Answer:
motor unit
The impulses that initiate muscle contraction originates in the. brain or spinal cord. A group of muscle cells stimulated by a single motor neuron is known as a. motor unit
A single motor neuron, however, can innervate many muscle fibers. The combination of an individual motor neuron and all of the muscle fibers that it innervates is called a motor unit. The number of fibers innervated by a motor unit is called its innervation ratio.
