The lumbricals arise from the tendons of which muscle?

• A. Flexor digitorum profundus
• B. Flexor digitorum superficialis
• C. Extensor digitorum
• D. Flexor pollicis longus

Answer: (A)

Lumbricals originate from the tendons of the flexor digitorum profundus in the palm. From those tendon slips, they insert into the sides of the extensor expansions on digits 2–5. This arrangement lets them flex the metacarpophalangeal joints while extending the interphalangeal joints, which is how they fine-tune finger movements during grasp. The flexor digitorum superficialis provides tendons for flexing the proximal phalanges but does not serve as the origin for the lumbricals. The extensor digitorum is a separate dorsal muscle that extends the fingers and is not the source of lumbrical origins. The flexor pollicis longus acts on the thumb and likewise does not give rise to lumbricals of digits 2–5.