304 



DISEASES OF THE HORSE. 



[For an intimate acquaintance of the foot of the horse, otlier 

 works may be consulted : but a careful inspection of the plates 

 in this work will give a very good general idea of the situation 

 of the parts, and this will be greatly assisted by a comparison of 

 these 23arts with the foot and leg itself. 



Fi"'. 1. The Foot with the Wall or Crust 

 removed. 



a, The sensible lamina; attached to the 

 coffin bone by elastic substance, se- 

 cretes the horny lamince, and the 

 internal layer of the crust. 



b. The coronary substance or ligament 

 which secretes the greater portion 



Fig. 2. The Bottom of the Sensible Foot, 

 the horny parts being removed. 



a. The sensible sole. 



b h. The sensible bars. 



c c, The sensible frog. 



These parts being largely supplied with 

 blood, secrete the horny sole, bars, 

 and trog to which they are attached. 



of the crust. 



Fig. 1., p. 3('4., represents the foot with the crust removed, 

 thereby exposing to view the sensible lamina?, the natural colour 

 of which is red, and the coronary substance above, which secretes 

 the greater part of the crust. 



Figs. 3. and 4. represent the bones of the foot and pastern 



and the other foot being now held up, the border of the crust was marked with 

 a pencil, taking care that the marks were not made more exterior to the border 

 of the crust than before. On comparing the papers together, the one last 

 taken was found perceptibly wider than the other. The increased width was 

 seen to commence gradually about the middle of the foot, till it reached about 

 half an inch anterior to the heels, when it very slightly diminished. The dif- 

 ference was found to be, as near as possible, one twelfth of an inch at the 

 lieels. The experiment was conducted with care and exactness, and clearly 

 proved that the foot expanded from superincumbent weight ; and if the horse 

 had been in fast motion, the pressure would, of course, have been greater and 

 the expansion more. It did not appear from the experiment that the front 

 part of the foot expanded at all, so without asserting that it possesses no 

 power of the sort, we must be contented with observing that if possessed, it 

 is not in asufBcient degree to be detected by admeasurement. We are there- 

 fore justified in concluding, that the parts anterior to the toe of the frog 

 possess very little expansive power ; and this theory, if correct, will agree 

 with tlie experiments we have detailed. The case, however, is very different 

 with the posterior parts. The navicular bone, we have seen, rests on the 

 llexor sinew, and the sinew upon the elastic frog in the centre, and on the 

 commissures and sole on each side. These commissures are the highest part 

 of the sole, and form, indeed, a sort of a ridge, so that, as any pressure on this 

 part must tend to llatten the ridge, it must consequently expand the foot. 

 Whatever weight, then, is supported by the navicular joint must contribute 

 to the expansion of the foot. — Spooner on the Foot, ^r. 



