Transverse Head of the Abductor Pollicis, Anterior View

Description

Framed from an anterior (palmar) angle in a male hand, the transverse head of the adductor pollicis occupies the deep plane of the thenar compartment, running transversely along the shafts of the second and third metacarpals toward the ulnar base of the proximal phalanx of the thumb. Medially it lies adjacent to the intermetacarpal spaces and the dorsal interossei, while laterally it approaches the first metacarpal and the deep surface of flexor pollicis brevis and opponens pollicis. Distally, its tendon blends with the ulnar sesamoid and the extensor expansion of the thumb at the metacarpophalangeal joint. The deep branch of the ulnar nerve and branches of the deep palmar arch course in close proximity. A tight neighborhood. This anterior view matters when you are teaching or planning around pinch mechanics and ulnar-innervated intrinsic function, because the transverse head provides the transverse vector that stabilizes the thumb metacarpophalangeal joint during key pinch. Ulnar nerve lesions at Guyon canal or the deep motor branch classically weaken adductor pollicis, producing a positive Froment sign as flexor pollicis longus substitutes and the interphalangeal joint of the thumb flexes during paper pull. The same anatomical relationships guide operative dissection for deep palmar lacerations and for approaches around the adductor interval when addressing thumb metacarpophalangeal instability. Use this asset in hand anatomy teaching for medical or occupational therapy curricula, in surgical atlases covering ulnar nerve palsy and intrinsic muscle testing, or in clinical education materials explaining pinch weakness after ulnar-sided palm trauma. Anatomical accuracy verified by SciePro's Medical Advisory Board.