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Year 2 Neuro > Motor Cortical Control > Flashcards

Motor Cortical Control Flashcards

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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
What is the motor homunculus?
The little man that shows the distribution of innervation
26
What is the somatotropic representation?
Maps regions of the brain and where they control
27
What is the function of the corticobulbar tract?
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
28
What are the nuclei that provide facial movements?
``` Oculomotor nucleus (Eye) Trochlear nucleus Trigeminal motor nucleus (Jaw muscles) Abducens nucleus (Eye) Facial nucleus (Muscles of the face) Hypoglossal nucleus (tongue) ```
29
What is the function of the vestibulospinal tract?
Stabilise head during body movements, or as head moves Coordinate head movements with eye movements Mediate postural adjustments
30
What is the function of the reticulospinal tract?
Most primitive descending tract - from medulla and pons Changes in muscles tone associated with voluntary movement Postural stability
31
What is the function of the tectospinal tract?
From superior colliculus of midbrain | Orientation of the head and neck during eye movements
32
What is the function of the rubrospinal?
From red nucleus of midbrain In humans mainly taken over by corticospinal tract Innervate lower motor neurons of flexors of the upper limb
33
What are the negative affects of an upper motor neurone lesions?
Loss of voluntary motor function Paresis: graded weakness of movements Paralysis (plegia): complete loss of voluntary muscle activity
34
What is meant by negative?
Loss of function
35
What is meant by positive?
Unwanted gain of function
36
What are the positive affects of an upper motor neurone lesions?
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
What is apraxia?
Consequence of UMN lesion disorder of skilled movement Patients are not paretic but have lost information about how to perform skilled movements
38
What can cause apraxia?
Lesion of inferior parietal lobe, the frontal lobe e.g. stroke and dementia
39
What are the symptoms of a lower motor neurone lesions?
Weakness Hypotonia (reduced muscle tone) Hyporeflexia (reduced reflexes) Muscle atrophy Fasciculations Fibrillations
40
What are fasciculations?
damaged motor units produce spontaneous action potentials, resulting in a visible twitch
41
What are fibrillations?
spontaneous twitching of individual muscle fibres; recorded during needle electromyography examination
42
What is MND?
Motor Neuron Disease
43
What is motor neurone disease?
Progressive neurodegenerative disorder of the motor system Affects UMN and LMN's Also known as Amyotrophic Lateral Sclerosis (ALS)
44
Which muscles are particularly affected by MND?
Tongue Upperlimb Intercostal muscles Lower limb
45
What are the signs of upper motor neurone disease? in MND
``` Spasticity (increased tone of limbs and tongue) Brisk limbs and jaw reflexes Babinski’s sign Loss of dexterity Dysarthria (difficulty speaking) Dysphagia ```
46
What are the signs of lower motor neurone disease? in MND
``` Weakness Muscle wasting Tongue fasciculations and wasting Nasal speech Dysphagia ```
47
What makes up the basal ganglia?
Caudate nucleus Lentiform nucleus Nucleus accumbens Subthalamic nuclei Substantia nigra (midbrain) Ventral pallidum claustrum, nucleus basalis (of Meynert)
48
What makes up the lentiform nucleus?
(putamen + external globus pallidus) – together caudate and putamen are known as the striatum
49
What are the functions of the basal ganglia?
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
Summarise the structures of the basal ganglia
``` caudate nucleus putamen (external) globus pallidus thalamus nucleus accumbens amygdala anterior commisure ```
51
What disorders are associated with basal ganglia dysfunction?
Parkinson's Huntington's Ballism
52
What causes Parkinson's?
Degeneration of the dopaminergic neurons that originate in the substantia nigra and project to the striatum
53
What are the symptoms of Parkinson's?
``` Bradykinesia Hypomimic face Akinesia Rigidity Tremor at rest ```
54
What is bradykinesia?
slowness of (small) movements (doing up buttons, handling a knife)
55
What is hypomimic face?
expressionless, mask-like (absence of movements that normally animate the face)
56
What is akinesia?
difficulty in the initiation of movements because cannot initiate movements internally
57
What is rigidity?
muscle tone increase, causing resistance to externally imposed joint movements
58
What are the main feature of the Parkinson's tremor?
4-7 Hz, starts in one hand (“pill-rolling tremor”); with time spreads to other parts of the body
59
What causes Huntington's disease?
Degeneration of GABAergic neurons in the striatum, caudate and then putamen Genetic neurodegenerative disorder Chromosome 4, autosomal dominant CAG repeat
60
What are the symptoms of Huntington's?
``` Choreic movements Speech impairment Difficulty swallowing Unsteady gait Later stages, cognitive decline and dementia ```
61
What are choreic movements?
(chorea - dance) | rapid jerky involuntary movements of the body; hands and face affected first; then legs and rest of body
62
What is Ballism?
Usually from stroke affecting the subthalamic nucleus. Sudden uncontrolled flinging of the extremities Symptoms occur contralaterally.
63
Where is the cerebellum located?
Located in posterior cranial fossa
64
What separates the cerebrum and the cerebellum?
Separated from cerebrum above by tentorium cerebelli
65
What is the function of the cerebellum?
Coordinator and predictor of movement
66
What is the function of the vestibulocerebellum?
Regulation of gait, posture and equilibrium | Coordination of head movements with eye movements
67
What does damage of the vestibulocerebellum result in?
Damage (tumour) causes syndrome similar to vestibular disease leading to gait ataxia and tendency to fall (even when patient sitting and eyes open)
68
What is the function of the spinocerebellum?
Coordination of speech Adjustment of muscle tone Coordination of limb movements
69
What does damage of the spinocerebellum result in?
Damage (degeneration and atrophy associated with chronic alcoholism) affects mainly legs, causes abnormal gait and stance (wide-based)
70
What is the function of the cerebrocerebellum?
Coordination of skilled movements Cognitive function, attention, processing of language Emotional control
71
What does damage of the cerebrocerebellum result in?
Damage affects mainly arms/skilled coordinated movements (tremor) and speech
72
What are the main signs of cerebellar dysfunction?
``` Ataxia Dysmetira Intention tremor Dysdiadochokinesia Scanning speech ```
73
What is ataxia?
General impairments in movement coordination and accuracy. Disturbances of posture or gait: wide-based, staggering (“drunken”) gait
74
What is dysmetria?
Inappropriate force and distance for target-directed movements (knocking over a cup rather than grabbing it)
75
What is intention tremor?
Increasingly oscillatory trajectory of a limb in a target-directed movement (nose-finger tracking)
76
What is dysdiadochokinesia?
Inability to perform rapidly alternating movements (rapidly pronating and supinating hands and forearms)
77
What is scanning speech?
Staccato, due to impaired coordination of speech muscles

Year 2 Neuro (15 decks)

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