Video narration
Why does your hand yank away from a hot pan before you even consciously feel the pain? The instant your skin detects heat, a signal travels along a sensory nerve to your spinal cord. You might think your brain has to notice the danger, decide what to do, and send the order back. But the withdrawal reflex takes a shorter protective route. The spinal cord receives the warning and sends instructions along a motor nerve to the muscles in your arm. Your hand pulls away. At the same time, the danger information travels onward to your brain. Your brain is not bypassed; it receives the signal as pain. But conscious awareness arrives after the protective movement has already begun. So why do you pull away first? In this reflex action, the spinal cord triggers the muscle before your brain has consciously felt the pain.