Week 1 part 2 Flashcards Preview

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Flashcards in Week 1 part 2 Deck (91):
1

What do lower motor nuerones command?

Muscle contraction

2

What neurones does the LMNs comprise of?

Alpha motor neurones - generate force
Gamma motor neurones - innervate sensory muscle spindle

3

Where do axons of the LMNs exit the spinal cord?

`In ventral roots (or via cranial nerves)

4

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

Mixed spinal nerve

5

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

Motor neurone pool

6

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

1. Frequency of action potential discharge
2. Recruitment of additional, synergistic motor units

7

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

Axial are more medial

8

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

Flexors are dorsal

9

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

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

10

What do fast and slow muscle fibre types differ in?

How fast myosin ATPase splits ATP to probide energy

11

How is ATP derived in type I fibres?

Oxidative phosphorylation

12

How is ATP derived in type IIb fibres?

Glycolysis

13

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

`Big

14

What motor neurone innervates intrafusal fibres in spindles?

Gamma motor neruone

15

What spinal level is assessed in supinator wrist?

C5-C6

16

What spinal level is assessed in Biceps?

C5-C6

17

What spinal level is assessed in triceps

C7

18

What spinal level is assessed in quadriceps

L3-L4

19

What spinal level is assessed in gastrocnemius (ankle)

S1

20

In what activities are static gamma motor neurones active?

When muscle length changes slowly and predictably

21

In what activitres are dynamic gamma motor neurones active?

Muscle length changes rapidly and unpredictably

22

What are golgi tendon organs in series with?

Extrafusal fibres

23

What are golgi tendon organs innervated by>?

Group Ib sensory afferents

24

What do golgi tendon orgabns do?

Act to regulate muscle tension to protect them from overload

25

What is the role of spinal interneurones?

Limb movement control of flexors and extensors

26

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

Inhibitory interneurones

27

What do excitatory interneurones mediate?

The flexor reflex
The crossed extensor reflex

28

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

Crossed extensor reflex

29

What structures control strategy in motor control?

Neocrotical association areas basal ganglia

30

What structures conrol tactics in motor control?

Motor cortex
cerebellum

31

What strucutres control execution in motor control?

Brain stem
Spinal cord

32

Where do descending spinal tracts originate from?

Cerebral cortex and brain stem

33

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

Cerebral cortex

34

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

Brainstem

35

What is the major lateral pathway?

Corticospinal or pyramidal tract (longest tract)

36

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

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

37

What does left hemisphere control?

Right musculature

38

Name a minor lateral pathway?

Rubrospinal tract

39

Where do axons in rubrospinal tract decussate?

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

40

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

The lumbar spinal cord (hold upright balanced posture)

41

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

Cervical spinal cord (control nbeck and back muscles)

42

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

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

43

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

In dorsal tegmental decusssation

44

What two things arise from the reticular formation?

Pontine (medial) and medullary (lateral) reticulospinal tracts

45

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

Standing posture due to contraction of extensors in lower limb

46

What side does the medullary reticulospinal tract descend?

Bilaterally - opposes action of medial tract

47

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

Nociceptors

48

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

Alpha delta fibres (thinly myelinated)

49

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

C-fibres

50

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

Frequency coding

51

What do type I Adelta fibres mediate?

First pain to intense mechanical stimuli

52

What do type II Adelta fibres mediate?

First pain to heat (sensitive to capsaicin)

53

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

C-MH

54

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

C-M

55

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?

C-H

56

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

C-MiHi (silent)

57

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

Central terminal

58

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?

Peripheral terminal

59

What signalling direction is by nociceptors?

Bidirectional

60

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

In dorsal root ganglia

61

Where do axons of primary afferent cell bodies terminate?

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

62

Where do nociceptive C and Adelta fibres mostly terminate superficially?

In lamiae I and II (also V for Adelta)

63

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

They are proprioceptive

64

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

Visceral pain

65

Where do terminals of visceral nociceptors terminate?

In laminae I and V but not II

66

Where does referred pain from the heart go?

T1 - T5

67

Where is gallbladder pain referred to?

C4

68

What does the spinoreticular tract transmit?

Slow C-fibre pain

69

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

Spinoreticular tract

70

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

In posterior nucleus of thalamus

71

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

In posterior and ventroposterior nucleus of the thalamus

72

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

Limbic area of forebrain

73

What pathway registers the emotional/motivational component of pain?

Spinoreticualr tract

74

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

Lamina II inhibtory interneurones that suppress firing of projection neurone

75

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

Opens - C/Adelta dibres active
Closes - Abeta fibres active

76

Name three important brainstem regions for pain modulation?

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

77

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

1. Diret presynaptic inhibition
2. Direct post synaptic inhibition
3. Indirect inhibition

78

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?

Direct presynaptic inhibition

79

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?

Direct post synaptic inhibition

80

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?

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

81

What is opoid action mediated by?

GPC opiod receptors

82

What are the four classes of opiod receptors>

1. mu
2. delta
3. kappa
4. ORL

83

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?

Mu

84

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

Delta

85

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

Kappa

86

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

ORL

87

What should pethidine not be used together with?

MAO inhibitors

88

Is codeine given orally or IV?

Oral

89

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

Epileptics

90

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

Naloxone

91

What limits selective COX-2 inhibitor use?

Prothrombotic