Sciatica, and Why Does It Travel Down Your Leg: How It Works, Explained Simply

Video Transcript

Sciatica is that sharp, shooting pain that runs from the lower back or buttock down the back of the leg. But sciatica isn't a diagnosis. It's a symptom. It comes from a spinal nerve root being irritated where it exits the lower spine, most often the roots called L5 and S1. In cross-section you can see why. A disc that bulges backward can press on the nearby nerve root as it leaves the canal. But pressure is only half the story. The disc material also releases inflammatory chemicals that irritate the nerve, which is why pain can be severe even without dramatic compression. Each nerve root serves a specific strip of the leg. So a problem in the back is felt far away, down the thigh, the calf, even into the foot. That is the key to sciatica: the trouble is at the spine, but the pain shows up along the path the nerve travels. The encouraging part is that most sciatica improves over weeks to a few months, often without surgery. Injections may ease it for a while, but they don't change the disc itself. Go to the emergency room now if back pain comes with loss of bladder or bowel control, numbness in the groin or saddle area, or new weakness in both legs. This can be cauda equina syndrome, and waiting can cause permanent damage. And see a doctor promptly if one foot starts to drag or a leg grows steadily weaker. A nerve that is losing strength needs timely attention. This video is for general education only. It is not medical advice. Ask your doctor what's right for you.