What nerve!

Your neurons are fragile cells, and for the most part can’t be replaced if they get damaged. So instead of bare axons running through our bodies, we have nerves. A nerve is like an electrical cable housing thousands – or millions – of axons in a protective sheath of tissue. Nerves extend out from your brain and spinal column, known as the central nervous system, to the rest of your body. There are 12 pairs of nerves extending from the brain and 31 pairs extending from the spinal cord. The nerves branch off in your body, forming a network called the peripheral nervous system. The afferent division of the peripheral nervous system relays signals from sensory neurons back to the central nervous system, while the efferent division relays instructions from the central nervous system to muscles and glands. Most nerves carry both types of signals.