Origin: Lateral head: posterior humerus
Insertion: Olecranon process of ulna
Artery: Profunda brachii
Nerve: Radial nerve
Action: Extends forearm
Antagonist: Biceps brachii muscle
The lateral head arises from the posterior surface of the body of the humerus, between the insertion of the Teres minor and the upper part of the groove for the radial nerve, and from the lateral border of the humerus and the lateral intermuscular septum; the fibers from this origin converge toward the tendon of insertion.