20 



ANATOMY AND PHYSIOLOGY OF 



their fibres, the vessels destined to conduct 

 the nutritious fluid are contracted and 

 obliterated ; whence proceeds that dryness 

 of the part which renders the horn brittle 

 and liable to split.' * 



" Division. — To the common observer 

 the hoof appears to consist of one entire 

 or indivisible case ; but the anatomist finds, 

 by subjecting it to maceration, or coction, 

 or even to putrefaction, that it resolves 

 itself into three separate pieces : still, so 

 long as the hoof maintains its integrity, 

 such is the force of cohesion existing be- 

 tween these three parts, that we as easily 

 rend it in any other place as dissever one 

 of its jointures. These constituent parts 

 are the wall^ the sole, and i\\efrog. 



THE WALL. 



" The wall or crust is the part of the 

 hoof which is visible while the foot stands 

 upon the ground. It forms a circular 

 boundary wall or fence inclosing the inter- 

 nal structures. On taking up the foot, we 

 find the wall prominent all round beyond 

 the other parts, making the first impression 

 upon the ground, and evidently taking the 

 largest share of bearing. It is the part to 

 which the shoe is nailed. It is, in fact, the 

 most important division of the hoof; ap- 

 pearing to form (in the words of IVIr. Clark) 

 'the basis or first principle in the mechan- 

 ism of the hoof, the other parts being all 

 subordinate to this.' 



" Situations and Relations. — The wall 

 takes its beginning at the coronet, from the 

 terminating circular border of the skin, 

 with which it is intimately united ; their 

 line of union being concealed by a row of 

 overhanging hairs. From the coronet the 

 wall descends in an oblique direction to 

 the bottom of the foot, where it em- 

 braces the sole, and terminates in a cir- 

 cular projecting border. The anterior and 

 lateral parts of the hoof are formed entirely 

 by the wall ; but at the posterior part, in- 

 stead of the heels of the wall being con- 

 tinued one into the other so as to complete 

 the circle, they become inflected, first down- 



* Sainbel's Lectures on the Elements of Farriery. 



ward, afterwards forward and inward, and 

 are elongated in the latter direction until 

 they reach the centre of the bottom of the 

 foot, where they terminate : these inflec- 

 tions or processes of the wall constitute the 

 bars. Altogether, the wall may be said to 

 form about two-thirds of the entire hoof. 



" Connection. — Superiorly, around the 

 coronet, the wall is united with the skin ; 

 inferiorly, within its circumferent border, 

 with the sole ; posteriorly, between its heels, 

 with the heels of the frog; inferiorly, be- 

 tween the bars, with the sides of the frog ; 

 and internally, with the sensitive laminae. 

 Let us now consider the wall in its detached 

 or separate state. 



" Figure. — That of a hollow cylinder, 

 having the sides presented to the ground cut 

 much aslant, and whose circle exhibits a 

 hiatus or deficiency behind, from the lateral 

 boundaries of which issue tvvo narrow pro- 

 cesses or appendages. Taking a lateral 

 view, the wall assumes a conical shape, 

 being broad and deep in fi'ont, and gradually 

 narrowing as it stretches backward. 



^^ Division. — For facility of reference, and 

 in aid of our descriptions, we distinguish 

 in the wall. First, the toe; secondly, the 

 quarters; thirdly, the heels; fourthly, the 

 superior or coronary border ; fifthly, the in- 

 ferior or solar border ; sixthly, the lamince 

 or lamellae; lastly, the bars or appendages. 



" The Toe forms the bow or front of the 

 hoof, and comprehends about two-thirds of 

 the superfices of the wall. It is the deep- 

 est, broadest, and thickest part of the wall ; 

 for reasons that will appear hereafter. It 

 exhibits a degree of slant about equal, nat- 

 vnally, to an angle of forty-five degrees; 

 though there are variations from this which 

 (as was explained before) will be found, in 

 a measure, to be dependent upon the oblique 

 truncation of the cylinder. When we come 

 to understand the physiology of this part, 

 however, a more operative and efficient 

 cause for this variation will be found in the 

 weight the wall has to sustain, and in its 

 own mechanical strength or force of resist- 

 ance : on which principle it is that light 

 horses, thorough-breds, and ponies, as well 



