Neuro - Motor Control Flashcards
(83 cards)
What is the hierarchal organisation of motor control?
→ high order areas of hierarchy = more complex tasks (programme + decide on movements, coordinate muscle activity)
→ lower level areas of hierarchy = lower level tasks (execution of movement)
What is functional segregation?
motor system organised in a no. of different areas that control different aspects of movements
How is the hierarchy organised for motor systems?
What are the 2 types of major descending tracts?
→ pyramidal tracts : passes thru the pyramids of the medulla
→ extrapyramidal tracts : do not pass through the pyramids of the medulla
What are pyramidal tracts? What are 2 examples of pyramidal tracts?
→ pass through the pyramids of medulla
→ motor cortex to spinal chord or cranial nerve nuclei in brainstem
→ voluntary movements of body and face
→ corticospinal + corticobulbar
What are extrapyramidal tracts? What are 4 examples of extrapyramidal tracts?
→ doesn’t pass through the pyramids of medulla
→ brainstem nuclei to spinal chord
→ involuntary movements for balance, posture and locomotion
→ vestibulospinal + tectospinal + reticulospinal + rubrospinal
Where is the primary motor cortex and what does it do?
→ located in precentral gyrus, anterior to the central sulcus
→ controls fine, discrete, precise voluntary movements
→ provides descending signals to execute movements
What is the premotor cortex and what does it do?
→ located anterior to primary motor cortex
→ involved in planning movements
→ regulates externally cued movements e.g. reaching for something after seeing it
What is the supplementary motor area and what does it do?
→ located anterior + medial to primary motor cortex
→ involved in planning complex movements e.g. internally cued, speech
→ becomes active prior to voluntary movements
What route does the corticospinal tract take from the brain to the muscles?
What is a part of the lateral corticospinal tract? What does it do?
→ 85 - 90% crossed fibres
→ innervates limb muscles
What is a part of the anterior corticospinal tract? What does it do?
→ 10-15 % uncrossed fibres
→ innervates trunk muscles
What does the corticobulbar tract do?
principal motor pathway for voluntary movements of face and neck
What route does the corticobulbar tract take?
v
What does the reticulospinal tract do?
→ Most primitive descending tract - from medulla and pons
→ Changes in muscles tone associated with voluntary movement
→ Postural stability
What does the tectospinal tract do?
→ From superior colliculus of midbrain
→ Orientation of the head and neck during eye movements
What does the rubrospinal tract do?
→ From red nucleus of midbrain
→ In humans mainly taken over by corticospinal tract
→ Innervate lower motor neurons of flexors of the upper limb
What are the negative signs of upper motor neurone lesions?
→ Loss of voluntary motor function
→ Paresis: graded weakness of movements
→ Paralysis (plegia): complete loss of voluntary muscle activity
What are the positive signs of 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
What is apraxia?
→ disorder of skilled movement
→ Patients are not paretic but have lost information about how to perform skilled movements
What can cause apraxia?
stroke, dementia or disease of these areas:
→ Lesion of inferior parietal lobe
→ the frontal lobe (premotor cortex
→ supplementary motor area - SMA)
What are the signs of a lower motor neurone lesion?
→ 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
What is motor neurone disease?
→ Progressive neurodegenerative disorder of the motor system
→ Spectrum of disorders
What is MND also known as?
ASL (Amyotrophic Lateral Sclerosis)