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BRS Year 2 > Motor control & movement disorders > Flashcards

Motor control & movement disorders Flashcards

1
Q

what are the main principles of motor control?

A

hierarchical organisation and functional segregation

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2
Q

what is hierarchical organisation?

A

higher order areas = more complex tasks e.g planning

lower level areas = lower level tasks e.g movement execution

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3
Q

what is functional segregation in terms of motor control?

A

motor system is organised in a number of different areas that control different aspects of motion ie basal ganglia, brainstem etc

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4
Q

what are the major descending tracts?

A

pyramidal and extrapyramidal tracts

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5
Q

what is the function of the pyramidal tract?

A

voluntary movements of body and face

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6
Q

what is contained within the pyramidal tracts

A

corticospinal and corticobulbar

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7
Q

what is contained within the extrapyramidal tracts?

A

Vestibulospinal
Reticulospinal
Tectospinal
Rubrospinal

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8
Q

what is the pathway for pyramidal tracts?

A

pass through pyramids of the medulla

motor cortex to spinal cord or cranial nerve nuclei in brainstem

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9
Q

what is the pathway for extrapyramidal tracts?

A

brainstem nuclei to spinal cord

do not pass through pyramids of the medulla

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10
Q

where is the area for primary motor control

A

precentral gyrus

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11
Q

what is the role of the primary motor cortex?

A

controls fine, discrete precise voluntary movement - descending signals for execution

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12
Q

where is the premotor control area?

A

anterior to primary motor cortex but not up to top of brain

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13
Q

what is the role of the premotor area?

A

planning movements, regulating externally cued movements (reactions to environment e.g catching an apple)

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14
Q

where is the supplementary motor area?

A

above premotor area extending to longitudinal fissure

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15
Q

what is the role of the supplementary motor area?

A

planning complex movements and regulating internally cued movements (things you think about before doing it e.g speech)
active prior to voluntary movements

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16
Q

what is the corticospinal tract split into?

A

lateral (limb muscles) and anterior (trunk) corticospinal tract

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17
Q

which corticospinal fibres cross in the pyramids of decussation?

A

lateral corticospinal tract (85-90%) of corticospinal

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18
Q

which corticospinal fibres don’t decussate in the pyramids?

A

anterior corticospinal tract (10-15%)

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19
Q

what is the function of the corticobulbar tract?

A

principle motor pathway for voluntary movements in the face and neck

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20
Q

what nuclei do eye movements originate from?

A

oculomotor, trochlear and abducens nucleus

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21
Q

what nucleus controls the muscles of the jaw?

A

trigeminal motor nucleus

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22
Q

what nucleus controls the muscles of the face?

A

facial nucleus

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23
Q

what nucleus controls the tongue?

A

hypoglossal nucleus

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24
Q

what is the role of the vestibulospinal tract?

A

stabilise head during body/head movements
coordinates head & eye movement
mediates postural adjustments

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25
Q

what is the role of the reticulospinal tract?

A

changes in muscle tone associated with voluntary movement

postural stability

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26
Q

what is the role of the tectospinal tract?

A

orientation of the head and neck during eye movements

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27
Q

what is the role of the rubrospinal tract?

A

innervate lower motor neurones of flexors of upper limb (mainly taken over by corticospinal)

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28
Q

what are the negative signs of upper motor neuron lesions?

A

loss of voluntary motor function
paresis
paralysis (plegia)

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29
Q

what are the positive signs associated with upper motor neuron lesions?

A 
increased abnormal motor function
inhibitory descending inputs
spasticity
hyperreflexia
clonus
babinskis sign
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30
Q

what are the signs of a lower motor neuron lesion?

A 
weakness
hypotonia/reflexia
muscle atrophy
fasciculations
fibrillations
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31
Q

what is apraxia?

A

disorder of skilled movement caused by lesion of inferior parietal lobe or frontal lobe (premotor and supplementary areas)

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32
Q

what is motor neuron disease also known as?

A

ALS (amyotrophic lateral sclerosis)

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33
Q

what is ALS?

A

progressive degenerative disorder spectrum of NS

34
Q

what are the upper motor neuron signs of ALS?

A 
spasicity
brisk limbs and jaw reflexes
babinskis sign
loss of dexterity
dysarthria (difficulty speaking)
dysphagia
35
Q

what are the lower motor neuron signs of ALS?

A 
weakness
muscle wasting
tongue fasciculations and wasting
nasal speech
dysphagia
36
Q

what does the basal ganglia consist of?

A

caudate nucleus
lentiform nucleus (putamen+external globus pallidus)
nucleus accumbens
subthalamic nucleus
substantia nigra
ventral pallidum, claustrum, nucleus basalis

37
Q

what is the striatum?

A

caudate and putamen combined

38
Q

what is the function of the basal ganglia?

A

decision to move
elaborating associated movements e.g arm swing when walking
moderating and coordinating movement
performing movements in order

39
Q

what is parkinsons disease?

A

degeneration of dopaminergic neurons originating in substantia nigra and project to striatum

40
Q

what are the symptoms of parkinsons disease?

A 
bradykinesia, akinesia
rigidity
resting tremor/pin roll tremor
shuffling gait
hypomimic face
41
Q

what is a hypomimic face? (parkinsons)

A

expressionless, mask-like face (absence of facial animation)

42
Q

what is huntingtons disease?

A

degeneration of GABAergic neurons in striatum, caudate and putamen

43
Q

what is the genetic component of huntingtons disease?

A

neurodegenerative - chromosome 4 abnormal dominant (CAG repeat)

44
Q

what are the symptoms of huntingtons disease?

A 
hyperkinesia/choreic movements
speech impairment
difficulty swallowing
unsteady gait
cognitive decline and dementia eventually
45
Q

what is ballism?

A

sudden, uncontrolled flinging of extremities

46
Q

what is ballism the result of?

A

usually stroke subthalamic nucleus

symptoms appear contralaterally

47
Q

what is the function of the cerebellum/

A

coordinator and predictor of movement

48
Q

what is the function of the vestibulocerebellum?

A

gait, posture and equilibrium

coordinates head & eye movement

49
Q

what does damage to the vestibulocerebellum cause

A

ataxia, tendency to fall even with eyes open and sat down

50
Q

what is the function of the spinocerebellum?

A

speech coordination, adjustment of muscle tone and coordination of limb movement

51
Q

what is a common cause of damage to the spinocerebellum?

A

degeneration and atrophy associated with chronic alcoholism

52
Q

what does damage to the spinocerebellum present as?

A

abnormal gait and wide based stance

53
Q

what is the function of the cerebrocerebellum?

A 
coordination of skilled movement, 
cognitive function,
attention, 
language processing, 
emotional control
54
Q

what does damage to the cerebrocerebellum present as?

A

mainly arms - skilled coordinated movement tremor and speech issues

55
Q

what is ataxia?

A

general impairment in movement coordination and accuracy, disturbances of posture/gait

56
Q

what is dysmetria?

A

inappropriate force and distance for target-directed movements

57
Q

what is an intention tremor?

A

increasingly oscillatory trajectory of limb in target-directed movements

58
Q

what is dysdiadochokinesia?

A

inability to perform rapidly alternating movements

59
Q

what is scanning speech?

A

staccato, impaired coordination of speech muscles

60
Q

what are the signs of cerebellar dysfunction?

A 
ataxia
dysmetria
intention tremor
dysdiadochokinesia
scanning speech
61
Q

what are alpha motor neurons

A

lower motor neurons of the brainstem and spinal cord that innervate extrafusal muscle fibres of skeletal muscle, responsible for reflex actions

62
Q

what is a motor unit?

A

a single neuron and all the muscles it innervates

smallest functional unit with which to produce force

63
Q

what are the main classifications of muscle fibre

A

slow S type I
fast fatigue resistant FR type IIA
fast fatiguable FF type IIB

64
Q

what are the features of type I muscle fibres?

A

smallest diameter cell bodies
small dendritic trees
thinnest axons
slowest conduction velocity

65
Q

what are the features of type IIA muscle fibres?

A

larger diameter cell bodies
larger dendritic trees
thicker axons
faster conduction velocity

fast fatigue resistant

66
Q

what are the features of type I muscle fibre contractions?

A

least force, slow to contract but maximal force is maintained

67
Q

what are the features of a type IIA muscle fibre contraction? (fast fatigue resistant)

A

more force, fairly fast contraction but held for long time

68
Q

what are the features of a type IIB muscle fibre contraction?

A

most force, fast contraction but fairly short

69
Q

what are the mechanisms by which the brain regulates force of a single muscle?

A

recruitment- number of motor units involved

rate coding- how fast the units contract

70
Q

what is the principle of recruitment for muscle fibres?

A

size principle - smaller units recruited first(usually slow twitch fibres), as more force is required, more units recruited
allows fine control when low force levels are required

71
Q

what is rate coding?

A

motor unit has a range of frequencies they can fire at
as rate firing increases, force produced by the unit increases

  • summation occurs when units fire at frequency too fast to allow the muscle to relax between arriving action potentials
    muscle fibres are unrecruited in the order they were recruited
72
Q

what is the significance of neurotrophic factors?

A

motor unit and fibre characteristics are dependent on the nerve which innervates them
this shows plasticity

73
Q

when is the most common change of IIB to IIA?

A

muscular endurance training

74
Q

what can cause a change of I to II fibres?

A

spaceflight
spinal cord injury
(deconditioning)

75
Q

how does ageing affect muscle fibre types?

A

preferential loss of fast muscles (type II)

76
Q

describe the course of a monosynaptic reflex?

A

sensory receptor - sensory neuron - motor neuron = action

77
Q

what is the jendrassik manoeuvre?

A

creating larger reflexes by clenching teeth, making a fist, pulling against locked fingers and then testing a reflex

78
Q

what is hyperreflexia associated with?

A

upper motor neuron lesions (loss of inhibition)

79
Q

what is clonus?

A

rhythmic involuntary muscle contraction after manual stretch

80
Q

what is the babinski sign?

A

sole of foot stimulated by blunt instrument (stroked) the big toe should react

81
Q

what is a positive babinski sign?

A

big toe curls upwards (but normal in infants)

82
Q

pathway for corticospinal tract

A

motor cortex (from motor homunculus)
to cerebral peduncle
in medulla pyramids - anterior stays ipsilateral, lateral goes contralateral (lateral =limbs)
travel through spinal cord as anterior or lateral corticospinal tracts
synapse in ventral horn of spinal level they exit at
continue as lower motor neurons

BRS Year 2 (67 decks)

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