OINAS of posterior arm, forearm, and hand

Origin of anconeus

Lateral epicondyle of humerus, posterior surface

Insertion of anconeus

Lateral side of olecranon process, proximal posterior ulna

Action of anconeus

Extends elbow, stabilizes ulna during pronation and supination

Peripheral innervation of anconeus

Radial nerve

Segmental innervation of anconeus

C7, 8

Origin of abductor pollicis longus

Posterior ulna, interosseous membrane, middle posterior radius

Insertion of abductor pollicis longus

Base of radial side of 1st metacarpal

Action of abductor pollicis longus

Extends CMC joint of thumb with slight abduction, radially deviates wrist

Peripheral innervation of abductor pollicis longus

Radial nerve, posterior interosseus branch

Segmental innervation of abductor pollicis longus

C7, 8

Origin of extensor pollicis brevis

Posterior radius, interosseus membrane

Insertion of extensor pollicis brevis

Base of dorsal proximal phalanx of thumb

Action of extensor pollicis brevis

Extends thumb MP joint, extends and abducts CMC joint

Peripheral innervation of extensor pollicis brevis

Radial nerve, posterior interosseus branch

Segmental innervation of extensor pollicis brevis

C7, 8

Origin of extensor carpi radialis longus

Distal 1/3 of lateral supracondylar ridge of humerus and intermuscular septum

Insertion of extensor carpi radialis longus

Dorsal surface of base of 2nd metacarpal

Action of extensor carpi radialis longus

Peripheral innervation of extensor carpi radialis longus

Segmental innervation of extensor carpi radialis longus