HORSESHOEING. 37 



than usual in the large arteries carrying blood to the inflamed 

 foot. 



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

 lies an artery called the digital artery (Fig. 21, a). The pulse 

 can be felt in it as it passes over the fetlock at A, Fig. 21. It 

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

 of the first phalanx (perpendicular artery), with anterior and pos- 

 terior branches. 2. The artery of the plantar cushion, which sup- 

 plies with blood the plantar cushion, the velvety tissue of the 

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

 sitive laminae 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 arteries. The preplantar artery passes 

 through the notch in the wing of the os pedis, then along the 

 preplantar fissure, splitting up into many branches, which spread 

 over and penetrate the porous surface of the os pedis. The 

 plantar artery courses along the plantar fissure, enters the 

 plantar foramen, and passes into the semilunar sinus of the os 

 pedis, where it unites with the terminal branch of the opposite 

 digital artery, forming the semi-lunar arch. 



After the arterial or pure blood passes through the capillaries 

 it is collected by the veins, to be returned to the heart ; then it 

 is driven to the lungs for purification, and is again returned to the 

 heart, from whence it is pumped through the arteries to all parts 

 of the body. 



The veins are more numerous than the arteries ; they have 

 thinner walls, and the larger ones are provided with valves 

 that prevent the impure blood from flowing backward. The 

 veins carry impure or dark-red blood towards the heart, and 

 if one is opened the dark blood flows in a steady stream ; it 

 does not spurt. The great number of veinlets in the lower parts 

 of the foot form a complex net-work (plexus) of vessels which 

 are in such manifold and close union with one another that 



