peripheral nervous system

The peripheral nervous system, or PNS, is everything in the nervous system outside the brain and spinal cord. It is made of nerves, which are bundles of long signal-carrying fibres, and ganglia, which are small clusters where nerve cell bodies gather along the way. Together they form the wiring that links the central command center to the rest of you, reaching your skin, muscles, and internal organs. Where the brain and spinal cord are the head office, the PNS is the field network that gathers reports from the body and delivers orders back out to it.

It carries traffic in both directions. Sensory (afferent) fibres bring news inward, such as a pinprick on your finger, a sound, or the feeling of a full stomach, while motor (efferent) fibres carry commands outward to muscles and glands. The PNS is usually grouped into a somatic part, which handles the senses and the voluntary muscles you move on purpose, and an autonomic part, which quietly manages heartbeat, digestion, and other jobs you rarely think about.

Unlike the central nervous system, peripheral nerves can often regrow and repair themselves after injury, although slowly and imperfectly. That difference is one reason a cut nerve in your hand may recover feeling over many months, while damage to the spinal cord usually does not heal on its own.