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BRS Phase 1b > Motor Cortical Control > Flashcards

Motor Cortical Control Flashcards

1
Q

What is the Hierarchical organization of Motor control?

A

Higher orders - more complex tasks, e.g. programme & decide on movements, coordinate muscle activity.

Lover level areas - lower level tasks e.g. execution of movement.

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2
Q

How is the Motor system segregated?

A

Number of different areas that control different aspects of movement.

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3
Q

What are the two types of Major descending tracts?

A 
Pyramidal
Extrapyramidal (do not pass through the pyramids of the medulla)
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4
Q

What are some examples of Pyramidal tracts and their functions?

A

Corticospinal, Corticobulbar

Motor cortex to spinal cord or cranial nerve nuclei in brainstem.

Voluntary movements of body and face.

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5
Q

What are some examples of Extrapyramidal tracts and their function?

A

Vestibulospinal, Tectospinal, Reticulospinal, Rubrospinal.

Brainstem nuclei to spinal cord.

Involuntary (autonomic) movements for balance, posture & locomotion.

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6
Q

Where is the Primary motor cortex located, and what is its function?

A

Precentral gyrus, anterior to the central sulcus.

Controls fine, discrete, precise voluntary movements.

Provides descending signals to execute movements

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7
Q

Where is the Premotor area located, and what is its function?

A

Anterior to primary Motor cortex

Involved in planning movements and regulates externally cued movements. Seeing an apple and reaching out for it.

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8
Q

Where is the Supplementary motor area located, and what is its function?

A

Anterior and medial to PMC

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

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9
Q

What makes up the Corticospinal tract?

A

Lateral Corticospinal tract - 85-90% crossed fibres , Limb muscles.

Anterior Corticospinal tract - 10-15% uncrossed fibres, trunk muscles.

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10
Q

What does the corticospinal tract pass through to get to the medulla

A

Cerebral Peduncle

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11
Q

What does somatotopic mean in regard to the brain?

A

A particular region in the brain correlates to contol of a particular region in the body

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12
Q

What is the Corticobulbar tract responsible for?

A

Principal motor pathway for voluntary face movements of the face and neck.

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13
Q

Which nuclei are responsible for the movements of the Extra ochlear muscles?

A

Oculomotor nucleus
Trochlear nucleus
Abducens nucleus

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14
Q

Which nucleus is responsible for the muscles of mastication?

A

Trigeminal Motor nucleus

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15
Q

Which nucleus is responsible for muscles of the face?

A

Facial nucleus

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16
Q

Which nucleus is responsible for muscles of the tongue?

A

Hypoglossal nucleus

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17
Q

What is the responsibility 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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18
Q

What is the responsibility 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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19
Q

What is the responsibility of the Tectospinal tract?

A

From superior colliculus of midbrain

Orientation of the head and neck during eye moveme

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20
Q

What is the responsibility of the Rubrospinal tract?

A

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

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21
Q

What are the negative signs of an upper motor neuron lesion?

A

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

22
Q

What are the positive signs of an upper motor neurone lesion?

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

23
Q

What is Apraxia?

A

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

24
Q

What causes Apraxia?

A

Lesion of inferior parietal lobe, the frontal lobe (premotor cortex, supplementary motor area - SMA)
Stroke & dementia are the most common causes

25
Q

What are the signs of Lower motor neuron lesions?

A

Weakness
Hypotonia (reduced muscle tone)
Hyporeflexia (reduced reflexes)
Muscle atrophy
Fasciculations: damaged motor units produce spontaneous action potentials, resulting in a visible twitch
Fibrillations: spontaneous twitching of individual muscle fibres; recorded during needle electromyography examination

26
Q

What is an example of a disease that effects both upper and motor neurons?

A

Motor neuron disease MND e.g. ALS

27
Q

What does ALS effect?

A 
Progressive neurodegenerative disorder of the motor system. Affecting;
Upper motor neurons
Brainstem lower motor neurons
Axon bundles
tongue
intercostal muscles
spinal cord lower motor neurons
lower limb muscles
upper limb muscles
28
Q

What are the upper motor neuron signs of MND?

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
29
Q

What are the lower Motor neuron signs of MND?

A 
Weakness
Muscle wasting
Tongue fasciculations and wasting
Nasal speech
Dysphagia
30
Q

What makes up the structure 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)

31
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

32
Q

What is the structural order of the basal ganglia?

A 
C - caudate nucleus
P – putamen
G – (external) globus pallidus
T - thalamus
Acc – nucleus accumbens
Am – amygdala
AC – anterior commisure
33
Q

What happens in Parkinson’s disease?

A

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

34
Q

What are the signs of Parkinson’s disease?

A

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

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

Akinesia - difficulty in the initiation of movements because cannot initiate movements internally

Rigidity - muscle tone increase, causing resistance to externally imposed joint movements

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

35
Q

What happens in Huntington’s disease?

A

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

36
Q

What are the signs of Huntington’s disease?

A

Choreic movements (chorea - dance)
rapid jerky involuntary movements of the body; hands and face affected first; then legs and rest of body
Speech impairment
Difficulty swallowing
Unsteady gait
Later stages, cognitive decline and dementia

37
Q

What are the genetics of Huntington’s disease?

A

Genetic neurodegenerative disorder
Chromosome 4, autosomal dominant
CAG repeat

38
Q

What is Ballism?

A

Symptoms occur contra laterally, uncontrolled flinging of the extremities.

Usually occurs due to a stroke affecting the subthalamic nucleus.

39
Q

Where is the Cerebellum located, and what is its function?

A

Located in posterior cranial fossa

Separated from cerebrum above by tentorium cerebelli

Coordinator & predictor of movement

40
Q

What is the function of the Vestibulocerebellum?

A

Regulation of gait, posture and equilibrium

Coordination of head movements with eye movements

41
Q

What are the signs of dysfunctions of the Vestibulocerebellum?

A

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

42
Q

What is the function of the Spinocerebellum?

A

Coordination of speech
Adjustment of muscle tone
Coordination of limb movements

43
Q

What does damage to the Spinocerebellum present as?

A

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

44
Q

What is the function of the Cerebrocerebellum?

A

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

45
Q

What does damage to the Cerebrocerebellum present as?

A

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

46
Q

Define Ataxia

A

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

47
Q

Define Dysmetria

A

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

48
Q

Define Intention tremor

A

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

49
Q

Define Dysdiadochokinesia

A

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

50
Q

Define scanning speech

A

Staccato, due to impaired coordination of speech muscles

51
Q

What is similar in all the main signs of cerebellar dysfunction?

A

Apparent only on movement

BRS Phase 1b (80 decks)

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