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
2
Q
explain the definition of hierarchical organisation
A
the motor system is organised in a hierarchical fashion
3
Q
sensory ___ enter the spinal cord via the dorsal root
A
sensory afferents enter the spinal cord via the dorsal root
4
Q
sensory afferents enter the spinal cord via what
A
the dorsal root
5
Q
sensory afferents enter _____ via the dorsal root
A
spinal cord
6
Q
motor neurons leave the spinal cord via what
A
ventral root
7
Q
what neurons leave the spinal cord via the ventral root
A
motor neurons
8
Q
alpha motor neurons (or lower motor neurons) innervate what
A
skeletal muscles
9
Q
what neurotransmitter do alpha motor neurons release
A
acetylcholine
10
Q
at what synapse do alpha motor neurons release acetylcholine
A
neuromuscular junction
11
Q
what neurons innervate skeletal muscle
A
alpha motor neurons
12
Q
what neurons are clustered into spinal motor nuclei
A
alpha motor neurons
13
Q
alpha motor neurons are clustered into what
A
spinal cord nuceli
14
Q
all of the motor neurons in a nucleus innervate what
A
a single muscle
15
Q
_____ in a nucleus innervate a single muscle
A
all of the motor neurons in a nucleus
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
17
Q
each motor neuron can innervate how many fibres
A
many
18
Q
a motor neuron and all of the fibres it innervates is known as what
A
a motor unit
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
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
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
22
Q
the higher the firing rate of a tetanus the
(finish the sentence)
A
the higher the force of contraction
23
Q
one way of increase the force of contraction is increasing the firing rate, what is another way
A
recruiting more motor units
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
25
what is the difference between S and F units
F units contain larger numbers of muscle fibres
26
what kind of athlete would require larger number of S units
marathon runner
27
why would a marathon runner require more S units
(S)low contraction speed, highly fatigue resistant
contains I slow-twitch muscle fibres
motor neurons have small cell bodies and dendritic trees
28
what does a motor neuron look like
small cell bodies and dendritic trees
29
how is FR known as
fast fatigue resistant
30
what kind of athletes would need FR
800/1500 metre runners
31
why would a 800/1500m runner need FR
fast contraction speed
intermediate force
fatigue resistant
contains type IIa (fast twitch, high fatigue resistant
motor neurons have larger cell bodies
32
what is FF motor unit
Fast fatiguable
33
what athletes would require FF motor units
60/100m runners
34
why would 60/100m athletes require FF motor units
fast contraction speed, low fatigue resistant
contain type IIb/x
fast twitch low fatigue resistant
muscle fibres have large cell bodies
35
list the types of motor units and arrange them regarding the size of their cell bodies (smallest to largest)
S - small cell body and dendritic trees
FR - larger cell bodies
FF - large cell bodies
36
explain the size principle
orderly activation of motor units according to their size of cell bodies of their alpha motor units
-> smaller motor neurons are activated first
37
in the size principle, why are smaller motor neurons activated first
small surface area
-> increased membrane resistance which means more rapid depolarisation due to
V=IR
38
what is the speed of reflexes
rapid -> automatic
39
how are reflexes generated
by the circuitry of the spinal cord
40
what do reflexes provide
feedback adjustments to environmental perturbations
-> increase in muscle length with a reflex contraction
41
as well as reflexes controlling automatic behaviour, the same circuitry that mediates reflexes can also play an important role in what
voluntary movement
42
how can the circuitry that mediates reflexes can also play a role in voluntary movement ?
the same interneurons that coordinate excitation of extensor and inhibition of flexor muscles during the stretch reflex also coordinate contraction during voluntary movement
43
muscle spindles contain specialised what
muscle fibres
44
what are the principle receptors mediating proprioception
muscle spindles
45
muscle spindles contain specialised muscle fibres, and are the principle receptors mediating what
proprioception
46
what is proprioception
perception or awareness of the position and movement of the body
47
muscle stretching (increasing length) causes stretch sensitive _____ channel to open and depolarise sensory fibres
cation (Na+)
48
muscle stretching (increasing length) causes cation channels to open and do what
depolarise sensory fibres
49
muscle stretch causes the activation of what
Ia spindle afferents
50
Ia spindle afferents make _____ connections with alpha motor neurons
monosynaptic
51
Ia spindle afferents make monosynaptic connections with what
alpha motor neurons
52
Ia spindle afferents make monosynaptic connections with aloha motor neurons innervating the same muscle causing ________
contraction
53
in the stretch reflex, at the same time of Ia afferent fibres causing contraction, inhibitory neurons inhibit the activation of what
antagonist muscles
54
in the muscle spindle
what do gamma motor neurons cause the intrafusal fibres to do
contract - thus control sensitivity of the muscle spindle
55
gamma motor neurons maintain muscle spindle sensitivity during
muscle contraction
56
gamma motor neurons modulate the gain of
the stretch reflex
57
when do gamma motor neurons exhibit their highest activity
dynamic movements
falling
58
where is the golgi tendon
located at the transition between muscle and tendon
59
what does the golgi tendon organ signal the force of
muscle contraction (responds linearly on a graph)
60
golgi tendon organs send __ afferents that contract Ib inhibitory neurons
Ib
61
golgi tendon sends Ib afferents that contract what
Ib inhibitory interneurons
62
Golgi tendon
an increase in muscle force thus causes a reflex ______ of the same muscle
inhibition
as the golgi tendon organs send Ib afferents that contract Ib inhibitory interneurons
63
Ib interneurons receive input from where (2)
cutaneous and joint receptors
64
what do cutaneous afferents trigger
a reduction in muscle contraction when a limb contacts an object in the course of movement
65
the fact that when golgi tendon organs send Ib afferents that contract Ib inhibitory interneurons, what does this allow
may protect the muscle from excessive contraction - also serves to keep muscle tension within optimal range
66
the fact that when golgi tendon organs send Ib afferents that contract Ib inhibitory interneurons, what does this allow
may protect the muscle from excessive contraction - also serves to keep muscle tension within optimal range
67
where are cutaneous nociceptors located
skin
68
what do the sensory terminals of cutaneous nociceptors respond to
damaging stimuli
69
how do the terminals of cutaneous nerve endings differ
the free nerve endings are without a specialised sensory structure
70
A delta fibres respond to what
extremes of temperature or strong mechanical forces
71
Unmyelinated C fibres respond to what
types of noxious stimulation
72
nociceptor afferents can trigger what in response to a painful cutaneous stimuli
a withdrawal reflex
73
flexion withdrawal occurs after what
a painful stimulus
74
nociceptors afferents make what connections with motor neurons innervating a flexor muscle
nociceptors afferents make polysynaptic excitatory connections with motor neurons innervating a flexor muscle
75
nociceptor afferents make poly synaptic connections with what motor neurons innervating a flexor muscle
nociceptor afferents make polysynaptic excitatory connections with motor neurons innervating a flexor muscle
76
nociceptor afferents make polysynaptic excitatory connections with motor neurons innervating what
flexor muscle
77
flexor and crossed extensor reflexes
connections with inhibitory interneurons cause inhibition of what
antagonist extensor muscle
78
flexor and crossed extensor reflexes
connections with what cause inhibition of the antagonist extensor muscle
connections with inhibitory neurons cause inhibition of the antagonist extensor muscle
79
flexor and crossed extensor reflexes
what pathway causes an opposite pattern of extensor activation and flexor inhibition that provides postural support
contralateral pathway
80
what does the contralateral pathway cause
an opposite pattern of extensor activation and flexor inhibition that provides postural support
81
what do cutaneous mechanoreceptors provide
sensory feedback from the skin
82
cutaneous mechanoreceptors forces ion channel open that
depolarise the receptor neuron
83
meissner's corpuscles exhibit what fibres
RA1 fibres
84
Pacinian corpuscles exhibit what fibres
RA2 fibres
85
Merkel disk receptors exhibit what fibres
SA1
86
Ruffini endings exhibit what fibres
SA2
87
where are meissner's corpuscles located
what do they respond to
1. superficially
2. respond to stroking, flutter
88
Pacinian corpuscles are located where
and what do they respond to
1. deeper tissues
2. respond to vibration
89
where are Merkel disk receptors located and what do they respond to
1. superficially
2. pressure and texture
90
what do Ruffini endings respond to
skin stretch
91
cutaneous feedback and precision grip
meissner's corpuscles detect what during precision lifting
microslips
92
cutaneous feedback and precision grip
meissner's corpuscles detect microslips during what
precsion lifting
93
what corpuscles detect microslipds during precision lifting
meissner's corpuscles
94
when meissner's corpuscles detect a microslip during precision lifting what does this cause
a reflex increase in grip ensuring the object does not fall
95
investigating the deep tendon reflex in the wrist (supination) can be used to assess the functional integrity of what spinal cord level
C5-C6
96
investigating the deep tendon reflex in the biceps (elbow) can be used to assess the functional integrity of what spinal cord level
C5-C6
97
investigating the deep tendon reflex in the triceps (elbow) can be used to assess the functional integrity of what spinal cord level
C7
98
investigating the deep tendon reflex in the quadriceps (knee) can be used to assess the functional integrity of what spinal cord level
L3-L4
99
investigating the deep tendon reflex in the ankle (gastrocnemius) can be used to assess the functional integrity of what spinal cord level
S1
