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. So this is the axon of the motor neuron that's coming from the central nervous system and it basically splits in its synapses with our muscle cell. And at the given synapse we have the neuromuscular junction where our neurotransmitter acetylcholine basically transfers the action potential from the neuron to our muscle cell. So basically this muscle cell shown in red as well as the motor neuron is our motor unit.