Ape hand deformity indicates injury to which nerve?

• A. Ulnar nerve
• B. Median nerve
• C. Radial nerve
• D. Musculocutaneous nerve

Answer: (B)

Ape hand deformity shows injury to the median nerve because the thumb’s opposition relies on the thenar muscles (opponens pollicis, abductor pollicis brevis, flexor pollicis brevis) that are innervated by the median nerve’s recurrent branch. When the median nerve is damaged proximally, these muscles weaken or atrophy, the thenar eminence flattens, and the thumb can’t oppose (it becomes adducted and lacks the fine rotation across the palm). This results in the characteristic ape-like appearance of the hand. Injuries to other nerves don’t produce this pattern: radial nerve injury causes wrist drop, ulnar nerve injury commonly leads to clawing of the ring and little fingers, and musculocutaneous injury affects forearm flexion/supination but not thumb opposition.