Name
Pronunciation
(eks-TEN-sor POL-uh-sus LONG-gus)
Origin/Proximal Attachment
Postero-lateral surface of ulnaInterosseous membraneAntebrachial fascia
Insertion/Distal Attachment
Distal phalanx of thumb
Action/Relevance
Extends distal phalanx of thumbExtends distal phalanx of thumbAssists to extend the hand at the wrist
Innervation
Radial nerve - posterior interosseous (C6, 7,8)
Notes
Extensor pollicis longus arises from the middle posterior ulna surface below abductor pollicis longus. It passes distally and radially. It inserts into the dorsal base of the distal phalanx of the thumb and on route uses the tubercle of the radius as a pulley.
It acts to extend the metacarpophalangeal joints and interphalangeal joints of the thumb.
Extensor pollicis longus is supplied by the posterior interosseous nerve (C7,C8), a branch of the radial nerve.
Spontaneous rupture may occur and it is thought to be secondary to ischaemia of the interosseous vessels or fraying of the tendon after a Colles' fracture or rheumatoid arthritis: 'thumb drop' may occur. Tendon transfer of extensor indicis may be required.