A 43-year-old man had a previous injury to his wrist. The ulnar nerve was severed, as indicated by which of the following?: (A) Claw hand involving the ring and little fingers, (B) Claw hand involving the index and middle fingers, (C) Atrophy of the thenar muscles, (D) Absent sensation in the index finger
Answer is A. The lumbrical muscles arise from the flexor digitorum profundus tendons at a level distal to the small bones in the hand. The hypothenar muscles are on the ulnar side, and the thenar muscles are on the thumb side of the hand. The medial two lumbrical muscles are paralyzed, and this leads to the typical deformity.