Posterior Full Body View of the Abductor Pollicis Longus

Description

Running along the posterolateral forearm, the abductor pollicis longus arises from the posterior surfaces of the ulna and radius and the intervening interosseous membrane, deep to extensor digitorum and extensor carpi ulnaris, then narrows into a tendon that courses distally toward the radial side of the wrist. At the distal forearm, its tendon sits lateral to extensor pollicis longus and in close company with extensor pollicis brevis as they approach the dorsoradial carpus. Proximally, the muscle belly lies inferior to the lateral epicondyle region, then tracks distally toward the base of the first metacarpal on the thumb ray. A clear dorsal landmark. Clinically, this posterior pathway matters because the abductor pollicis longus tendon, often paired with extensor pollicis brevis, forms the lateral boundary of the anatomical snuffbox and the tendinous compartment involved in De Quervain tenosynovitis at the radial styloid. That relationship guides palpation for snuffbox tenderness when screening for a suspected scaphoid fracture and helps explain why repetitive thumb abduction and wrist deviation can provoke pain and crepitus over the first dorsal compartment. For injection or surgical release, appreciating the tendon’s oblique distal course and its proximity to the superficial branch of the radial nerve reduces surprises. Ideal for upper-limb anatomy teaching in gross anatomy and kinesiology courses, and for illustrating clinical hand conditions in orthopedic, sports medicine, and occupational health publications where a posterior forearm-to-thumb line of pull needs to be unambiguous. Also fits patient-facing education on De Quervain management when paired with surface landmarks. Anatomical accuracy verified by SciePro's Medical Advisory Board.