08 Organiz Motor & Spinal Cord

08 Organiz Motor & Spinal Cord - LEARNING...

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N-82 LEARNING OBJECTIVES: ORGANIZATION OF MOTOR SYSTEM; SPINAL CORD 1. Identify the structures that comprise each part of the motor system hierarchy. 2. Sketch a motor unit, define the “size principle,” and describe the relationship between motor units and the size principle. 3. Describe the function and operation of the muscle spindle. Describe the effects of gamma motoneurons on spindle function. 4. Describe the function and operation of the Golgi tendon organ. 5. Sketch the circuits for the stretch, tendon, withdrawal, and crossed extensor reflexes. Identify which of these reflexes is the only monosynaptic reflex.
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Robert W. Blair, Ph.D. ORGANIZATION OF MOTOR SYSTEM; SPINAL CORD Reading: Widmaier et al., Human Physiology, 12 th ed., pp. 259-260, 271-272, 293-300 I. Hierarchy of the Motor System (Fig. 10-1, p. 293, and Table 10-1, p. 295) Motor system can be thought of as having a hierarchy of three main levels. A. Lowest (local) level 1. Consists of the α -motoneurons that innervate skeletal muscle (final common pathway). 2. Originates in spinal cord and brainstem. 3. Provides the actual command to contract muscles, at whatever intensity of contraction is specified by the higher centers. B. Middle level 1. Consists of brain regions that directly or indirectly influence the lowest level. 2. Regions include the sensorimotor cortex (areas giving rise to the corticospinal tract), brainstem nuclei giving rise to descending pathways (reticulospinal and vestibulospinal pathways), cerebellum, and basal ganglia system. 3. Function is to execute the movement commands intended by the highest level. This involves selecting the motor programs that are required for the movements, and coordinating the postural requirements with the movements of the distal limbs. C. Highest level 1. Consists of brain regions that initiate the desire to move. 2. Regions include the premotor and supplementary motor cortices, association areas of cortex, and regions involved in memory and emotion (limbic cortex). 3.
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This note was uploaded on 10/01/2011 for the course PSYO 5016 taught by Professor Staff during the Fall '11 term at The University of Oklahoma.

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08 Organiz Motor & Spinal Cord - LEARNING...

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