402 THE COMPLETE GRAZIER. BOOK in. 



THE HOOF. The coffin bone, the navicular, and the lower end of 

 the coronet form " the articulation of the foot." Four ligaments bind 

 this articulation together. In addition, the extensor tendon passes 

 down in front, and the flexor tendon behind. Outside these structures 

 are the two fibro-cartilages, one on each side, united behind and below 

 by the plantar cushion. Outside, again, and fitting on the foregoing 

 like a sock on a foot, is the keratogenous (i.e., horn-forming) mem- 

 brane, which secretes externally the epidermal material known as horn, 

 of which the hoof is composed. The entire region is richly supplied 

 with blood-vessels and nerves. The hoof is seen to become continuous 

 with the ordinary skin at a circular line extending round the middle of 

 the coronet ; below, both in front and at the sides, is a semicircular 

 protuberance, the coronary cushion. That part of the keratogenous 

 membrane spread over the anterior face of the coffin bone is called the 

 laminal or leafy tissue, because of the laminae or parallel leaves seen 

 on its surface ; inflammation of this structure is called laminitis. 



The hoof fits closely on the keratogenous membrane, of which, 

 indeed, it is the product. Its general shape is that of a cylinder cut 

 across obliquely. Prolonged maceration causes it to separate into 

 three parts : the wall, the sole, and the frog. 



The wall, or crust, is that part which remains visible when the hoof 

 rests upon the ground. The middle anterior part is the toe (outside 

 and inside) ; the lateral regions are the quarters ; the angles of inflec- 

 tion at its hinder extremities are the heels ; from thence, passing along 

 the inner border of the sole are the bars, which form outwardly the 

 external faces of the frog. The sole has a large external curved border, 

 and a much shorter internal border taking the form of a deep V-shaped 

 notch, widest behind. This latter corresponds with the bars, at the 

 meeting of which the point of the frog is fixed. The frog is a pyramidal 

 mass of horn lodged between the two re-entering portions of the wall. 

 A median lacuna divides the inferior face of the frog into two divergent 

 branches, the round, flexible, elastic, free ends of which are the glomes. 

 The inclination of the wall of the hoof is from 50 to 56, not 45 as is 

 often supposed. The flexibility of the hoof is promoted by a fluid 

 thrown out by the keratogenous membrane. At the junction of the 

 wall and sole is the white line ; it is soft and flexible and so prevents 

 the breaking of the sole from the wall. The growth of the wall may 

 continue indefinitely, but the sole and frog after attaining a certain 

 thickening begin to peel off, unless otherwise kept down. The wall 

 grows from its superior to its inferior border, like the human nail. 

 The sole and frog grow from their internal to their external face. 



THE SKULL. The head of the horse is nearly vertical, and the bones 

 composing it are distinct and separate only when very ) r oung. Those 

 that enter into the boundaries of the brain-case are called the cranial 

 bones, the external ones of which are the occipitals, parietals, frontals, 

 and temporals. The frontal bones, in the space between the eyes, are 

 pierced by the pole-axe when a horse is slaughtered. By far the larger 

 part of the horse's skull is that occupied by the facial bones. Of these, 

 the most prominent as seen from the outside, are the malar or jugal, 



