The use of the word rank for Navy enlisted personnel is incorrect. The term is rate.. The rating badge is a combination of rate (pay grade, as indicated by the chevrons) and rating (occupational specialty, as indicated by the symbol just above the chevrons).
Neurons are nerve cells that are constantly sending signals to your brain, muscles and glands. You have over 100 billion neurons in your brain sending signals. The signals help the different parts of your body communicate with each other.
When an action potential reaches the end of a neuron, the acetylcholine is released and a new action potential begins in the muscle tissue. Nerves connecting to muscles are called motor neurons. Each neuromuscular junction is connected to a bundle of muscle fibers. A motor neuron may branch several times and connect to several bundles. All of these bundles will contract together upon getting a signal from the motor neuron.