Optimal Length: all myosin-binding sites are available to bind to myosin
Control of Muscle Tension
Motor Units
Each skeletal muscle fibre (cell) has only one single NMJ. However, the axon of a somatic motor neuron branches out and forms NMJs with many different muscle fibres (average of 150 muscle fibres) and all contract in unison. This is a Motor Unit. Because of this, the total strength of a contraction depends in part on the size of the motor units and the number that are activated at a given time. Skeletal muscle can have as many as 2000 to 3000 muscle fibres in some motor units. A Motor Unit consists of a somatic motor neuron plus all the skeletal muscle fibres it stimulates.
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