THE SKELETON. 



29 



both legs. The same effect which the muscles of the 

 hose, in connection with the Achill-chord, perform on 

 the iever of the hock, the extensor tendons will 

 perform on the lever of the elbow. The muscles of 

 the hose draw the lever of the hock toward the thigh 

 bone, and, the thigh bone being simultaneously 

 moved backward by the muscles of the croup, all the 

 upper joints will be opened. 



Fig. la. 



This sudden extension of the leg represents the 

 propelling activity of the hind leg, the hock joint 

 forming the near and the ground the more remote ful- 

 crum. The same is the case with the fore leg. The 

 extensors acting on the elbow, at the same time the 

 shoulder joint being opened at the front side by the 

 long flexor of the fore arm, the same sudden elonga- 



