the quadratus lumborum muscle or “q.l.” Is a muscle located in your lower back. It originates on the iliac crest and iliolumbar ligament, and interns onto the last rib and transverse processes of the lumbar vertebrae. This muscle functions to stabilize the lumbar spine as well as laterally flex the spine. It will also hike the hip. Acting bilaterally it will extend the lumbar spine. Trigger points will often develop in this muscle. Trigger point referral will produce pain in the S.I. Joint and the lateral hip as well as the buttock. The pain referred into the S.I. Joint is often misdiagnosed as S.I. Joint dysfunction.