150 ANATOMY AND PHVSIOLOGY OF THE HORSE'* S FOOT. 
region of the hoof a different appearance to that which it 
presents at the toe or quarters. About midway between the 
coronet and the lower margin of the hoof, in the situation 
corresponding to the upper border of the wings of the os 
pedis, the wall in these cases changes its oblique direction 
outw r ards — the line it commenced with — and inclines directly 
downwards or even inwards towards the centre of the foot ; 
and it is particularly worthy of remark that this change of 
direction takes place at a level corresponding to the dimin- 
ished surface of the external face of the pedal bone, on the same 
plane as its wings or retrossal processes. However this may 
he, it is certain that the inner quarter and heel is more ver- 
tical than the outer. 
The angle of the inflection, or point of the heel, is dowm- 
wards and forwards, in a direction parallel to that of the toe, 
■while the bars incline downwards and outwards. 
The form of the hoof in the same animal, at different periods 
of life, varies to a notable extent — as before birth, soon after 
that event, at two or three years old, as well as after being 
subjected to improper shoeing for some time. It also varies 
according to the amount of wear or paring it undergoes. But 
more of this hereafter. 
Neither is the thickness of the wall the same in every part 
of its circumference. On the contrary, its width and thick- 
ness appear to be directly related to the depth and extent of 
the coronary cushion, no matter at w 7 hat point we may exa- 
mine it. For this reason it is that we find the wall thickest 
and highest at the toe and mammillae, gradually thinning 
towards the quarters, between w 7 hich and the point of the 
heel it offers the thinnest part. At the inflexure, however, 
it becomes again massive, but immediately diminishes in 
forming the bars. 
The wall, in every region, is of the same thickness from top 
to bottom, except, of course, at the cutigeral cavity ; below 
this, until it reaches the sole, it is the same. But its thick- 
ness varies even in corresponding parts of both sides, the 
inner side being, on the whole, thinner than the outer. The 
relations of different parts with regard to thickness have been 
pretty correctly estimated in the following ratio : — (1) the 
toe and mammillae ; ( 2 ) the anterior portion of the outer 
quarter ; (8) the anterior portion of the inner quarter ; (4) 
the angles of inflexion ; (5) the posterior part of the outer 
quarter ; (6) the posterior part of the inner quarter ; (7) the 
outer bar ; (8) the inner bar. 
The density of the wall likewise varies, not only in differ- 
ent parts of its contour, but also at different points of its 
