This is a broad, flat muscle placed beneath the loins, and extending from beneath the spine backward to the upper part of the thigh.

Origin. - From the bodies of the last two dorsal vertebrae, from the under surfaces of the last two ribs, and from the transverse processes of the lumbar vertebrae.

Insertion. - By a short tendon common to this and another muscle- the iliacus - into the internal trochanter of the femur or thigh bone.

Action. - To flex the thigh on the pelvis and rotate it outwards. When both thighs are fixed it arches the back by flexing the spine. When a horse rears, this muscle is mainly concerned in preventing him falling backwards.

Muscles of the Lumbar and Pubio Femoral Regions.

Fig. 376.-Muscles of the Lumbar and Pubio-Femoral Regions.

1, Intercostal Muscles. 2, Psoas Parvus. 3, Iliacus. 4, Quadratus Lumborum. 5, Sartorius. 6, Pubic Tendon. 7, Fascia. 8, Adductor Magnus. 9, Semitendinosus. 10, Rectus Femoris. 11, Adductor Longus. 12, Vastus Internus. 13, Adductor Brevis. 14, Pectineus.