The ulna is curved and rather stout; it articulates with both carpal bones; the cubital quills often cause rugosities on its dorsal surface.
The outer condyle articulates mainly with the fibula.
There are four functional toes in front and three behind; while the calcaneum, unlike that of the other three groups, articulates with the fibula.
In the fore-limb the upper and lower series of carpal bones scarcely alternate, but in the hindfootthe astragalus overlaps the cuboid, while the fibula, which is quite distinct from the tibia(as is the radius from the ulna in the fore-limb), articulates with both astragalus and calcaneum.
The os magnum 1, lunar; sc, scaphoid; u, unciform; of the carpus articulates freely m, magnum; td, trapezoid; tm, with the scaphoid.