THE POSTERIOR METATARSALS, &C. 89 



whole knee. Then between the inferior bones, of which 

 there are two imperfect rows, there is a kind of rotatory 

 grinding movement, that allows the animal to move the 

 limb to a certain degree outward ; for if horses swung their 

 hoofs in very quick action, nearly as close as they are 

 placed, they would then be sadly in danger of cutting ; and 

 from the superior power of the hind muscles, of cutting very 

 severely ; especially as the speed prevented any great care 

 being taken in directing the foot. The lower part of the 

 hock, for the same reason as was alluded to when discussing 

 the knee, receives the principal shock when the foot reaches 

 the ground ; in consequence of this it is often the seat of 

 incurable lameness ; and even more often is united by bony 

 junction to the great cannon bone. 



THE POSTERIOR METATARSALS, CORONARY, AND COFFIN BONES. 



These bones have so much general resemblance to those 

 of the fore extremities, that I shall only point out the par- 

 ticular variations which occur in them. The large meta- 

 tarsal, or cannon bone {Skel. K), is longer, and altogether 

 larger than that of the anterior extremity ; it is articulated 

 above with the lower part of the hock, and below with the 

 great pastern and sessamoids {Skel. Mand N). The external 

 small 7netatarsal {Skel. L) is considerably larger than the 

 internal ; articulating superiorly with the cuboid, and late- 

 rally with the cannon. The great pastern bone is longer ; 

 and its situation is less oblique, which constitute its prin- 

 cipal differences. The sessamoids of this limb are two ; and 

 do not differ from those already described. The coronary 

 hone (Skel. 0), resting more on the coffin, and less on the 

 navicular bones here than in the anterior limb, shows that 

 the leg has a more extended movement than the fore limb ; 

 the hind, especially in the gallop, being brought far under, 

 as well as propelled a great distance behind the animal. 

 In the coffin bone {Skel. P) the articulation is deeper ; the 

 reason of which appears to be, that, as a horse has fre- 

 quently to support his whole weight on his hinder extremi- 

 ties, so it was necessary that these bones should be opposed 

 to each other in a more direct line, whereby they acquire 



