Origin of quadratus lumborum?

• A. Iliac crest; iliolumbar ligament; thoracolumbar fascia
• B. Sacrum and coccyx
• C. Spinous processes of T12-L1
• D. Transverse processes of L2-L5

Answer: (A)

Origin of the quadratus lumborum: This muscle begins from the iliac crest, the iliolumbar ligament, and the thoracolumbar fascia. The iliac crest provides a broad pelvic anchor, the iliolumbar ligament secures the lumbosacral region, and the thoracolumbar fascia gives a strong fascial origin. From there, the fibers run upward to insert on the inferior border of the twelfth rib and on the transverse processes of the upper lumbar vertebrae. This pattern fits its role in stabilizing the lower thoracic and lumbar spine and assisting with lateral flexion and rib movement during breathing.

Other origins listed don’t match QL anatomy: sacrum and coccyx are associated with muscles in the gluteal region or back, not QL; spinous processes of T12–L1 point to muscles that attach there rather than originate there; and the transverse processes of L2–L5 aren’t the typical origin for quadratus lumborum, which more commonly involves L1–L4 transverse processes.