THE FOOT 



501 



to examine, commencing from without, are — 1st. The lioniy case or hoof; 

 2nd. The parts which secrete it ; 3rcl. The arteries Avhich supply it with 

 blood ; and 4th. The pedal-bone and cartilages, as well as the navicular bone, 

 which it encases. 



The nooF consists of three distinct parts, which, though in the recent 

 state they are inseparably united, may be readily separated after maceration 

 for a few days in strong soda-water. These are the external wall or crust, 

 the sole or slightly concave surface forming the bottom or floor of the case, 

 and the triangular central portion of this called the frog. The crust reaches 

 from the edge of the hairy skin to the ground, and averages about thi'ee 



Fig. 85.— Section of the papi 



A. Os suffragiuis. 



B. Os coronaj. 



C. Os pedis. 



D. Os naviculare. 

 I. The perforaus and pi 



i-foratus tendons. 



G. Inferior sesauioideal ligament. 



L'left. 



Cleft of frof; 



Side of frog 



Sole. 



Crust. 



Coronary substance. 



inches and a half in depth. The front is the toe, the back the heel, and 

 the intermediate part the quarter on each side. It is described as a section 

 of a truncated cone. When examined from the side, the anterior surface 

 should form an angle of about forty-five degrees with the line of the sole, 

 and the upper edge or coronary band should join the sole, so as to leave a 

 moderate substance at the heel ; for if too great the foot does not exi^and, 

 and is liable to disease from that cause ; or if too thin and narrow, the foot 

 is weak and gives way downwards, ending in a convexity of the sole instead 

 of the reverse. The front of the crust is i-ather more than half an inch in 

 thickness, and in a strong foot of average size gradually diminishing to the 

 quarters, at the back of which it is generally barely a quarter of an inch 

 thick, especially at the inner of the two. This proportion is however 

 confined to the fore-foot, for in the hind there is little difiercnce between 

 the toe and quarters in point of thickness. The superior border, or coronary 



