Abductor Pollicis Brevis Muscle, Anterior View

Description

Arising from the flexor retinaculum and the tubercles of the scaphoid and trapezium, the abductor pollicis brevis occupies the superficial thenar eminence on the palmar (anterior) aspect of the male hand. Its muscle belly lies lateral to the central palmar aponeurosis and anterior to the carpal bones, then narrows distally into a tendon that passes toward the radial side of the thumb. Insertion occurs on the lateral base of the proximal phalanx of the thumb, often blending with the lateral sesamoid and the extensor expansion, placing the tendon anterior to the first metacarpal and metacarpophalangeal joint. Palmar orientation makes the relationship to the carpal tunnel and flexor retinaculum easy to teach, since abductor pollicis brevis forms part of the roof of the tunnel while the median nerve courses deep to the retinaculum and then supplies the muscle via its recurrent branch. That recurrent thenar motor branch is at risk during open and endoscopic carpal tunnel release, and denervation produces thenar wasting with loss of palmar abduction, the clinical pattern many clinicians look for at the bedside. A clear landmark. For anatomy lab manuals and hand surgery texts, this anterior view supports explanations of thenar compartment boundaries, tendon insertions on the proximal phalanx, and how abductor pollicis brevis contributes to precision grip and opposition mechanics alongside opponens pollicis and flexor pollicis brevis. It also fits EMG teaching sets and neurologic exam guides that compare median nerve thenar function against ulnar innervation of adductor pollicis. Anatomical accuracy verified by SciePro's Medical Advisory Board.