HORSESHOEING. 41 



E. The Blood-Vessels and Nerves. 



Vessels which carry blood from the heart to the tissues are 

 called arteries, while those which return the blood to the heart 

 from the tissues are called veins. Arteries and veins are con- 

 nected by very small, thread-like vessels called capillaries, which 

 originate in the smallest arteries and are so minute that they 

 can not be seen without the aid of a microscope. The capillaries 

 penetrate the soft tissues in every direction, and finally unite to 

 form small veins. For our purpose we need consider only the 

 arteries and veins. 



The arteries carrying blood from the heart ramify and sub- 

 divide in all parts of the body, and thus reach the foot. Tliey 

 are thick-walled, very elastic tubes, without valves, and carry 

 bright-red blood, which flows in spurts, as can be seen when an 

 artery is cut. If a finger be pressed lightly over an artery lying 

 near the surface, the blood-w^ave can be felt as a light stroke 

 (pulse). The character of the pulse is important, because in 

 inflammations of the pododerm or horn-producing membrane 

 of the foot we can ascertain by feeling that the pulse is stronger 

 than usual in the large arteries cai*rying blood to the inflamed 

 foot. 



On either side of the phalanges below the fetlock-joint there 

 lies an artery called the digital artery (Fig. 25, a). The pulse 

 can be felt in it as it passes over the fetlock at A, Fig. 25. It 

 gives off the following collateral (side) branches: 1. The artery 

 of the first phalanx (pei*pendicular artery), with anterior and 

 posterior branches. 2. The artery of the plantar cushion, which 

 supplies with blood the plantar cushion, the velvety tissue of 

 the sole and frog, the bar portion of the coronary band, and the 

 sensitive laminje of the bars. 3. The coronary artery, which 

 carries blood to the coronary band, os coronse, ligaments of the 

 coronary and pedal joints, flexor tendons, and skin. 



The terminal branches of the digital arteries are the preplan- 

 tar and plantar ungual artenes. The preplantar artery passes 



