NRSC 2200 1st Edition Lecture 21 Brain Control of Voluntary Movements 1 Descending pathways from multiple brain regions Upper motor neurons influence activity of lower motor neurons 2 Hierarchy of controls organization of cortex Highest level Strategy Association Cortical Areas and Basal Ganglia Middle level Tactics Motor cortex and Cerebellum Lowest level Execution Brainstem and Spinal cord Sensorimotor system Sensory information used by all levels of the motor system Hapsis Pain and Proprioception Major Descending Motor Pathways 1 Axons from brain descend along two major pathways Lateral Pathways Tracts arms hands feet control Ventromedial Pathways Tracts posture reflexes Lateral Pathways 1 Voluntary movement originates in cortex Mostly arms hands movement control Corticospinal tract pyramidal tract and Rubrospinal tract Cross at medullary spinal junction Run in lateral dorsal spinal column Ventromedial Pathways 1 Posture reflexes and locomotion originates in brainstem Vestibulospinal tract head upper body balance head turning These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Tectospinal tract orienting response Ventromedial Pathways 1 The Pontine and Medullary Recticulospinal tracts Pontine enhances antigravity reflexes Medullary inhibits axial extensor muscles Sensorimotor Cortical Regions Area 4 Primary motor cortex M1 precentral gyrus Area 6 Premotor cortex Lateral region Premotor area PMA Medial region Supplementary motor area SMA Motor maps present in all regions PMA sensory guided movements SMA internallyguided movements Primary Motor Cortex Organization 1 Somatotopic organization of precentral gyrus like postcentral gyrus 2 Contralateral representation Planning of Voluntary Movements The Contributions of Posterior Parietal and Prefrontal Cortex Represent highest levels of motor control Decisions made about actions and their outcome Area 5 Inputs from areas 3 1 and 2 Area 7 Inputs from higher order visual cortical areas such as MT
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