THE 1 OT. 



295 



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 structures with 

 blood, and the veins taking it 

 back, are of great importance, 

 and doubly so because it is in 

 these vessels that an operation is 

 often performed in inflammation 

 of the foot, calculated to afford 

 relief by a local abstraction of 

 blood. Commencing with the 

 large metacarpal artery, which 

 is the continuation of the radial 

 below the knee, we find it de- 

 scending by the side of the 

 tendo-perforatus under the pos- 

 terior-annular ligament. Imme- 

 diately 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 arte- 

 ries, descend on each side the 

 postero- lateral parts of the cor- 

 onary 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 

 coraplete fringe of vessels, which 

 are displayed in the accompanying representation of an injected 

 preparation of the foot. The branches uniting in front of the foot 

 and encircling the coronary ligament are called the superior cor- 

 onary 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 substance of the sensible frog, and 

 divides into two branches within it, after which it supplies the whole 

 of that substance with numerous vessels, and then goes on to the sole, 

 to which it gives off a number of radiating branches. 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 laminae Thus the whole of 



Fig. 17. — viem" of the arteries op the frou 

 and sole, injected. 



A. Lower porous surface of pedal bone. 



B. Lateral surface nf pedal bone. 



C. C. The plaiitai' v<-ins. 



D. D. The plantar arteries. 



E. Lateral cartilage contracted by drying. 



F. Veins of the frog, injected. 



