ANATOMY AND PHYSIOLOGY OF THE FOOT 



437 



Fig. 628. — Lateral Cartilages, kc, of the Foot 



A, Os pedis. B, Lateral cartilage, c. Peripole. D, Peri- 

 polic band. E, Coronary cushion. F, Sensitive laniinse, or 

 fleshy leaves. G, Section of skin. H, Fleshy frog. I, Horny 

 frog. J, Horny sole. 



basis of the front and sides of the hoof, but towards the heels is replaced 

 on each side by plates of gristle or cartilage (fig. 628). This elastic material 

 can be felt at the inner and outer sides of the coronet through the skin of 

 the living horse. When diseased 

 and converted into bone it 

 forms the so-called side -bones, 

 which sometimes cause lame- 

 ness, and always destroy the 

 natural elasticity of the foot. 

 These cartilages, replacing bone 

 at the back parts of the foot, 

 give resiliency to the hoof, and 

 so prevent concussion. 



The Frog. — If we examine 

 the under surface of the foot, 

 we .find another provision 

 against jar, for whilst the sole 

 rests upon a bony basis, the 

 frog does not (fig. 629). The 

 body of the coffin-bone only extends backwards to about an inch pa.st 

 the point of the frog. It there divides into two processes which extend 

 nearly to the heels, but leaving between them 

 a large space which is filled by a pad of elastic 

 material, over which the frog rests. This 

 arrangement permits the frog great freedom 

 of movement, and gives to the back portion 

 of the hoof the special feature of elasticity so 

 necessary to its function of breaking concus- 

 sion when the foot comes to the gi'ound 

 during progression. The front part of the 

 foot, by the thickness and hardness of the 

 wall, and by the rigid basis of bone within, 

 is specially fitted to sustain the strain which 

 is placed upon it when the toe takes the 

 weight of the horse, as it does in all forward 

 movements. The back part of the foot, by 

 its thinner and more elastic horn, by its 



pi'ominent and soft frog, and by the partial substitution of cartilage for 

 bone as its inner basis, is specially endowed for receiving its first impact 

 with the ground during progression. That the foot may preserve its func- 

 tions intact the hoof must be maintained in its best form. No parts must 



Fig. 629.— Under Surface of the Coffin- 

 Bone, showing its Position within the 

 Hoof 



A, Os pedis. B, Sensitive and insensitive 

 laminae, c, Wall of hoof. D, Horny frog. 



