Digital bones of the hand

The phalanges are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones.

The original pattern of the phalanges comprises five rays but vary between species : they are designated numerically in a mediolateral sequence (from first to fifth digit):

• Carnivores have all five rays (1-5)
• Pig: four rays (2-5)
• Ruminant: two rays (3-4) with two non functional rays (2 and 5)
• Horse: only third ray (3)