Lecture+20+FTD+ALS - The corticospinal pathway is the...

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1 The corticospinal pathway is the primary motor output from the cortex to the limbs ALS is the degeneration of motor neurons in the cortical, brainstem and spinal components of this system Motor Unit: a single motor neuron, its axon and the muscle fibers that it innervates. Originates in the anterior horn of the spinal cord (“anterior horn cells”) and receives descending inputs from the pyramidal tract. Degeneration of the motor unit causes severe muscle atrophy in the muscle fibers innervated by the motor neuron. Corresponding motor neurons in the brainstem also degenerate
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2 Brainstem Motor Neurons Muscles of Face Spinal Motor Neurons Muscles of Limbs and trunk Neurons in Motor Cortex In ALS motor neurons in cortex (origin of the corticospinal tract), brainstem, and spinal cord degenerate This is a motor system degeneration Amyotrophic Lateral Sclerosis A disease of the motor system Relatively common - 1-2/100,000 people but increasing, perhaps due to aging Affects anterior horn cells in the spinal cord (loss of cells), brainstem and the large motor neurons in the motor strip in the cortex (M1) Late or subtle cognitive changes reflecting damage to frontal lobes
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Amyotrophic lateral sclerosis (ALS) begins in middle age and proceeds to death in several years. There is loss of anterior horn cells, so that patients present with progressive weakness that proceeds to paralysis from neurogenic muscular atrophy. Because of the loss of anterior horn cells, the anterior (ventral) spinal motor nerve roots demonstrate atrophy, as seen here in comparison with a normal spinal cord. Normal muscle biopsy
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Lecture+20+FTD+ALS - The corticospinal pathway is the...

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