Spinal Cord and Movement 2: Reflexes Lec19 Flashcards

(42 cards)

1
Q

Extrafuscal (normal) muscle fibers are innervated by

A

α motor neurons

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2
Q

Intrafuscal (muscle spindle / stretch receptors) fibers are innervated by

A

γ motor neurons
and by Type Ia and Type II sensory neurons

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3
Q

Spindles are arranged in ___ with extrafuscal muscle fibers

A

parallel

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4
Q

what do γ motor neurons affect?

A

only spindle stiffness, not contraction

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5
Q

Muscle spindles send stretch signals via

A

type Ia and type II neurons:

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6
Q

Type ___ central (bag) region

A

Ia:

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7
Q

type ___ fire intensely at onset of stretch,

! then slows down.

A

1a

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8
Q

type II firing is at what rate

A

static, increases linearly with increasing strethc

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9
Q

Stretch reflex?

A
muscle spindle senses stretch --\> spinal cord --\> original (homonymous)
 and synergist (heteronymous) muscles excited and anatagonist inhibited to counter perturbation
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10
Q

during stretch reflex, the Antagonist

muscle is___

A

inhbhited by interneruons

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11
Q

Contraction response:

when extrafuscal muscle contracts,____fire to
shorten intrafuscal fibers

A

the γ motor neurons

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12
Q

why do the the γ motor neurons fire during contraction response?

A

to shorten the intrafusal fibers and to keep them sensitive

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13
Q

Golgi Tendon Organs (GTO) only fire when muscle ___

A

actively contracts

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14
Q

muscle spindle cares about ___

A

length

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15
Q

golgi tendon cares about ___

A

tension

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16
Q

holgi tendon organs are receptors are ___ fibers

A

Type Ib

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17
Q

golgi tendon organ receptors arranged in ____ with extrafuscal muscle fibers

18
Q

muscle spindle is the only afferent that ___

A

receives a nerve supply

19
Q

difference between gamma motor neurons and alpha MN?

A

gamma has a smaller soma and a lower conduction velocity

20
Q

____ motor.. innervate intrafusal not at center point
but lower down

21
Q

____ contraction makes the muscle spindle more sensitive to stim.

22
Q

sensory receptors on intrafusal fibers

A

type 1a and II

23
Q

___ receptor fires with stretch from distal muscle spindle

24
Q

biceps and brachialis are examples of

25
triceps and biceps are
anatagonists
26
increased load about the elbow causes rotation --\> spindle in biceps are stretched --\> afferents sent to spinal cord activating the
biceps motor neurons
27
when an anatagonist muscle is inhibited it is by a
1a inhibitory interneuron
28
correction is ____ perturbation
resisting
29
if you ___ of a spindle it becomes silent
reduce
30
when alpha motor neuron is activated without ___ you get silent
gamma MN
31
golgi tendon reflex involves the ___ interneuron
1b
32
in golgi tendon reflex action 1b interneuron does what
excites the anatgonist muscle inhibits the agonist muscle
33
Flexion-crossed-extension reflex: if one limb reflexively withdraws, the limb across the midline ____ to keep you balanced.
extends
34
Central pattern generators are defined as neurons that
produce coordinated movements in the absence of higher inputs
35
in cats & humans central pattern generators are for ___ movements
stepping
36
central pattern generators are activated by (2)
2. stim of Mesencephalic Locomotor Region 2. noradrenergic inputs
37
if one limb reflexively withdraws, theipsilateral limb ____ to keep you balanced.
flexes
38
central pattern input can be modified by
training
39
with emg demonstration Low amplitude action potentials...could mean
lost neurons
40
its difficult to activate a nerve AP with direct electrical stimulation but easy to
monitor or record
41
emg -- Can only recruit a few motor units...suggests a
partial problem
42
emg -- Spontaneous, non-rhythmic activity...suggests
dennervated muscle