Summary Extensor Pollicis Longus Origin Posterior surface of middle 1/3 of ulna and interosseous membrane Insertion Base of distal phalanx of thumb Action Extends distal phalanx of thumb at metacarpophalangeal and interphalangeal joints Innervation Posterior interosseous nerve (C7, C8) Arterial supply Posterior interosseous artery
Extensor Pollicis Longus summary OBC What is the origin? Origin Posterior surface of middle 1/3 of ulna and interosseous membrane Show Bullets