Quadratus Lumborum and Low Back Pain The Quadratus Lumborum (QL) muscles are very important muscles for core stability and are culprits in many cases of low back pain. The QL muscles attach the pelvis to the lumbar vertebrae. These muscles are very important to the back for… By Dr. Travis Scott | February 8, 2013 | Spinal Care, Wellness Tips | No Comments | Read more