Advanced Extensor Carpi Ulnaris Quiz

Q1. What specialized structure helps stabilize the extensor carpi ulnaris tendon in its groove at the distal ulna?

• Flexor retinaculum
• Extensor carpi ulnaris subsheath
• Bicipital aponeurosis
• Transverse carpal ligament

Q2. Injury to the extensor carpi ulnaris subsheath can result in which abnormality?

• Rupture of the biceps tendon
• Dislocation of the median nerve from the carpal tunnel
• Subluxation of the extensor carpi ulnaris tendon
• Dislocation of the radial head in every case

Q3. Which symptom is commonly associated with extensor carpi ulnaris tendinopathy?

• Anterior shoulder pain only
• Isolated numbness of the thenar eminence
• Loss of sensation over the lateral arm
• Ulnar-sided wrist pain

Q4. A lesion of the posterior interosseous nerve can directly weaken which action of extensor carpi ulnaris?

• Wrist extension with ulnar deviation
• Forearm pronation
• Thumb opposition
• Wrist flexion with radial deviation

Q5. Why may attempted wrist extension become radially deviated when extensor carpi ulnaris is significantly weakened?

• Pronator quadratus directly extends the wrist
• Flexor carpi ulnaris becomes a radial deviator
• The median nerve becomes the primary wrist extensor
• The radial wrist extensors act without adequate ulnar opposition

Q6. Why can wrist extension remain possible despite isolated paralysis of extensor carpi ulnaris?

• Palmaris longus becomes the primary wrist extensor
• Pronator teres substitutes for wrist extension
• Flexor carpi ulnaris becomes a wrist extensor
• The radial wrist extensors can still extend the wrist

Q7. Which combination of muscles can produce ulnar deviation with relatively little net flexion or extension?

• Extensor carpi ulnaris and flexor carpi ulnaris
• Brachioradialis and brachialis
• Extensor carpi radialis longus and flexor carpi radialis
• Pronator teres and supinator

Q8. Which combination can produce wrist extension with relatively little radial or ulnar deviation?

• Pronator quadratus with supinator
• Extensor carpi ulnaris with the radial wrist extensors
• Flexor carpi ulnaris with flexor carpi radialis
• Flexor digitorum profundus with palmaris longus

Q9. Why can extensor carpi ulnaris pathology be difficult to distinguish from other causes of ulnar-sided wrist pain?

• Its tendon forms the floor of the anatomical snuffbox
• Its tendon passes through the carpal tunnel with the median nerve
• Its tendon inserts directly into the triangular fibrocartilage complex
• Its tendon lies near other clinically important ulnar-sided wrist structures

Q10. Which description best summarizes the anatomy of extensor carpi ulnaris?

• It is an intrinsic hand muscle supplied by the ulnar nerve that abducts the little finger
• It is a superficial posterior forearm muscle supplied by the posterior interosseous nerve that inserts on the fifth metacarpal and extends and ulnarly deviates the wrist
• It is a deep anterior forearm muscle supplied by the median nerve that inserts on the second metacarpal and flexes the wrist
• It is a superficial anterior forearm muscle supplied by the median nerve that inserts on the third metacarpal and radially deviates the wrist