This muscle originates on the bodies and disks of T12-L5 and the inner ilium. It inserts on the lesser trochanter of the femur. The psoas flexes the hip when the spine is fixed. When the leg is fixed it extends the lumbar spine increasing lumbar lordosis. This Muscle is often chronically shortened due to inactivity and sitting posture. When trigger points are present they will refer pain primarily to the lower lumbar area and the sacrum as well as into the anterior thigh. Trigger points in the iliopsoas muscle can mimic appendicitis.