The human body organizes neurons and muscles into units we call motor units. Now simply put, a motor unit consists of the motor neuron as well as all the muscle cells that that particular motor neuron innervate. So to see what we mean, let's take a look at the following diagram. So let's suppose we have a single muscle cell as shown in red. So the muscle cell is also known as the muscle fiber or the myocides. So we have a single motor neuron that comes from the central nervous system and it basically connects its synapses with our muscle cell.