Advanced Adductor Pollicis Quiz

Q1. A patient flexes the thumb interphalangeal joint while trying to hold a sheet of paper between the thumb and index finger. Weakness of which muscle is this maneuver designed to reveal?

• Adductor pollicis
• Abductor pollicis longus
• Pronator quadratus
• Extensor pollicis longus

Q2. Why does thumb interphalangeal flexion occur in a positive Froment sign?

• Extensor pollicis longus compensates by flexing the thumb
• Abductor pollicis brevis produces interphalangeal flexion
• Flexor pollicis longus compensates for weak thumb adduction
• First dorsal interosseous directly flexes the distal thumb phalanx

Q3. Which nerve supplies the compensating muscle responsible for thumb interphalangeal flexion in Froment sign?

• Superficial branch of the radial nerve
• Anterior interosseous nerve
• Posterior interosseous nerve
• Deep branch of the ulnar nerve

Q4. An isolated lesion of the deep branch of the ulnar nerve in the hand would most directly impair which adductor pollicis function?

• Forceful thumb adduction during key pinch
• Thumb interphalangeal flexion
• Thumb interphalangeal extension
• Forearm supination

Q5. Which anatomical relationship of the radial artery is important when exposing the adductor pollicis surgically?

• It passes through the carpal tunnel with the median nerve
• It passes between the oblique and transverse heads
• It terminates within the transverse head
• It passes superficial to the palmar aponeurosis

Q6. Which movement would be most weakened by paralysis of adductor pollicis while median-innervated thenar muscles remain intact?

• Supination of the forearm
• Extension of the thumb interphalangeal joint
• Extension of the wrist
• Adduction of the thumb against resistance

Q7. Why is adductor pollicis especially important during a lateral, or key, pinch?

• It extends the index finger against the thumb
• It flexes the distal phalanx of the index finger
• It abducts the thumb away from the hand
• It presses the thumb toward the index finger

Q8. A patient has weak thumb adduction but preserved thumb interphalangeal flexion. Which combination best explains these findings?

• Posterior interosseous nerve dysfunction with preserved radial sensory function
• Ulnar motor dysfunction with preserved anterior interosseous nerve function
• Anterior interosseous nerve dysfunction with preserved ulnar motor function
• Axillary nerve dysfunction with preserved musculocutaneous function

Q9. Which finding most specifically demonstrates preserved adductor pollicis function during examination?

• Strong wrist extension
• Strong index finger abduction alone
• Strong key pinch without compensatory thumb interphalangeal flexion
• Strong thumb interphalangeal extension

Q10. Which description best summarizes the anatomy of adductor pollicis?

• It is a two-headed intrinsic hand muscle supplied by the deep branch of the ulnar nerve that primarily adducts the thumb
• It is a superficial forearm muscle supplied by the median nerve that primarily abducts the thumb
• It is a posterior forearm muscle supplied by the posterior interosseous nerve that extends the thumb
• It is a hypothenar muscle supplied by the superficial radial nerve that flexes the little finger