The quadratus lumborum is a deep muscle located in the lower back. It originates from the iliac crest and inserts into the twelfth rib and lumbar vertebrae. It laterally flexes the spine (bends it to the side) and stabilizes the lumbar region. It also assists in extending the spine. Tight quadratus lumborum muscles are a common cause of lower back pain.

Encara no hi ha cap exercici del catàleg que treballi aquest múscul.