122 MUSCULAR SYSTEM. 



MUSCLES OF THE ABDOMEN. 

 LUMBAR REGION. 



The muscles included within this region constitute the fleshy 

 parts of the loins. They are six pairs in number, altogether ; 

 and two of them are placed externally ; the other four, internally. 



SEMI-SPINALIS LUMBORUM. 



Consisting of regular layers of fleshy fibres, similarly distri- 

 buted in the loins to what those of the semi-spinalis dorsi are in 

 the back ; and continued along the sacrum. They are covered 

 by thin tendinous faschiaj, extended from transverse to spinous 

 process. 



INTER-TRANSVERSALES LUMBORUM. 



Small muscular slips running from the sharp border of one 

 transverse process to that of the next to it ; and included be- 

 tween two strong and tense inter-transverse ligaments. 



Action. — To approximate those processes, 



s A CRO-LU M B A L 1 s . — Sacro-costttlis. 



Situation — Deep-seated, in the loins: above the psoas. 



Form. — Flat, thin ; border, semicular. 



Attachment. — Posteriorly, to the transverse process of the last 

 lumbar vertebra, and to the body of the sacrum ; anteriorly, to 

 the other transverse processes of the loins ; and to the last rib. 



Relations. — Superiorly, it is opposed to the transverse pro- 

 cesses of the loins ; inferiorly, to the psoas magnus. 



Structure. — A strong and flattened tendon attaches it to the 

 sacrum, which curves forwards, but disappears before it reaches 

 the last rib : the other parts consist of pale disgregated fibres, 

 intermixed with thin, curvilinear slips of tendon. 



Action. — To co-operate with the inter-transversales lumborum 

 in approaching the transverse processes ; and, at the same time, 

 to draw back and render fixed the last rib. 



PSOAS MAGN us. — Sub-lumbo-trochautineus. 



Situation. — Postero-lateral parts of the spine ; and superior 

 part of the inlet of the pelvis. 



Form. — Elongated ; fusiform ; thicker in the middle than at 

 the extremities; anterior extremity, flattened, extended and 

 pointed. 



Attachment. — Anteriorly, to the inner surfaces of the two last 

 ribs, close to their vertebral articulations ; to the body and trans- 

 verse process of the last dorsal vertebra, and to the same of all 



