Review Question - QID 7825

A Wartenberg's sign, where the little finger is held in an abducted position, is associated with an ulnar nerve palsy. This happens when there is an accessory slip of the extensor digiti minimi, which is innervated by the radial nerve, crossing ulnar to the center of the MCP joint to attach to the tendon of the abductor digiti minimi and the proximal phalanx. The abductor digiti minimi and the volar interosseous muscles are both innervated by the ulnar nerve; therefore, there is no tetanic contraction of the abductor digiti minimi. Unopposed pull of the flexor digitorum profundus results in excess flexion of the proximal interphalangeal and distal interphalangeal joints of the hand as seen with a clawing-type deformity. A Martin-Gruber anastomosis, which is a neural connection between the ulnar and median nerves in the forearm, cannot explain this finger position.