Transverse Head of the Abductor Pollicis, Anterior View

Description

Centered in the first web space of the male hand, the highlighted muscle belly corresponds to the transverse head of adductor pollicis, lying deep to the thenar eminence and spanning from the palmar aspect of the third metacarpal toward the ulnar (medial) side of the base of the proximal phalanx of the thumb. Its fibers run predominantly transverse across the palm, anterior to the metacarpals and intermetacarpal ligaments, and converge on a tendon that blends with the ulnar sesamoid and the extensor expansion at the thumb metacarpophalangeal joint. Adjacent bony landmarks include the first and second metacarpals laterally, the proximal phalanges distally, and the carpal row proximally, with joint surfaces subtly indicated where cartilage caps the articular margins. Deep relationships with the first dorsal interosseous and the oblique head of adductor pollicis are implied by the muscle’s position between the thumb and index metacarpals. Clear landmarks. Palmar, anterior emphasis on this structure matters because the transverse head is a primary contributor to pinch strength and stabilizes the thumb metacarpophalangeal joint during key pinch, a function that becomes clinically obvious in ulnar nerve palsy when adductor pollicis weakness produces a positive Froment sign. Surgeons also rely on this anatomy during approaches to the first web space and in tendon transfers or trauma reconstruction, where preserving the deep motor branch of the ulnar nerve and understanding the adductor’s insertion into the ulnar sesamoid can prevent postoperative instability or loss of pinch. Use this anterior hand illustration for gross anatomy and upper limb teaching modules on thenar and deep palmar compartments, for exam figures contrasting abductor pollicis brevis versus adductor pollicis, or for clinical handouts on ulnar neuropathy affecting pinch mechanics. It also fits operative atlases discussing first web space release, thumb metacarpophalangeal stabilization, and tendon transfer planning. Anatomical accuracy verified by SciePro's Medical Advisory Board.