42 THE ABMY HORSE IN ACCIDENT AND DISEASE. 



surface is covered with cartilage, which forms a smooth surface for 

 the movements of the tendon of the flexor pedis perforans muscle. 



Elastic structures of the foot. 



All of the parts of the foot, except the bones, are more or less elastic 

 or "springy" and yield when pressure is applied; but certain parts 

 have a very high degree of elasticity, their special use being to over- 

 come the effects of concussion or jar when the foot strikes the ground 

 and to prevent injury, and these parts are referred to as the elastic 

 structures of the foot. They are the lateral cartilages and plantar 

 cushion, or fatty frog, as it is sometimes called. 



The lateral cartilages are thin plates of cartilage, one attached to 

 the top of each wing of the os pedis, and extending backward and 

 upward so far that their upper borders may be felt under the skin 

 above the coronet at the heels. 



The plantar cushion is a very elastic wedge-shaped pad, which fills 

 up the space between the two lateral cartilages on the sides, the sen- 

 sitive frog below, and the flexor pedis perforans tendon above. 



The point or anterior part of the plantar cushion, extends foi-ward 

 to the ridge which separates the sole from the tendinous surface of 

 the OS pedis. The base is covered by the skin above the heels. 



Sensitive structures of the foot. 



Over the bones and elastic structures of the foot is found a com- 

 plete coverifig of very sensitive flesh, and from each part of this cover- 

 ing some part of the hoof is secreted or formed. The divisions of this 

 layer of flesh are called the sensitive parts or structures of the foot. 

 They are the coronary hand, sensitive laminse, sensitive sole, sensitive 

 frog, and the coronary frog hand. 



The coronary hand is a thick convex band of tough flesh, about four- 

 fifths of an inch wide, and extends entir.ely around the top of the hoof 

 from one bulb of the heel to the other; in front it is attached to the 

 extensor pedis tendon, and on the sides to ligaments of the coffin joint, 

 to the lower end of the os coronse, and to the lateral cartilages. The 

 surface of the coronary band is covered with small pointed projections 

 or villi. The coronary band secretes or forms the principal part 

 (middle layer) of the wall of the hoof. 



The sensitive laminx (fleshy leaves) cover and are fixmly attached 

 to the anterior or wall surface of the os pedis and to the lower part of 

 the outer surface of the lateral cartilages. These delicate leaves of 

 the flesh dovetail into the homy laminse which they secrete and, with 

 them, serve to fasten the wall of the hoof to the os pedis and to the 

 lateral cartilages. 



The sensitive sole covers the sole surface of the os pedis, is covered 

 with villi, and secretes the homy sole. 



