Posterior Forearm

Question 1

Brachioradialis

Answer 1

Origin: proximal 2/3 of lateral supracondylar ridge of humerus

Insertion: lateral side of distal end of radius

Innervation: radial nerve

Blood Supply: radial recurrent artery

Action: weak flexion of forearm when forearm is midpronated

Question 2

Extensor Carpi Radialis Longus

Answer 2

Origin: distal 1/3 of lateral supracondylar ridge of humerus

Insertion: dorsal base of 2nd and 3rd metacarpal

Innervation: radial nerve

Blood Supply: radial recurrent artery

Action: extends hand at wrist and abducts hand at wrist

Question 3

Extensor Carpi Radialis Brevis

Answer 3

Origin: lateral epicondyle

Insertion: dorsal base of 2nd and 3rd metacarpal

Innervation: deep branch of radial nerve

Blood Supply: radial recurrent artery

Action: extends hand at wrist and abducts hand at wrist

Question 4

Extensor Digitorum

Answer 4

Origin: lateral epicondyle

Insertion: extensor expansion of medial 4 digits

Innervation: posterior interosseous nerve

Blood Supply: posterior interosseous artery

Action: extends medial 4 digits and assists with wrist extension

Question 5

Extensor Digiti Minimi

Answer 5

Origin: lateral epicondyle

Insertion: extensor expansion of 5th digit

Innervation: posterior interosseous nerve

Blood Supply: posterior interosseous artery

Action: extends 5th digit

Question 6

Extensor Carpi Ulnaris

Answer 6

Origin: lateral epicondyle and posterior border of ulna

Insertion: dorsal base of 5th metacarpal

Innervation: posterior interosseous nerve

Blood Supply: posterior interosseous artery

Action: extends hand at wrist and adducts hand at wrist

Question 7

Anconeus

Answer 7

Origin: posterior surface of lateral epicondyle

Insertion: lateral surface of olecranon and posterior proximal ulna

Innervation: radial nerve

Blood Supply: deep brachial artery

Action: assists triceps in extending elbow and abducts ulna in pronation

Question 8

Supinator

Answer 8

Origin: lateral epicondyle and supinator crest of ulna

Insertion: lateral, posterior, and anterior surface of proximal 1/3 of radius

Innervation: deep branch of radial nerve

Blood Supply: radial recurrent artery and posterior interosseous artery

Action: supinates forearm

Question 9

Extensor Pollicis Longus

Answer 9

Origin: posterior surface of middle 1/3 of ulna and interosseous membrane

Insertion: dorsal base of distal phalanx of thumb

Innervation: posterior interosseous nerve

Blood Supply: posterior interosseous artery

Action: extends distal phalanx of thumb at IP and MCP

Question 10

Abductor Pollicis Longus

Answer 10

Origin: posterior surface of ulna, posterior surface of radius, and interosseous membrane

Insertion: base of 1st metacarpal

Innervation: posterior interosseous nerve

Blood Supply: posterior interosseous artery

Action: abducts thumb at CMC and extends thumb at CMC

Question 11

Extensor Pollicis Brevis

Answer 11

Origin: posterior surface of ulna and interosseous membrane

Insertion: dorsal base of proximal phalanx of thumb

Innervation: posterior interosseous nerve

Blood Supply: posterior interosseous artery

Action: extends proximal phalanx of thumb at CMC

Question 12

Extensor Indicis

Answer 12

Origin: posterior surface of ulna and interosseous membrane

Insertion: extensor expansion of 2nd digit

Innervation: posterior interosseous nerve

Blood Supply: posterior interosseous artery

Action: extends 2nd digit and helps extend hand at wrist