32 DISEASES OF THE HORSE’S FOOT 
behind which it blends with the plantar cushion. The 
posterior border is oblique from before to behind, and above 
to below, and joins the preceding two. The anterior border 
is oblique in the same direction, and is intimately attached 
to the antero-lateral ligament of the pedal articulation. 
The cartilages of the fore-feet are thicker and more 
extensive than those of the hind. 
2. Tue Puanrar Cusnion or Frero-ratry Froeg.—Com- 
posed of a fibrous meshwork, in the interstices of which are 
lodged fine elastic and connective fibres and fat cells, this 
wedge-shaped body occupies the space between the two 
lateral cartilages, the extremity of the perforans tendon, 
and the horny frog. It offers for consideration an antero- 
superior and an infero-posterior face, a base, an apex, and 
two borders. 
The antero-superior face is in contact with the terminal 
expansion of the perforans tendon. The infero-posterior 
face is covered by the keratogenous membrane, and follows 
closely the shape of the horny frog, on whose inner surface 
itis moulded. It presents, therefore, at its centre a single 
conical prolongation, the Pyramidal Body, which is con- 
tinued behind, as is the horny frog, in the shape of two 
lateral ridges divided by a median cleft. The base of the 
cushion lies behind, and consists of two lateral masses, 
the Bulbs of the Plantar Cushion. In front these are 
continuous with the ridges of the pyramidal body, while 
behind they become confounded with the lateral cartilages 
and the coronary cushion. The apex is fixed into the 
plantar surface of the os pedis, in front of its semilunar 
ridge. The borders, right and left, are wider behind than 
before, and are in relation with the inner faces of the 
lateral cartilages. 
H. THE KERATOGENOUS MEMBRANE. 
Tue Keratocenous, orn Horn-propucinc MeEmprang, is 
in reality an extension of the dermis of the digit It 
covers the extremity of the digit as a sock covers the foot, 
