26 HORSESHOEING. 



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. and situated behind and below 



the OS pedis and between the 

 wings of the latter. It adds to 

 the articular surface of the pedal 



Fig. 9 represents the upper surface of the joint. Its Under SUrface is 



navicular tone ;Mg. 10 the lower surface of gj^ooth, and acts aS a ghding 



the same : a, anterior border ; b, slight ele- ' c o 



Tation in middle of undersurfaee. SUrface for the pcrforans teudoU, 



which is quite wide at this point. 

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

 ronse, 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 re- 

 spective 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 fetlock, 

 coronary, and pedal joints. All are hinge-joints, the fetlock 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- 

 faces of the sesamoids and the upper end of the first phalanx. 

 The following ligaments are about this joint : 



