Pinch Grip Test indicates pathology to which nerve segment?

• A. Anterior interosseous nerve of the median nerve
• B. Ulnar nerve
• C. Median nerve at the carpal tunnel
• D. Radial nerve

Answer: (A)

Pinch grip test targets the anterior interosseous nerve, a motor branch of the median nerve. This nerve supplies flexor pollicis longus and the lateral half of flexor digitorum profundus (index finger). When it is injured, those muscles can’t flex the thumb’s interphalangeal joint or the index finger’s distal interphalangeal joint, so a true tip-to-tip pinch can’t be formed. Instead, the thumb and index finger pinch with pads touching, because the flexor digitorum superficialis remains active while the FPL and lateral FDP are weak. This specific failure to achieve tip-to-tip pinch points to anterior interosseous nerve pathology, distinguishing it from other nerve injuries like the ulnar nerve, median nerve at the carpal tunnel, or the radial nerve, which produce different patterns of weakness.