Ulnar nerve palsy affects which digits with the classic clawing?

Ulnar nerve palsy affects which digits with the classic clawing?

• A. Ring and little fingers.
• B. Index and middle fingers.
• C. Thumb and index finger.
• D. Ring and middle fingers.

Answer: (A)

Ulnar nerve palsy causes clawing by destroying the intrinsic hand muscles that fine-tune finger movements, especially the interossei and the medial two lumbricals. Without these intrinsic muscles, the extensor digitorum can extend the metacarpophalangeal joints unopposed, while the finger flexors pull the interphalangeal joints into flexion, producing a claw-like posture. This pattern is most evident in the ring and little fingers because their intrinsic muscles are supplied by the ulnar nerve, whereas the index and middle fingers retain more function from the median nerve innervation, reducing clawing in those digits.

Ulnar nerve palsy causes clawing by destroying the intrinsic hand muscles that fine-tune finger movements, especially the interossei and the medial two lumbricals. Without these intrinsic muscles, the extensor digitorum can extend the metacarpophalangeal joints unopposed, while the finger flexors pull the interphalangeal joints into flexion, producing a claw-like posture. This pattern is most evident in the ring and little fingers because their intrinsic muscles are supplied by the ulnar nerve, whereas the index and middle fingers retain more function from the median nerve innervation, reducing clawing in those digits.