Deeply situated at the region of the elbow, the short supinator has little interest for us. All that we will say of it is that it goes from the external part of the inferior extremity of the humerus to the superior part of the radius; and that it is, in carnivora, the essential agent in the production of the movement of supination. =Extensor Communis Digitorum= (Fig. 73, 9, 10, 11; Fig. 74, 10, 11, 12).--Also named in veterinary anatomy the _anterior extensor of the phalanges_, this muscle is situated external to and behind the anterior extensor of the metacarpus already described. In the human being, the common extensor of the fingers springs, in its superior part, from the bottom of a depression, situated on the outer side of and behind the elbow, and limited in front by the muscular prominence which the long supinator and the first radial extensor form at that level. At the bottom of this hollow or fossette is found the epicondyle, which gives origin, amongst other muscles, to the common extensor of the fingers. It is necessary to add that it is most prominently visible during supination, and that it tends to be effaced during pronation. [Illustration: FIG. 74.--MYOLOGY OF THE OX: LEFT ANTERIOR LIMB, EXTERNAL ASPECT. 1, Mastoido-humeralis; 2, pectoralis major; 3, deltoid; 4, brachialis anticus; 5, triceps; 6, triceps, external head; 7, olecranon; 8, radial extensors (anterior extensor of the metacarpus); 9, insertion of the tendon of the anterior extensor of the metacarpus to the tubercle of the superior extremity of the principal metacarpal; 10, 11, extensor communis digitorum (10, proper extensor of the inner digits; 11, common extensor of the two digits); 12, tendon of the common extensor of the two digits; 13, band of reinforcement from the suspensory ligament of the fetlock; 14, external tuberosity of the superior extremity of the radius; 15, extensor minimi digiti (proper extensor of the external digit); 16, tendon of the proper extensor of the external digit; 17, posterior ulnar (external flexor of the metacarpus); 18, pisiform; 19, extensor ossis metacarpi pollicis and extensor primi internodii pollicis (oblique extensor of the metacarpus); 20, ulnar portion of the deep flexor of the toes; 21, tendon of the superficial flexor of the toes (superficial flexor of the phalanges); 22, tendon of the deep flexor of the toes (deep flexor of the phalanges); 23, suspensory ligament of the fetlock.] An analogous arrangement is met with in animals. But the muscular prominence is formed by the united radial extensors, and the fossette, because of the permanent pronation of the forearm, is scarcely recognisable. Likewise, with regard to the dog, we may say that it does not exist, on account of the prominence which the epicondyle forms in that animal (Fig. 73, 7).