Superficial muscles of the posterior forearm

Question 1

What are the superficial muscles of the posterior forearm? (7)

Answer 1

• Brachoradialis
• Extensor carpi radialis longus
• Extensor carpi radialis brevis
• Extensor digitorum
• Extensor digiti minimi
• Extensor carpi ulnaris
• Anconeus

Question 2

Brachoradialis

Answer 2

O: Proximal aspect of the lateral supracondylar ridge of the humerus

I: Distal end of the radius

I: Radial nerve

A: Flexion at the elbow

Question 3

Extensor Carpi Radialis Longus (ECRL)

Answer 3

O: Lateral supracondylar ridge of the humerus

I: Dorsal surface of the second metacarpal bone

I: Radial nerve

A: Extension and abduction at the wrist

Question 4

Extensor Carpi Radialis Brevis (ECRB)

Answer 4

O: Common extensor origin on the lateral epicondyle

I: Dorsal surface of the base of the third metacarpal bone

I: Deep branch of the radial nerve

A: Extension and abduction at the wrist

Question 5

Extensor Digitorum

Answer 5

O: Common extensor origin on the lateral epicondyle

I: 4 tendons insert into extensor hood of the four fingers

I: Posterior interosseous branch of the radial nerve

A: Main extensor of the fingers and extends all four fingers at the metacarpophalangeal and interphalangeal joints

Question 6

What is the juncturae tendinum

Answer 6

Fibrous bands on the dorsum of the hand that links the 4 tendons of the extensor digitorum. prevents full extension of the middle or ring finger if other fingers are flexed.

Question 7

Extensor Digiti Minimi

Answer 7

O: Common extensor origin on the lateral epicondyle of the humerus

I: Ulnar (medial) side of the extensor digitorum tendon into extensor hood of the little finger (pinky)

I: Posterior interosseous branch of the radial nerve

A: Extends the little finger and assists extension at the wrist

Question 8

Extensor Carpi Ulnaris

Answer 8

O: Common extensor origin on the lateral epicondyle of the humerus (humeral head) and olecranon (ulnar head)

I: Base of the fifth metacarpal

I: Posterior interosseous branch of the radial nerve

A: Adduction and extension at the wrist (as its located at the ulnar/medial aspect of the posterior forearm)

Question 9

Anconeus

Answer 9

O: Common extensor origin on the lateral epicondyle of the humerus

I: Radial side of the olecranon and posterior surface of proximal ulna

I: Radial nerve

A: Weak extensor, stabilises elbow joint and prevents impingement by abducting ulna during pronation