific motor pathways won’t work and also you won’t get inhibition of involuntary movements and so you get dyskineasia.

57
Q

What happens in huntingston?

A

Loss of brain, especially within the basal ganglia - caudate, putamen and globus pallidus.

58
Q

What is chorea? Why do you get chorea n huntingston?

A

Spontaneous, uncontrolled, rapid flicks and jerks with no purpose - due to lack of indirect pathway, so no inhibition of the involuntary movements passing through the globus pallidus

59
Q

What affect does alcohol have on the cerebellum?

A

Reduces it’s influence on our movements - nb why you become ataxic

60
Q

What are the pontine nuclei?

A

Nuclei in the pons

61
Q

What part of the cerebellum play a role in hte cortico-ponto-cerebellar projection?

A

M1 Layer 5, areas 4 & 6

62
Q

What does the cerebrllum do to help with movements?

A

Reports back to the cortex via venertolateral thalamus - direction, force and timiings (basically makes everything a lot more smooth and coordinated

Neuro 4 (8 decks)

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