The triceps brachii (“three-headed muscle of the arm”) is the muscle on the back of your upper arm. Its main function is straightening your elbow. Each head has a different origin point near ...

Type 1 Medial head of the triceps remains posterior to the medial epicondyle with passive elbow flexion. Type 2 Triceps subluxates onto but not anterior to the medial epicondyle with elbow flexion.