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Year 2 Neuro > Motor Cortical Control > Flashcards

Motor Cortical Control Flashcards

1
Q

What are the two principles of motor control?

A

Hierarchical organisation

Functional segregation

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2
Q

What is Hierarchical organisation?

A

high order areas of hierarchy are involved in more complex tasks

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3
Q

What are considered to be more complex tasks (hint: secondary cortices function)?

A

programme and decide on movements, coordinate muscle activity

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4
Q

What is considered to be a lower level task?

A

execution of movement

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5
Q

What is functional segregation?

A

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

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6
Q

What are the major tracts downwards?

A

Pyramidal tracts

Extrapyramidal tracts

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7
Q

What is the the pathway of the pyramidal tracts?

A

Pass through the pyramids in the medulla

Output neurones in the motor cortex

Project down to the spina cord or cranial nerve nuclei

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8
Q

What are the two pyramidal tracts?

A

Corticospinal

Corticobulbar

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9
Q

What are the 4 extrapyramidal tracts?

A

Vestibulospinal
Tectospinal
Reticulospinal
Rubrospinal

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10
Q

What is the pathway for the extrapyramidal tracts?

A

Do not pass down through the pyramids of the medulal

Upper MN in the cortex

Lower MN in the brain stem nuclei

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11
Q

What is the function of the pyramidal tracts?

A

Voluntary movements of body and face

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12
Q

What is the function of the extrapyramidal tracts?

A

involuntary (automatic) movements for balance, posture and locomotion

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13
Q

Where is the primary motor cortex located?

A

Located in precentral gyrus, anterior to the central sulcus

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14
Q

What is the function of the primary motor cortex?

A

controls fine, discrete, precise voluntary movements.
Provides descending signals to execute movements.
last common pathway from the brain to the lower motor neurons in the brainstem or spinal cord

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15
Q

Where is the premotor cortex located?

A

Located anterior to primary motor cortex

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16
Q

What is the function of the premotor area?

A

involved in planning movements

Regulates externally cued movements

e.g. seeing an apple and reaching out for it

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17
Q

Where is the supplementary motor area located?

A

Located anterior and medial to primary motor cortex

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18
Q

What is the function of the supplementary motor area?

A

Involved in planning complex movements (e.g. internally cued, speech)

Becomes active prior to voluntary movement

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19
Q

Where is the cerebral peduncle located?

A

Midbrain

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20
Q

Where does the corticospinal tract decussate?

A

Medulla

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21
Q

What is the name given to the tract that decussates?

A

Lateral corticospinal tract

85-90%

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22
Q

What is the name given to the tract that stays on the same side?

A

Anterior corticospinal tract

10-15%

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23
Q

Whats the function of the lateral corticospinal tract?

A

Responsible for limb muscle control

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24
Q

Whats the function of the anterior corticospinal tract?

A

Responsible for innervation of the axial musculature

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25
Q

What is the motor homunculus?

A

The little man that shows the distribution of innervation

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26
Q

What is the somatotropic representation?

A

Maps regions of the brain and where they control

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27
Q

What is the function of the corticobulbar tract?

A

Responsible for voluntary movements of the face

Motor cortex contains the UMN synapse with brainstem cranial nerve nuclei to go to muscles that control movements of the face

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28
Q

What are the nuclei that provide facial movements?

A 
Oculomotor nucleus (Eye)
Trochlear nucleus 
Trigeminal motor nucleus (Jaw muscles)
Abducens nucleus (Eye)
Facial nucleus (Muscles of the face)
Hypoglossal nucleus  (tongue)
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29
Q

What is the function of the vestibulospinal tract?

A

Stabilise head during body movements, or as head moves
Coordinate head movements with eye movements
Mediate postural adjustments

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30
Q

What is the function of the reticulospinal tract?

A

Most primitive descending tract - from medulla and pons
Changes in muscles tone associated with voluntary movement
Postural stability

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31
Q

What is the function of the tectospinal tract?

A

From superior colliculus of midbrain

Orientation of the head and neck during eye movements

32
Q

What is the function of the rubrospinal?

A

From red nucleus of midbrain
In humans mainly taken over by corticospinal tract
Innervate lower motor neurons of flexors of the upper limb

33
Q

What are the negative affects of an upper motor neurone lesions?

A

Loss of voluntary motor function

Paresis: graded weakness of movements

Paralysis (plegia): complete loss of voluntary muscle activity

34
Q

What is meant by negative?

A

Loss of function

35
Q

What is meant by positive?

A

Unwanted gain of function

36
Q

What are the positive affects of an upper motor neurone lesions?

A

Increased abnormal motor function due to loss of inhibitory descending inputs

Spasticity: increased muscle tone

Hyper-reflexia: exaggerated reflexes

Clonus: abnormal oscillatory muscle contraction

Babinski’s sign

37
Q

What is apraxia?

A

Consequence of UMN lesion

disorder of skilled movement

Patients are not paretic but have lost information about how to perform skilled movements

38
Q

What can cause apraxia?

A

Lesion of inferior parietal lobe, the frontal lobe

e.g. stroke and dementia

39
Q

What are the symptoms of a lower motor neurone lesions?

A

Weakness

Hypotonia (reduced muscle tone)

Hyporeflexia (reduced reflexes)

Muscle atrophy

Fasciculations

Fibrillations

40
Q

What are fasciculations?

A

damaged motor units produce spontaneous action potentials, resulting in a visible twitch

41
Q

What are fibrillations?

A

spontaneous twitching of individual muscle fibres; recorded during needle electromyography examination

42
Q

What is MND?

A

Motor Neuron Disease

43
Q

What is motor neurone disease?

A

Progressive neurodegenerative disorder of the motor system

Affects UMN and LMN’s

Also known as Amyotrophic Lateral Sclerosis (ALS)

44
Q

Which muscles are particularly affected by MND?

A

Tongue
Upperlimb
Intercostal muscles
Lower limb

45
Q

What are the signs of upper motor neurone disease? in MND

A 
Spasticity (increased tone of limbs and tongue)
Brisk limbs and jaw reflexes 
Babinski’s sign
Loss of dexterity
Dysarthria (difficulty speaking)
Dysphagia
46
Q

What are the signs of lower motor neurone disease? in MND

A 
Weakness
Muscle wasting
Tongue fasciculations and wasting
Nasal speech
Dysphagia
47
Q

What makes up the basal ganglia?

A

Caudate nucleus

Lentiform nucleus

Nucleus accumbens

Subthalamic nuclei

Substantia nigra (midbrain)

Ventral pallidum claustrum, nucleus basalis (of Meynert)

48
Q

What makes up the lentiform nucleus?

A

(putamen + external globus pallidus) – together caudate and putamen are known as the striatum

49
Q

What are the functions of the basal ganglia?

A

Decision to move

Elaborating associated movements (e.g. swinging arms when walking; changing facial expression to match emotions)

Moderating and coordinating movement (suppressing unwanted movements)

Performing movements in order

50
Q

Summarise the structures of the basal ganglia

A 
caudate nucleus
putamen
(external) globus pallidus
thalamus
nucleus accumbens
 amygdala
 anterior commisure
51
Q

What disorders are associated with basal ganglia dysfunction?

A

Parkinson’s
Huntington’s
Ballism

52
Q

What causes Parkinson’s?

A

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

53
Q

What are the symptoms of Parkinson’s?

A 
Bradykinesia
Hypomimic face
Akinesia
Rigidity
Tremor at rest
54
Q

What is bradykinesia?

A

slowness of (small) movements (doing up buttons, handling a knife)

55
Q

What is hypomimic face?

A

expressionless, mask-like (absence of movements that normally animate the face)

56
Q

What is akinesia?

A

difficulty in the initiation of movements because cannot initiate movements internally

57
Q

What is rigidity?

A

muscle tone increase, causing resistance to externally imposed joint movements

58
Q

What are the main feature of the Parkinson’s tremor?

A

4-7 Hz, starts in one hand (“pill-rolling tremor”); with time spreads to other parts of the body

59
Q

What causes Huntington’s disease?

A

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

Genetic neurodegenerative disorder
Chromosome 4, autosomal dominant
CAG repeat

60
Q

What are the symptoms of Huntington’s?

A 
Choreic movements 
Speech impairment
Difficulty swallowing
Unsteady gait
Later stages, cognitive decline and dementia
61
Q

What are choreic movements?

A

(chorea - dance)

rapid jerky involuntary movements of the body; hands and face affected first; then legs and rest of body

62
Q

What is Ballism?

A

Usually from stroke affecting the subthalamic nucleus.

Sudden uncontrolled flinging of the extremities

Symptoms occur contralaterally.

63
Q

Where is the cerebellum located?

A

Located in posterior cranial fossa

64
Q

What separates the cerebrum and the cerebellum?

A

Separated from cerebrum above by tentorium cerebelli

65
Q

What is the function of the cerebellum?

A

Coordinator and predictor of movement

66
Q

What is the function of the vestibulocerebellum?

A

Regulation of gait, posture and equilibrium

Coordination of head movements with eye movements

67
Q

What does damage of the vestibulocerebellum result in?

A

Damage (tumour) causes syndrome similar to vestibular disease leading to gait ataxia and tendency to fall (even when patient sitting and eyes open)

68
Q

What is the function of the spinocerebellum?

A

Coordination of speech
Adjustment of muscle tone
Coordination of limb movements

69
Q

What does damage of the spinocerebellum result in?

A

Damage (degeneration and atrophy associated with chronic alcoholism) affects mainly legs, causes abnormal gait and stance (wide-based)

70
Q

What is the function of the cerebrocerebellum?

A

Coordination of skilled movements
Cognitive function, attention,
processing of language
Emotional control

71
Q

What does damage of the cerebrocerebellum result in?

A

Damage affects mainly arms/skilled coordinated movements (tremor) and speech

72
Q

What are the main signs of cerebellar dysfunction?

A 
Ataxia
Dysmetira
Intention tremor
Dysdiadochokinesia
Scanning speech
73
Q

What is ataxia?

A

General impairments in movement coordination and accuracy. Disturbances of posture or gait: wide-based, staggering (“drunken”) gait

74
Q

What is dysmetria?

A

Inappropriate force and distance for target-directed movements (knocking over a cup rather than grabbing it)

75
Q

What is intention tremor?

A

Increasingly oscillatory trajectory of a limb in a target-directed movement (nose-finger tracking)

76
Q

What is dysdiadochokinesia?

A

Inability to perform rapidly alternating movements (rapidly pronating and supinating hands and forearms)

77
Q

What is scanning speech?

A

Staccato, due to impaired coordination of speech muscles

Year 2 Neuro (15 decks)

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