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phys > exam 2: skeletal muscle reflexes > Flashcards

exam 2: skeletal muscle reflexes Flashcards

1
Q

skeletal muscle reflexes:
a
b

A

a. stretch reflex (muscle receptors)
b. golgi tendon reflex (tendon receptors)

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2
Q

muscle receptors

A

stretch reflex

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3
Q

tendon receptors

A

golgi tendon reflex

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4
Q

sensory nerve fiber that sends messages back to the CNS from the muscle spindle

type of sensory fiber

A

1a fiber (muscle spindle)

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5
Q

sensory fiber that is coming from the golgi tendon and sends message to CNS

A

1b fiber (golgi tendon)

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6
Q

myelinated nerve fibers
large diameter
fastest conduction velocity

A

1a muscle spindle
1b golgi tendon

(sensory fibers)

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7
Q

travels from cns to ends of muscle fibers in the spindle

A

gamma motor neuron (Ay) motor neuron

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8
Q

two motor nuerons for skeletal muscle reflexes

A

alpha motor neuron (LMN)
and
gama motor neuron (Ay)

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9
Q

innervates the ends of the intrafusal muscle fibers in the spindle

A

gamma motor neurons

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10
Q

skeletal muscle fibers/cells that produce the contraction

A

extrafusal fibers

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11
Q

efferent neuron that releases Ach and causes contraction of the extrafusal fiber (skeletal muscle)

A

alpha motor neuron (LMN)

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12
Q

small structure within the extrafusal fibers that contain _____ that have sensory nerve endings wrapped around that are sensitive to changes in:

A

muscle spindle with 1a sensory fibers wrapped around

changes in MUSCLE LENGTH aka stretch

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13
Q

1a sensory nerve fibers that are wrapped around muscle spindle are sensitive to changes in

A

muscle length aka stretch

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14
Q

efferent neuron that causes contraction of intrafusal fibers so they mimic what the extrafusal fibers are doing

A

gamma motor neuron (found at the end of intrafusal fibers)

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15
Q

as muscle stretches, this does what to 1a afferent neuron

A

increases AP frequency making it stretch

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16
Q

jaw closers have a lot of:
jaw openers:

A

closers: lot of muscle spindles
openers: have few to none

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17
Q
  1. when the muscle stretches, the sensory fibers of the muscle spindle are
A

squeezed

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18
Q
  1. when afferent information enters the spinal cord:
    1
    2

which then stimulates:

A
  1. this activates the alpha motor neuron (LMN)

which then stimulates
a. muscle contraction (extrafusal fiber)
b. inhibition of alpha motor neuron of antagonistic muscles

  1. activates gamma motor neuron
    a. stimulates intrafusal fiber contraction
    b. if intrafusal fibers didn’t contraction, sensory fibers would not be able to sense a further change in muscle length since they would be slack
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19
Q

afferent info entering spinal cord activates:

A

alpha motor neurons and gamma motor neurons

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20
Q

the activation of alpha motor neurons stimulates:

A

muscle (extrafusal fiber) contraction
(also inhibition of the alpha motor neuron of antagonistic muscles)

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21
Q

the activation of gamma motor neurons stimulates:

A

intrafusal fiber contraction

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22
Q

if the intrafusal fiber doesn’t contraction from activation of gamma motor neuron, then the sensory fibers would not be able to

A

send a further change in muscle length since they would be slack

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23
Q

the stimulus for the muscle spindle reflex is

A

stretch

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24
Q

the effect of muscle spindle activation is

A

contraction

25
Q

the reflex has ______(immediate) and _____ (maintains tone-constant contraction) reflex components

A

dynamic and static

26
Q

dynamic:

static:

A

dynamic: immediate
static: maintains tone-contstant contraction

27
Q

anytime the alpha motor neuron is activated, what is also activated

A

gamma motor neuron

28
Q

if the ___________ did not contract, then the sensory fibers would not be able to sense a further change in muscle length since they would be slack

A

intrsfusal fibers

29
Q

with LMN and gamma activated together, this allows muscle spindle to maintain sensitivity to changes in

A

muscle length during contraction

30
Q

mechanosensitive receptors found at the junction of tendons and muscle

A

golgi tendon organs

31
Q

golgi tendon organs are sensitive to a change in

A

force

32
Q

the golgi tendon organ reflex is a

A

protective reflex

33
Q

if GTO (golgi tendon organ) is activated, it will

A

inhibit muscle contraction

34
Q

golgi tendon organ synapses with:

which will then block activity of

A

inhibitory interneuron

block 1a LMN

35
Q

tendons stretch in response to

A

contraction (particulary isometrix maximal contraction)

36
Q

extreme stretch of the tendon will squeeze the GTO and

A

afferent neurons will send info into spinal cord

37
Q

with an extreme stretch of GTO and afferent neurons sending info into spinal cord, what will happen:

A
  1. stimulate inhibitory interneuron
  2. this neuron decreases the activity of the alpha motor neuron LMN
  3. skeletal muscle contraction is decreased= relaxation
38
Q

excess tension-> 1b to CNS-> stimulate inhibitory response-> neuron decreases LMN activity-> relaxation

A
39
Q

control of mastication
is mix of

A

mix of voluntary, reflex, and central (subconscious) processes

40
Q

control of mastication requires coordination of muscles controlling:

A

lips, tongue and cheeks

41
Q

mastication voluntary control is usually ____, although people tend to favor one side of the mouth over the other

A

bilateral

42
Q

control component.

mastication is a cyclical movement with develops early in life. it is controlled by

A

central pattern generator (CPG) of the brainstem

43
Q

when the central patten generator CPG of brainstem is stimulated, it elicits rhythmic, coordinated

A

activation and inactivation of jaw-closers and jaw-openers

44
Q

CPG cannot by itself adjust muscle force to deal with changing conditions that occur when diff food are chewed. ____ are important modifiers of force

A

reflexes

45
Q

input from higher cortical regions can regulate the CPG frequency via the

to activate jaw closers and jaw openers

A

corticobulbar pathway

46
Q

pain inhibits the alpha motor neuron of jaw closing muscles such as when you bite down on your tongue, metal spoon, with your incisors

A

jaw opening reflex

=jaw opens

47
Q

strong tap to the chin stretches the jaw closers
-jaw closers respond by contraction so the jaw closes

A

jaw jerk reflex

48
Q

stretch reflex:

A

jaw jerk reflex

49
Q

how do you determine the force needed to take a bite of something hard?

begins with

A

CPG starts chewing by activating jaw closer muscles

50
Q

GPG starts chewing by activating

A

jaw closer muscles

51
Q

when the jaw closing musclces connect with food, they initially meet with resistance:

A

the force of contraction is insufficient to overcome to load of food=isometric contraction!

52
Q

intrafusal fibers in muscle spindle are still contracting and stretching the muscle spindle so this signals further contraction of

A

jaw closing muscles

53
Q

constant feedback from the muscle spindle in the jaw closing muscles in sufficient to overcome the load of the food=

A

isotonic contraction

54
Q

with subsequent chewing strokes, the response is greater and matches the load of the food with appropriate force more

A

quickly

55
Q

protection by muscle spindles.

With nut, lot of force is required and can damage intraoral structures.

_______decreases contraction in these situations.

when the nut cracks, the force is _____ than the load (nut)
and there is MORE SLACK in the muscle spindle which leads to:
so dont hurt teeth

A

muscle spindles

force greater than load

leads to less activation of the muscle (due to decreases alpha/gamma co-activation)

56
Q

powerful isometric contractions stimulate both jaw closing and opening muscles. the jaw _____ keep the jaw from snapping shut

A

jaw openers

57
Q

at rest, ____mm normally separate the occlusal surfaces of teeth

A

3-8mm

58
Q

when jog or run, ___ is applied to mandible.

with each step, there is a ____ movement of the mandible in relation to the head.

this movement stretches the_____ which causes a reflex contraction of jaw CLOSING muscles

A

force

down movement

muscle spindle

phys (16 decks)

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