There are two groups of muscles at

the back of forearm.

1. Superficial Muscle group

2. Deep Muscle group

There are seven muscles in the

superficial group.

1. Anconeus

2. Brachioradialis

3. Extensor carpi radialis longus

4. Extensor carpi radialis brevis

5. Extensor digitorum

6. Extensor digiti minimi

7. Extensor carpi ulnaris

Origin:

Lateral epicondyle of

humerus

Insertion:

Lateral and inferior to

olecranon process of ulna

Action:

1. Not a prime mover in any

joint action;

2. Assists in elbow extension

Nerve supply:

Radial nerve (C7, C8)

Origin:

Lateral supracondylar

ridge on the humerus

Insertion:

Styloid process of the

radius

Action:

Elbow flexion

Nerve supply:Radial nerve (C5, C6)

Origin:

Supracondylar ridge of

humerus

Insertion:

Base of second

metacarpal

Action:

1. Wrist extension

2. Radial deviation

Nerve supply:

Radial nerve (C6, C7)

Origin:

Lateral epicondyle of

humerus

Insertion:

Base of third

metacarpal

Action:

Wrist extension

Nerve supply:

Radial nerve

(C6, C7)

Origin:

Lateral epicondyle

of the humerus

Insertion:

Base of distal

phalanx of the second

through fifth fingers

Action:Extends all three joints of the

fingers (MCP, PIP, and DIP)

Nerve supply:Radial nerve (C6, C7, C8)

Origin:Lateral epicondyle of humerus

Insertion:Base of distal phalanx of fifth

finger

Action:Extends all three joints of fifth

finger (MCP, PIP, and DIP)

Nerve supply:Radial nerve (C6, C7, C8)

Origin:Lateral epicondyle of humerus

Insertion:Base of fifth metacarpal

Action:Wrist extension, ulnar deviation

Nerve supply:Radial nerve (C6, C7, C8)

There are 5 muscles in the deep muscle

group.

1. Supinator

2. Abductor pollicis longus

3. Extensor pollicis brevis

4. Extensor pollicis longus

5. Extensor indicis

Origin:Lateral epicondyle of

humerus and adjacent ulna

Insertion:Anterior surface of the

proximal radius

Action:Forearm supination

Nerve supply:Radial nerve (C6)

Origin:Posterior radius, interosseous

membrane, middle ulna

Insertion:Base of the first metacarpal

Action:Abducts thumb (CMC)

Nerve supply:Radial nerve (C6, C7)

Origin:Posterior distal radius

Insertion:Base of the proximal

phalanx of thumb

Action:Extends CMC and MCP

joints of thumb

Nerve supply:Radial nerve (C6, C7)

Origin:Middle posterior ulna and

interosseous membrane

Insertion:Base of distal phalanx of

thumb

Action:Extends all three joints of the

thumb (CMC, MCP, and IP)

Nerve supply:Radial nerve (C6, C7, C8)

Origin:Distal ulna

Insertion:Base of distal phalanx

of the second finger

Action:Extends all three joints of

the second finger (MCP, PIP, and

DIP)

Nerve supply:Radial nerve (C6, C7, C8)