MODULE 8- ARPIN STUDY GUIDE Flashcards

1
Q

what does each lower motor neuron innervate

A

muscle fibers within a single muscle

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2
Q

motor neuron pool

A

all the motor neurons innervating a single muscle

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3
Q

somatotopic organization of motor neuron pools in dorsal/ventral horn of SC

A

ventral

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4
Q

medial ventral horn

A

-terminates bilaterally
-control of posture + locomotion

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5
Q

lateral ventral horn

A

-terminates only ipsilatterally
-fine control of distal extremities

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6
Q

2 types of lower motor neurons

A

-α-motor neurons (striated muscles)
-γ-motor neurons (sensory receptors/muscle spindles)

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7
Q

motor unit

A

α-motor neuron + all the muscle fibers it innervates

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8
Q

innervation number

A

number of muscle fibers innervated by one α-motor neuron

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9
Q

size principle

A

orderly recruitment of motor neurons

S -> FR -> FF

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10
Q

regulation of muscle force (2)

A

-number of active motor units
-firing rate of active motor units

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11
Q

muscle spindle

A

intrafusal fibers arranged in PARALLEL

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12
Q

what 3 intrafusal fibers do muscle spindles have

A

-dynamic nuclear bag fibers
-static nucleus bag fibers
-nuclear chain fibers

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13
Q

3 neurons of muscle spindle

A

-Ia afferent
-II afferent
-gamma (γ) motor neuron

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14
Q

what does gamma (γ) motor neuron do

A

contracts intrafusal fibers making Ia afferents more sensitive (gain)

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15
Q

stretch reflex

A

stretching muscle ->
increased discharge from Ia afferents

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16
Q

stretch reflex increases/decreases alpha motor neurons of agonist

A

increases

17
Q

stretch reflex increases/decreases alpha motor neurons of antagonist

A

decreases
-reciprocal innervation

18
Q

golgi tendon organs

A

sense changes in tension

19
Q

what axons innervate GTOs

A

Ib axons

20
Q

positive/negative feedback system for GTOs

A

negative

21
Q

negative feedback system of GTOs

A

increased tension ->
increase in Ib neuron activity ->
inhiits alpha motor neuron of agonist + excites alpha motor neuron of antagonist

22
Q

flexion reflex

A

-stimulates cutaneous (nociceptor)
-excites interneuron circuits in SC

23
Q

what does flexion reflex lead to

A

withdrawal of limb from painful stimuli

24
Q

flexion reflex- inhibition/excitation of extensor of stimulated foot

A

inhibition

25
Q

flexion reflex- inhibition/excitation of flexor of the stimulated foot

A

excitation

26
Q

flexion reflex- what happens to other limb

A

opposite response
-crossed extension reflex

27
Q

central pattern generator (CPG)

A

-rhythmic patterns of movement
-supraspinal commands are not necessary