THE FOOT 



21 



The sole is composed of horny material resembling that of the 

 wall. It is concave below, convex above. Its outer border 

 unites with the wall at the "white line." Its upper surface is 

 covered by the vascular velvety tissue. 



The frog is a V-shaped elastic pad with a depression, called 

 by horsemen "the cleft," in its ground surface. It is located 

 between the bars on each side, and below the plantar cushion. 

 Its function is to act as a pad and to lessen jar when traveling. 



Matrix.— The matrix (horn-generating membrane) fits inside 

 of the horny part of the hoof and covers like a stocking the 

 other parts within the hoof. It is 

 from this that all the horny parts 

 grow. It is composed of three 

 parts: (1) coronary band; (2) 

 sensitive lamina; (3) velvety tis- 

 sue. 



The coronary hand is the elastic 

 ring that may be felt at the crown 

 of the hoof. It is studded with 

 little papilla'. From these grow 

 downward the tubular fibers which 

 make up the hard layer of the wall. 



The sensitive lamina; are 500 to 

 600 layers of vascular tissue into 

 which fit and from which grow 

 the horny lamina? of the w'all. An 

 inflammation here is called lamin- 

 itis or founder. 



The velvctij tissue covers the upper surface of the hard sole. 

 Like the coronary band and sensitive lamina?, it is sensitive and 

 richly supplied witli blood. The under surface is thickly 

 studded with papilke, similar to those of the coronary band, and 

 from these in a similar way grow the shorter tubular fibers 

 which make up the hard sole and frog. Tiic student can easily 

 understand why injury to the coronary band, e.g. a wire cut 

 which results in a healing by scar tissue, leaves a split which 

 lengthens downward in the hoof ; why founder is so ])ainful ; and 

 why deep injuries to the sole are so apt to be serious. 



Plantar cushion. — This is a wedge-shaped mass of elastic tis- 

 sue located between the lateral cartilages on each side, below 

 the sole of the third phalanx and above the horny sole of the 



Fig. 15. — The Hoop Matrix. 



1, Periople ring; 2, coronary- 

 baud; 3, sensitive lamina; 4, 

 heel. Velvety tissue ou the 

 sole not shown. 



