Origin: Long head: scapula
Insertion: Olecranon process of ulna
Artery: Profunda brachii
Nerve: Radial nerve
Action: Extends forearm, caput longum adducts shoulder
Antagonist: Biceps brachii muscle
The long head arises by a flattened tendon from the infraglenoid tuberosity of the scapula, being blended at its upper part with the capsule of the shoulder-joint; the muscular fibers pass downward between the two other heads of the muscle, and join with them in the tendon of insertion.