20 HORSESHOEING. 



the chief means of union of the bones. The immovable articu- 

 lations are termed sutures; they are found principally in the 

 head. The mixed joints are found between the bodies of the 

 vertebrae, each two of Avhich are united by an elastic fibro-carti- 

 lage which, in the form of a pad, lies between them, and by its 

 elasticity allows of very shght movement, though the spinal col- 

 umn as a whole can execute manifold and wide movements, as 

 shown by the neck and tail. 



Joints which permit motion in all directions are known as free 

 joints; such are the shoulder- and hip-joints (ball-and-socket 

 joints). Those which admit of motion in but two directions 

 (flexion and extension), and often to a very limited extent, are 

 called hinge-joints, — e.g., the elbow, hock, and fetlock. The 

 joints between the long and short pasterns and between the 

 latter and the pedal bone are imperfect hinge-joints, because 

 they allow of some other movements besides flexion and exten- 

 sion. The articulation between the first and second cervical 

 vertebrae (atlas and axis) is called a pivot-joint. 



The skeleton represents a framework which closely ap- 

 proaches the external form of the body, and by reason of its 

 hardness and stiffness furnishes a firm foundation for all other 

 parts of the body. By reason of the great variety of position 

 and direction of the bones, and of the fact that changes of posi- 

 tion of each single part of this complicated system of levers 

 may result in the greatest variety of bodily movements, we can 

 readily understand how the horse is enabled to move from place 

 to place. Of course, the bones have no power of themselves to 

 move, but this power is possessed by other organs that are 

 attached to the bones. These organs are the muscles, and, 

 owing to their ability to contract and shorten themselves, and 

 afterwards to relax and allow themselves to be stretched out, 

 they furnish the motive power that is communicated to and 

 moves the bones. 



The muscles of the body massed together are the red flesh 

 which we observe in every slaughtered animal. They are not, 



