Somatic Motor Pathways

Somatic Motor Pathways - posture, blocking unwanted...

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Somatic Motor Pathways: Levels of Motor Control: - some lower-level motor control is mediated by reflex arcs, but complex motor activities appear to be regulated by fixed-action patterns (stereotyped sequential motor actions triggered internally or by environmental stimuli) - Segmental level: segmental circuits of spinal cord Segmental circuits activate anterior horn segments of the spinal cord to stimulate a specific group of muscle fibers pattern generators (CPGs) - Projection level: cortical motor areas that produce the direct (pyramidal) system & indirect (extrapyramidal or multineuronal) system . axons of the neurons at this level project to the spinal cord both reflex & fixed-action pattern activities, and produce voluntary movement - Programs & Instructions Level: neurons in the basal nuclei of the cerebrum and of the cerebellum ( precommand areas ) that regulate motor activity
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Unformatted text preview: posture, blocking unwanted movements & maintaining muscle tone Cerebellum: center for sensorimotor integration & control, correcting errors in muscle activity, & fine-tuning motor activity o damage to the cerebellum results in disorders of synergy & muscle tone, disturbances of equilibrium & speech disorders Basal nuclei: receive inputs from all cortical areas & send output to the premotor & prefrontal cortex to coordinate more complex motor activities- Organization of Upper Motor Neuron Pathways: cortical motor areas that produce the direct (pyramidal) system & indirect (extrapyramidal or multineuronal) system Direct Motor Pathways o lateral corticospinal tracts: conveys nerve impulses from motor cortex to skeletal muscles on opposite side of the body for precise, voluntary movements of hands & limbs o anterior corticospinal tracts: conveys nerve impulses from motor cortex to skeletal muscles on opposite side of the body for movements of axial skeleton page4...
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Somatic Motor Pathways - posture, blocking unwanted...

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