Iliocostalis Lumborum Muscle, Posterior View

Description

Seen from the posterior torso, the iliocostalis lumborum forms the lateral column of the erector spinae, running longitudinally along the posterolateral lumbar spine and thoracolumbar fascia. Muscle fibers arise inferiorly from the iliac crest and the sacrum via the common erector spinae tendon, then course superiorly to the angles of the lower ribs and the transverse processes at the thoracolumbar junction. Medial to it sit longissimus thoracis and spinalis, while more superficially you would expect latissimus dorsi to overlie parts of the lumbar region if included. It sits lateral. For teaching deep back anatomy, this posterior emphasis matters because iliocostalis lumborum is the most lateral and often the hardest for learners to separate from quadratus lumborum, which lies anterior to the erector spinae and is approached from the flank rather than the midline. Palpation and dry needling targets are often described near the rib angles and just superior to the iliac crest, where myofascial trigger points can refer pain into the low back and lateral hip. In posterior lumbar approaches, splitting the erector spinae and recognizing this lateral column helps maintain orientation relative to the transverse processes and the thoracolumbar fascia. Use this figure in gross anatomy and kinesiology modules when you need a clean reference for the erector spinae columns and their attachments, or in physiotherapy and sports medicine materials covering lumbar extension, ipsilateral lateral flexion, and postural endurance testing. It also supports surgical and anesthesia education that discusses posterior landmarks and muscle-splitting trajectories in the lumbar region. Anatomical accuracy verified by SciePro's Medical Advisory Board.