Definition of psoas in English:


(also psoas major)


  • 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 psoas and iliacus muscles are occasionally completely independent 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.’
    • ‘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.’
    • ‘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.’


Late 17th century: from Greek, accusative plural of psoa, interpreted as singular.