The abductores pollicis muscles. Clinical considerations based on electromyographical and anatomical studies.

The abductor pollicis longus (APL) muscle consists of two separate functional divisions with separate insertions. The muscle is composed of a deep and a superficial division. The APL and the abductor pollicis brevis (APB) are discussed in relation to assessment and clinical conditions on the basis of anatomic and electromyographic studies. It has been found that in some movements of the thumb and the hand, the function of the APL is related to the function of the APB, and vice versa. The APL is an important muscle for the function of the human thumb and hand, and knowledge of its function is important in clinical assessment and reconstructive surgery.