Question

1. which statement best defines a motor unit?

branches located in each individual muscle cell
a nerve supplying a muscle originating from the spinal cord
single nerves found in each muscle
a motor nerve and the muscle cells it stimulates

Explanation:

A motor unit is defined as a motor neuron (nerve) and all of the muscle fibers (cells) that it innervates (stimulates). The other options do not accurately describe the composition of a motor unit. For example, a motor unit is not just branches in a muscle cell (too limited), not just a nerve from the spinal cord supplying a muscle (doesn't mention the muscle cells), and not single nerves in each muscle (incomplete - needs to include the muscle cells).

Answer:

a motor nerve and the muscle cells it stimulates