326 HEALTH AND DISEASE 



Quad rat US Lumber um. Situated underneath the loins, and covered 

 over below by the great psoas muscle. The quadratus lumborum is 

 composed of several flat, narrow slips of muscle, whose fibres pass in 

 a direction forward and inward, extending from the sacrum to the last 

 rib but two. 



Origin. From the sacro-iliac ligament behind. 



Insertion. By its outermost slip to the posterior border of the last rib, 

 by the others to the ends of the transverse processes of the lumbar vertebrae 

 and the under surfaces of the three last ribs at their junction with the spine. 



Action. To draw the last rib backward and incline the lumbar vertebrae 

 to one side. 



Intertransverse Muscles of the Loins. These are short, flat 



muscles filling in the spaces between the transverse processes of the 

 lumbar vertebrae. They are attached to the anterior border of the trans- 

 verse process of one vertebra and the posterior border of the one in front 

 of it. 



Action. They incline the loins to one side. 



Erector Coccygis. 



Origin. From the sides and upper extremities of the three or four 

 sacral spines. 



Insertion. To the superior surfaces of the tail bones by a succession of 

 small tendons. 



Action. When acting with the corresponding muscle of the opposite 

 side it would raise the tail. Acting alone, it would elevate it and incline 

 it outwards. 



Depressor Coccygis. This muscle is situated beneath the tail, and 

 consists of two muscular segments. 



Origin. From the under surface of the sacrum. 



Insertion. Into the inferior face of the bones of the tail. 



Action. It pulls the tail downward or to one side, according as it acts 

 together with its fellow or alone. 



Curvator Coccygis. 



Origin. From the spines of the two or three posterior lumbar verte- 

 brae and from the posterior sacral bones. 



Insertion. Into the side of the bones of the tail. 



Action. To move the tail to the side on which the muscle acts. 



Compressor Coccygis. A small triangular muscle situated at the 

 posterior part of the pelvis. 



