Horse Anatomy Exam 1 Practice

The central weight-bearing bone of the horse’s limb is the cannon bone. It’s the third metacarpal/metatarsal bone (MC3 in the forelimb, MT3 in the hindlimb) and serves as the main pillar of the limb, bearing most of the load during standing and motion. It sits between the fetlock joint (proximal to the cannon bone) where it meets the carpal bones, and the pastern region where it articulates with the proximal phalanx (the pastern bone). The slender splint bones run along the sides (the second and fourth metacarpals/metatarsals) and can fuse with MC3. The pastern bone refers to the proximal phalanx, and the coffin bone is the distal phalanx inside the hoof. The term cannon suture isn’t a standard name for a bone. So the cannon bone is the correct name for the third metacarpal/metatarsal bone.