_Origin._—By a short, strong, subcylindrical tendon from the lower posterior of the external condyle of the humerus. _Insertion._—To the latero-radial side of the ulna somewhat beyond its middle. _Shape._—Fusiform. _Relations._—Superiorly, the extensor indicis longus, and inferiorly, the ulna. _Action._—A flexor of the forearm. =Extensor Indicis Longus= (Fig. 13, No. 22; Fig. 15, No. 13). _Location._—Infero-lateral to the radius. _Origin._—From about one-half the surface of the proximal portion of the radius. _Insertion._—Possesses a long tendon which passing over a groove at the distal end of the ulna and receiving muscular fibers at the base of the metacarpus, extends down the anterior part of the hand and is inclosed in a sheath in front of the superior part of the first phalanx of the index-finger. This tendon is inserted into the anterior upper rim of the distal phalanx. _Shape._—Small, thin. _Relations._—Supero-laterally with the radius. _Action._—Extensor of the digit. =Flexor Digitorum Sublimis.= _Location._—The forearm. _Origin._—From the internal condyle of the humerus. _Insertion._—Passing over the wrist, it is inserted to the middle phalanx of the hand. _Shape._—A musculo-tendinous band, rather delicate and rudimentary. _Relations._—Closely adhering to the integument that stretches from the internal condyle of the humerus to the wrist. _Action._—Assists these muscles. A flexor. =Flexor Digitorum Profundus= (Fig. 13, No. 21). _Location._—Lateral side of the ulna. _Origin._—By two heads from the proximal extremity of the ulna, between which the brachialis anticus passes. _Insertion._—The two bellies uniting are attached to the under side of the shaft of the ulna. It becomes tendinous about the middle of the shaft, and inserts to the ulnar side of the base of the distal joint of the index-finger. _Shape._—A fleshy belly with long tendon. _Relations._—Inferiorly, with the flexor carpi ulnaris, superiorly, with the pronator brevis. _Action._—A flexor of the digit. =Flexor Carpi Ulnaris= (Fig. 13, No. 19). _Location._—Inferior part of the forearm. _Origin._—By two strong tendons; one from the side and posterior of the internal condyle of the humerus, passing through the humero-ulnar pulley at the side of the base of the olecranon process; the other, to the posterior of the internal condyle of the humerus. It does not pass through a pulley. _Insertion._—A subcylindrical tendon extends back of the ulnare ossicle of the carpus giving off a tendinous slip to the flexor digitorum profundus, and becomes inserted to the anterior rim of the proximal phalanx of the index digit. It has an attachment at the carpus. _Shape._—A strong fleshy belly terminating in a long tendon. _Relations._—The outermost inferior muscle of the forearm. _Action._—A powerful flexor of the hand upon the forearm. =Flexor Carpi Ulnaris Brevior= (Fig. 13, No. 20). _Location._—Inferior part of the antibrachial region.