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JL Neurology > Week 1 part 2 > Flashcards

Week 1 part 2 Flashcards

1
Q

What do lower motor nuerones command?

A

Muscle contraction

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2
Q

What neurones does the LMNs comprise of?

A

Alpha motor neurones - generate force

Gamma motor neurones - innervate sensory muscle spindle

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3
Q

Where do axons of the LMNs exit the spinal cord?

A

`In ventral roots (or via cranial nerves)

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4
Q

Each ventral root joints with a dorsal root to form what?

A

Mixed spinal nerve

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5
Q

What is the collection of alpha motor neurones that innervate a single muscle termed?

A

Motor neurone pool

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6
Q

Force of muscle contraction is graded by alpha motor nuerones by 2 principles - what are they?

A
  1. Frequency of action potential discharge

2. Recruitment of additional, synergistic motor units

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7
Q

What can be said about the positioning of LMN innervating axial muscles compared to distal muscles?`

A

Axial are more medial

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8
Q

What can be said about the positioning of LMN innervating flexors compared to extensors?

A

Flexors are dorsal

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9
Q

What are the three sources of input to an alpha motor neurone that regulate its activity?

A
  1. Central terminals of dorsal root ganglion cells whose axons innervate muscle spindles
  2. UMNs in motor cortex and brain stem
  3. Spinal interneurones
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10
Q

What do fast and slow muscle fibre types differ in?

A

How fast myosin ATPase splits ATP to probide energy

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11
Q

How is ATP derived in type I fibres?

A

Oxidative phosphorylation

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12
Q

How is ATP derived in type IIb fibres?

A

Glycolysis

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13
Q

In fast type muscle what size are the alpha motor neurones?

A

`Big

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14
Q

What motor neurone innervates intrafusal fibres in spindles?

A

Gamma motor neruone

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15
Q

What spinal level is assessed in supinator wrist?

A

C5-C6

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16
Q

What spinal level is assessed in Biceps?

A

C5-C6

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17
Q

What spinal level is assessed in triceps

A

C7

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18
Q

What spinal level is assessed in quadriceps

A

L3-L4

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19
Q

What spinal level is assessed in gastrocnemius (ankle)

A

S1

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20
Q

In what activities are static gamma motor neurones active?

A

When muscle length changes slowly and predictably

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21
Q

In what activitres are dynamic gamma motor neurones active?

A

Muscle length changes rapidly and unpredictably

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22
Q

What are golgi tendon organs in series with?

A

Extrafusal fibres

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23
Q

What are golgi tendon organs innervated by>?

A

Group Ib sensory afferents

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24
Q

What do golgi tendon orgabns do?

A

Act to regulate muscle tension to protect them from overload

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25
Q

What is the role of spinal interneurones?

A

Limb movement control of flexors and extensors

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26
Q

What mediates the inverse stretch reflex and reciprocal inhibition between extensor and flexor muscles?

A

Inhibitory interneurones

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27
Q

What do excitatory interneurones mediate?

A

The flexor reflex

The crossed extensor reflex

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28
Q

What reflex enhances postural support during withdrawel of foot from painful stimulus?

A

Crossed extensor reflex

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29
Q

What structures control strategy in motor control?

A

Neocrotical association areas basal ganglia

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30
Q

What structures conrol tactics in motor control?

A

Motor cortex

cerebellum

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31
Q

What strucutres control execution in motor control?

A

Brain stem

Spinal cord

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32
Q

Where do descending spinal tracts originate from?

A

Cerebral cortex and brain stem

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33
Q

What controls lateral pathways which are important for voluntary control of distal musculature (hands and fingers)?

A

Cerebral cortex

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34
Q

What controls ventromedial pathways which are important for control of posture and locomotion?

A

Brainstem

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35
Q

What is the major lateral pathway?

A

Corticospinal or pyramidal tract (longest tract)

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36
Q

In the corticospinal or pyrimidal tract where do most fibres decussate?

A

At the pyramidal decussation to form lateral corticospinal tract (from medullary pyramid_

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37
Q

What does left hemisphere control?

A

Right musculature

38
Q

Name a minor lateral pathway?

A

Rubrospinal tract

39
Q

Where do axons in rubrospinal tract decussate?

A

At ventral tegmental decussation (and descend the spinal cord ventrolateral to the lateral corticospinal tract, terminating in ventral horn)

40
Q

Axons from the lateral vestibular nucleus (deiters) descend as far as?

A

The lumbar spinal cord (hold upright balanced posture)

41
Q

Axons from the medial vestibular nucleus descend as far as the?

A

Cervical spinal cord (control nbeck and back muscles)

42
Q

In relation to the tectospinal tract: where do cell bodies redide?

A

In superior colliculus (optic tectum) - receives direct input from retina

43
Q

In relation to the tectospinal tract: where do axons decussate?

A

In dorsal tegmental decusssation

44
Q

What two things arise from the reticular formation?

A

Pontine (medial) and medullary (lateral) reticulospinal tracts

45
Q

What does the pontine reticulospinal tract ( descends ipsilaterally) help to maintain?

A

Standing posture due to contraction of extensors in lower limb

46
Q

What side does the medullary reticulospinal tract descend?

A

Bilaterally - opposes action of medial tract

47
Q

What are first order neurones that relay information to second order neurones in the CNS by chemical synaptic transmission?

A

Nociceptors

48
Q

What fibres are mechanical/thermal nociceptors and mediate first, or fast pain?

A

Alpha delta fibres (thinly myelinated)

49
Q

What fibres are nociceptors, unmyelinated and collectively respond to all nloxious stimuli (polymodal), mediate second or slow pain?

A

C-fibres

50
Q

What is the term for when the rate of action potential discharge correlates with the intensity of the applied stimulus?

A

Frequency coding

51
Q

What do type I Adelta fibres mediate?

A

First pain to intense mechanical stimuli

52
Q

What do type II Adelta fibres mediate?

A

First pain to heat (sensitive to capsaicin)

53
Q

What subclassification of Cfibre - contributes to heat pain and location of stimulus and shows sensitisation to repeated stimuli?

A

C-MH

54
Q

What subclassification of Cfibre - responds to noxious mechanical stimuli, insensitive to heat and capsaicin?

A

C-M

55
Q

What subclassification of Cfibre - responds to notious heat, sensitive to capsaicin, mediates heat hyperalgesia, does not contribute to location and requires a sensitivity to mechanical stimulation in the context of inflammation?

A

C-H

56
Q

What subclassification of Cfibre - is normally insensitive to both mechanical and heat stimuli but aquires sensitivity following sensitisation by inflammatory mediators?

A

C-MiHi (silent)

57
Q

What nociceptor terminal is the site of Ca dependent transmitter release (glutamate) and is targeted by endogenous molecules that regulate activity?

A

Central terminal

58
Q

What nociceptor terminal is the site of release of molecules that influence local tissue environment (e.g. substance P causes vasodilation and extravasation of plasma proteins, calcitonin gene related pepetide causes vasodilation), and is targeted by endogenous molecules that regulate sensitivity?

A

Peripheral terminal

59
Q

What signalling direction is by nociceptors?

A

Bidirectional

60
Q

Where are primary afferent cell bodies (apart from trigeminal system) located?

A

In dorsal root ganglia

61
Q

Where do axons of primary afferent cell bodies terminate?

A

Centrally in dorsal horn of spinal cord in various laminae of Rexed (I-V)

62
Q

Where do nociceptive C and Adelta fibres mostly terminate superficially?

A

In lamiae I and II (also V for Adelta)

63
Q

What can be said about cells that only receive input from Adelta fibres?

A

They are proprioceptive

64
Q

What pain originates from stretching, twisting, inflammation and ischaemia but not cutting or burning?

A

Visceral pain

65
Q

Where do terminals of visceral nociceptors terminate?

A

In laminae I and V but not II

66
Q

Where does referred pain from the heart go?

A

T1 - T5

67
Q

Where is gallbladder pain referred to?

A

C4

68
Q

What does the spinoreticular tract transmit?

A

Slow C-fibre pain

69
Q

What tract in the anterolateral system is invoved in autonomic responses to pain, arousal, emotional response and fear of pain?

A

Spinoreticular tract

70
Q

In relation to the spinothalamic tract: where do prohjection neurones originating from lamina I (fast Adelta pain) terminate?

A

In posterior nucleus of thalamus

71
Q

In relation to the spinothalamic tract: where do projection neurones originating from lamina V terminate?

A

In posterior and ventroposterior nucleus of the thalamus

72
Q

In relation to the slow pathway (spinoreticular tract) where are signals from the thalamus relayed by thalamocortical neurones to?

A

Limbic area of forebrain

73
Q

What pathway registers the emotional/motivational component of pain?

A

Spinoreticualr tract

74
Q

What does stimulation of non-nociceptive afferents (e.g. Abeta fibres) activate?

A

Lamina II inhibtory interneurones that suppress firing of projection neurone

75
Q

In relation to controlling spinal gates: with physiological influence what opens and closes the gate?

A

Opens - C/Adelta dibres active

Closes - Abeta fibres active

76
Q

Name three important brainstem regions for pain modulation?

A
  1. Periaqueductal grey - excitation produces profound analgesia
  2. nucleus raphe magnus
  3. locus coeruleus
77
Q

Name three mechanisms involved in suppression of nociceptive transmission of dorsal horn?

A
  1. Diret presynaptic inhibition
  2. Direct post synaptic inhibition
  3. Indirect inhibition
78
Q

What inhibition is being described here (suppression of nociceptive transmission of dorsal horn): inhibition of neurotransmitter release from nociceptors. Works via GPCR suppressing the opening of vltage gated calcium channels and calcium influx?

A

Direct presynaptic inhibition

79
Q

What inhibition is being described here (suppression of nociceptive transmission of dorsal horn): works via GPCR opening K channels in the projection neurone causing hyperpolarisation and reduced excitability?

A

Direct post synaptic inhibition

80
Q

What inhibition is being described here (suppression of nociceptive transmission of dorsal horn): works by activation of inhibitory interneurons (enkephalinergic) thay suppress transmission of both pre- and post synaptic mechanisms?

A

Indirect inhibition - opoid agonsit drugs mimic the activity of enkephalinergic interneurones

81
Q

What is opoid action mediated by?

A

GPC opiod receptors

82
Q

What are the four classes of opiod receptors>

A
  1. mu
  2. delta
  3. kappa
  4. ORL
83
Q

What opiod receptor is responsible for most analgesic action of copoids but has some major adverse effects such as depression, constipation, euphoria, sedation and dependence?

A

Mu

84
Q

What opiod receptor contributes to analgesia bt activation can be proconvulsant?

A

Delta

85
Q

What opiod receptor contributes to alagesia at the spinal and peripheral level and activation associated with sedation, dysphora and hakllucinations?

A

Kappa

86
Q

What opiod receptor when activated produces an anti-opoid effect?

A

ORL

87
Q

What should pethidine not be used together with?

A

MAO inhibitors

88
Q

Is codeine given orally or IV?

A

Oral

89
Q

What patients should not be given tramadol - weak u-receptor agonist?

A

Epileptics

90
Q

What drug - antagonist - is used to reverse opoid toxicity?

A

Naloxone

91
Q

What limits selective COX-2 inhibitor use?

A

Prothrombotic

JL Neurology (12 decks)

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