somatic nervous system

The somatic nervous system is the part of your body's wiring that you can boss around on purpose. When you decide to wave hello, kick a ball, or pick up a cup, this is the system carrying that command from your brain out to your muscles. It is the "voluntary" channel — the one under your conscious control — as opposed to the parts that quietly run your heartbeat and digestion without asking you.

It works as a two-way street. On the outbound lane, nerves carry orders from the brain and spinal cord to your skeletal muscles (the muscles attached to bones that move your body), telling them when to contract. On the inbound lane, the same system delivers conscious sensations from your skin, eyes, ears, and other senses back to the brain — the feel of warm water, the sight of a face, the sound of a doorbell. So it both moves you and lets you knowingly feel the world, which is why it underlies nearly every deliberate action you take.