quadratus lumborum (muscle)

quad·ra·tus lum·bo·rum (mus·cle)

[TA] flat muscle of posterior abdominal wall; origin, iliac crest, iliolumbar ligament, and transverse processes of lower lumbar vertebrae; insertion, twelfth rib and transverse processes of upper lumbar vertebrae; action, abducts trunk; nerve supply, ventral primary rami of upper lumbar spinal nerves. Synonym(s): musculus quadratus lumborum [TA], lumbar quadrate muscle, quadrate muscle of loins