Cannon bone The horse has three bones in the lower leg. The cannon bone is the largest, and the main support. The two smaller bones, called splint bones, are attached to the cannon on each side and toward the rear. In the front legs the splint; bones are technically called the second and fourth metacarpal (the cannon bone is the third metacarpal); in the hind leg they are the second and fourth metatarsal.

Also See Skeleton of a horse