functional hierarchy of the motor system Flashcards
how are muscles directly controlled?
via alpha motoneurones
what controls spinal reflexes?
brainstem nuclei
what are spinal reflexes integrated into?
higher order reflexes
what do higher order reflexes control?
posture and balance
what do trunk and limb muscles involved with higher order reflexes receive input from?
vestibulospinal and reticulospinal tracts
what controls brainstem nuclei?
cerebral cortex
basal ganglia
cerebellum
what 4 systems control movement?
descending control pathways
basal ganglia
cerebellum
local spinal cord and brainstem circuits
what do LMNs do?
directly innervate muscles to initiate reflexes and vountary movements
what would a LMN lesion cause?
flaccid paralysis and muscle atrophy
where are LMNs located?
cranial and spinal levels
where are UMNs located?
brainstem or cortex?
what do UMNs do?
synapse with multiple lower circuit neurones to regulate alpha motoneurone activity
control complex spatiotemporal skilled movements
what wold an UMN lesion cause?
spasticity
some paralysis
what would happen if there were many lesions in posture regulating pathways?
spastic paralysis
what would corticospinal lesions cause?
weakness rather than paralysis
what is the mediolateral map of the spinal cord?
proximal muscles are mapped to medial motoneurones and distal muscles are mapped to much more lateral motoneurones
where does the spinal cord receive descending input from?
brainstem