Origin: Posterior surface of the Ulna, the radioulnar interosseous membrane and the middle third of posterior surface of the Radius
Insertion: Radial dorsal base of the Thumb Metacarpal, Variably the dorsal Trapezium and the radial surface of the Abductor pollicis longus muscle
Function: Abducts the thumb basal joint, along with other muscles which radially abduct the thumb. Also radially deviatesthe wrist along with other mucles which produce wrist radial abduction
Nerve: Posterior Interosseous Nerve
Artery: Posterior Interosseous artery