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functional anatomy BY CHRISTY CAEL QUADRATUS LUMBORUM Quadratus lumborum is a deep, multifunctional muscle of the spine. It connects the ilium to the lateral lumbar spine and 12th rib. The fibers of quadratus lumborum run slightly diagonal from the rib and spine inferiorly and laterally toward the posterior ilia. Quadratus lumborum lies deep to the latissimus dorsi and erector spinae muscles and posterior to the psoas major, helping form the posterior abdominal wall. Functionally, the quadratus lumborum muscles help position the spine relative to the pelvis when the lower body is fixed. It maintains upright posture, creating fine lateral movements and extension when coordinating with the erector spinae muscles. When we stand, the paired quadratus lumborum muscles work with the gluteus medius muscles to position the body over the lower extremities. During walking, quadratus QUADRATUS LUMBORUM Attachments • Origin: posterior iliac crest and iliolumbar ligament • Insertion: transverse processes of L1–4 and inferior border of 12th rib Lippincott Williams & Wilkins Figure 07.37 Innervation • T12–L3 • Lumbar plexus Dragonfly Media Group 02/18/09 04/21/09 Actions • Extends the vertebral column (bilateral action) • Laterally flexes the vertebral column (unilateral action) • Depresses/fixes the last rib during inhalation. CAEL: Functional Anatomy: A Guide of Musculoskeletal Anatomy for Profs lumborum and gluteus medius help stabilize the pelvis as the weight of the body shifts onto one foot, then the other. These muscles prevent the pelvis from shifting laterally, directing movement forward rather than side to side. Also, quadratus lumborum raises the pelvis toward the rib cage as weight shifts to the opposite foot. This action allows the leg to swing forward without the foot hitting the ground. connect with your colleagues on massageprofessionals.com 97