Iliocostalis lumborum
Back
Deep muscle — it lies under other muscles. X-ray makes the muscles over it see-through.
- Origin
- Sacrum and iliac crest (common erector spinae origin)
- Insertion
- Angles of the lower six or seven ribs
- Action
- Extends and laterally flexes the lumbar spine
- Nerve supply
- Dorsal rami of the spinal nerves
The lowest and thickest section of the iliocostalis, rising from the pelvis to the lower ribs. With the longissimus thoracis it forms the thick muscle ridge on either side of the lower back.