Dorsal Forearm And Dorsum Of Hand

Question 1

Brachioradialis

Answer 1

Origin: proximal 2/3 of lateral supraepicondylar ridge of humerus
Insertion: lateral surface of distal end of radius superior to styloid process
Action: weak flexion of elbow joint, maximal when forearm’s in midpronated position
Innervation: radial nerve (C5, C6, C7)
Blood supply:

Question 2

Extensor carpi radialis longus

Answer 2

Origin: lateral supraepicondylar ridge of humerus
Insertion: dorsal aspect of base of 2nd metacarpal
Action: extend and abduct wrist joint
Innervation: radial nerve (C6, C7)
Blood supply:

Question 3

Extensor carpi radialis brevis

Answer 3

Origin: lateral epicondyle of humerus
Insertion: dorsal aspect of base of 3rd metacarpal
Action: extend and abduct wrist joint; active during fist clenching
Innervation: deep branch of radial nerve (C7, C8)

Question 4

Extensor digitorum

Answer 4

Origin: lateral epicondyle of humerus
Insertion: extensor expansions of medial 4 fingers
Action: extend wrist joint; extend medial 4 fingers
Innervation: posterior interosseous nerve (C7, C8)- continuation of deep branch of radial nerve

Question 5

Extensor digiti minimi

Answer 5

Origin: lateral epicondyle of humerus
Insertion: extensor expansion of 5th finger
Action: extend wrist joint; extend 5th finger (primarily at metacarpophalangeal joint, secondarily at interphalangeal joint)
Innervation: posterior interosseous nerve (C7, C8)- continuation of deep branch of radial nerve

Question 6

Extensor carpi ulnaris

Answer 6

Origin: lateral epicondyle of humerus; posterior border of ulna via a shared aponeurosis
Insertion: dorsal aspect of base of 5th metacarpal
Action: extend and adduct wrist joint; also active during fist clenching
Innervation: posterior interosseous nerve (C7, C8)- continuation of deep branch of radial nerve

Question 7

Supinator

Answer 7

Origin: lateral epicondyle of humerus, radial collateral and anular ligaments, supinator fossa, crest of ulna
Insertion: lateral, posterior and anterior surfaces of proximal 1/3 of radius
Action: supinates forearm; rotates radius to turn palm anteriorly or superiorly (if elbow’s flexed)
Innervation: deep branch of radial nerve (C7, C8)
Blood supply:

Question 8

Abductor pollicis longus

Answer 8

Origin: posterior surface of proximal halves of ulna, radius and interosseous membrane
Insertion: base of 1st metacarpal
Action: extends wrist joint; abducts and extends thumb
Innervation: posterior interosseous nerve (C7, C8)
Blood supply:

Question 9

Extensor pollicis longus

Answer 9

Origin: posterior surface of middle 1/3 of ulna and interosseous membrane
Insertion: dorsal aspect of base of distal phalanx of thumb
Action: extends wrist joint; extends distal phalanx of thumb at interphalangeal joint; extends metacarpophalangeal and carpophalangeal joints
Innervation: posterior interosseous nerve (C7, C8)
Blood supply:

Question 10

Extensor pollicis brevis

Answer 10

Origin: posterior surface of middle 1/3 of radius and interosseous membrane
Insertion: dorsal aspect of base of proximal phalanx of thumb
Action: extends wrist joint; extends proximal phalanx of thumb at metacarpophalangeal joint; extends carpometacarpal joint
Innervation: posterior interosseous nerve (C7, C8)
Blood supply:

Question 11

Extensor indicis

Answer 11

Origin: Posterior surface of distal 1/3 of ulna and interosseous membrane
Insertion: extensor expansion of 2nd finger
Action: extends wrist joint; extends 2nd finger; helps extend hand at wrist
Innervation: posterior interosseous nerve (C7, C8)
Blood supply: