12/11/2025
THE QUADRATUS LUMBORUM.
✅ The quadratus lumborum (QL) is a deep, quadrilateral-shaped muscle in the lower back that helps stabilize the spine and rib cage, aids in side bending, and assists with breathing. It connects the pelvis (iliac crest) to the lumbar vertebrae and the bottom of the 12th rib. Pain in this area can be a symptom of QL strain and may require treatment like rest, ice or heat, or over-the-counter pain medication.
✅ Anatomy
Location: Deep in the lower back, on either side of the spine.
Attachments: Originates from the iliac crest and iliolumbar ligament, and inserts on the transverse processes of the lumbar vertebrae (L1-L4) and the inferior border of the 12th rib.
Nerve and Blood Supply: Receives innervation from the ventral rami of the T12-L4 nerves and is supplied by lumbar arteries.
✅ Function
Stabilization: Provides stability to the vertebral column and rib cage.
Side bending: Flexes the vertebral column to the side when acting unilaterally.
Breathing: Helps depress the 12th rib during forceful exhalation, which can make breathing more efficient.