426 ANATOMY AND PHYSIOLOGY OF THE HOUSES FOOT. 
a dark-tinted pigment, when the adjoining skin is of a black 
colour. 
We will have occasion, hereafter, to describe this cushion 
more carefully; I have only included it here because the 
share it takes among the elastic appurtenances of this organ 
lias been very much overlooked, if not entirely neglected. 
The Plantar Cushion (fig. 3, q ) . — The third elastic body we 
have now to glance at, and which has been named, from its 
position and principal function, the “ plantar cushion,” has 
been at various times designated the internal,” “ fleshy,” and 
“ fatty frog,” also the “ pyramidal body.” 
It occupies nearly the whole of the large space included 
between the wings of the pedal bone and its lateral cartilages 
at the posterior part of the foot. In form it is somewhat 
polyhedral, though it really appears to be triangular or wedge- 
shaped, the base or widest part lying towards the heels, and 
the apex or thin end extending well towards the anterior 
margin of the plantar surface of the bone ; thus covering in, 
and moulding itself, as it were, to the highly important articu- 
lations, tendons, and delicate membranes in this region of the 
limb, while in turn it is protected inferiorly on the ground 
surface by the horny frog, and posteriorly by the skin. 
As will be seen in fig. 3, it rises as high as the middle of 
the posterior face of the small pastern bone, adapting itself to 
the angle formed by the flexor tendon in its passage over the 
navicular bone, and is interposed between the tendon and 
the horny frog to beyond the insertion of the former in the 
sole of the os pedis. So that it will be immediately perceived 
that one of its chief offices is to guard and support the 
tendon, especially at its "weakest point — the bend over the 
navicular bone. This upper or anterior face is covered by a 
strong fibrous membrane — the “ proper tunic” — which in- 
timately adheres to it b} 7 means of fibres passing into its sub- 
stance, at the same time that its superior surface contracts a 
slight adhesion to the accessory fibrous sheath of the tendon. 
The thick portion of the cushion is divided into two pro- 
minences, or “ bulbs,” by a longitudinal furrow, and here this 
enveloping fibrous membrane attaches itself more closely to 
the sheath through which the tendon plays, and accompanies 
it as high as the back of the fetlock. On each side of the 
cushion this tunic is bordered by a kind of thick pearly-white 
ligamentous band or hem, that divides into two portions at 
its upper extremity, the widest and thinnest of which runs 
upwards and backwards to the fetlock joint, where it meets its 
fellow of the opposite side, and both conjoin to maintain the 
small pellicle of yellow fibrous tissue on which rests the horny 
