The adductor pollicis is a triangular muscle located in the hand that plays a key role in thumb movement, particularly in adduction (bringing the thumb toward the palm or index finger). Anatomy • Origin: • Oblique head: Bases of the 2nd and 3rd metacarpal bones, capitate, and adjacent carpal bones. • Transverse head: Anterior surface of the shaft of the 3rd metacarpal bone. • Insertion: Medial side of the base of the proximal phalanx of the thumb and the extensor expansion. Innervation • Nerve: The adductor pollicis is innervated by the deep branch of the ulnar nerve (C8, T1). Blood Supply • Arteries: Supplied by branches of the deep palmar arch. Action • Adducts the thumb at the carpometacarpal (CMC) and metacarpophalangeal (MCP) joints. • Contributes to grip strength by helping to oppose the thumb during tasks like pinching or grasping objects. Clinical Relevance • Weakness or atrophy of the adductor pollicis may be observed in conditions involving ulnar nerve damage, such as cubital tunnel syndrome or ulnar nerve entrapment.
