Muscles of the Hand

Question 1

Abductor pollicis brevis

Proximal Attachment

Distal Attachment

Action

Innervation

Answer 1

• Proximal Attachment: Flexor retinaculum, scaphoid, trapezium
• Distal Attachment: Base of proximal phalanx of thumb
• Action: Abducts thumb
• Innervation: Recurrent branch of median nerve

Question 2

Flexor pollicis brevis

Proximal Attachment

Distal Attachment

Action

Innervation

Answer 2

• Proximal Attachment: Flexor retinaculum, scaphoid, trapezium
• Distal Attachment: Base of proximal phalanx of thumb
• Action: Flexes thumb
• Innervation: Recurrent branch of median nerve

Question 3

Opponens pollicis

Proximal Attachment

Distal Attachment

Action

Innervation

Answer 3

• Proximal Attachment: Flexor retinaculum, scaphoid, trapezium
• Distal Attachment: 1st metacarpal
• Action: Opposes thumb
• Innervation: Recurrent branch of median nerve

Question 4

Lumbricals

Proximal Attachment

Distal Attachment

Action

Innervation

Answer 4

• Proximal Attachment: Tendons of flexor digitorum profundus
• Distal Attachment: Extensor expansions of digits 2-5
• Action: Flex metacarpophalangeal joints, extend interphalangeal joints of digits 2-5
• Innervation:
  
  • Lumbricals 2-3: Median nerve
  • Lumbricals 4-5: Ulnar nerve

Question 5

Abductor digit minimi

Proximal Attachment

Distal Attachment

Action

Innervation

Answer 5

• Proximal Attachment: Pisiform
• Distal Attachment: Proximal phalanx of digit 5
• Action: Abducts digit 5
• Innervation: Deep branch of ulnar nerve

Question 6

Flexor digiti minimi brevis

Proximal Attachment

Distal Attachment

Action

Innervation

Answer 6

• Proximal Attachment: Hook of hamate and flexor retinaculum
• Distal Attachment: Proximal phalanx of digit 5
• Action: Flexes proximal phalanx of digit 5
• Innervation: Deep branch of ulnar nerve

Question 7

Opponens digiti minimi

Proximal Attachment

Distal Attachment

Action

Innervation

Answer 7

• Proximal Attachment: Hook of hamate and flexor retinaculum
• Distal Attachment: 5th metacarpal
• Action: Opposes 5th digit to thumb
• Innervation: Deep branch of ulnar nerve

Question 8

Adductor pollicis

Proximal Attachment

Distal Attachment

Action

Innervation

Answer 8

• Proximal Attachment:
  
  • Oblique head: Base of 2nd and 3rd metacarpals and capitate
  • Transverse head: Base of 3rd metacarpal
• Distal Attachment: Proximal phalanx of digit 1
• Action: Adducts thumb
• Innervation: Deep branch of ulnar nerve

Question 9

Dorsal Interosseus Muscles

Proximal Attachment

Distal Attachment

Action

Innervation

Answer 9

• Proximal Attachment: Adjacent sides of 2 metacarpals
• Distal Attachment: Base of proximal phalanges and extensor expansion of digits 2-4
• Action: Abducts digits 2-4
• Innervation: Deep branch of ulnar nerve

Question 10

Palmar Interosseous Muscles

Proximal Attachment

Distal Attachment

Action

Innervation

Answer 10

• Proximal Attachment: 2nd, 4th, and 5th metacarpals
• Distal Attachment: Base of proximal phalanges and extensor expansions of digits 2, 4, 5
• Action: Adduct digits 2, 4, 5
• Innervation: Deep branch of ulnar nerve

Question 11

Carpal Tunnel

Boundaries

Contents

Answer 11

• Boundaries:
  
  • Carpal bones form floor and walls
  • Flexor retinaculum forms roof
• Contents:
  
  • Flexor pollicis longus tendon
  • Flexor digitorum superficialis tendons
  • Flexor digitorum profundus tendons
  • Median nerve

Question 12

Guyon’s Canal (Ulnar tunnel)

Boundaries

Contents

Answer 12

• Boundaries:
  
  • Floor: Flexor retinaculum
  • Roof: Palmar carpal ligament
  • Medial border: Pisiform
  • Lateral border: Hamate
• Contents:
  
  • Ulnar artery
  • Ulnar nerve