Sciatica is a condition caused by encroachment of the sciatic nerve where it exits the lumbar spine. More often, the "sciatica-type" pain is caused peripherally, that is further away from the spine.

Frequently, the problem lies in the Piriformis muscle, with related trigger points occurring in other muscles as well. Actually the condition that I most often encounter with symptoms of pain in the low back and buttocks, radiating down the side or back of the thigh or even into the front of the thigh or groin is more correctly called Piriformis Syndrome.

Here the sciatic nerve is being irritated by the muscles that lie "on top" of it, which can become inflamed and swollen, tweaking the nerve and causing usually diffused pain.