Wartenberg's test is used to assess entrapment of which nerve?

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

Answer: (B)

Wartenberg's test evaluates the intrinsic hand muscles supplied by the ulnar nerve, especially the interossei that control finger abduction and adduction. If the ulnar nerve is entrapped or damaged, these interossei weaken, making it difficult for the little finger to adduct toward the ring finger or to maintain that position when tested. This weakness is what the test is designed to reveal, so a positive finding points to ulnar nerve involvement. In contrast, other nerves innervate different muscle groups (radial for extension, median for many thenar and lateral lumbricals, musculocutaneous for forearm flexors), so they don’t produce this specific interossei-related deficit.