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1. Neurology > Physiology of Movement > Flashcards

Physiology of Movement Flashcards

1
Q

Where are upper motor neurons found?

A

in the brain

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2
Q

Where are lower motor neurons found?

A

in the brainstem

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3
Q

What are lower motor neurons made up of?

A

alpha and gamma MNs

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4
Q

What are alpha motor neurons responsible for?

A

muscle contraction - innervate a bulk of fibres within the muscle

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5
Q

What are gamma motor neurons responsible for?

A

muscle tone - innervate the muscle spindle

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6
Q

Where do alpha and gamma motor neurons arise from?

A

laminae VIII and IX

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7
Q

What is a motor neuron pool?

A

collection of alpha motor neurons that innervate a single muscle

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8
Q

What is a motor unit?

A

alpha motor neuron and all of the skeletal muscle fibres that it innervates

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9
Q

What is force of muscle contraction graded/controlled by?

A

frequency of action potential discharge of the alpha MN

recruitment of additional synergic motor units

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10
Q

Which is more medial - LMNs innervating distal or axial muscles?

A

LMNs innervating axial muscles

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11
Q

What is more dorsal - LMNs innervating flexors or extensors?

A

LMNs innervating flexors

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12
Q

What does muscle strength depend on?

A

The activation of muscle fibres - firing rates of LMNs, no of LMNs fired simultaneously
The force production by innervated muscle fibres

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13
Q

What are small motor units innervated by?

A

small alpha MNs

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14
Q

What are large motor units innervated by?

A

large alpha MNs

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15
Q

Are fast motor units made up of small or large MNs?

A

large alpha MNs

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16
Q

What colour are slow oxadative type 1 muscle fibres?

A

RED

17
Q

What colour are fast oxadative type 2a muscle fibres?

A

RED

18
Q

What colour are fast oxadative type 2b muscle fibres?

A

WHITE

19
Q

Describe slow oxidative type 1 muscle fibres?

A

ATP derived from oxidative phosphorylation
slow contraction and relaxation
small alpha MNs
low threshold

20
Q

Describe fast oxidative type 2a muscle fibres?

A

ATP derived from oxidative phosphorylation
fast contraction and relaxation
intermediate alpha MNs
intermediate threshold

21
Q

Describe fast oxidative type 2b muscle fibres?

A 
ATP derived from glycolysis 
fast contraction but not fatigue resistant
not commonly found in man/mammals
large alpha MNs
high threshold
22
Q

How are LMNs excited?

A

by activation of UMNs

23
Q

How are LMNs and the muscle fibres they innervate recruited?

A

in order of their size - small ones more easily recruited

- allows for fine control of muscle

24
Q

Describe the monosynaptic reflex arc?

A

stretch of muscle spindle -> Ia afferent fires out action potentials -> excitory synaptic transmission in spinal cord -> activation of alpha MNs -> contraction of homonymous muscle

25
Q

What makes up a muscle spindle?

A

intrafusal fibres
sensory afferents
fibrous capsule
gamma motor neuron efferents

26
Q

What regulates the monosynaptic reflex arc?

A

gamma motor neuron efferents

27
Q

What do intrafusal fibres consist of?

A

a non contractile region innervated by Ia sensory neurons

contractile polar ends that recieve input from gamma MNs

28
Q

What causes the muscle spindle to contract?

A

gamma MNs

29
Q

What is the role of spinal interneurones?

A

gather information to generate an output

30
Q

What are the two types of spinal interneurones?

A

inhibitory

excitory

31
Q

What do inhibitory interneurones mediate?

A

the inverse myotatic response and reciprocal inhibition between extensor and flexor muscles

32
Q

What is the flexor reflex?

A

noxious stimuli causes the limb to flex by contraction of flexor muscles (via excitory interneurones) and relaxation of extensor muscles via excitatory and inhibitory interneurones

33
Q

What is the myotatic response?

A

when a muscle is pulled, it pulls back

34
Q

What mediates the flexor reflex?

A

excitory interneurones

35
Q

Whats the crossed extensor reflex?

A

noxious stimuli causes limb to extend by contraction of extensor muscles by excitory interneurones
- ehances postural support during the withdrawl of your foot

36
Q

What is the role of the vestibulospinal pathway?

A

control head and neck

37
Q

What is the role of the tectospinal tract?

A

muscles of upper trunk, neck and shoulders

38
Q

What tracts are part of the lateral pathway?

A

corticospinal tract

rubrospinal tract

39
Q

What tracts are part of the ventromedial pathway?

A

vestibulospinal tract
tectospinal tract
medial and lateral reticulospinal tract

1. Neurology (32 decks)

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