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MED221A/B Lectures > MSK 17 - Motor control 1 > Flashcards

MSK 17 - Motor control 1 Flashcards

1
Q

what innervates the motor uni

A

alpha motor neurons

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2
Q

what region of the brain is responsible for voluntary muscle contractions

A

primary motor cortex

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3
Q

what is the path of the AP in the primary motor cortex

A

AP sent to upper motor neuron of primary motor cortex in pre central gyrus initiate movement

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4
Q

where is the primary motor cortex located in relation to the gyrus

A

pre central gyrus

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5
Q

what are the 3 classes of movement

A

voluntary

reflexes

rhythmic motor patterns

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6
Q

what are voluntary movements

A

purposeful, goal directed movements initiated from within CNS

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7
Q

what are reflex movements

A

somatic/automatic movements triggered in response to a specific sensory stimulus

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8
Q

what are rhythmic motor pattern movements

what are 2 examples

A

initiation and termination is voluntary but actual movement is much more stereotyped

eg breathing, chewing

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9
Q

what must be taken into account when considering the initiation and coordination of movement

A

the starting position of individual muscle fibres and body position

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10
Q

what gives input about the starting position of individual muscle fibres and body position

A

proprioceptors

muscle receptors

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11
Q

the forebrain is responsible for which of the 3 movement patterns

A

voluntary movements

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12
Q

the spinal cord and brainstem is responsible for which of the 3 movement patterns

A

reflex movements and rhythmic motor patterns

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13
Q

what are the 3 components of the brainstem which are involved in the motor system

A

thalamus

cerebellum

basal ganglia

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14
Q

what does the thalamus do in the motor system

A

relay station for incoming motor and sensory signals

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15
Q

what does the basal ganglia do in the motor system

A

approve or reject movement signals

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16
Q

what does the cerebellum do in the motor system

A

detects and corrects motor errors

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17
Q

where are motor neurons located

A

brain stem

spinal cord

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18
Q

what are the 2 types of motor neurons

A

alpha and gamma motor neurons

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19
Q

what do alpha motor neurons do

A

carry movement instructions from the brain and spinal cord to the muscles

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20
Q

where do alpha motor neurons synapse

A

synapse on extrafusal muscle fibres

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21
Q

the longest axons in the body belong to what neurons

A

alpha motor neurons

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22
Q

where are gamma motor neurons located

A

in the same motor nucleus as alpha motor neurons

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23
Q

where do gamma motor neurons synapse

A

synapse on intrafusal muscle fibres within muscle spindles

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24
Q

what do muscle spindles do

A

send information about the position of muscle and muscle length

25
Q

where are alpha motor neurons located

A

in the anterior/ventral horns in the grey matter of spinal cord at every level

26
Q

what locations are alpha motor neurons concentrated in

A

in cervical and lumbosacral enlargments

27
Q

which nervous system controls movement

A

somatic motor pathway

28
Q

where are the cell bodies of somatic motor neurons located in

A

either in the ventral/anterior horn of spinal cord
or the brain

29
Q

somatic motor neurons branch where relative to their target muscles

A

branch close to their target muscles

30
Q

each muscle fibre is innervated by how many motor neurons at how many neuromuscular junctions/end plates

A

only one motor neuron

at one NMJ

31
Q

what are the 2 classifications of motor units

A

S (slow or type 1) type

FF (fast/faitgable or Type 2 B) type

32
Q

when do the small motor units fire and what is their threshold like

A

fire first

lower threshold

33
Q

the larger motor units are oxidative/glycolytic

A

glycolytic

34
Q

the larger motor units are oxidative/glycolytic

A

oxidative

35
Q

what are the 3 myosin heavy chain proteins in human skeletal muscles

A

MyHC 1, 2A and 2X.z

36
Q

what is the implication of having 3 myosin heavy chain proteins in human skeletal muscles

A

muscle fibre type composition exists along a continuum such that a single or multiple MyHC isoforms can be expressed

the fast/slow muscle fibre types are determined by the MyHC isoforms and their properties

37
Q

what is the number of motor units for S type fibres relative to FF type fibres and vice versa

A

S type have many motor units

FF type have few motor units

38
Q

what is the axon diameter for S type fibres relative to FF type fibres and vice versa

A

S type have smaller axon diameters

FF type have larger axon diameters

39
Q

what is the number of terminals for S type fibres relative to FF type fibres and vice versa

A

S type have few terminals

FF type have many terminals

40
Q

what is the tetanic tension for S type fibres relative to FF type fibres and vice versa

A

S type have small tetanic tension

FF type have large tetanic tension

41
Q

what is the speed of contraction for S type fibres relative to FF type fibres and vice versa

A

S type slow speed

FF type fast speed

42
Q

what is the fatigue level for S type fibres relative to FF type fibres and vice versa

A

S type have little/none fatigue and can maintain contractions at higher levels for much longer

FF type have rapid fatigue

43
Q

what is the metabolism method for S type fibres relative to FF type fibres and vice versa

A

S type have aerobic metabolism

FF type has anaerobic metabolism

44
Q

what is the myoglobin level for S type fibres relative to FF type fibres and vice versa

A

S type plentiful

FF type scanty

45
Q

what is the glycogen level for S type fibres relative to FF type fibres and vice versa

A

S type little

FF type much

46
Q

what is the mitochondria density for S type fibres relative to FF type fibres and vice versa

A

S type high density

FF type low density

47
Q

what is the capillary supply level for S type fibres relative to FF type fibres and vice versa

A

S type high density

FF type few

48
Q

what is the muscle fibre characteristics for S type fibres relative to FF type fibres and vice versa

A

S type small red

FF type large pale

49
Q

what is the recruitment timeframe for S type fibres relative to FF type fibres and vice versa

A

S type early

FF type late

50
Q

force produced by a muscle is increased in what 2 ways

A

increasing the frequency of APs in individual alpha motor neurons

recruitment of additional motor units

51
Q

how does AP frequency relate to the muscle force

A

increase AP freq increases the muscle force

52
Q

describe small motor units in terms of excitability level, AP conduction and number and type of fibres excited

A

more excitable

conduct APs more slowly

excite fewer fibres that tend to be slow twitch type 1

53
Q

describe large motor units in terms of excitability level, AP conduction and number and type of fibres excited

A

less excitable

conduct APs more rapidly

excite many fibres that tend to be fast twitch type 2

54
Q

why is the conduction velocity of small diameter motor neurons low

A

smaller diameter means there is more resistance so conduction velocity decreases

55
Q

what do interneurons do

A

links input with the output within the spinal cord

56
Q

how many terminal branches do small diameter and large diameter motor neurons have relative to each other

A

large diameter motor neurons have many more terminal branches

57
Q

S type motor units are best suited for what load

A

for carrying sustained but small loads

58
Q

why do we need to exercise hard for the FF units

A

as they atrophy rapidly

MED221A/B Lectures (23 decks)

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