OF THE DIFFERENT MUSCLES. 149 



Origin. — From the anterior and lateral part of the body 

 of the sacrum, and last lumbar vertebrae. 



Insertion. — Into the fibres that traverse the loins, and into 

 the last rib. 



Use. — They assist the intertransversales lumborum. 



PSOAS MAGNUS 



Runs along the inner part of the loins above the kidney. 



Origin. — From the inward surfaces of the two last ribs, 

 close to their articulations with the vertebrae ; and from the 

 bodies and transverse processes of the last dorsal vertebrae, 

 and all the lumbar vertebrae. In its passage to the thigh, 

 some of its fibres are blended with those of the iliacus. 



Use. — To bend the femur upon the pelvis ; to pull the 

 haunch forwards in progression. 



PSOAS PARVUS. 



A smaller muscle than the last, placed between it and the 

 spine. 



Origin. — From the heads of the sixteenth, seventeenth, 

 and eighteenth ribs, from the bodies of the three posterior 

 dorsal, and from those of the lumbar, vertebrae. 



Insertion. — By a tendon inta the rough surface upon the 

 os innominatum, below the acetabulum. 



Use. — To draw the pelvis forward. When one acts, it 

 may incline it to one side. It also assists the psoas magnus 

 in arching the spine. 



ILIACUS. 



A muscle of considerable substance and power, placed 

 above and in part exterior to the psoas magnus. 



Origin. — From that part of the crest of the ileum that 

 has no bearing upon the sacrum, and from the anterior spinous 

 process, and inferior edge of the bone. 



Insertion. — It passes down the thigh in company with 

 the psoas magnus, with which it is inserted. 



Use. — To advance the haunch. 



