09 Motor Brainstem Cortex

09 Motor Brainstem Cortex - LEARNING OBJECTIVES: MOTOR...

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N-90 LEARNING OBJECTIVES: MOTOR CONTROL: BRAINSTEM AND CEREBRAL CORTEX 1. List the brainstem descending pathways that make up the lateral and medial systems. Identify the general functions of the medial and lateral systems pathways. 2. Identify the locations and functions of the cortical regions that give rise to the corticospinal tract. 3. Identify the course of the corticospinal tract as it travels from the cortex to the spinal cord. 4. Define the terms “upper motor neuron” and “lower motor neuron.” Compare and contrast the signs associated with damage to upper vs. lower motor neurons.
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N-91 Robert W. Blair, Ph.D. MOTOR CONTROL: BRAINSTEM AND CEREBRAL CORTEX Reading: Widmaier et al., Human Physiology, 12 th ed., pp. 300-301, 303-306 I. Brainstem Descending Pathways (Fig. 10-12, p. 304) A. Organized into two major functional groups 1. Medial systems: Primarily influence posture a. Vestibulospinal tracts - originate in vestibular nuclei and project to spinal cord 1. Uncrossed (ipsilateral) 2. Mainly excites extensors and inhibits flexors b. Reticulospinal tracts - originate in medullary and pontine reticular formation and project to spinal cord 1. Uncrossed (mainly) and crossed (contralateral) 2. Pontine reticulospinal tract mainly excites extensors and inhibits flexors, and medullary reticulospinal tract mainly excites flexors and inhibits extensors 2. Lateral systems: Mainly control fine dexterous movements a. Corticospinal tract - originates in cerebral cortex and projects to spinal cord 1. Crossed (85%) 2. Mainly excites flexors in distal limbs and digits, and inhibits extensors. Medial Systems Reticulospinal tracts Vestibulospinal tracts Figure 1: Medial systems pathways. Lateral Systems Corticospinal tract Rubrospinal tract Figure 2: Lateral systems pathways.
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N-92 b. Rubrospinal tract - originates from red nucleus in midbrain and projects to spinal cord 1. Crossed 2. Mainly excites flexors in proximal limbs and hands, and inhibits extensors B. Function of the two systems is coordinated II. Cerebral Cortical Control of Movement (Fig. 10-10, p. 301) 5,7 5,7 3,1,2 4 6 24 Frontal eye field Primary motor Supplementary Somatosensory Parietal Lateral premotor Cingulate 6 3,1,2 8 4 Figure 3: Regions of cortex associated with motor functions. A. Overall View 1. The cerebral cortical motor regions control voluntary movements .
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N-93 2. The areas in the cerebral cortex that produce movements when electrically stimulated are termed “motor cortex.” There are two major conceptual divisions of motor cortex: a. Primary motor cortex (sometimes mentioned without the term “primary”): Low intensity electrical stimulation produces focal movements (can be limited to a single muscle). b.
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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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09 Motor Brainstem Cortex - LEARNING OBJECTIVES: MOTOR...

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