Oblique Head of Adductor Pollicis (Caput obliquum musculi adductoris pollicis)
Educational content only — not medical advice.
Anatomy
The larger head of the adductor pollicis, arising from the capitate and the bases of the second and third metacarpals and converging with the transverse head onto the ulnar sesamoid of the thumb. It lies deep in the adductor compartment, its fibres fanning toward the thumb — the muscle that pins the thumb against the index finger in every firm pinch.
Origin & insertion
From the capitate and the bases of the second and third metacarpals, to the ulnar base of the proximal phalanx of the thumb with the ulnar sesamoid.
Action
Adducts the thumb toward the index finger and assists metacarpophalangeal flexion.
Innervation
Deep branch of the ulnar nerve (C8–T1).
Clinical notes
The ulnar sesamoid lodged in its insertion is the radiographic partner of the radial sesamoid; their separation on the film tracks the severity of a first-web-space contracture. Weakness of this head blunts key pinch long before grip is affected.
Related structures
Educational references
FAQ
What is the role of the Oblique Head of Adductor Pollicis?
The larger head of the adductor pollicis, arising from the capitate and the bases of the second and third metacarpals and converging with the transverse head onto the ulnar sesamoid of the thumb. It lies deep in the adductor compartment, its fibres fanning toward the thumb — the muscle that pins the thumb against the index finger in every firm pinch.
Why is the Oblique Head of Adductor Pollicis clinically important?
The ulnar sesamoid lodged in its insertion is the radiographic partner of the radial sesamoid; their separation on the film tracks the severity of a first-web-space contracture. Weakness of this head blunts key pinch long before grip is affected.
Source & license
BodyParts3D, © The Database Center for Life Science licensed under CC Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/). license details