Myology of the Wrist and Hand

Question 1

Anatomical snuff box

Answer 1

Triangular depression above the thumb.
Bordered by 3 tendons: 
- Extensor pollicis longus.
- Extensor pollicis brevis.
- Abductor pollicis longus.
Radial nerve, radial artery and cephalic vein pass through.

Question 2

Extrinsic muscles

Answer 2

Longer muscles.

Origin in the forearm, insertion in the hand or fingers.

Question 3

Intrinsic muscles

Answer 3

Small muscles with origin and insertion in the area of the hand.

Question 4

Polyarticular muscles

Answer 4

Cross multiple articulations. Therefore can produce movement in multiple areas.

Question 5

Thenar muscles

Answer 5

Anterior, most lateral part of the hand (underneath the thumb).
M. abductor pollicis brevis
M. adductor pollicis
M. flexor pollicis brevis
M. opponens pollicis

Question 6

Hypothenar muscles

Answer 6

Anterior, medial part of hand. Provide movement to the 5th finger.
M. abductor digiti minimi
M. flexor digiti minimi brevis
M. opponens digiti minimi
M. palmaris brevis

Question 7

Flexor vs. extensor muscles

Answer 7

Flexor muscles on medial side.

Extensor muscles on lateral side.

Question 8

Flexor pollicis longus

Answer 8

• Origin: Interosseus membrane, anterior surface of the
  radius.
• Insertion: Palmar surface of the distal phalanx I.
• Action: Wrist: flexion and abduction. MCP and IP I: flexion.
  Carpometacarpal I: opposition.
• Innervation: Median nerve.

Question 9

Abductor pollicis longus

Answer 9

- Origin: Dorsal surface of radius and ulna.
  Interosseus membrane.
- Insertion: Base metacarpal I.
- Action: Wrist: flexion and abduction.
  Carpometacarpal joint I: abduction.
- Innervation: Radial nerve.

Question 10

Extensor pollicis brevis

Answer 10

• Origin: Dorsal surface of radius. Interosseus membrane.
• Insertion: Base phalanx prox I.
• Action: Wrist: extension, abduction.
  Carpometacarpal and MCP joint I: extension.
• Innervation: Radial nerve.

Question 11

Extensor pollicis longus

Answer 11

• Origin: Dorsal surface of ulna. Interosseus membrane.
• Insertion: Base phalanx distal I.
• Action: Carpometacarpal joint I: adduction. MCP and IP I:
  extension. Wrist: extension, abduction.
• Innervation: Radial nerve.

Question 12

Extensor digiti minimi

Answer 12

• Origin: Lateral epicondyle of humerus.
• Insertion: Medial and distal phalanges V via dorsal
  aponeurosis.
• Action: Wrist: extension, ulnar deviation.
  MCP, PIP, DIP V: extension, abduction.
• Innervation: Radial nerve.

Question 13

Extensor indicis

Answer 13

• Origin: Dorsal surface of ulna. Interosseus membrane.
• Insertion: Dorsal aponeurosis II.
• Action: II: extension, adduction. Wrist: extension, abduction.
• Innervation: Radial nerve.

Question 14

Abductor pollicis brevis

Answer 14

Intrinsic, Thenar muscle.
From lateral carpal bones to thumb.
Action: Art. trapezium-MC: abduction. Art. MCP: synergic action with flexor.

Question 15

Adductor pollicis

Answer 15

Intrinsic, Thenar muscle.
From 3rd metacarpal to thumb.
Action: CMC I: opposition. MCP: flexion.

Question 16

Flexor pollicis brevis

Answer 16

Intrinsic, thenar muscle.
From carpal bones to to thumb.
Action: CMC I: flexion, opposition.

Question 17

Opponens pollicis

Answer 17

Intrinsic, thenar muscle.
From proximal carpal bones to 1st metacarpal.
Action: CMC I: opposition.

Question 18

Abductor digiti minimi

Answer 18

Intrinsic, hypothenar muscle.
From proximal carpal to 5th phalange.
Action: MCP V: flexion, ABD (PIP and DIP V: extension).

Question 19

Palmaris brevis

Answer 19

Intrinsic, hypothenar muscle.
Proximal part of 5th metacarpal. Horizontally.
Action: Tightens aponeurosis.

Question 20

Opponens digiti minimi

Answer 20

Intrinsic, hypothenar muscle.
From distal carpal to distal 5th metacarpal.
Action: MC: Opposition.

Question 21

Flexor digiti minimi

Answer 21

Intrinsic, hypothenar muscle.
From distal carpal to proximal 5th phalange.
Action MCP V: flexion, abduction.

Question 22

Lumbricales I-IV

Answer 22

Intrinsic muscle.
From middle tendons to phalanges 2-5.
Action: MCP II-V: flexion. PIP and DIP II-V: extension.

Question 23

Interossei dorsales I-IV

Answer 23

Intrinsic muscles.
From metacarpal 1-5 to phalanges 2-5.
Action: MCP II-IV: flexion. PIP and DIP II-IV: extension, ABD of II and IV.

Question 24

Interossei palmares I-III

Answer 24

Intrinsic muscles.
From metacarpal 2,4,5 to phalanges 2,4,5.
Action: MCP II, IV, V: flexion. PIP and DIP II, IV, V: extension and adduction for II and IV.