Muscles of the extensor surface of the forearm and hand

Extensor carpi radialis longus Origin

Lateral supracondylar ridge of humerus.

Extensor carpi radialis longus Insertion

Metacarpal 2

Extensor carpi radialis longus Action

Extends and abducts hand at wrist joint (ulnar deviation).

Extensor carpi radialis longus Innervation

Radial nerve

Extensor carpi radialis brevis Origin 

Lateral epicondyle of humerus.

Extensor carpi radialis brevis Insertion

Metacarpal 3.

Extensor carpi radialis brevis Action

Extends and abducts hand at wrist joint

Extensor digitorum Innervation

radial nerve

Extensor digitorum Origin

Lateral epicondyle of humerus

Extensor digitorum Insertion

Distal and middle phalanges of each finger.

Extensor digitorum Action 

Extends distal and middle phalanges of each finger at interphalangeal joints, proximal phalanx of each finger at metacarpophalangeal joint, and hand at wrist joint.

Extensor digitorum Innervation

Radial nerve

Extensor digiti minimi Origin

Lateral epicondyle of humerus.

Extensor digiti minimi Insertion

Tendon of extensor digitorum on phalanx 5.

Extensor digiti minimi Action 

Extends proximal phalanx of little finger at metacarpophalangeal joint and hand at wrist joint.

Extensor digiti minimi Innervation

Radial nerve

Extensor carpi ulnaris Origin

Lateral epicondyle of humerus and posterior border of ulna.

Extensor carpi ulnaris Insertion

Metacarpal 5

Extensor carpi ulnaris Action

Extends and adducts hand at wrist joint (ulnar deviation).

Extensor carpi ulnaris Innervation

Radial nerve

Anconeus Origin

Lateral epicondyle of humerus.

Anconeus Insertion

Olecranon and superior portion of shaft of ulna.

Anconeus Action

Extends forearm at elbow joint.

Anconeus Innervation

Radial nerve.

Abductor pollicis longus Origin

Posterior surface of middle of radius and ulna and interosseous membrane.

Abductor pollicis longus Insertion 

Metacarpal 1

Abductor pollicis longus Action 

Abducts and extends thumb at carpometacarpal joint and abducts hand at wrist joint.

Abductor pollicis longus Innervation

Radial nerve

Extensor pollicis brevis Origin

Posterior surface of middle of radius and interosseous membrane.

Extensor pollicis brevis Insertion 

Base of proximal phalanx of thumb

Extensor pollicis brevis Action 

Extends proximal phalanx of thumb at metacarpophalangeal joint, first metacarpal of thumb at carpometacarpal joint, and hand at wrist joint.

Extensor pollicis longus Innervation

Radial nerve

Extensor pollicis longus Origin

Posterior surface of middle of ulna and interosseous membrane.

Extensor pollicis longus Insertion

Base of distal phalanx of thumb.

Extensor pollicis longus Action

Extends distal phalanx of thumb at interphalangeal joint, extends first metacarpal of thumb at carpometacarpal joint, and abducts hand at wrist joint.

Extensor pollicis longus Innervation

Radial nerve

Extensor Indicis Origin

Posterior surface of ulna and interosseous membrane.

Extensor Indicis Insertion

Tendon of extensor digitorum of index finger

Extensor Indicis Action

Extends distal and middle phalanges of index finger at interphalangeal joints, proximal phalanx of index finger at metacarpophalangeal joint, and hand at wrist joint.

Extensor Indicis Innervation

Radial nerve.

Supinator Origin 

Lateral epicondyle of humerus and ridge near radial notch of ulna (supinator crest).

Supinator Insertion 

Lateral surface of proximal one-third of radius.

Supinator Action

Supinates forearm at radioulnar joints.

Supinator Innervation

Radial nerve.