Each of a pair of large muscles which run from the lumbar spine through the groin on either side and, with the iliacus, flex the hip. A second muscle, the psoas minor, has a similar action but is often absent.‘The internal iliac artery (ie, hypogastric) enters the pelvis and supplies the psoas major and quadratus lumborum muscles, the pelvic viscera, and parts of the bony pelvis.’
- ‘The psoas and iliacus muscles are occasionally completely independent muscles.’
- ‘Another group of muscles of the pelvic girdle act to flex the hip, and include the psoas, the iliacus, a combination of the two called the iliopsoas, the pectineus, and the sartorius muscles.’
- ‘The femoral nerve may run buried in a cleft of the iliacus under the psoas.’
- ‘The primary muscles involved in raising the legs (hip flexion) are the psoas and iliacus - collectively known as the iliopsoas - as well as the rectus femoris and pectineus.’
Late 17th century from Greek, accusative plural of psoa, interpreted as singular.