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 anterolateral ligament of the pedal articulation. 

 The cartilages of the fore-feet are thicker and more exten- 

 sive than those of the hind. 



2. The Plantar Cushion or Fibro-fatty Frog. — 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 

 it is 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. 



The Keratogenous, or Horn-producing Membrane, is 

 in reality an extension of the dermis of the digit. It 

 covers the extremity of the digit as a sock covers the foot, 



