371 



Three tendons serve to move the bones of the foot one on another. 

 Two of these flex or bend the joints, while the other extends or 

 straightens the column of bones. (Plate XXX, Fig. 5.) 



The flexor pedis perforans^ or deep flexor of the foot, x)asses down 

 behind the cannon bone, lying against the suspensory ligament in 

 front, crosses the fetlock joint in the groove made by the union of 

 the two sesamoids, and is attached to the bottom of the coffin bone, 

 after covering the navicular, by a wide expansion of its fibers. It is 

 the function of this tendon to flex the coffin bone and with it the 

 horny box. 



The flexor pedis perforatus, or superficial flexor of the foot, follows 

 the course of the preceding tendon and is attached to the middle of 

 the ankle. Tlio function of this tendon is to flex the foot at the fetlock. 



The extensor pedis runs down in front of the leg, is attached on 

 the most i)rominent i)oint of the coffin bone, and has for function the 

 straightening of the bones of the ankle and foot. 



The bones, ligaments, and tendons are covered by a loose connect- 

 ive tissue, which gives a symmetry to the i^arts by filling up and 

 rounding off, and all are protected by the skin and hoof. 



The shin of the fetlock and ankle is generally characterized by its 

 thickness and the length of its hairs, especially around the hind j)arts 

 of the fetlock joint in certain breeds of horses. The most important 

 part of this envelope is that known as the coronary band. 



The coronarij hand is th^t i^ortion of the skin which secretes the 

 horn by which the wall 9£ the hoof is made. This horn much resem- 

 bles tlie nail wliich grows on the fingers and toes of man. It is com- 

 posed of hollow, cylindrical tubes, extending from the coronary band 

 to the lower border of the hoof, which are held together by a tenacious 

 opaque matter. (Plate XXIX, Fig. 1.) 



The hoof is a box of horn, consisting of a wall, sole, and frog, and 

 contains, besides the coffin, navicular and jinvt of the small ]3astern 

 bones, the sensitive lamina?, plantar cushion and the lateral cartilages. 

 (Plate XXX, Fig. 4.) 



The sole of the foot incloses the box on the ground surface, is shaped 

 like the cii-cumference of the foot, except that a V-shaped opening is 

 left behind for the reception of the frog, and is concave on the lower 

 surface. The sole is produced by the velvety tissue, a thin mem- 

 brane covering the plantar cushion and other soft tissues beneath 

 the coffin bone. The horn of the sole differs from the horn of the wall, 

 in that its tubes are not straight, and from the fact that it scales off 

 in j)ieces over the whole surface. 



The frog is a triangular shajjed body, divided into two equal parts 

 by a deep fissure, extending from its apex in front to the base. It 

 fills the triangular space in the sole to Avhich it is intimately attached 

 by its borders. The horn of the frog is i^roduced in the same manner 

 as the sole, but it differs from both the wall and sole, in that the liorn 



