Carpal Bones in Horses

Horses have two rows of carpal bones

1. Proximal row (from medial to lateral):

- Radial carpal bone

- Intermediate carpal bone

- Ulnar carpal bone

- Accessory carpal bone (palmar, lateral position)

2. Distal row (from medial to lateral):

- First carpal bone (often absent or small)

- Second carpal bone

- Third carpal bone

- Fourth carpal bone

Carpal Bones in Cattle

Cows also have two rows of carpal bones, but the anatomy reflects fusion and simplification:

1. Proximal row (from medial to lateral):

- Radial carpal bone

- Intermediate carpal bone

- Ulnar carpal bone

- Accessory carpal bone (palmar, lateral position)

2. Distal row:

- First carpal bone (absent)

- Second and third carpal bones (fused into a single bone)

- Fourth carpal bone

Anatomical Differences

1. Number of Carpal Bones:

- Horses typically have 7 or 8 carpal bones, depending on the presence of the first carpal bone.

- Cows have 6 carpal bones, due to the fusion of the second and third carpal bones and the absence of the first.

2. Fusion in the Distal Row:

- In cows, the second and third carpal bones are fused, forming a single bone. This fusion is absent in horses, where each bone is distinct.

3. Size and Shape:

- In horses, the carpal bones are more elongated and robust, reflecting their role in absorbing impact during high-speed locomotion.

- In cows, the carpal bones are more compact and designed to support weight-bearing and slower movement.

4. Accessory Carpal Bone:

- In both species, the accessory carpal bone is prominent and serves as a leverage point for flexor tendons. However, its relative size and shape may vary slightly.

5. Functional Adaptation:

- The horse's carpus allows greater mobility and shock absorption, essential for running and jumping.

- The cow's carpus is adapted for stability to support their weight during grazing and slow locomotion.