The Quadratus Lumborum (QL) is a deep lower back muscle that lies on both sides of the lumbar spine. The QL muscle is critical for spinal stability and side bending, and it has the capacity to cause a lot of pain and imbalance when it gets tight. Quadratus Lumborum (QL) Muscle QL Muscle Pain The QL muscle has the capacity to cause a lot of pain in the body when it is ridden with trigger points, also known as knots. Trigger points are tight, shortened bands of muscle that constantly pull on joints when present. Constant muscle tension induced by