Week 16: Motor Systems L1 Flashcards
Motor hierarchy and organisation motor output and control
where do sensory afferents enter spinal cord
dorsal horn
why do cervical and lumbar have enlarged motor pools
increased number of motor neurones as more and bulkier muscles innervated
where do motor neurons sit
ventral horn
what are the two main types of motor control pathways
hierarchical and parallel
what is the hierarchical pathway of motor control
1.limbic system and association cortex
2.premotor and supplemetary motor cortices
3.primary motor cortex
4. brain stsm
5. spinal cord
why are parallel motor pathways important
if one pathway is damaged, other pathways can contribute to the movement
which pathways in the motor organisation are parallel
- premotor and supplementary motor cortices
- brain stem
- spinal cord
role of basal ganglia in motor control
initiates and refines voluntary movements
role of cerebellum in motor control
coordinates and fine-tines movement accuracy and balance
what is a motor unit
muscle fibre innervated by an axon ( a motor unit and all the fibres in innervates) varies in size, tension produced and contractility
in the spinal cord, where are motor neurons innervating axial musculature located
medially
in the spinal cord, where are motor neurons innervating distal muscles located
laterally
what is the order of motor unit recruitment
low threshold first, larger motor neurons recruited as progresses as they require more charge (ion transfers)
function of alpha motor neurons
directly control skeletal muscle contraction to generate movement,
innervate extrafusal muscle fibres,
involved in voluntary movement and reflexes
function of gamma motor neurons
regulate the sensitivity of muscle spindles,
innervate intrafusal muscle fibres (muscle spindles),
maintain muscle tone and adjust sensitivity of stretch reflex
