REGIONAL ANATOMY 33 



spreading over the insertion of the extensor pedis, the 

 lower half of the external face of the lateral cartilages, 

 the bulbs of the plantar cushion, the pyramidal body, the 

 anterior portion of the plantar surface of the os pedis, and 

 over the anterior face of the same bone. In turn, as the 

 human foot with its sock is covered by the boot, this is 

 encased by the hoof, the formation of which we shall study 

 later. 



To expose the membrane for study the hoof must be 

 removed. This may be done in two ways. By roasting in 

 a fire, and afterwards dragging off the horny structures 

 with a pair of pincers, a knife having first been passed 

 round the superior edge of the horny box. Or by macera- 

 tion in water for several days, when the hoof will become 

 loosened by the process of decomposition, and may be easily 

 removed by the hands. The latter method is less likely 

 to injure the sensitive structures, and will expose them 

 with a fresh appearance for observation. 



For purposes of description the keratogenous membrane 

 is divided into three regions : 



1. The Coronary Cushion. 



2. The Velvety Tissue. 



3. The Podophyllous Tissue, or the Sensitive Laminae. 



1. The Coronary Cushion. — In the foot stripped of the 

 hoof the coronary cushion is seen as a rounded structure 

 overhanging the sensitive laminae after the manner of a 

 cornice. It extends from the inner to the outer bulbs of 

 tfie plantar cushion, and is bounded above by the perioplic 

 ring, and below by the laminae. 



When in situ it is accommodated by the Cutigeral Groove, 

 a cavity produced by the bevelling out of the superior por- 

 tion of the inner face of the wall of the hoof. Its 

 superior surface is covered by numerous elongated papillae, 

 set so closely as to give the appearance of the 'pile' of 

 velvet. This is observed to the best advantage w T ith the 

 foot immersed in water. 



The Superior Border of the cushion is bounded by the 



