A 30-year-old man sustains a penetrating injury to the distal forearm and is unable to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. He also has weakness of the pronator quadratus. Sensation is intact over the thenar eminence. The injured structure is the:

• A Median nerve proper
• B Deep branch of ulnar nerve
• C Recurrent motor branch of median nerve
• D Anterior interosseous nerve ✓

Explanation

The anterior interosseous nerve (a purely motor branch of the median nerve in the forearm) supplies flexor pollicis longus, index and middle FDP, and pronator quadratus. Its lesion spares sensation (median proper sensory branches arise proximally) and spares thenar muscles (recurrent branch arises distally at the carpal tunnel).

Reference: Campbell's Operative Orthopaedics, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.