The extensor brevis is represented by a few fibers which come from the cannon bone, and unite with the tendon of the communis. The united tendon passes, as the corresponding one of the fore leg (Fig. 6, 5) to its insertion in the coffin bone. The arteries of the foot are branches of the radial, in the fore, and of the tibial in the hind legs. The former descends along the radius, accompanied by the radial nerve, to a point a little above the knee, where it divides into the large and small metacarpal arteries. Of these the large metacarpal is the principal trunk, pass ing under the posterior annular ligament. While passing down the cannon bone it divides into three branches. The middle one is distributed to surrounding tissues, while the other two become the plantar arteries, internal and external. The plantar arteries of the fore leg result from a division of the metacarpal, and in the hind leg from a similar division of the metatarsal, and the terminal distribution is alike in both. They descend to the lower part of the cannon bone (Fig. 8) pass the fetlock joint by the side of the sesamoid bones, in company with veins and nerves of the same names, and pass into the substance of what is sometimes called the fatty frog. They then pass the extremities of the coffin bone and enter the foramina on the posterior concavity of the bone. (Fig. 4, a, e, a, a). The branches of the plantar arteries are very numerous, and no part of the body is more fully supplied with blood than the foot (Fig. 5). The veins of the foot constitute a very intricate net-work of vessels. The veins of the frog, the sole, the laminae, the superficial and deep-seated coronary veins, unite to form coronary and plantar plexuses (Fig. 8),
from which are formed plantar veins, which, by their union, constitute metacarpal and metatarsal veins, which lie anterior to, and by the side of, the plantar arteries. Dissection of the horse's foot is shown at Fig. 8: 1, general integument, turned back; 2, fatty mass, forming a cushion behind the great pastern joint; 3, walf of hoof turned back, showing the vertically laminated processes pro jecting from its inner surface ; 4, section of wall of hoof; 5, the articulation between the cannon and pastern bones; 6, 6, 6, aponeurotic tissues; 7, 7, extensor tendon of the foot 1.8, 9, 10, flexor ten dons of the foot; 11, 12, 13, 14, 15, expansion of the great cartilage of the foot; 16, the coronary band raised from the hoof; 17, the vascular or sensitive hoof; 18, elastic cushion of the heels; 19, 20, 21, plantar artery; 22, 23, plantar veins; 25, part of coronary venous plexus raised from its position; 26, 27, 28, plantar nerves. The nerves of the foot are known by names corresponding to those of the blood-vessels which they accom pany. The plantar nerves (Fig. 8) lie by the side of and behind the corresponding artery, and, as they descend into the foot, are distributed to the same organs and regions. The final branches enter the foramina in the coffin bone, minutely subdivide in it, pass through its many canals, and escape at the edges of the sole to the sensitive parts of the foot, in company with the terminal twigs of the arteries as shown in figure five.