Male Abductor Pollicis Longus Muscle, Posterior View

Description

Posterior forearm anatomy is centered on the abductor pollicis longus arising from the posterior surfaces of the ulna and radius and the adjacent interosseous membrane, then running obliquely distally and laterally toward the radial side of the wrist. Its tendon courses deep to the extensor retinaculum within the first dorsal compartment, lying alongside the extensor pollicis brevis as both pass over the dorsolateral aspect of the distal radius near the radial styloid. Proximally, the muscle belly sits lateral to extensor digitorum and medial to brachioradialis and extensor carpi radialis longus and brevis, before narrowing toward its insertion at the base of the first metacarpal at the thumb. Clean lines. Clear relationships. Posterior orientation matters because abductor pollicis longus is a primary landmark for the lateral wrist and thumb base, where tendon pathology is common and anatomy can be clinically deceptive. Thickening of the first dorsal compartment retinaculum and friction between the abductor pollicis longus and extensor pollicis brevis contribute to De Quervain tenosynovitis, and this angle supports understanding of why pain localizes over the radial styloid and why corticosteroid injection targets that compartment. The distal tendon also helps explain thumb carpometacarpal biomechanics, including how excessive pull can accentuate radial deviation at the wrist and influence basal thumb osteoarthritis symptoms. Ideal use cases include gross anatomy and upper limb dissection teaching, hand surgery and sports medicine lecture slides, and atlas-style figures for chapters on wrist tendinopathies and first dorsal compartment release. The posterior view also pairs well with ultrasound or MRI correlates when discussing the extensor retinaculum and dorsal compartments in radiology education. Anatomical accuracy verified by SciePro's Medical Advisory Board.