Carpal bones

In domestic animals, the carpal bones are arranged in two rows:

• The proximal (antebrachial) row articulates with the radius and ulna in the antebrachiocarpal joint, and contends (from medial to lateral):
  • Radial carpal bone
  • Intermediate carpal bone
  • Ulnar carpal bone
  • Accessory carpal bone
• The distal (metacarpal) row articultes with the metacarpal bones to form the carpometacarpal joint, and contends (from medial to lateral):
  • First carpal bone
  • Second carpal bone
  • Third carpal bone
  • Fourth carpal bone

The number of bones differ between species:

• Human, pigs: 8
• Horse: 7 or 8 (presence or absence of first carpal bone)
• Carnivores: 7 (fusion of radial and intermediate carpal bones)
• Ruminant: 6 (first carpal bone is missing and II and III are fused)