100 Extensor pollicis longus
![](img/model2/no_100forearm.png)
Origin:
Posterior surface of middle third of ulna and interosseous membrane
Insertion:
Dorsal aspect of base of distal phalanx of thumb
Blood Supply:
Posterior interosseous artery
Innervation:
Posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve
Main Action:
Extends distal phalanx of thumb at interphalangeal joint; extends metacarpophalangeal and carpometacarpal joints