Upper Limb III: The Hand and Wrist

Question 1

Opponens pollicis

Answer 1

• Action: Oppose thumb and medially rotate 1st metacarpal

- Innervation: Recurrent branch of median nerve

Question 2

Abductor pollicis brevis

Answer 2

• Action: Abduct thumb, aid in opposition

- Innervation: Recurrent branch of median nerve

Question 3

Flexor pollicis brevis

Answer 3

• Action: Flexes thumb

- Innervation: Recurrent branch of median nerve (superficial head), deep branch of ulnar nerve (deep head)

Question 4

Adductor pollicis

Answer 4

• Action: Adducts thumb toward lateral border

- Innervation: Deep branch of ulnar nerve

Question 5

Abductor digiti minimi

Answer 5

• Action: Abducts 5th digit, aids in flexion of 5th proximal phalanx
• Innervation: Deep branch of ulnar nerve

Question 6

Flexor digiti minimi (brevis)

Answer 6

• Action: Flexes proximal phalanx of digit 5

- Innervation: Deep branch of ulnar nerve

Question 7

Opponens digiti minimi

Answer 7

• Action: Brings 5th metacarpal anterior and rotates it to bring it into opposition with thumb
• Innervation: Deep branch of ulnar nerve

Question 8

Lumbricals

Answer 8

• Action: Flex the metacarpophalangeal joints and extend interphalangeal joints (via the extensor expansion and extensor hood) of digits 2-5
• Innervation: Median nerve (1st and 2nd lumbricals), and deep branch of ulnar nerve (3rd and 4th lumbricals)

Question 9

Palmar interossei

Answer 9

• Action: Adduct 2nd, 4th, and 5th fingers toward axial line; also assist lumbricals
• Innervation: Deep branch of ulnar nerve

Question 10

Dorsal interossei

Answer 10

• Action: Abduct 2nd-4th fingers toward axial line; also assist lumbricals
• Innervation: Deep branch of ulnar nerve