The number of muscle fibers in a motor unit is
A) dependent on the size of the individual
B) fewer in muscles where precise control is needed
C) fewer in muscles that maintain posture
D) greater in muscles that move the fingers
E) the same for all muscles

Question

Quizplus · Accepted Answer

A motor unit consists of a single motor neuron and all the muscle fibers it innervates. The number of muscle fibers in a motor unit varies depending on the muscle and its function. Muscles that require precise control, such as those in the fingers and eyes, have fewer muscle fibers per motor unit. Meanwhile, muscles that need more force, such as those in the legs and back, have more muscle fibers per motor unit. Therefore, option B is the correct answer.

The Number of Muscle Fibers in a Motor Unit Is