Part 38

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.

Origin.—From a broad area on the middle third of the upper side of the shaft of the ulna.

Insertion.—Near the top of the outer edge of the anchylosed os magnum of the carpo-metacarpus.

Shape.—Thin, somewhat flat.

Relations.—To the inside of the flexor digitorum profundus.

Action.—Flexes the hand upon the forearm and rotates the hand toward the body.

OTHER MUSCLES OF THE DIGITS

Extensor proprius pollicis Flexor minimi digiti Abductor minimi digiti Interosseous palmaris Flexor brevis pollicis Flexor minimi digiti brevis Interosseous dorsalis Flexor metacarpi brevis

=Extensor Proprius Pollicis= (Fig. 13, No. 29a). Location.—Anterior to the radio-carpal joint.