Anterior Perspective of the Oblique Head of the Adductor Pollicis

Description

Arising from the capitate and the bases of the second and third metacarpals, the oblique head of adductor pollicis runs distally and laterally across the deep palm toward the ulnar sesamoid at the metacarpophalangeal joint of the thumb. Its tendon blends with the ulnar side of the extensor expansion and inserts on the base of the proximal phalanx, sitting deep to the long flexor tendons and the palmar aponeurosis. Superficial and radial to it lie the thenar muscles (flexor pollicis brevis and opponens pollicis), while the first dorsal interosseous sits dorsolaterally at the first web space. Bone and pulley landmarks remain readable. Pinch strength lives here. The deep branch of the ulnar nerve typically courses adjacent to the adductor pollicis as it sweeps across the palm, so an ulnar neuropathy at Guyon canal or a deep palmar laceration can selectively denervate this muscle and produce a positive Froment sign, with compensatory flexion of the thumb interphalangeal joint by flexor pollicis longus. Surgeons also care about this layer during approaches to the deep palmar space and when tracking the relationship of the adductor compartment to the deep palmar arterial arch and princeps pollicis artery. Hand anatomy faculty can drop this plate straight into a thenar and midpalmar compartment lecture to clarify why the adductor pollicis is a deep palmar muscle rather than a thenar muscle. It also supports operative teaching files for ulnar nerve motor branch injuries, tendon balancing in thumb reconstruction, and rehabilitation content focused on key pinch mechanics and metacarpophalangeal joint stability. Anatomical accuracy verified by SciePro's Medical Advisory Board.