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Y2 NEUROLOGY > Motor control > Flashcards

Motor control Flashcards

1
Q

In terms of motor control, what is meant by hierarchical organisation?

A

High order areas of hierarchy are involved in more complex tasks (programme and decide movements, coordinate muscle activity), lower level areas perform lower level tasks (execution of movement)

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2
Q

In terms of motor control, what is meant by functional segregation?

A

Motor system organised in as number of different areas that control different aspects of movement

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3
Q

In terms of motor control, what is meant by the motor system hierarchy?

A

Different parts of the brain interact with each other in order to bring out voluntary or involuntary movement

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4
Q

What are the three broad principles of motor control?

A

Hierarchical organisation, functional segregation and motor system hierarchy

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5
Q

What are the two types of major descending tracts associated with motor control?

A

Pyramidal tracts and extrapyramidal tracts

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6
Q

What are the two major descending pyramidal tracts?

A

The corticospinal (movement from the neck down) and corticobulbar tracts (movement of the head and neck)

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7
Q

Why are pyramidal tracts called pyramidal tracts?

A

Pass through the pyramids of the medulla, whereas the extrapyramidal tracts do not

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8
Q

Outline the path of the major descending pyramidal tracts

A

Motor cortex to spinal cord or cranial nerve nuclei in brainstem

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9
Q

What is the function of the major descending pyramidal tracts?

A

Voluntary movements of the body and face

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10
Q

What are the 4 major descending extrapyramidal tracts?

A

Vestibulospinal, tectospinal, reticulospinal, rubrospinal

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11
Q

Outline the path of the major descending extrapyramidal tracts

A

Brainstem nuclei to spinal cord

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12
Q

what is the function of the major descending extrapyramidal tracts?

A

Involuntary movements for balance, posture and locomotion

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13
Q

What is the function of the premotor area?

A

Involved in the planning of movements, regulates externally cued movements

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14
Q

The premotor area is located where?

A

Anterior to primary motor cortex

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15
Q

What is the function of the supplementary motor area?

A

Planning complex movements, becomes active prior to voluntary movement

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16
Q

Where is the supplementary motor area located?

A

Anterior and medial to the primary motor cortex

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17
Q

Outline the pathway of the corticobulbar tract

A

Upper motor neurones in the primary motor cortex synapse with brainstem nuclei to provide voluntary movement of the face and neck

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18
Q

Outline the pathway of the corticospinal tract

A

Upper motor neurones in the primary motor cortex descend and converge to form the corona radiata. The fibres then pass through the midbrain, the pons, into the medulla. The majority of fibres dessucate in the medulla forming the lateral tract, both tracts run along the spinal cord synapsing with lower motor neurones.

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19
Q

What is the function of the Vestibulospinal tract?

A

Stabilise head during body movements, coordinate head movements with eye movements. Mediate postural adjustments.

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20
Q

What is the function of the reticulospinal tract?

A

Changes in muscle tones associated with voluntary movement. Postural stability

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21
Q

What is the function of the tectospinal tract?

A

Orientation of the head and neck during eye movements

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22
Q

What is the function of the rubrospinal tract?

A

Mainly taken over by corticospinal tract, innervates lower motor neurones of flexors of the upper limb

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23
Q

What path does the reticulospinal tract take?

A

From medulla to pons

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24
Q

Where does the tectospinal tract originate?

A

From superior colloculus of midbrain

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25
Q

Where does the rubrospinal tract originate?

A

From red nucleus of midbrain

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26
Q

Outline the negative signs associated with a upper motor neurone lesion

A

Loss of voluntary motor function. Paresis (graded weakness of movements). Plegia of voluntary muscle activity

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27
Q

Outline the positive signs associated with an upper motor neurone lesion

A

Increased abnormal motor function due to loss of inhibitory descending inputs. Spasticity. Hyper-reflexia. Clonus. Babinskis sign.

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28
Q

What is spasticity?

A

Where a muscle is over-active

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29
Q

What is hyper-reflexia?

A

Exaggerated reflexes

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30
Q

What is clonus?

A

Abnormal oscillatory muscle contraction

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31
Q

What is babinskis sign?

A

Abnormal Dorsi flexion of toes with plantar stimulation

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32
Q

What is apraxia?

A

Disorder of skilled movement. Patients are not paretic but have lost information about how to perform skilled movements

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33
Q

Why does a lower motor neurone lesion result in hypotonia and not spasticity?

A

No signal from brain for contraction

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34
Q

What are the causes of apraxia?

A

Lesion of inferior parietal lobe, the frontal lobe. Stroke and dementia are the most common causes

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35
Q

What are the signs of a lower motor neurone lesion?

A

Weakness, hypotonia, hyporeflexia, muscle atrophy, fasciculations, fibrillations

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36
Q

What is hypotonia?

A

Reduced muscle tone

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37
Q

What is hyporeflexia?

A

Reduced reflexes

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38
Q

What are fasciculations?

A

Damaged motor units produces spontaneous action potentials resulting in a visible twitch

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39
Q

What are fibrillations?

A

Spontaneous twitching of individual muscle fibres, recorded during needle electromyography examination

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40
Q

What is motor neurone disease?

A

Progressive neurodegenerative disorders of the motor system.

41
Q

What are the signs associated with upper motor neurone disease?

A

Spasticity, brisk limbs and jaw reflexes, babinskis sign, loss of dexterity, dysarthria, dysphagia,

42
Q

What is dysarthria?

A

Difficulty speaking

43
Q

What is dysphagia?

A

Difficulty swallowing

44
Q

What are the signs associated with lower motor neurone disease?

A

Weakness. Muscle wasting. Tongue fasciculations and wasting. Nasal speech. Dysphagia

45
Q

What is the function of the basal ganglia?

A

Makes decision to move, elaborating associated movements, moderating and coordinating movements, performing movements in order

46
Q

What are the major structures located in the basal ganglia? (CPGTAccAmAc)

A

Caudate nucleus, putamen, globus pallidus, thalamus, nucleus accumbens, Amyglada, anterior commisure

47
Q

What is Parkinson’s disease?

A

Degeneration of the dopaminergic neurones that originate in the substantia nigra and project to the striatum

48
Q

What are the symptoms associated with Parkinson’s disease?

A

Bradykinesia, tremor at rest, rigidity, hypomimic face, akinesia

49
Q

What is bradykinesia?

A

Slowness of small movements

50
Q

How does a tremor develop in Parkinson’s?

A

Starts as a ‘pill-rolling tremor’ in one hand then spreads to other parts of the body

51
Q

In Parkinson’s, what is meant by rigidity as a symptom?

A

Muscle tone increase causing resistance to externally imposed joint movements

52
Q

What is a hypomimic face?

A

Expressionless, mask-like face

53
Q

What is akinesia?

A

Difficulty in the initiation of movements because cannot initiate movements internally

54
Q

What is huntingtons disease?

A

Degeneration of GABAergic neurons in the striatum, caudate and putamen.

55
Q

What signs and symptoms are associated with Huntingtons disease?

A

Choreic movements, speech impairment, dysphagia, unsteady gait, cognitive decline and dementia

56
Q

What is the cause of Huntington’s disease?

A

Is a genetic neurodegenerative disorder caused by autosomal dominant CAG repeats of chromosome 4

57
Q

What is Ballism?

A

Sudden uncontrolled flinging of the extremities

58
Q

What usually causes Ballism?

A

A stroke affecting the subthalmic nucleus, symptoms occur contralaterally

59
Q

Where is the cerebellum located?

A

Posterior cranial fossa, separated from the cerebrum by tentorium cerebelli

60
Q

What is the function of the cerebellum?

A

Coordination and prediction of movement

61
Q

What are the three functional regions of the cerebellum?

A

Vestibulocerebelum, spinocerebelum, cerebrocerebelum

62
Q

what is the function of the vestibulocerebellum?

A

regulation of gait, posture, and equilibrium. coordination of head and eye movements.

63
Q

what occurs as a result of damage to the vestibulocerebellum?

A

gait ataxia, and tendency to fall

64
Q

what is the function of the spinocerebellum?

A

coordination of speech, adjustment of muscle tone, coordination of limb movements.

65
Q

what occurs as a result of damage to the spinocerebellum?

A

affects mainly the legs, causes abnormal gait and stance (wide-based)

66
Q

what would be the most likely cause of damage to the vestibulocerebellum?

A

tumour

67
Q

what would be the most likely cause of damage to the spinocerebellum?

A

degeneration and atrophy associated with chronic alcoholism

68
Q

what is the function of the cerebrocerebellum?

A

coordination of skilled movements, cognitive function, atention, processing of language. emotional control

69
Q

what occurs as a result of damage to the cerebrocerebellum?

A

affects mainly arms and skilled coordinated movements causing tremor and abnormal speech

70
Q

when are the main signs of cerebellar dysfunction most present?

A

apparent only on movement

71
Q

What are the five cardinal signs of cerebellar dysfunction? (ADIDyS)

A

ataxia, dysmentria, intention tremor, dysdiadochokinesia, scanning speech

Dysmetria is the inability to control the distance, speed, and range of motion necessary to perform smoothly coordinated movements.

72
Q

what is ataxia?

A

general impairments in movement coordination and accuracy. disturbances of posture or gait

73
Q

what is dysmetria?

A

innapropriate force and distance for target-directed movements

74
Q

what is intention tremor?

A

increasing oscillatory trajectory of a limb in a target-directed movement

75
Q

what is dysdiadochokinesia?

A

inability to perform rapidly alternating movements

76
Q

what is meant by ‘scanning speech’?

A

speaking in short, choppy sentences due to impaired coordination of speech muscles

77
Q

What are alpha motor neurones?

A

the lower motor neurons of the brainstem and spinal cord

78
Q

what do alpha motor neurones innervate?

A

the extrafusal muscle fibres of the skeletal muscles

79
Q

what results as alpha motor neurons are activated?

A

muscle contraction

80
Q

what is a motor unit?

A

a single motor neuron along with all the muscle fibres it innervates

81
Q

what is the name of the smallest motor unit able to produce force?

A

a motor unit

82
Q

what happens when a motor unit is stimulated?

A

contraction of all muscle fibres in that unit

83
Q

what are the three types of motor unit?

A

Slow (S, type 1), fast fatigue resistant (FR, type 2a), fast fatiguable (FF, type 2B)

84
Q

what is the difference between slow and fast type motor units?

A

slow = smallest diameter cell bodies, small dendritic trees, thinner axons, slowest conduction velocity

85
Q

which type of motor unit produces the most force in response to a single motor neuron action potential?

A

type 2b (fast fatiguable)

86
Q

what are the two mechanisms by which the brain regulates the force that a single muscle can produce?

A

recruitment and rate coding

87
Q

In terms of motor control, what is recruitment?

A

smaller units are recruited first, as more force is required, more units are recruited, this allows for fine control

88
Q

which of the two regulatory mechanisms for muscle force allows for fine control?

A

recruitment

89
Q

in terms of motor control, what is rate coding?

A

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

90
Q

when does summation occur?

A

when units fire at frequency too fast to allow the muscle to relax between arriving action potentials

91
Q

what are neurotrophic factors?

A

growth factor that prevents neuronal death and promotes growth of neurons after injury

92
Q

What muscle fibre switch could you expect to see following training?

A

type 2B to 2A

93
Q

what muscle fibre switch would you expect to see following severe deconditioning or spinal cord injury?

A

type 1 to type 2

94
Q

what switch in muscle fibres occurs with aging?

A

preferential loss of type 2 fibres, larger proportion of type 1 fibres in aged muscle

95
Q

Define reflex

A

automatic, stereotyped response to a peripheral stimulus resulting in involuntary coordinated pattern of muscle contraction and relaxation without reaching the level of consciousness

96
Q

what is the Jendrassik manoeuvre?

A

pulling against locked fingers when having a patellar tendon tapped makes the reflex larger

97
Q

explain the role of the CNS in reflex movement

A

higher centers of CNS exert inhibitory and excitatory regulation upon the stretch reflex. inhibitory control dominates in normal conditions, decerebration reveals the excitatory control from supraspinal areas

98
Q

what are the five pathways that make up the descending control of reflexes?

A

activating alpha motor neurons, activating inhibitory interneurons, activating propiospinal neurons, activating gamma motor neurones, activating terminals of afferent fibres

99
Q

What is hyper-reflexia?

A

overeactive reflexes with loss of descending inhibition, associated with upper motor neurone lesions

Y2 NEUROLOGY (10 decks)

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