sensory and motor neuroscience (intro to motor control) Flashcards

1
Q

explain the definition of functional segregation

A

the motor system is divided into a number of different areas that control different aspects of movement

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2
Q

explain the definition of hierarchical organisation

A

the motor system is organised in a hierarchical fashion

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3
Q

sensory ___ enter the spinal cord via the dorsal root

A

sensory afferents enter the spinal cord via the dorsal root

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4
Q

sensory afferents enter the spinal cord via what

A

the dorsal root

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5
Q

sensory afferents enter _____ via the dorsal root

A

spinal cord

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6
Q

motor neurons leave the spinal cord via what

A

ventral root

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7
Q

what neurons leave the spinal cord via the ventral root

A

motor neurons

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8
Q

alpha motor neurons (or lower motor neurons) innervate what

A

skeletal muscles

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9
Q

what neurotransmitter do alpha motor neurons release

A

acetylcholine

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10
Q

at what synapse do alpha motor neurons release acetylcholine

A

neuromuscular junction

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11
Q

what neurons innervate skeletal muscle

A

alpha motor neurons

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12
Q

what neurons are clustered into spinal motor nuclei

A

alpha motor neurons

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13
Q

alpha motor neurons are clustered into what

A

spinal cord nuceli

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14
Q

all of the motor neurons in a nucleus innervate what

A

a single muscle

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15
Q

_____ in a nucleus innervate a single muscle

A

all of the motor neurons in a nucleus

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16
Q

each individual muscle fibre is innervated by how many motor neurons

A

each individual muscle fibre is innervated by only one motor neuron

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17
Q

each motor neuron can innervate how many fibres

A

many

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18
Q

a motor neuron and all of the fibres it innervates is known as what

A

a motor unit

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19
Q

define a muscle twitch

A

when a motor neuron fires an action potential, the muscle fibres of the motor unit contract, then relax

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20
Q

what does this statement explain
when a motor neuron fires an action potential, the muscle fibres of the motor unit contract, then relax

A

a muscle twitch

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21
Q

what is a tetanus

A

if the firing rate is high enough, an individual muscle twitches fuse together forming a tetanus

a continuous contraction

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22
Q

the higher the firing rate of a tetanus the
(finish the sentence)

A

the higher the force of contraction

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23
Q

one way of increase the force of contraction is increasing the firing rate, what is another way

A

recruiting more motor units

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24
Q

in what order are motor neurons recruited

A

small fine units - requires activation of S units
as more force is required, increasing number of F units

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25
Q

what is the difference between S and F units

A

F units contain larger numbers of muscle fibres

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26
Q

what kind of athlete would require larger number of S units

A

marathon runner

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27
Q

why would a marathon runner require more S units

A

(S)low contraction speed, highly fatigue resistant
contains I slow-twitch muscle fibres
motor neurons have small cell bodies and dendritic trees

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28
Q

what does a motor neuron look like

A

small cell bodies and dendritic trees

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29
Q

how is FR known as

A

fast fatigue resistant

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30
Q

what kind of athletes would need FR

A

800/1500 metre runners

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31
Q

why would a 800/1500m runner need FR

A

fast contraction speed
intermediate force
fatigue resistant
contains type IIa (fast twitch, high fatigue resistant
motor neurons have larger cell bodies

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32
Q

what is FF motor unit

A

Fast fatiguable

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33
Q

what athletes would require FF motor units

A

60/100m runners

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34
Q

why would 60/100m athletes require FF motor units

A

fast contraction speed, low fatigue resistant
contain type IIb/x
fast twitch low fatigue resistant
muscle fibres have large cell bodies

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35
Q

list the types of motor units and arrange them regarding the size of their cell bodies (smallest to largest)

A

S - small cell body and dendritic trees
FR - larger cell bodies
FF - large cell bodies

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36
Q

explain the size principle

A

orderly activation of motor units according to their size of cell bodies of their alpha motor units
-> smaller motor neurons are activated first

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37
Q

in the size principle, why are smaller motor neurons activated first

A

small surface area
-> increased membrane resistance which means more rapid depolarisation due to
V=IR

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38
Q

what is the speed of reflexes

A

rapid -> automatic

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39
Q

how are reflexes generated

A

by the circuitry of the spinal cord

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40
Q

what do reflexes provide

A

feedback adjustments to environmental perturbations
-> increase in muscle length with a reflex contraction

41
Q

as well as reflexes controlling automatic behaviour, the same circuitry that mediates reflexes can also play an important role in what

A

voluntary movement

42
Q

how can the circuitry that mediates reflexes can also play a role in voluntary movement ?

A

the same interneurons that coordinate excitation of extensor and inhibition of flexor muscles during the stretch reflex also coordinate contraction during voluntary movement

43
Q

muscle spindles contain specialised what

A

muscle fibres

44
Q

what are the principle receptors mediating proprioception

A

muscle spindles

45
Q

muscle spindles contain specialised muscle fibres, and are the principle receptors mediating what

A

proprioception

46
Q

what is proprioception

A

perception or awareness of the position and movement of the body

47
Q

muscle stretching (increasing length) causes stretch sensitive _____ channel to open and depolarise sensory fibres

A

cation (Na+)

48
Q

muscle stretching (increasing length) causes cation channels to open and do what

A

depolarise sensory fibres

49
Q

muscle stretch causes the activation of what

A

Ia spindle afferents

50
Q

Ia spindle afferents make _____ connections with alpha motor neurons

A

monosynaptic

51
Q

Ia spindle afferents make monosynaptic connections with what

A

alpha motor neurons

52
Q

Ia spindle afferents make monosynaptic connections with aloha motor neurons innervating the same muscle causing ________

A

contraction

53
Q

in the stretch reflex, at the same time of Ia afferent fibres causing contraction, inhibitory neurons inhibit the activation of what

A

antagonist muscles

54
Q

in the muscle spindle
what do gamma motor neurons cause the intrafusal fibres to do

A

contract - thus control sensitivity of the muscle spindle

55
Q

gamma motor neurons maintain muscle spindle sensitivity during

A

muscle contraction

56
Q

gamma motor neurons modulate the gain of

A

the stretch reflex

57
Q

when do gamma motor neurons exhibit their highest activity

A

dynamic movements
falling

58
Q

where is the golgi tendon

A

located at the transition between muscle and tendon

59
Q

what does the golgi tendon organ signal the force of

A

muscle contraction (responds linearly on a graph)

60
Q

golgi tendon organs send __ afferents that contract Ib inhibitory neurons

A

Ib

61
Q

golgi tendon sends Ib afferents that contract what

A

Ib inhibitory interneurons

62
Q

Golgi tendon
an increase in muscle force thus causes a reflex ______ of the same muscle

A

inhibition
as the golgi tendon organs send Ib afferents that contract Ib inhibitory interneurons

63
Q

Ib interneurons receive input from where (2)

A

cutaneous and joint receptors

64
Q

what do cutaneous afferents trigger

A

a reduction in muscle contraction when a limb contacts an object in the course of movement

65
Q

the fact that when golgi tendon organs send Ib afferents that contract Ib inhibitory interneurons, what does this allow

A

may protect the muscle from excessive contraction - also serves to keep muscle tension within optimal range

66
Q

the fact that when golgi tendon organs send Ib afferents that contract Ib inhibitory interneurons, what does this allow

A

may protect the muscle from excessive contraction - also serves to keep muscle tension within optimal range

67
Q

where are cutaneous nociceptors located

A

skin

68
Q

what do the sensory terminals of cutaneous nociceptors respond to

A

damaging stimuli

69
Q

how do the terminals of cutaneous nerve endings differ

A

the free nerve endings are without a specialised sensory structure

70
Q

A delta fibres respond to what

A

extremes of temperature or strong mechanical forces

71
Q

Unmyelinated C fibres respond to what

A

types of noxious stimulation

72
Q

nociceptor afferents can trigger what in response to a painful cutaneous stimuli

A

a withdrawal reflex

73
Q

flexion withdrawal occurs after what

A

a painful stimulus

74
Q

nociceptors afferents make what connections with motor neurons innervating a flexor muscle

A

nociceptors afferents make polysynaptic excitatory connections with motor neurons innervating a flexor muscle

75
Q

nociceptor afferents make poly synaptic connections with what motor neurons innervating a flexor muscle

A

nociceptor afferents make polysynaptic excitatory connections with motor neurons innervating a flexor muscle

76
Q

nociceptor afferents make polysynaptic excitatory connections with motor neurons innervating what

A

flexor muscle

77
Q

flexor and crossed extensor reflexes
connections with inhibitory interneurons cause inhibition of what

A

antagonist extensor muscle

78
Q

flexor and crossed extensor reflexes
connections with what cause inhibition of the antagonist extensor muscle

A

connections with inhibitory neurons cause inhibition of the antagonist extensor muscle

79
Q

flexor and crossed extensor reflexes
what pathway causes an opposite pattern of extensor activation and flexor inhibition that provides postural support

A

contralateral pathway

80
Q

what does the contralateral pathway cause

A

an opposite pattern of extensor activation and flexor inhibition that provides postural support

81
Q

what do cutaneous mechanoreceptors provide

A

sensory feedback from the skin

82
Q

cutaneous mechanoreceptors forces ion channel open that

A

depolarise the receptor neuron

83
Q

meissner’s corpuscles exhibit what fibres

A

RA1 fibres

84
Q

Pacinian corpuscles exhibit what fibres

A

RA2 fibres

85
Q

Merkel disk receptors exhibit what fibres

A

SA1

86
Q

Ruffini endings exhibit what fibres

A

SA2

87
Q

where are meissner’s corpuscles located
what do they respond to

A
  1. superficially
  2. respond to stroking, flutter
88
Q

Pacinian corpuscles are located where
and what do they respond to

A
  1. deeper tissues
  2. respond to vibration
89
Q

where are Merkel disk receptors located and what do they respond to

A
  1. superficially
  2. pressure and texture
90
Q

what do Ruffini endings respond to

A

skin stretch

91
Q

cutaneous feedback and precision grip
meissner’s corpuscles detect what during precision lifting

A

microslips

92
Q

cutaneous feedback and precision grip
meissner’s corpuscles detect microslips during what

A

precsion lifting

93
Q

what corpuscles detect microslipds during precision lifting

A

meissner’s corpuscles

94
Q

when meissner’s corpuscles detect a microslip during precision lifting what does this cause

A

a reflex increase in grip ensuring the object does not fall

95
Q

investigating the deep tendon reflex in the wrist (supination) can be used to assess the functional integrity of what spinal cord level

A

C5-C6

96
Q

investigating the deep tendon reflex in the biceps (elbow) can be used to assess the functional integrity of what spinal cord level

A

C5-C6

97
Q

investigating the deep tendon reflex in the triceps (elbow) can be used to assess the functional integrity of what spinal cord level

A

C7

98
Q

investigating the deep tendon reflex in the quadriceps (knee) can be used to assess the functional integrity of what spinal cord level

A

L3-L4

99
Q

investigating the deep tendon reflex in the ankle (gastrocnemius) can be used to assess the functional integrity of what spinal cord level

A

S1