Illustration of how nerves run through the body

The peripheral nervous system is all the nerves in your body, aside from the ones in your brain and spinal cord. It acts as a communication relay between your brain and your extremities. For example, if you touch a hot stove, the pain signals travel from your finger to your brain in a split second. In just as short a time, your brain tells the muscles in your arm and hand to snatch your finger off the hot stove.