Clinical aspects of muscle imbalance in the hand due to ulnar nerve lesions and a proposed thumb-index finger grip classification.

This study deals with the anatomical and clinical bases of the thumb-index finger grip, emphasizing not only its general importance, but also its ergonomic role. A classification according to the different functions of two muscular groups (extrinsic and intrinsic), with special reference to muscular imbalance due to ulnar nerve lesions is proposed. After some general considerations on the function of the hand practical conclusions are drawn.