Sciatica describes leg pain that arises from the lower back region. The pain in the leg is referred (pain that arises in one region – the low back and felt at another site – the leg). The diagram shows the patterns of leg pain arising from the lower back region. The pain in the leg does not arise due to damage in the leg. The main difficulty for the doctor when a patient arrives with sciatica is that leg pain can be caused by a variety of structures in the low back and buttock region. These include the low back, hip joint and the sacro-iliac joints. Besides these three structures there are a range of muscles, tendons and ligaments in the back and buttock region that can cause leg pain.