12.4 Musculature of the Hand

Question 1

Abductor pollicis brevis origin and insertion

Answer 1

Origin: Scaphoid and trapezium (+flexor retinaculum)

Insertion: Lateral base of proximal phalanx of thumb

Question 2

List the thenar muscles of the hand

Answer 2

• Abductor/adductor pollicis brevis
• Opponens pollicis
• Flexor pollicis brevis

Question 3

Flexor pollicis brevis origin and insertion

Answer 3

Origin: Flexor retinaculum (superficial) and capitate and trapezoid (deep); deep = lateral leverage

Insertion: Lateral proximal phalanx of the thumb

Question 4

Innervation of thenar nerves

Answer 4

The thenar branch of the median nerve

Question 5

Opponens pollicis origin and insertion

Answer 5

Origin: Trapezium, flexor retinaculum

Insertion: lateral border of first metacarpal

Question 6

Adductor pollicis origin and insertion

Answer 6

Origin: Base of metacarpal 3 (transverse) + base of metacarpal 2 and 3 (oblique)

Insertion: Medial border of proximal phalanx 1

Question 7

Abductor digiti minimi

Question 8

Flexor digiti minimi brevis

Question 9

Opponens digiti minimi

Question 10

List the muscles of the hypothenar eminence

Answer 10

• Abductor digiti minimi
• Flexor digiti minimi
• Opponens digiti minimi
• Palmaris brevis

Question 11

Hand lumbricals origin, insertion, and action

Answer 11

Origin: between tendons of flexor digitorum profundus

Insertion: Extensor hood of digits

Action: Flexes fingers at MCP joints while extending PIPs and DIPs (Leyton Hewitt)

Question 12

Origin and insertion of the palmar/dorsal interosseus muscles of the hand + a mnemonic to remember their action

Answer 12

Origin: Palmar/dorsal aspect of metacarpals

Insertion: Extensor hood of digits

Action Mnemonic: PAD and DAB — Palmar ADduct the fingers, Dorsal ABduct them.

Question 13

What is the mnemonic for the hand muscles innervated by the median nerve (all else are ____)?

Answer 13

LOAF

Lateral two lumbricals
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis