A 26-year-old man with borderline tuberculoid leprosy notices progressive weakness of his right hand. Examination shows hyperextension at the metacarpophalangeal joints with flexion at the interphalangeal joints of the ring and little fingers, and inability to adduct the thumb. Which nerve is involved?
- A Median nerve at the carpal tunnel
- B Radial nerve in the spiral groove
- C Ulnar nerve at the elbow ✓
- D Posterior interosseous nerve
Correct answer: C. Ulnar nerve at the elbow
Explanation
Ulnar nerve palsy produces the classic claw hand deformity of the ring and little fingers: hyperextension at the MCP joints with flexion at the IP joints, caused by paralysis of the interossei and medial lumbricals, plus loss of thumb adduction via adductor pollicis. In leprosy, the ulnar nerve is palpably thickened near the elbow. Median palsy gives ape thumb, radial palsy gives wrist drop, and posterior interosseous palsy spares finger flexion.
Reference: IAL Textbook of Leprosy, 2nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.