504 



THE ANATOMY OF THE HORSE 



body is suspended /;-o??i these plates, and not carried w;;oh the sole. The 

 laminfe are continuous at the toe with the sensible sole, which is a vascular 

 membrane covering the floor of the pedal-bone, and secreting the horny sole. 

 In the centre of the posterior part of this is the sensible frog, which is of 

 nearly the same shape as the horny frog, and is still more liberally supplied 

 with blood than the sensible sole. 



The arteries supplying these vascular sti-uctures with blood, and the 

 veins taking it back, are of great importance. Commencing with the large 



metacarpal artery, which is the continu- 

 ation of the radial below the knee, we 

 find it descending by the side of the 

 tendo-perforatus under the posterior- 

 annular ligament. Immediately above 

 the fetlock joint it splits into three 

 branches ; the middle one passing to 

 the deep parts of the leg, and the two 

 others, forming the plantar arteries, 

 descend on each side the posterior joint 

 to the postero-lateral parts of the co- 

 ronary substance. Here they divide 

 into two leading portions, the anterior 

 running round to meet its fellow of the 

 opposite side, and giving off with it a 

 complete fringe of vessels, which are 

 displayed in the accompanying repre- 

 sentation of an injected preparation of 

 the foot. The branches uniting in 

 front of the foot and encircling the 

 coronary ligament are called the supe- 

 rior coronary circle. The posterior 

 division of the plantar artery gives off, 

 opposite the pastern joint, the artery 

 of the frog, which descends obliquely 

 inwards through the subf-tance of the 

 sensible frog, and divides into two 

 branches within it, after which it sup- 

 plies the whole of that substance with 

 numerous vessels, and then goes on to the sole, to which it gives off a 

 number of radiating brandies. After giving off the artery of the frog, the 

 plantar artery ends posteriorly in the lateral laminal branch which passes 

 through the foramen in the ala of the os pedis, and supplies the laminiB. 

 Thus the whole of these structures are full of blood-vessels, for not only 

 ai'e the arteries above described ramifying thus extensively upon them, but 

 the blood is returned by corresponding veins. 



The pedal and navicular bones have been minutely described at page 

 383, but there are also two cartilaginous plates at the back of each ala of 

 the pedal-bone, which are of considerable importance. These are called the 

 lateral and inferior cartilages. The lateral cartUiKjcs extend backwards and 

 outwards from the posterior and upper borders of the coffin or pedal-bone. 

 They are united in front with the expanded terminations of the extensor 



Fig. 00.— View of the Arteries of the Frog 

 AXD Sole, injected. 



A. Lower rorou.s surface of pedal-bone. 



B. Lateral surface of pedal-bone. 



C. C. The plantar veins. 



D. D. The plantar arteries. 



E. Lateral cartilage contracted by drying. 



F. Veins of the frog, injected. 



