[Campbell Biology P.1179] Based on Figure 50.32 and the accompanying text, which of the follo... | Practice Question

Based on Figure 50.32 and the accompanying text, which of the following best describes a motor unit?

  • A: A single motor neuron.
  • B: A muscle fiber and all the motor neurons that innervate it.
  • C: A motor neuron and all the muscle fibers it controls.
  • D: All the muscle fibers in a single muscle.

Explanation

The text states: 'A motor neuron and all the muscle fibers it controls constitute a motor unit.' This definition is clearly illustrated in Figure 50.32 showing Motor unit 1 and Motor unit 2, each consisting of a single motor neuron innervating multiple muscle fibers.