424 NAYIX ox THE HOESE. 



hoofs of colts. They have no connection with the sensitive 

 lamelljB except contact. 



THE INTERNAL FOOT. 



As before stated, the principal internal parts of the foot are 

 the coffin-bone, the navicular bone, the lateral cartilages, the 

 coronary substance, or ligament, the sensitive lamella?, the 

 sensitive sole, the sensitive frog, and certain ligaments. Each 

 of these I shall now proceed to explain. 



The coffin-hone occupies the principal part of the cavity of the 

 foot. It is the base, or foundation, of the bony structure. It 

 is the shape of a half-moon, (semilunar). It is divided, for de- 

 scription, into the wall, sole, tendonous surface, articulating sur- 

 face, and wings. Throughout, it corresponds with the shape 

 of the foot quite well. The wall corresponds with the wall of 

 the foot, having the same degree of shape, and becoming shal- 

 lower back toward the quarters. Its surface is quite rough 

 for the attachment of the fibrous membrane to which the sensi- 

 tive lamellae are attached. It is also pierced by man}^ little 

 holes, for blood-vessels and nerves to pass through. The up- 

 per border of the wall rises into quite a prominence, called 

 the coronal process, which forms the upper and forward part 

 of the coffin-joint, and to which the extensor tendon is attached. 

 The sole of the coffin-bone is concave, or hollowed, and corre- 

 sponds with the convexity, or ovalness, of the upper surface of 

 the sole, from which it is separated by the sensitive sole. The 

 back and middle part of the sole is sloped out into a semicir- 

 cular (half-circle) excavation, more than half as broad as the 

 sole, called the tendonous surface, for the attachment of a very 

 broiid, strong tendon, called the flexor tendon, {flexor iiedis per- 

 forans), and whose office it is to turn the foot back, as a man 

 shuts his hand. 



The wings of the coffin-bone are backward projections term- 

 inating in the heels. They are much grooved, and perforated 

 with many holes for blood-vessels and nerves, making them 



