Upper Limb II: The Arm and Forearm

Question 1

Biceps brachii

Answer 1

• Action: Supinates forearm, when supine will flex forearm; resists dislocation of shoulder (short head)
• Blood supply: Brachial artery
• Innervation: Musculocutaneous nerve (C5, C6)

Question 2

Coracobrachialis

Answer 2

• Action: Flexes and adducts arm at shoulder joint; resists dislocation of shoulder joint
• Blood supply: Brachial artery
• Innervation: Musculocutaneous nerve

Question 3

Brachialis

Answer 3

• Action: Flexes forearm at elbow
• Bloody supply: Brachial artery
• Innervation: Musculocutaneous nerve (C5, C6), lateral portions may receive radial nerve contributions

Question 4

Anconeus

Answer 4

• Action: Assists triceps in extension of forearm and stabilizes elbow joint; also abducts ulna during pronation
• Blood supply: Deep brachial artery
• Innervation: Radial nerve (C7, C8, T1)

Question 5

Triceps brachii

Answer 5

• Action: Extends forearm at elbow joint (main); resists dislocation of shoulder joint (long head)
• Blood supply: Deep brachial artery
• Innervation: Radial nerve (C6, C7, C8)

Question 6

Pronator teres

Answer 6

• Action: Pronates and flexes forearm at elbow

- Innervation: Median nerve

Question 7

Flexor carpi radialis

Answer 7

• Action: Flexes and abducts hand at wrist

- Innervation: Median nerve

Question 8

Palmaris longus

Answer 8

• Action: Flexes hand at wrist, tenses palmar aponeurosis

- Innervation: Median nerve

Question 9

Flexor carpi ulnaris

Answer 9

• Action: Flexes and adducts hand at wrist

- Innervation: Ulnar nerve

Question 10

Flexor digitorum superficialis

Answer 10

• Action: Flexes middle phalanges at proximal interphalangeal joint, flexes proximal phalanges at metacarpophalangeal joints
• Innervation: Median nerve

Question 11

Flexor digitorum profundus

Answer 11

• Action: Flexes distal phalanges at interphalangeal joints (power grip)
• Innervation: Median and ulnar nerves

Question 12

Flexor pollicis longus

Answer 12

• Action: Flexes thumb

- Innervation: Median nerve via anterior interosseous nerve (branch of medial nerve)

Question 13

Pronator quadratus

Answer 13

• Action: Pronates forearm, deep fibers bind radius and ulna together
• Innervation: Median nerve via anterior interosseous nerve

Question 14

Brachioradialis

Answer 14

• Action: Flexes forearm when it is pronated (about midprone position)
• Innervation: Radial nerve

Question 15

Extensor carpi radialis longus

Answer 15

• Action: Extend and abduct hand at wrist

- Innervation: Radial nerve

Question 16

Extensor carpi radialis brevis

Answer 16

• Action: Extend and abduct hand at wrist

- Innervation: Deep branches of radial nerve

Question 17

Extensor digitorum

Answer 17

• Action: Extends medial 4 fingers at metacarpophalangeal joints and somewhat at interphalangeal joints
• Innervation: Posterior interosseous nerve

Question 18

Extensor digiti minimi

Answer 18

• Action: Extends 5th finger at metacarpophalangeal joint and secondarily at interphalangeal joints
• Innervation: Posterior interosseous nerve

Question 19

Extensor carpi ulnaris

Answer 19

• Action: Extends and adducts hand at wrist

- Innervation: Posterior interosseous nerve

Question 20

Supinator

Answer 20

• Action: Supinates forearm, bringing radius back to anatomical position
• Innervation: Deep branch of radial nerve

Question 21

Extensor indicis

Answer 21

• Action: Independent extension of 2nd finger, but also helps with extension of wrist
• Innervation: Posterior interosseous nerve (this nerve is the continuation of the deep branch of the radial nerve)

Question 22

Abductor pollicis longus

Answer 22

• Action: Abducts thumb and extends it at carpometacarpal joint
• Innervation: Posterior interosseous nerve (this nerve is the continuation of the deep branch of the radial nerve)

Question 23

Extensor pollicis brevis

Answer 23

• Action: Extends proximal phalanx of thumb at its metacarpophalangeal joint, also extends carpometacarpal joint
• Innervation: Posterior interosseous nerve

Question 24

Extensor pollicis longus

Answer 24

• Action: Extends distal phalanx of thumb at its interohalangeal and carpometacarpal joint
• Innervation: Posterior interosseous nerve