Extensor+Digitorum

Origin
Lateral Epicondyle of the Humerus

Insertion
Posterior Base of 2-5 middle and distal phalanges

Action
Extension of the 2-5th middle and distal phalanges Extension of 2nd-5th proximal phalanges and the hand by it's continued action

Innervation
Radial Nerve (posterior interosseous)