Extensor carpi radialis longus is one of the five main muscles that control movement at the wrist.
As the name suggests, this muscle is an extensor at the wrist joint, and travels along the radial side of the arm, so will also abduct the hand at the wrist.
This muscle is quite long, starting on the lateral side of the humerus, and attaching to the base of the 2nd metacarpal.
Being an extensor contained in the forearm, it is innervated by the radial nerve.
Blood is supplied by the radial artery.