o2 VEBTEBRATED AMMALS. 



cles, passing from one process to the other, through the 

 whole line, thus combining the twenty-four pieces into one 

 entire and firm column. 



234. It is by the action of these muscles, thus passing 

 longitudinally along the spine, that we are enabled to 

 bend it backward and forward, or from right to left. Thus 

 the back is made hollow, or bent backward, when the 

 muscles attached to the spinal processes are contracted j 

 and when those attached to the transverse processes are 

 contracted on the one side, and relaxed on the other, then 

 the column is bent from the right toward the left, or the 

 contrary, as the case may be. 



Fig. 65. 



235. The connection of the spine of the human frame 

 with the ribs and arms, is shown by Fig. 65. The ribs are 



How is the spinal column made to bend backward, or from right to 

 left? 



