28 HORSESHOEING. 



tinguished by variations in the surfaces of wall and sole. The 

 shape of the os pedis corresponds to the form of the horny box 

 or hoof, and therefore a knowledge of this bone is absolutely 

 necessary. 



The navicular bone (os naviculare, nut-bone, Figs. 9 and 10) 

 is an accessory or sesamoid bone to the os pedis. It is a small 



bone, transversely elongated 

 Fig. 9. Fig. 10. ^^^ situated behind and below 



the OS pedis and between the 

 wings of tlie latter. It adds to 

 the articular surface of the 

 pedal joint. Its under surface 



Fig. 9 representa the upper surface of the • , i i , t j • 



navicular bone; Fig. 10 the lower surface of IS SmOOth, and actS aS a gliding 



^^^nr^^Z^Z^'^f'oe^''''^'- surfacefortheperforanstendon, 



which is quite wide at this point. 

 The long axes of the three phalanges (cf& suffraginis, os co- 

 ronge, and os pedis) should unite to form a straight line, when 

 viewed either from in front or from one side ; that is, the direc- 

 tion of each of these three bones should be the same as the com- 

 mon direction of the three considered as a whole. 



In young colts both the long and short pasterns are in three parts 

 and the pedal bone in two parts, all of which unite later in life to form 

 their respective single bones. 



In mules and asses the os pedis is comparatively small and narrow. 

 In cattle all three phalanges are double, and split hoofs cover the divided 

 OS pedis. 



B. The Articulations of the Foot. 



There are three articulations in the foot — namely, the fet- 

 lock, coronary, and pedal joints. All are hinge-joints, the fet- 

 lock being a perfect hinge-joint, and the other two imperfect 

 hinge-joints. Each has a capsular ligament, and also several 

 funicular or cord-like ligaments which are placed at the sides of 

 (lateral ligaments), or behind (on the side of flexion) the joints. 



I. The fetlock or metacarpo-phalangeal articulation is 

 formed by the condyles at the lower end of the cannon bone and 

 the glenoid cavities formed by the union of the articular sur- 



