86 



VERTEBRATED ANIMALS. 



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

 whole line, thus combining the twenty-four pieces into 

 one entire, and firm column. 



It is by the action of these muscles, thus passing lon- 

 gitudinally along the spine, that we are enabled to bend 

 it backwards and forwards, or from right to left. Thus 

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

 muscles attached to the spinal processes are contracted ; 

 and when those attached to the transverse processes 

 are contracted on the one side, and relaxed on the oth- 

 er, then the column is bent from the right towards the 

 left, or the contrary, as the case may be. 

 Fig. 65. 



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 backwards, or from right to 

 left? 



