Question: what is the origin insertion and action of quadratus lumborum?
Answer: The quadratus lumborum is a thick, square-shaped muscle located at the very back of the abdominal wall. Specifically, this muscle originates from the iliac crest and then travels up the lower back and inserts on the 12th rib on both sides of the rib cage as well as the first four lumbar vertebrae (L1-L4).