Image of some  Muscles Abductor s Forearm and Hand Source: Wikimedia  Commons  Public  Domain Details:   Click Here Forearm Muscles Abductors "Thumb Abductor length" Long abductor muscle of thumb (APL), is one of the extrinsic muscles (external) of the hand. It is just below the supinator muscle and is sometimes united with him. Muscle origin and insertion Thumb Abductor Abductor muscle of thumb, originates from the side of the dorsal surface of the body below the insertion of the ulnar Anconæus. Interosseous membrane, and the middle third of the dorsal surface of the body of radio. Passing obliquely downward and laterally, ending in a tendon, which runs through a slot in the side of the lower end of the radio, accompanied by the tendon of extensor pollicis brevis, and inserted into the radial side of the base first metacarpal bone. From time to time issued two sheets near its insertion: A multi-angle ...