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MED221A/B Lectures > MSK 18 - Motor Control 2 > Flashcards

MSK 18 - Motor Control 2 Flashcards

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1
Q

the motor system controls movement together with which other system

A

the sensory system

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2
Q

what are some sensory inputs that assist the motor system

A

retina

vestibular system

auditory system

olfactory system

skin receptors

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3
Q

what are the 4 main receptors controlling movement

A

muscle spindles

golgi tendon organs

pain/nociceptors

joint receptors

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4
Q

what do muscle spindles monitor

A

muscle length

rate of change in muscle length (speed of length change)

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5
Q

what do golgi tendon organs monitor

A

muscle tension when muscles contract

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6
Q

what do joint receptors monitor and what do they signal

A

position

signal hyperextension/hyperflexion at joint

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6
Q

what do pain/nociceptors respond to

A

respond to damaging stimuli or potentially damaging stimuli

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7
Q

what are muscle spindles and where are they located

A

muscle spindles are encapsulated muscle fibres scattered throughout skeletal muscle/extrafusal muscle

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8
Q

muscle spindles are kept in what

A

sheaths

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9
Q

muscle spindles are innervated by what

A

by gamma motor neurons

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10
Q

when gamma motor neurons innervate the spindle fibres is this an afferent/efferent path

A

efferent

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11
Q

when alpha motor neurons innervate the extrafusal muscle is this an afferent/efferent path

A

efferent

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12
Q

what is the difference between extra and intrafusal muscles

A

extrafusal muscle makes up bulk of the muscle

intrafusal muscle are spindle fibres

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13
Q

how are the muscle spindles orientated in relation to the extrafusal fibres

A

lie in parallel

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14
Q

what carries signals from muscle spindle fibres back to CNS

A

group 1a afferent fibres

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15
Q

what is the function of group 1a afferent fibres

A

carries signals from muscle spindle fibres back to CNS

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16
Q

what kind of organs are the golgi tendon organs

A

mechanoreceptive organs

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17
Q

where are the golgi tendon organs located

A

at the myotendinous junction of skeletal muscles

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18
Q

what is the innervation of the golgi tendon organs

A

group 1b afferent fibres

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19
Q

what do group 1b afferent fibres innervate

A

golgi tendon organs

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20
Q

what do golgi tendon organs respond to

A

muscle tension

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21
Q

golgi tendon organs are contained within what structure

A

within a capsule in the tendon

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22
Q

what are reflexes

A

involuntary, stereotypical response of the muscle following stimulation of receptors

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23
Q

reflexes occur following what

A

following successive activation of mutually connected neurons

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24
reflexes occur following successive activation of mutually connected neurons with the last neuron doing what
last neuron innervating the effector tissue (muscle)
25
what makes up a reflex arc
neurons and effector tissue (muscle)
26
what is the basic unit of a reflex
reflex arc
27
reflexes are categorized as what two types
monosynaptic and polysynaptic
28
monosynaptic and polysynaptic reflexes are categorised based on what
based on how many neurons participate in one reflex arc
29
what are the 4 spinal reflexes
stretch/myotatic reflex reverse/inverse myotatic reflex flexion reflex crossed extension reflex
30
in the stretch/myotatic reflex what happens from when a tendon is tapped to the final step of a muscle contraction
stretches muscle and sends info back to spinal cord via the 1a afferents from the muscle spindles which can activate motor neurons and get contraction of muscle
31
what does myotatic mean
muscle is relaxed
32
what causes muscles to relax in the reverse/inverse myotatic reflex
golgi tendon organs - sensors of muscle force in the tendon
33
testing of reflexes allows for what
determines the integrity of the motor system and provides information on the condition of the upper and lower motor neurons
34
describe the monosynaptic arc from tendon tap to what structures the signal goes through the brain and back out to the muscle
tendon tapped info goes via sensory receptors to the spinal cord via the dorsal root ganglion then the dorsal root spinal cord sends back info to the muscles via the ventral root to the peripheral nerve which achieves the motor response in the muscle fibre
35
what are the 5 elements of the stretch reflex in order describe for a knee jerk reflex
receptors - muscle spindles afferent fibres - type 1a synaptic central relays - 1a afferents to alpha MN and MN to muscle efferent fibres - axons of alpha MN effectors - extrafusal skeletal muscles
36
in the stretch reflex what is the reciprocal
reciprocal inhibition
37
why is there reciprocal inhibition involved in the stretch reflex, what nerves are involved in this
the 1a afferents to 1a interneurons within the spinal cord inhibits the MNs innervating the antagonist muscles
38
intrafusal muscle fibres have what properties
spring like properties
39
what spinal cord segment is responsible for the jaw jerk reflex
5th cranial nerve
40
what spinal cord segment is responsible for the bicep jerk reflex
C5 and C6
41
what spinal cord segment is responsible for the triceps jerk and finger flexion reflex
C7 and C8
42
what spinal cord segment is responsible for the knee jerk reflex
L3 and L4
43
what spinal cord segment is responsible for the ankle jerk reflex
S1
44
alpha motor neurons innervate which muscle fibres
innervates extrafusal muscle fibers
45
are alpha motor neurons afferent/efferent
efferent
46
gamma motor neurons innervate which muscle fibres
intrafusal muscle fibres
47
are gamma motor neurons afferent/efferent
efferent
48
afferent fibres are which fibre types
type 1a and type 2 fibres
49
what is the only sensory receptor to have its own motor supply
muscle spindle fibers
50
gamma motor neurons innervate what portions of the intrafusal fibres
the striated portions of the intrafusal fibres
51
what is the other name for gamma motor neurons
fusimotor neurons
52
what is the similarities and difference between type 1a and type 2 endings
both are afferents that innervate muscle spindles differentiated by structure and function
53
what size are the gamma motor neuron cell bodies
small
54
do gamma motor neurons have direct input from the proprioceptive sensory afferents, if so where from
no
55
what size are the alpha motor neuron cell bodies
large
56
do alpha motor neurons have direct input from the proprioceptive sensory afferents, if so where from
yes direct group 1a derived proprioceptive sensory input
57
what do gamma motor neurons monitor and do for muscle fibres
keeps muscle spindles at appropriate length so they remain active during muscle shortening prevents muscle from being overstretched
58
what do alpha motor neurons do for muscle fibres
evoke muscle shortening
59
what are the 5 elements of the reverse myotatic reflex in order
receptor - golgi tendon organs (in series with the muscle) afferents - 1b fibres synaptic relays - 1b afferents to 1b interneurons which inhibit alpha motor neurons efferents - axons of alpha motor neurons effectors - muscles
60
what does the reverse myotatic reflex do under extreme circumstances
protects muscle from overload in situations that would damage the muscles fibres
61
what does the reverse myotatic reflex do in normal circumstances
maintain muscle tension/length in optimal range
62
what is the myotatic reflex
when muscle is passively stretched and lengthened
63
what are the neurons involved in the reverse myotatic reflex
1b afferents from golgi tendon organ synapse on inhibitory interneurons which inhibits the alpha motor neurons this decreases contraction of the muscle
64
what are the 5 elements of the flexion/flexor/withdrawal reflex in order
receptor - nociceptors afferents - type 3 and 4 fibres synaptic relays - to excitatory interneurons which excite flexor alpha motor neurons (afferents project to multiple spinal segments) efferents - axons of alpha motor neurons effectors - flexor muscles
65
what does the flexion/flexor/withdrawal reflex do
evokes fast withdrawal of limb from a nociceptive stimulus
66
during the withdrawal reflex what do the flexors and extensors do in the affected limb
the flexors contract the extensors relax
67
during the withdrawal reflex what do the flexors and extensors do in the unaffected/other limb what other reflex is occurring here
the flexors relax the extensors contract as part of the crossed extensor reflex
68
Why do opposite things happen to the flexor and extensor muscles in the withdrawal reflex
maintains balance when nociceptive receptors in the foot are activated makes sure that the other leg can weight bear when the affected foot is lifted

MED221A/B Lectures (23 decks)

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