Advanced Flexor Pollicis Longus Quiz

Q1. An anterior interosseous nerve lesion would most directly weaken which action of flexor pollicis longus?

• Abduction of the little finger
• Flexion of the thumb interphalangeal joint
• Extension of the thumb interphalangeal joint
• Extension of the index finger

Q2. A patient with anterior interosseous nerve palsy may have difficulty forming a normal tip-to-tip OK sign because of weakness of flexor pollicis longus and which other muscle component?

• Flexor digitorum superficialis to the little finger
• Extensor digitorum to the index finger
• Flexor digitorum profundus to the index finger
• First dorsal interosseous

Q3. What shape may the patient produce instead of a normal circular OK sign in anterior interosseous nerve palsy?

• A clenched fist with complete distal flexion
• A fully closed circular pinch
• A flattened or triangular pinch
• A wrist drop

Q4. Which finding helps distinguish an isolated anterior interosseous nerve palsy from a more extensive median nerve lesion?

• Complete anesthesia of the little finger
• Motor weakness without cutaneous sensory loss
• Loss of sensation over the anatomical snuffbox
• Complete sensory loss over the posterior forearm

Q5. A complete laceration of the flexor pollicis longus tendon distal to the wrist would cause which specific deficit?

• Loss of active thumb interphalangeal flexion
• Loss of wrist extension
• Loss of finger abduction
• Loss of active thumb interphalangeal extension

Q6. Which clinical maneuver most directly distinguishes flexor pollicis longus function from flexor pollicis brevis function?

• Testing wrist extension
• Testing isolated interphalangeal flexion of the thumb
• Testing finger abduction
• Testing forearm supination

Q7. Why is the flexor pollicis longus tendon clinically relevant to infections of the thumb flexor sheath?

• Its digital synovial sheath usually communicates with the radial bursa
• Its tendon communicates directly with the olecranon bursa
• Its tendon passes through Guyon's canal with the ulnar nerve
• Its tendon has no synovial covering

Q8. Which other muscle supplied by the anterior interosseous nerve lies in the deepest distal part of the anterior forearm?

• Flexor carpi ulnaris
• Palmaris longus
• Brachioradialis
• Pronator quadratus

Q9. Why can flexor pollicis longus assist with flexion at more proximal thumb joints?

• It inserts directly on every thumb bone
• Its tendon crosses the more proximal thumb joints before reaching the distal phalanx
• It attaches directly to the trapezium as its primary insertion
• It joins the extensor expansion of the thumb

Q10. Which description best summarizes the anatomy of flexor pollicis longus?

• It is a superficial posterior forearm muscle supplied by the radial nerve that extends the thumb
• It is an intrinsic thenar muscle supplied only by the recurrent median nerve
• It is a deep anterior forearm muscle supplied by the anterior interosseous nerve that inserts on the distal phalanx of the thumb and flexes its interphalangeal joint
• It is an ulnar nerve supplied wrist flexor inserting on the pisiform