Motor unit
From Free net encyclopedia
A motor unit is a single motor neuron and all of the corresponding muscle fibers it innervates. Groups of motor units often work together to coordinate the contractions of a single muscle. The number of muscle fibers within each unit can vary: thigh muscles can have a thousand fibers in each unit, eye muscles might have ten. In general, the number of muscle fibers innervated by a motor unit is a function of a muscle's need for refined motion. Muscles requiring more refined motion are innervated by motor units that synapse with fewer muscle fibers.
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