Below the carpal and tarsal joints, the fore and hind limbs correspond almost exactly in structure as well as function.
The carpal joint, corresponding to the wrist of man, is commonly called the " knee " of the horse, the joint between the metacarpal and the first phalanx the " fetlock," that between the first and second phalanges the " pastern," and that between the second and third phalanges the " coffin joint."
Its plumage is plain in colour, being of an almost uniform greyish black above, the space round the eyes and a ring round the neck being variegated with white, and a patch of pale rufous appearing above the carpal joint, while the lower parts of the body are white.
Small round or oval plates of horny epithelium called " chestnuts," callosities growing like the hoof from enlarged papillae of the skin, are found on the inner face of the fore-arm, above the carpal joint in all species of Equidae, and in the horse (E.
The ulna is curved and rather stout; it articulates with both carpal bones; the cubital quills often cause rugosities on its dorsal surface.
R', u', Radial and ulnar carpal bones; with the three digits I., II., III.
The flexor digitorum sublimis muscle arises fleshy from the long elastic band which extends from the inner humeral condyle along the ventral surface of the ulna to the ulnar carpal bone, over which the tendon runs to insert itself on the radial anterior side of the first phalanx of the second digit.