CHT CHT Hand Anatomy & Biomechanics 2 — Questions and Answers
Question 1: The radial nerve innervates which muscle that is commonly tested in high radial nerve palsy?
- Flexor carpi radialis
- Extensor carpi radialis longus (Correct answer)
- Pronator teres
- Flexor pollicis longus
Correct answer: Extensor carpi radialis longus
The extensor carpi radialis longus is innervated by the radial nerve proximal to the lateral epicondyle and is used to assess the level of radial nerve palsy.
Question 2: During pinch, the first dorsal interosseous muscle is responsible for:
- Thumb opposition
- Index finger radial abduction (Correct answer)
- MCP hyperextension of the index
- Thumb IP flexion
Correct answer: Index finger radial abduction
The first dorsal interosseous abducts the index finger radially, stabilizing it during lateral (key) pinch against the thumb.
Question 3: The proximal interphalangeal (PIP) joint is a hinge joint whose stability is primarily provided by:
- Volar plate and collateral ligaments (Correct answer)
- Extensor hood only
- A2 and A4 pulleys
- Dorsal capsule alone
Correct answer: Volar plate and collateral ligaments
PIP joint stability relies on the volar plate preventing hyperextension and the proper collateral ligaments resisting lateral stress.
Question 4: Which forearm rotation motion is primarily performed by the supinator muscle?
- Pronation
- Supination with elbow extended (Correct answer)
- Supination with elbow flexed
- Radial deviation
Correct answer: Supination with elbow extended
The supinator muscle is the primary supinator when the elbow is extended; biceps brachii becomes more effective at supination with the elbow flexed.
Question 5: Froment's sign is used to assess the integrity of which muscle, indicating ulnar nerve dysfunction?
- Opponens pollicis
- Adductor pollicis (Correct answer)
- Abductor pollicis brevis
- Flexor pollicis longus
Correct answer: Adductor pollicis
Froment's sign tests the adductor pollicis; when weakened from ulnar nerve palsy, the patient compensates with FPL flexion to maintain lateral pinch.
Question 6: The anatomic snuffbox is bordered by which two structures?
- EPL and EPB/APL (Correct answer)
- FCR and FCU
- ECRL and ECRB
- EDC and EI
Correct answer: EPL and EPB/APL
The anatomic snuffbox is bounded by extensor pollicis longus (EPL) ulnarly and extensor pollicis brevis/abductor pollicis longus (EPB/APL) radially, overlying the scaphoid.
CHT CHT Hand Anatomy & Biomechanics 2
The radial nerve innervates which muscle that is commonly tested in high radial nerve palsy?