176 



THE STRUCTURE OF THE HORSE 



somewhat constricted, but broadens out again into a 

 sort of spoon-shaped end. The upper or dorsal surface 

 is convex, the under or palmar surface flat. The ends 

 of two tendons, which are worked by muscles situated a 

 long way up in the limb, are fixed, one on the upper and 

 the other on the under surface of the bone, and by their 

 alternating contractions and relaxations cause it, with 

 the structures around, to move in either direction on its 

 hinge-like articulation. Between the bone and the skin 

 are various soft structures, the terminations of arteries, 

 veins, lymphatics, and nerves, embedded in a web of cellu- 

 lar or areolar fibrous tissue, with a considerable amount 

 of fat, of which there is a special accumulation, forming 

 a rounded pad, on the under surface of the end of the 

 finger, called the bulb. In the skin over this part the 

 sense of touch is especially developed. 



The external surface is completely covered with a 

 general continuation of the skin of the rest of the limb, 

 the structure of which has been briefly described at 

 p. 165. A part of this covering has, however, under- 

 gone a special modification to form the nail, which is a 

 hard protecting shield for the most exposed part of the 

 finger, and the freely-projecting edge of which serves 

 many useful purposes. The nail is nothing more than 

 a flattened plate of dry, hard, and. horn-like epidermis, 

 growing from a semilunar groove in the derm and from 

 a depressed surface in front of this. This surface is 



