Thoracic Limb - Extensor group OIAs

Extensor carpi radialis m.

Origin: lateral epicondyle of the humerus (and its crest)

Insertion: dorsal base of 2nd and 3rd metacarpal bones

Action: extend the carpal joints

Common digital extensor m.

Origin: lateral epicondyle of the humerus

Insertion: extensor processes of distal phalanges

Action: extend the carpal joints; extend the digital joints

Lateral digital extensor m.

Origin: lateral epicondyle of the humerus

Insertion: phalanges of the lateral-most digits

Action: extend the carpal joints; extend the digital joints of the lateral-most digits

Ulnaris lateralis (extensor carpi ulnaris m.)

Origin: lateral epicondyle of the humerus

Insertion: accessory carpal bone; lateral base of 5th metacarpal bone

Action: awkwardly flex the antebrachiocarpal joint; abduct the manus

Supinator m.

Origin: lateral epicondyle of the humerus

Insertion: body of radius

Action: supination of the manus

Abductor digit I longus m.

Origin: body of the ulna (in the carnivore)

Insertion: base of 1st metacarpal bone

Action: abduct the 1st digit