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Control of movement > Spinal reflexes > Flashcards

Spinal reflexes Flashcards

1
Q

what is a reflex

A

reflex is coordinated involuntary movement - initiated by the brain

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2
Q

reflexes can sometimes involve

A

supraspinal components

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3
Q

what is supra spinal components

A

something above part of the spine - can be the brain or ligaments or fascia

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4
Q

why do reflexes occur

A

in response to danger

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5
Q

what is the stretch reflex

A

a monosynaptic reflex which lengthens the skeletal muscle

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6
Q

how is the stretch reflex evoked

A

tendon tap

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7
Q

what does a stretch reflex rely on

A

mechanical response and sensory afferent feedback

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8
Q

how do u abolish the stretch reflex

A

cutting dorsal root

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9
Q

muscle spindles are receptors that detect changes in the

A

muscle length during contraction

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10
Q

the stretch in stretch reflex evokes an increase in

A

spindle firing rate

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11
Q

the sensory signal in the stretch reflex is sent to where

A

dorsal horn by type 1a afferent neurons

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12
Q

a motor neurons are activated in the spinal ventral horn leading to

A

muscle contraction of the agonist and synergist muscles

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13
Q

stretch reflex - what muscles are inhibited

A

antagonist

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14
Q

muscle spindles consist of what

A

bundles of thin fibres contained within capsule

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15
Q

9spindles) situated in parallel with main intrafusal muscle fibres but

A

generates no force

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16
Q

muscle spindles wrapped around by what

A

sensory axons - 1a and 2

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17
Q

muscle spindles have y motor neurons cause active contraction of

A

spindles

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18
Q

muscle spindle detects - 2

A

length and stretch of muscle - position
and rate of change - velocity

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19
Q

intrafusal fibres are innervated by what

A

y motor neurons

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20
Q

what are the 2 types of intrafusal fibres

A
  • nuclear bag fibres - 1a afferents- annulospiral endings
    -nuclear chain fibres - both 1a and 2 afferents
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21
Q

what is bigger intrafusal fibres

A

nc. bag fibres - bc of nuclei bunched together

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22
Q

both types of intrafusal fibres respond to

A

stretch

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23
Q

stretch reflex-
faster the response means

A

the fewer neurons and synapses

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24
Q

u can use latency in a reflex to calculate what

A

how many neurons involved

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25
Q

the earliest onset is what for stretch reflex

A

<1ms

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26
Q

stretch reflex - the antagonist muscles are inhibited at

A

slightly longer latencies

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27
Q

reciprocal inhibition
antagonist muscles which may interfere with …

A

desired movement are suppressed by contraction of the agonist muscle

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28
Q

reciprocal inhibition
co contraction is what

A

when we want to contract antagonist and agonist at the same time

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29
Q

why is reciprocal inhibition useful

A

to help stop co contraction and modulates inputs from the brain

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30
Q

what is klippel feil syndrome

A

a rare condition in which premotor neurons from cortex bifurcate to innervate both sides of the body

31
Q

moving one hand ipsilateral leads to

A

mirror movements in other hand

32
Q

hyperreflexia / spasticity

A

descending input from the brain normally acts to regulate reflex gain in spinal cord

33
Q

what can abolish the input for hyperrflexia

A

sci, stroke and other conditions

34
Q

what is Intrathecal baclofen

A

treatment for spasticity

35
Q

what is the proceedure is intrathecal baclofen -

A

catheter is placed in spinal fluid and a pump in the abdominal which pumps baclofen - allowing dorsal horn inhibition

36
Q

what does the treatment for specificity result in

A

decreased ,muscle spasms and tone

37
Q

what is the purpose of the stretch reflex

A

it is a negative feedback loop
preventing major disturbances to regulation of controlled variable - muscle length

38
Q

what does the stretch reflex maintain

A

accuracy of movement (in face of small deviations)

39
Q

voluntary commands come from which part of the brain

A

motor cortex

40
Q

the stretch reflex helps correct what

A

small deviations from desired trajectories caused by unpredictable things

41
Q

an unpredictable increase in load is a disturbance detected by

A

muscle spindles and will compensate for deviation from desired muscle length

42
Q

what is the Hoffman reflex

A

the finger reflex, which identifies possible problems within the corticospinal tract

43
Q

what does the hoffman reflex do

A

evokes a muscle contraction from type 1a sensory nerves

44
Q

what can hoffman reflex be shown on

A

EMG

45
Q

sensory type 1a afferent fibres are activated at a what threshold than motor fibres

A

lower

46
Q

how can the hoffman reflex be altered

A

conditioning a stimulus

47
Q

what is flexion withdrawal reflex

A

A reflex which contracts a muscle in response to danger or pain

48
Q

the flexion withdrawal reflex stimulates what

A

ipsilateral flexor muscles whilst extensors are inhibited

49
Q

what type of fibres in withdrawal reflex

A

thinly myelinated type 3

50
Q

withdrawal reflex provides extension in

A

contralateral limb to compensate for unloading in the ipsilateral limb

51
Q

the reflex withdrawal reflex persists after spinal cord what

A

transection

52
Q

reflex adaptability -
golgi tendon input inhibits what

A

ongoing muscle activity via negative feedback

53
Q

Golgi tendons are sensitive to tension and force and active what type of afferent neurons

A

type 1b

54
Q

what is locomotion

A

movement or ability to move from one place to another

55
Q

during lococmotion - golgi tendons input increases extension muscles a activity to produce what

A

positive feedback

56
Q

gait phase dependant golgi feedback - GTO reflex contributes to transition between what 2 phases

A

stance and swing

57
Q

what type of feedback is during the gait phase of stance

A

positive

58
Q

what type of feedback is used for swing gait phase

A

negative

59
Q

what is pulmonary stretch receptors

A

receptors which monitor the mechanoreceptors in the lungs

60
Q

what is the pulmonary stretch reflex

A

The reflex which monitors coughing and lung inflation - mediated by the receptors

61
Q

rapidly adapting receptors lie between what 2 cells

A

airway epitheial cells and trigger the cough reflex

62
Q

slowly adapting receptors lie in between what 2 things

A

airway smooth muscle cells and the trigger the lung inflation reflex

63
Q

what fibres trigger the cough reflex

A

RARS activting Ao and C fibres

64
Q

cough reflex is what

A

a mechanism for airway defense’s against aspiration

65
Q

irritatnt receptors are a type of what

A

nociceptor

66
Q

mechanical stimuli for cough reflex involves what

A

bronchoconstriction -dust - food - chemicals - activating type 3 fibres

67
Q

first step for affernt information travelling to medulla and then to

A

respiratory central pattern generators in brain stem

68
Q

effectors for cough reflex is what

A

inspiratory, expiratory and upper airway muscles

69
Q

mechanics of breathing
what are the 3 phases for a cough

A

inspiratory, compression and expiratory

70
Q

inspiration breathing
what are the 2 steps for cough - inspiratory

A

deep inspiration with the glottis open
diaphragm external intercostals

71
Q

what is the compression phase for a cough

A

expiratory muscle contract - against closed glottis - making pressure
trunk and upper airway compress

72
Q

what is the phase for expiratory phase for a cough

A

glottis opens causing a rapid ejection

73
Q

stretch relfex is caused by what

A

msucle spindles

Control of movement (15 decks)

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