MUSCLES OF THE INFERIOR LUMBAR REGION 



325 



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. 



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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. 



Psoas Parvus. Situated beneath the loins on the inner side of the 

 muscle last described. 



Origin. From the bodies of the three or four last dorsal and all the 

 lumbar vertebrae. 



Insertion. To a small bony eminence (ilio-pectineal) on the front of 

 the ilium. 



Action. When the loins are fixed, it draws the pelvis forward and 

 flexes it on the spine. When the pelvis is fixed, it roaches the back. 



Iliacus. The iliacus is a stout, fleshy muscle, extending from the 

 under part of the ilium or haunch bone to the thigh. 



Origin. From the under surface of the ilium. 



Insertion. To the small internal trochanter on the inner surface of the 

 femur by a tendon common to this muscle and the psoas magnus. 



Action. To flex the femur on the pelvis and rotate the femur outwards. 



