Functional Hierarchy of the Motor System Flashcards
What is the final comon path for the voluntary brain control of muscles?
Motoneurons in the spinal cord
What spinal level does reflex control of muscles occur?
Each segmental spinal level
Although reflex control occurs segmentally at each spinal level, what input does the brain have?
Brainstem nuclei exert control over spinal reflexes and integrate them into higher order reflexes to control posture and balance
What is an example of the brain regulating muscle reflexes?
Vestibulospinal and reticulospinal tracts regulate trunk and limb muscle reflexes
Where do the brainstem nuclei that regulate reflexes receive control inputs about voluntary movement from?
Higher centres:
cerebral cortex (motor, premotor and supplementary motor cortex)
Basal ganlia
Cerebellum
What 4 systems control movement?
Decending control pathways
Basal ganglia
Cerebellum
Local spinal cord/brain stem circuits
What function does the basal ganglia have for controlling movement?
Gating proper initiation of movement
What function does the cerebellum have for controlling movement?
Sensory motor coordination of ongoing movement
What function does the motor cortex have for controlling movement?
Planning, initiating and directing voluntary movement
What function does the brainstem have for controlling movement?
Basic movements and postural control
Where are the axons of the medial white matter from (descending)?
Brainstem
Where are the axons from the lateral white matter from (descending)?
Motor cortex
Are distal muscles controlled more by lateral or medial white matter?
Lateral white matter (from motor cortex)
Are proximal muscles controlled more by medial or lateral white matter?
Medial (brainstem)
What does the spinal cord receive descending input and direct cortical input via?
Descending - brainstem
Direct cortical - corticospinal (pyramidal) tract
What level does sensory input enter the spinal cord?
All levels
What kinds of sensory input enters at spinal cord level?
Proprioceptors
Touch
Pain
What kind of sensory input enters at the brainstem?
Vestibular system (informs about balance)
What kind of sensory input enters at cortical level?
Visual, olfactory, auditory, emotional and intellectual cues
What does damage to sensory inputs at spinal level lead to?
Paralysis as if the motoneurons themselves have been damaged
What system can be used for sensory information to allow movement if the proprioception is damaged?
Visual system
What is the simplest reflex and where is it found?
Stretch reflex which is found in all muscles