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Neuro > Motor cortical control > Flashcards

Motor cortical control Flashcards

1
Q

What is hierarchal organisation in motor control?

A

Higher order areas plan out when to do tasks and coordinate multiple muscles, lower order only execute tasks

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2
Q

What is functional segregation in motor control?

A

Specific areas of motor system carry out specific tasks

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3
Q

What are the two major descending tracts?

A

Pyramidal and Extrapyramidal

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4
Q

Give examples for the two tracts

A

Pyramidal - corticospinal and corticobulbar
Extrapyramidal - vestibulospinal, reticulospinal, tectospinal, rubrospinal

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5
Q

What parts of the brain do the tracts connect?

A

Pyramidal - motor cortex to spinal cord OR cranial nerve nuclei in the brainstem
Extrapyramidal - brainstem nuclei to spinal cord

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6
Q

What movements do pyramidal/extrapyramidal supply?

A

Pyramidal - voluntary movements to the body/face
Extrapyramidal - involuntary movements for balance, posture and locomotion

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7
Q

Why are they named pyramidal tracts?

A

Pass through the pyramids of the medulla
(except) the extrapyramidal tracts

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8
Q

Primary motor cortex

A
  • precentral gyrus (anterior to central sulcus)
  • fine, discrete, voluntary movements
  • provides descending signals to execute movement
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9
Q

Premotor area

A
  • anterior to primary motor cortex
  • involved in planning movements
  • reg externally cued movements (how we interact with our environment)
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10
Q

Supplementary motor area

A
  • anterior and medial to primary motor cortex
  • involved in planning complex movement (internally cued e.g. speech)
  • active prior to voluntary movement
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11
Q

Corticospinal tract
pathway of UMN to LMN

A

UMN in primary motor cortex, go through white matter through the cerebral peduncle. Reach the medulla and decussate (cross to the other side, this is why lesions affect the contralateral side)

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12
Q

Lateral corticospinal tract

A

85-90% crossed fibres (post decussation)
limb muscles

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13
Q

Anterior corticospinal tract

A

10-15% uncrossed fibres
trunk muscles

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14
Q

Motor homunculus

A

How much brain devoted to a specific part of the body
majority in the hands, then thee tongue/feet

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15
Q

Somatotopic representation

A

Shows the area of the motor cortex responsible for each part of the body

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16
Q

Explain the function of the corticobulbar tract

A

Cranial nerves - voluntary movements of eyes, face, jaw, neck and tongue

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17
Q

Explain the function of the vestibulospinal tract

A

Stabilise head during body movements
coordinate head and eye movements

balance and posture

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18
Q

Explain the function of the reticulospinal tract and where it comes from

A

postural stability

From medulla and pons, changes in muscle tone in voluntary movement

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19
Q

Explain the function of the tectospinal tract and where it comes from

A

From superior colliculus of midbrain,
coordinate head and neck movements during eye movements

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20
Q

Explain the function of the rubrospinal tract and where it comes from

A

innervate LMN of upper limb flexors

From red (rubro) nucleus of midbrain,

21
Q

What are the 3 negative signs of upper motor neuron lesions? LPP

A

Loss, of voluntary motor function,
Paresis (graded weakness of movements),
Paralysis/plegia (complete loss of movement)

22
Q

What are the 5 positive signs of upper motor neuron lesions?

A

Increased abnormal motor function (loss of inhibitory descending input)
Spasticity (increased muscle tone) - stiff //
Hyperreflexia //
Clonus (oscillatory contraction) //
Babinski’s sign, toes flex backwards

23
Q

What is apraxia?

A

Disorder of skilled movement - lost information about how to perform skilled movements

24
Q

Lesions to which lobes cause apraxia?

A

Inferior parietal lobe,
frontal lobe (including supplementary motor area and premotor cortex)

25
Q

What are the 5 signs of a lower motor neuron lesion?

A

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

26
Q

Fasciculations

A

Damaged motor units produce spontaneous action potentials which result in a visible twitch

27
Q

Fibrillations

A

Spontaneous twitching of individual muscle fibres
Require electromyography to see

28
Q

What is motor neuron disease and what is its other name?

A

Progressive neurodegenerative disorder, of the motor tract which involves loss of both UMN and LMN.
ALS - Amyotrophic Lateral Sclerosis

29
Q

What are the upper motor neuron signs of MND?

A

Dysarthria (trouble speaking),
Dysphagia
spasticity
babinski’s sign
loss of dexterity

30
Q

What are the lower motor neuron signs of MND?

A

Nasal speech,
dysphagia,
tongue wasting
weakness
muscle atrophy

31
Q

Give examples of 5 basal ganglia nuclei we need to be aware of, and 2 structures pairs of them form

A

Caudate nucleus,
Putamen,
External Globus Pallidus,
Substantia Nigra,
Subthalmic Nucleus

> > C+P are the striatum // P + EGP is lentiform nucleus

32
Q

What is the function of the basal ganglia?

A

Slight changes in movement - decision to move, changing facial expression for emotion, suppressing unwanted movements

33
Q

Which neurons does Parkinson’s disease affect?

A

Degeneration of dopaminergic neurons originating in substantia nigra projecting to striatum

34
Q

What are the 5 signs of Parkinson’s disease?
(think: parKINsons)

A

Bradykinesia, slowness
Hypomimic face (expressionless),
Akinesia (difficulty in initiating movements),
rigidity, increased muscle tone
tremor at rest, starts in one hand

(think: parKINsons - aKINesia, bradyKINesia)

35
Q

Which neurons does Huntington’s disease affect?

A

GABAergic neurons in striatum - caudate and putamen

36
Q

What are the 6 signs of Huntington’s disease?

A

Choreic movements (jerky involuntary),
Speech impairment, dysarthria
dysphagia,
unsteady gait,
cognitive decline,
dementia

37
Q

What is Huntington’s disease

A

Genetic neurodegenerative disorder
chromosome 4, autosomal dom
due to CAG repeat

38
Q

What neurons does Ballism affect?

A

Subthalamic neurons (from stroke)

39
Q

What are is the main symptom of ballism?
(ballistic)

A

Sudden uncontrolled flinging of contralateral extremities

40
Q

Cerebellum

A

coordinator and predictor of movement

41
Q

What separates the cerebellum from the cerebrum

A

tentorium cerebelli

42
Q

What does the vestibulocerebellum do?

A

balance, posture, head and eye movement coordination
region in the middle (axial plane) of the cerebellum

43
Q

What can damage to the vestibulocerebellum arise from and what are its presentations?

A

Tumour,
gait ataxia & tendency to fall (even when sitting and eyes open)

44
Q

What does the spinocerebellum do?

A

Motor execution
medial region of the cerebellum

45
Q

What can damage to the spinocerebellum arise from and what are its presentations?

A

degeneration and atrophy from chronic alcoholism,
causes wide based stance and gait (think drunk ppl struggle to stand straight)

46
Q

What does the cerebrocerebellum do?
(think frontal cortex - CALM)

A

Motor planning and cognitive fct

47
Q

What does damage to the cerebrocerebellum do?

A

Tremor and difficulty in speech

48
Q

What are the 5 main signs of cerebellar dysfunction?

A

ataxia (drunken gait),
dysmetria (inappropriate force),
intention tremor
dysdiadochokinesia (cannot perform rapidly alternating movements),
scanning speech (staccato)

Neuro (12 decks)

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