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BRS Year 2 > Cortical Motor Control > Flashcards

Cortical Motor Control Flashcards

1
Q

What is hierarchial organisation?

A

Areas of higher order are involved in more complex tasks (programme and decide movements, coordinate muscle activity e.g. primary motor cortex)
Lower level area of hierarchy perform lower level tasks (execution of movement e.g. spinal cord, brainstem)

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2
Q

What are the 2 types of descending tracts?

A

Pyramidal

Non-pyramidal

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3
Q

What are the 2 pyramidal tracts?

A

Corticospinal

Corticobulbar

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4
Q

What are the 4 non pyramidal tracts

A

Tectospinal
Rubrospinal
Reticulospinal
Vestibulospinal

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5
Q

What are pyramidal tracts for?

A

Voluntary movement of the body and face

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6
Q

What are non-pyramidal tracts for?

A

Non voluntary movements for balance, locomotion and posture

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7
Q

Describe how pyramidal tracts decend

A

Through pyramidal cells pf medulla

From the motor cortex to the spinal chord or cranial nerve nuclei in the brainstem

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8
Q

Describe how non-pyramidal tracts decend

A

Not through the pyramidal cells of the medulla

From brainstem nuclei to spinal chord

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9
Q

What is the vestibulospinal tract for?

A

Stabilises head during body movements

Coordinates head movements with eye movements

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10
Q

What is the reticulospinal tract for?

A

Changes muscle tone associated with voluntary movement and postural stability

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11
Q

What is the rubrospinal tract for?

A

Innervate lower motor neurons of flexors of the upper limb

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12
Q

What is the tectospinal tract for?

A

Orientation of the head and neck during eye movements

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13
Q

What is the role of the primary motor cortex?

A

Controls fine, discrete, precise voluntary movements

Provides descending signals to execute movement

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14
Q

What is the role of the supplementary area?

A

Involved in planning complex movements (e.g. internally cued, speech), is active prior to voluntary movement

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15
Q

What is the role of the premotor area?

A

Involved in planning externally cued movements

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16
Q

Where does the corticospinal tract decussate?

A

Pyramidal cells of the medulla

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17
Q

What symptoms are associated with an upper motor neuron lesion?

A

Negative signs:
Loss of voluntary motor function
Paresis: graded weakness of movements
Paralysis (plegia): complete loss of voluntary muscle activity

Positive signs:
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

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18
Q

What is Babinski’s sign?

A

Big toe curls upwards instead of down when sole of the foot is stroked (note this is normal for babies but in anyone older they should curl down)

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19
Q

What is apraxia?

Causes/ most common causes

A

Patients have lost information of how to perform skilled movement

Causes: lesion to inferior parietal lobe, frontal lobe

Most common causes: stroe and dementia

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20
Q

What symptoms are associated with a lower motor neuron lesion?

A

Weakness
Hypotonia
Hyporeflexia
Muscle atrophy
Fasciculations- damaged motor units producing spontaneous APs leading to twitch
Fibrillations- spontaneous twitching of individual muscle fibres- recorded during needle electromyography exam

21
Q

In MND, what upper motor neuron signs symptoms do patients have?

A 
Spasticity (increased tone of limbs and tongue)
Brisk limbs and jaw reflexes 
Babinski’s sign
Loss of dexterity
Dysarthria (difficulty speaking)
Dysphagia (difficulty swallowing)
22
Q

In MND, what lower motor neuron signs do patients have?

A 
Weakness
Muscle wasting
Dysphagia
Tongue fasciculations and wasting
Nasal speech
23
Q

What are key components of the basal ganglia?

A

Caudate nucleus
Lentiform nucleus (putamen + external globus pallidus) – together caudate and putamen are known as the striatum
Nucleus accumbens
Subthalamic nuclei
Substantia nigra (midbrain)
Ventral pallidum, claustrum, nucleus basalis (of Meynert)

24
Q

What are the functions of the basal ganglia?

A

Decision to move, elaborating associated movements, moderating and coordinating movement, performing movements in order

25
Q

What happens in Parkinsons?

A

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

26
Q

How does Parkinson’s present?

A

Bradykinesia- slow movements
Hyponomic (expressionless face)
Akinesia- difficulty initiating movements
Rigidity- increased muscle tone
Tremor at rest (starts in one hand)- starts in one hand and eventually spreads to other parts of the body

27
Q

What happens in Huntingtons?

A

Degeneration of GABAergic neurons in the striatum, caudate and then putamen due to chromosome 4 CAG repeat (autonomic dominant)

28
Q

How does Huntington’s present?

A

Choreic movements
Unsteady gait
Dysphagia
Speech impairment

Later: cognitive decline and dementia

29
Q

What is ballism?

A

Sudden flinging of extremities, happens contralaterally

30
Q

Why does ballism arise?

A

Due to stroke in subthalamic nucleus

31
Q

Where is the cerebellum located?

A

Posterior cranial fossa

32
Q

What is the role of the cerebellum?

A

Coordinator and predictor of movements

33
Q

What are the 3 subparts of the cerebellum?

A

Vestibulocerebellum
Spinocerebellum
Cerebrocerebellum

34
Q

How does damage to the vestibulocerebellum usually occour?

A

Tumor

35
Q

How does damage to the spinocerebellum usually occour?

A

Chronic alcoholism causes degeneration and atrophy

36
Q

How does damage to the vestibulocerebellum present?

A

Gait ataxia and tendency to fall

37
Q

How does damage to the spinocerebellum present?

A

Affects mainly legs, causes abnormal gait and stance

38
Q

How does damage to the cerebrocerebellum present?

A

Affects mainly arms/skilled coordinated movements (tremor) and speech

39
Q

What are the main signs of cerebellar dysfunction? When do they present?

A

Only apparent on movement:
Ataxia (impaired movements in coordination and accuracy)
Dysmetria (can’t judge distance)
Intention tremor
Dysdiadochokinesia (can’t perform rapid alternating movement)
Scanning speech (fragmented speech due to incoordination of speech muscles)

40
Q

What is the location of the primary motor cortex?

A

In precentral gyrus, anterior to central sulcus

41
Q

What is the location of the premotor area?

A

Anterior to primary motor cortex

42
Q

What are the 2 parts of the corticospinal tract and what do they innervate and what is their proportion of crossed/uncrossed fibres?

A

Lateral corticospinal tract- 85-90% crossed fibres, go to limb muscles
Anterior corticospinal tract- 10-15% uncrossed fibres, go to trunk muscles

43
Q

What is the role of the corticobulbar tract?

What are motor nerves from these nuclei are involved in?

A

Principal motor pathways for voluntary movements of face and neck

Motor nerves from these nuclei are involved in:

  • eye movements
  • muscles of the jaw
  • eye movements
  • muscles of the face
  • the tongue
44
Q

What is motor neurone disease also known as?

A

Amyotrophic lateral sclerosis

45
Q

What does motor neurone disease affect?

A 
Tongue
Upper limb muscles
Upper motor neurones
Brainstem LMNs
Axon bundles
Intercostal muscles
Spinal cord LMNs
46
Q

What separates the cerebellum and the cerebrum?

A

Tentorium cerebelli

47
Q

Explain denervation and reinnervation?

A

Denervation: muscle fibres of a motor neurone lose their nerve supply
Reinnervation: axons of remaining motor units will grow and reach out to denervated muscle fibres

48
Q

What is the result of denervation and reinnervation?

A

The resulting new motor unit is larger and less stable and prone to ectopic generation of electrical stimuli in the distal axon that cause contraction of the muscle fibres. A fasciculation.

BRS Year 2 (110 decks)

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