Opponens pollicis muscle

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The opponens pollicis muscle is one of the muscles of the thenar eminence, deep to abductor pollicis brevis, and is one of the intrinsic muscles of the hand. The three muscles that constitute the thenar eminence muscle group are abductor pollicis brevis, flexor pollicis brevis and opponens pollicis.

Summary

  • origin: extends from the trapezial tubercle and flexor retinaculum
  • insertion: lateral border and adjoining lateral half of the palmar surface of the first metacarpal bone
  • innervation: lateral terminal branch of median nerve (C8 and T1) and commonly a ramus of the deep terminal branch of the ulnar nerve  (C8 and/or T1)
  • action: flexes the metacarpal bone medially across the palm, also rotating it medially, causing opposition, the palmar aspect of the terminal segment of thumb contacts the flexor aspects of any other digit