Posterolateral Forearm

Question 1

Brachioradialis

Answer 1

Origin: Lateral supracondylar ridge of humerus

Insertion: Distal radius

Action: Elbow flexion

Innervation: Radial nerve (C5, C6)

Question 2

Extensor carpi radialis longus

Answer 2

Origin: Lateral supracondylar ridge of humerus

Insertion: Dorsal base of 2nd metacarpal

Action: Wrist extension and abduction

Innervation: Radial nerve (C6, C7)

Question 3

Extensor carpi radialis brevis

Answer 3

Origin: Lateral epicondyle of humerus

Insertion: Dorsal base of 3rd metacarpal

Action: Wrist extension and abduction

Innervation: Deep radial nerve (C7, C8)

Question 4

Extensor carpi ulnaris

Answer 4

Origin: Lateral epicondyle of humerus and posterior border of ulna

Insertion: Dorsal base of 5th metacarpal

Action: Wrist extension and adduction

Innervation: Deep radial nerve - posterior interosseous (C7, C8)

Question 5

Supinator

Answer 5

Origin: Lateral epicondyle of humerus, supinator crest of ulna

Insertion: Radius

Action: Forearm supination

Innervation: Deep radial nerve - posterior interosseous (C6, C7)

Question 6

Extensor digitorum

Answer 6

Origin: Lateral epicondyle of humerus

Insertion: Middle and distal phalanges 2-5 via extensor hoods

Action: Extends digits 2-5, assists in wrist extension

Innervation: Deep radial nerve - posterior interosseous (C7, C8)

Question 7

Extensor digiti minimi

Answer 7

Origin: Lateral epicondyle of humerus

Insertion: Extensor hood of 5th digit

Action: Extends 5th digit

Innervation: Deep radial nerve - posterior interosseous (C7, C8)

Question 8

Abductor pollicis longus

Answer 8

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

Insertion: Base of 1st metacarpal

Action: 1st CMC abduction

Innervation: Deep radial nerve - posterior interosseous (C7, C8)

Question 9

Extensor pollicis brevis

Answer 9

Origin: Radius and interosseous membrane

Insertion: Dorsal base of proximal phalanx of thumb

Action: 1st MCP extension, 1st CMC extension

Innervation: Deep radial nerve - posterior interosseous (C7, C8)

Question 10

Extensor pollicis longus

Answer 10

Origin: Ulna and interosseous membrane

Insertion: Dorsal base of distal phalanx of thumb

Action: 1st IP extension, 1st MCP extension, 1st CMC extension

Innervation: Deep radial nerve - posterior interosseous (C7, C8)

Question 11

Extensor indices

Answer 11

Origin: Ulna and interosseous membrane

Insertion: Extensor hood of 2nd digit

Action: 2nd digit extension

Innervation: Deep radial nerve - posterior interosseous (C7, C8)