The deformity shown below can be due to involvement of which nerve?
A. Ulnar nerve
B. Median nerve
C. Radial nerve
D. Musculocutaneous nerve
Ans: A. Ulnar nerve
(Ref Gray’s 40/e p837, 888)
- Hyperextension of 4th and 5th metacarpophalangeal joint with flexion at proximal interphalangeal joint is suggestive of claw hand. This deformity is due to injury of deep branch of ulnar nerve.
Ulnar claw hand:
- Division of the nerve at the elbow paralyses flexor carpi ulnaris, flexor digitorum profundus to the ring and little fingers and all the intrinsic muscles of the hand (apart from the radial two lumbricals).
- The clawing of the hand is less intense than occurs after division of the ulnar nerve at the wrist, reflecting the imbalance in action between the long flexors and extensors to the ring and little fingers when finger flexion is produced only by superficialis.
- In addition there is sensory loss over the little finger and the ulnar half of the ring finger.