MICROANATOMY

Detailed explanation-1: -The size of the motor unit correlates with the function of the muscle. In muscles involved with fine, coordinated control, the motor units are very small with 3-5 muscle fibers per motor neuron. Muscles that control eye movement and muscles in our hands have relatively small motor units.

Detailed explanation-2: -The Neuromuscular Junction. Each motor neuron innervates a population of muscle fibers termed a motor unit. The number of muscle fibers innervated by a single motoneuron varies depending on the size and function of the muscle, but averages about 150 muscle fibers per motor unit.

Detailed explanation-3: -In the hand and eye, fewer than 100 muscle fibers occupy a motor unit; in the lower leg, a single motor unit may contain as many as 1, 000 muscle fibers ( Generally, the larger the number of muscle fibers in a motor unit, the less precise the associated movements.

Detailed explanation-4: -The combination of an individual motor neuron and all of the muscle fibers that it innervates is called a motor unit.