THE MUSCULAR SYSTEM 47 



thin strap-like muscles along the ventral side of the abdo- 

 men and the ventrolateral surface of the thorax. Over 

 the greater part of the abdomen each muscle unites with its 

 fellow by means of the linea alba, along the midventral line. 

 Posterior to the xiphoid process the muscles diverge, run- 

 ning forward ventrolaterally along the thorax. It retracts 

 the sternum and compresses the abdomen. Origin, the 

 posterior part of the pubic symphysis, and the coxal bone 

 in the immediate vicinity. Insertion, the first rib, the 

 manubrium of the sternum, and the clavicle. 



Exercise XII. Outline the ventral aspect of the body and draw 

 the muscles into this outline. 



