Abductor pollicis longus muscle Abductor pollicis longus muscle In human anatomy, the abductor pollicis longus (APL) is one of the extrinsic muscles of the hand. As the name implies, its major function is to abduct the thumb at the wrist. Its tendon forms the anterior border of the anatomical snuffbox. The abductor pollicis longus lies immediately below the supinator and is sometimes united with it. It arises from the lateral part of the dorsal surface of the body of the ulna below the insertion of the anconeus, from the interosseous membrane, and from the middle third of the dorsal surface of the body of
Anatomical plane Anatomical plane An anatomical plane is a hypothetical plane used to transect the human body, in order to describe the location of structures or the direction of movements. In human and animal anatomy, three principal planes are used: There could be any number of sagittal planes; however, there is only one cardinal sagittal plane. The term "cardinal" refers to the one plane that divides the body into equal segments, with exactly one half of the body on either side of the cardinal plane. The term "cardinal plane" appears in some texts as the "principal plane". The terms are interchangeable. The