CHT CHT Hand Anatomy & Biomechanics 1 — Questions and Answers
Question 1: Which pulley in the flexor tendon sheath is considered the most biomechanically critical for efficient finger flexion?
- A1 pulley
- A2 pulley (Correct answer)
- A4 pulley
- C1 pulley
Correct answer: A2 pulley
The A2 pulley, located over the proximal phalanx, is the most critical annular pulley because its integrity prevents bowstringing of the flexor tendon during finger flexion.
Question 2: The intrinsic muscles of the hand are primarily responsible for which combined finger motion?
- IP extension with MCP flexion (Correct answer)
- MCP extension with IP flexion
- Full composite flexion
- Wrist radial deviation
Correct answer: IP extension with MCP flexion
The intrinsic muscles (lumbricals and interossei) produce MCP flexion combined with IP extension, enabling the intrinsic-plus hand posture.
Question 3: Which carpal bone is most commonly fractured and is at high risk for avascular necrosis due to its retrograde blood supply?
- Lunate
- Scaphoid (Correct answer)
- Capitate
- Trapezium
Correct answer: Scaphoid
The scaphoid receives its blood supply distally and retrogradely, so proximal pole fractures disrupt perfusion and risk avascular necrosis.
Question 4: The ulnar nerve provides motor innervation to all of the following EXCEPT:
- Hypothenar muscles
- Dorsal interossei
- Abductor pollicis brevis (Correct answer)
- Palmaris brevis
Correct answer: Abductor pollicis brevis
The abductor pollicis brevis is innervated by the median nerve (recurrent motor branch), not the ulnar nerve.
Question 5: The normal range of motion for metacarpophalangeal (MCP) flexion in the index finger is approximately:
- 50–60°
- 70–80°
- 85–90° (Correct answer)
- 95–100°
Correct answer: 85–90°
Normal MCP flexion in the index finger ranges from approximately 85° to 90°, progressively increasing toward the small finger.
Question 6: Which structure forms the floor of the carpal tunnel?
- Flexor retinaculum
- Palmar fascia
- Carpal bones (Correct answer)
- Transverse carpal ligament
Correct answer: Carpal bones
The carpal bones form the floor (dorsal wall) of the carpal tunnel, while the flexor retinaculum (transverse carpal ligament) forms the roof.
CHT CHT Hand Anatomy & Biomechanics 1
Which pulley in the flexor tendon sheath is considered the most biomechanically critical for efficient finger flexion?