Advanced Extensor Indicis Quiz

Q1. A lesion of the posterior interosseous nerve would most directly weaken which action of extensor indicis?

• Extension of the index finger
• Adduction of the little finger
• Opposition of the thumb
• Flexion of the index finger

Q2. Why may some index finger extension remain possible after isolated loss of extensor indicis function?

• Flexor digitorum profundus becomes an extensor
• Extensor digitorum also extends the index finger
• Pronator quadratus substitutes for finger extension
• Flexor carpi radialis extends the index finger

Q3. Why is the extensor indicis tendon commonly considered suitable for certain tendon transfer procedures?

• Its tendon normally flexes the thumb
• Its removal eliminates all index finger movement
• Extensor indicis has no function in the normal hand
• The index finger usually retains extension through extensor digitorum

Q4. Extensor indicis tendon transfer is classically used to restore function after rupture of which tendon?

• Extensor pollicis longus
• Flexor pollicis longus
• Abductor pollicis brevis
• Flexor carpi ulnaris

Q5. What functional deficit may remain after extensor indicis is harvested for tendon transfer?

• Complete loss of thumb opposition
• Complete loss of wrist flexion
• Reduced independent extension of the index finger
• Loss of forearm pronation

Q6. Why can posterior interosseous nerve palsy impair index finger extension without producing a cutaneous sensory deficit in the hand?

• Index finger extension is independent of peripheral nerves
• The posterior interosseous nerve is predominantly motor
• Extensor indicis is supplied by the median nerve
• The radial nerve has no sensory fibers

Q7. Which structure stabilizes the extensor tendons over the metacarpal head at the index metacarpophalangeal joint?

• Annular ligament of the radius
• Transverse carpal ligament
• Flexor retinaculum
• Sagittal bands

Q8. Why can extensor indicis contribute to extension at both interphalangeal joints of the index finger?

• Its tendon contributes to the extensor expansion
• Its tendon enters the flexor sheath
• It inserts directly into the flexor retinaculum
• It attaches to the palmar aponeurosis

Q9. Which finding most specifically suggests preserved extensor indicis function during examination?

• Resisted ulnar deviation of the wrist
• Resisted thumb opposition
• Resisted flexion of all four fingers together
• Independent resisted extension of the index finger

Q10. Which description best summarizes the anatomy of extensor indicis?

• It is a superficial posterior forearm muscle arising from the lateral epicondyle and inserting on the fifth metacarpal
• It is a superficial anterior forearm muscle supplied by the median nerve that flexes the index finger
• It is an intrinsic hand muscle supplied by the ulnar nerve that abducts the index finger
• It is a deep posterior forearm muscle supplied by the posterior interosseous nerve that joins the extensor expansion of the index finger