Motor Control Flashcards
What hierarchical levels are shown in control of the motor system?
High, middle, low
What is high level motor control?
Strategic (premotor)
Structures: association neocortex and basal ganglia
What is middle level motor control?
Tactical (motor)
Structures: motor cortex and cerebellum
What is low level motor control?
Execution
Structures: brainstem and spinal cord
What do lateral pathways control?
Voluntary movements
What tract is the most important lateral pathway?
Corticospinal tract (CST)
What tract is the second most important lateral pathway?
Rubrospinal Tract (RST)
Where does the majority of the CST originate?
Area 4 (Primary Motor Cortex)
Where do CST axons synapse and why?
Ventral horns with motor and interneurones to elicit control over them
Where is the origin of the RST?
Red nucleus of the midbrain
Where does the RST input?
Same as the CST
What do ventromedial pathways control?
Posture and locomotion
What tracts comprise the ventromedial pathways?
- Vestibulospinal tract
- Tectospinal tract
- Pontine and medullary reticulospinal tracts
What is Brodmann area 4?
Primary Motor Cortex
What is Brodmann area 6?
Divides into
PMA - premotor area
SMA - supplementary motor area
What is the function of the premotor area?
Connects reticulospinal neurones innervating proximal motor units
What is the function of the supplementary motor area?
Innervates distal motor units directly
What is the function of the vestibulospinal tract?
Stabilises the head and neck
What is the function of the tectospinal tract?
Ensures the eyes remain stable as the body moves
What is the function of the pontine and medullary reticulospinal tracts?
Reflexively maintains posture
What deficit would occur if a lesion effected the CST and RST?
Loss of fine movement and inability to move upper libs independently
What deficit would occur if a lesion only affected the CST?
Deficit would be short lived as RST takes over
What process occurs to orientate the body?
- Posterior parietal cortex (area 7) - produces a mental image of the body
- Prefrontal and parietal cortex decides what action to be taken
- Area 6 interprets intention into an impulse
- Impulses generated to muscles
What are PMA mirror neurones?
Fire when others perform an action - prepares the body to do likewise
How do anticipatory feedforward mechanism work?
A change in body position is initiates rapid compensatory feedback messages from brainstem vestibular nuclei to spinal cord motor neurones
