The quadratus lumborum is a flat sheet of deep muscle fibers located on each side of the spinal column.

Origin

The quadratus lumborum originates on the crest of the ilium and the ligament and transverse processes of the lower four lumbar vertebrae.

Insertion

Insertion is on the transverse processes of the upper two lumbar vertebrae and the lower border of the last rib.

Function

The Quadratus Lumborum is an important deep trunk muscle that contributes to spinal stability, posture, and side bending movements. It plays a key role in stabilizing the pelvis during walking and single-leg activities, while also supporting the lumbar spine during lifting, carrying, and other functional movements. A strong and well-conditioned quadratus lumborum helps improve trunk stability, movement efficiency, and lower back resilience.

Side Bend