ANATOMY AND PHYSIOLOGY OP THE HORSE’S FOOT. 355 
tendon above the upper end of the coronary bone, and blend- 
ing itself closely on its inner or anterior face, it passes down 
covering this face, and, gradually, the borders of the tendon, 
by its fibres radiating slightly outwards, in a contrary direc- 
tion to those on this side of the latter. On arriving at the 
navicular bone, as has been said, this elastic ligament leaves 
the tendon and inserts itself into the upper border of that 
piece to form what has been termed the “ bourrelet.” Thus it 
will be seen that through the medium of this band the 
navicular bone is directly connected with the second phalanx 
and the deep flexor tendon, none of the fibres of which, how- 
ever, go to fix themselves in the bone or to form this 
“ bourrelet,” but pass uninterruptedly downwards, so that 
at the upper border of the navicular pulley all connection 
between the ligament and tendon ceases. This ligament 
must be looked upon as playing the part of a suspensory or 
sustaining ligament, in so far as the tendon and navicular bone 
are concerned. At this point the tendon begins to commence 
its passage over the lower face of the navicular bone, and the 
relations it here establishes, as well as the shape and altera- 
tion in texture it assumes, have a particular and important 
bearing in the physiology and pathology of this region. 
Gradually becoming flattened and widened as it approaches 
the upper margin of the navicular bone, it somewhat sud- 
denly expands laterally, so as to occupy nearly the entire 
posterior face of that bone, presenting more the appearance 
of a wide membrane or band than a tendon. It continues to 
expand until it reaches the semilunar ridge, into which, and 
on both sides of which, it is fixed, its middle fibres attaching 
themselves to the ridge, the inner and shorter ones within it, 
and the outer and longer beyond it. Here, as has been said, 
the tendon becomes so expanded that it occupies not only 
the whole ridge, but implants its outermost fibres on both 
sides into the inner face of each retrossal process, where 
they are confounded, to some extent, with those of the plantar 
cushion. 
Above the navicular bone, and from the moment when it 
begins to widen, the perforans tendon offers a peculiar 
arrangement of its fibres, whereby one set would seem to be- 
come antagonistic, as it were, to another. Thus, above 
the navicular bone the tendon appears, and really is, 
divided before and behind by a superficial longitudinal groove 
into two halves (fig. 9, a) ; the posterior fibres incline down- 
wards and outwards from the groove, while those on the inner 
or front aspect look as if passing in a contrary direction, 
passing upwards and outwards (fig. 9, a) from the centre. 
