Tarsal bones

The tarsal bones (basipodium) compose the first row of the skeleton of the pes. The tarsal bones are arranged from proximal to distal into 3 rows:

• Proximal (crural) row: composed by tibial tarsal bone (talus) and fibular tarsal bone (calcaneus). It articulates with the tibia to form the tarsocrural joint
• Middle (intermetatarsal) row: composed only by the central tarsal bone (navicular bone). It articulates with the distal tarsal bones to form the centrodistal joint.
• Distal (metatarsal) row: composed by the first tarsal bone (Tarsal bone I; Medial cuneiform), second tarsal bone (Tarsal bone II; Intermediate cuneiform), third tarsal bone (Tarsal bone III; Lateral cuneiform) and foruth tarsal bone (Tarsal bone IV; Cuboid). The third row of carpal bones articulates with the metatarsals to form the tarsometatarsal joints.

The number of tarsal bones differs between species:

• Carnivores: 7 tarsal bones
• Ruminants: 5 tarsal bones (fusion of the central and IV, and II-III)
• Horses: 6 tarsal bones (fusion of tarsal bones I and II)