15 - Motor control and the corticospinal tract Flashcards

1
Q

How is skeletal muscle controlled?

A
  • voluntary movements have an UMN and a LMN
  • leaves the CNS (cerebral cortex), via the brainstem to the spinal cord
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define voluntary movement.

A
  • direct movement
  • contraction of muscles
  • pyramidal pathway
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define involuntary movement.

A
  • indirect movement
  • balance and fluidity of movement
  • unconscious and no delay
  • extrapyramidal pathway
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the extrapyramidal pathway.

A
  • has both alpha and gamma fibres
  • alpha fibres typically travel outwards from the CNS
  • gamma fibres typically travel inwards to the CNS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the pyramidal pathway.

A
  • alpha-alpha motor neurones
  • decision leaves motor cortex via alpha neurone to the spinal cord, synapses with another alpha neurone to the target muscle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the role of the basal ganglia in the corticospinal tract?

A

Initiate smooth movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the role of the thalamus in the CST?

A
  • acts as the relay centre for movement feedback
  • receives information from the BG, cerebellum and proprioception information
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the role of the extrapyramidal pathway in the CST?

A
  • acts to support voluntary movement
  • tells muscles not to move during actions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the role of gamma neurones?

A
  • PNS -> CNS
  • monitor muscle spindle sensitivity aka the starting point for contraction
  • known as the readiness potential
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Where is the pyramid located?

A

Anterior of the medulla, either side of the midline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the route of the UMN in the pyramidal pathway within the brain.

A
  • two tracts, anterior and lateral
  • axons leave from the PMC, SMC, pre-motor cortex and PSC
  • travels through the corona radiata through the posterior limb of the IC
  • travels to brainstem where 85% of fibres cross the medulla to form the LCST
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the role of the anterior CST?

A

Controls axial movements (muscles in the trunk) and posture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the role of the LCST?

A

Controls voluntary movement of the contralateral limbs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are signs and symptoms of UMN lesions?

A
  • spastic paralysis
  • no significant muscle atrophy (LMN functioning and nourishing muscle)
  • hyperreflexia and clonus (rigid twitching)
  • hypertonia
  • high gamma gain
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is gamma gain?

A

Amplified reaction of gamma fibres, when not received information from the CNS (usually due to an UMN lesion)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is a common cause for an UMN lesion?

A

Stroke

17
Q

What is a common cause for a LMN lesion?

A
  • trauma
  • poliomyelitis
18
Q

What are signs and symptoms of LMN lesion?

A
  • flaccid paralysis
  • muscle atrophy (LMN nourishing muscle has died)
  • fasciculations
  • hyporeflexia (reflex arc is damaged)
  • hypotonia (damaged gamma neurones)
19
Q

How does Babinski’s sign determine whether there is an UMN or LMN lesion?

A
  • positive sign (extensor plantar response) = UMN
  • negative sign (normal plantar response) = LMN