DISEASES OF THE FETLOCK, AX Kl.K. ANIJ FOOT. 397 



The lU'Xor pedis perforans, or deep llexur of the foot, passes down 

 behind tlie runnon bone, lyin«r against the siisi)enst)rv lij;anient in 

 front, ciost^es the fetlock joint in the pjroove made by the union of 

 the two sesamoids, and is attafhe<l to the bottom on the collin bone, 

 after eoveiin^ the navicuhir. by a ^vide expansion of its fibers. It is 

 the function of this tendon to Ilex the coffin bone and, with it, the 

 horny box. 



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

 the course of the i)recedinfr tendon and is attached to the middle of 

 the ankle. The 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 prominent jwint of the coffin bone, and has for function the 

 straiiihtenin<r of the liones of the ankle and foot. 



The bones, ligaments, and tendons are covered by a loose connective 

 tissue, which gives a symmetry to the parts by filling up and round- 

 ing off, and all are prot-ected by the skin and hoof. 



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

 thickness and the length of its hairs, e>specially around the hind parts 

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

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



The coronary band is that jiortion of the skin which secretes the 

 horn of which the wall of the hoof is made. This horn much resem- 

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

 posed of cylindrical tubes, which are held together by a tenacious, 

 opaque matter. The horn extends from the coronary band to the 

 lower border of the hoof. (Plate XXXII, fig. 1.) 



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

 contains, besides the coffin, navicular, and part of the small pastern 

 bones, the sensitive lamina^, plantar cushion, and the lateral cartileges. 

 (Plate XXXITI, fig. 4.) 



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

 like the circumference 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 membrane 

 a)vering the plantar cu.shion and other soft tissues bene^ith the coffin 

 bone. The horn of the sole ditTcrs from the hoi'u of the wall in that 

 its tubes are not straight and from the fact that it scales otT in pieces 

 over the whole surface. 



Tlie frog is a triangular-shaj^cMl body, dividetl into two equal parts 

 by a deep fissure, exti'nding from its apex in front to the i>ase. It 

 fills the triangular space in the sole, to which it is intimately attached 

 by its borders. The horn of the frog is produce<l in the same maimer 

 ;\s tlu' sole: but it difTtMs fj-<,iii both the wall and sole in tliat the horn 



