A single motor neuron together with all the skeletal muscle fibers it innervates is called a motor unit.
Motor neurons are more than just relays for the motor commands sent down the hierarchy from higher levels. They themselves are parts of intricate circuits that carry out extensive information processing.
Due to their highly branching, intricate dendritic trees, motor neurons are able to integrate inputs from several other neurons and generate accurate outputs.
A single motor neuron, and nothing else, innervates each and every muscle fiber (make sure you understand the difference between a muscle and a muscle fiber). However, several muscle fibers can be innervated by a single motor neuron.
A motor unit is the aggregate of a single motor neuron and all of the muscle fibers that it innervates. The innervation ratio refers to how many fibers a motor unit innervates.
Learn more about the motor unit with the help of the given link:
