Only Metacarpal III ('''cannon bone''') remains complete whilst metacarpals II and IV are greatly reduced and are known as the '''splint bones'''. Metacarpal III has a distal articular surface with two condylar areas separated by a '''sagittal ridge'''. This separates the two sesamoids on the palmar aspect of the joint and ensures only sagittal movement of the fetlock. There is also a transverse ridge leading to two radii of curvature. The proximal part has articulating facets on its palmar side where the splint bones articulate. It has a '''metacarpal tuberosity''' on the dorsomedial surface of the proximal end. The splint bones are held to metacarpal III by strong ligaments which are usually ossified and can lead to lameness if there is excessive bone production. They curve away distally from the main shaft and end in palpable nodules 2/3rds to 3/4s the way down the cannon bone. | Only Metacarpal III ('''cannon bone''') remains complete whilst metacarpals II and IV are greatly reduced and are known as the '''splint bones'''. Metacarpal III has a distal articular surface with two condylar areas separated by a '''sagittal ridge'''. This separates the two sesamoids on the palmar aspect of the joint and ensures only sagittal movement of the fetlock. There is also a transverse ridge leading to two radii of curvature. The proximal part has articulating facets on its palmar side where the splint bones articulate. It has a '''metacarpal tuberosity''' on the dorsomedial surface of the proximal end. The splint bones are held to metacarpal III by strong ligaments which are usually ossified and can lead to lameness if there is excessive bone production. They curve away distally from the main shaft and end in palpable nodules 2/3rds to 3/4s the way down the cannon bone. |