<P> Many mammals, such as dogs, cattle, and pigs, have a fourth head, the accessory head . It lies between the lateral and medial heads . In humans, the anconeus is sometimes loosely called "the fourth head of the triceps brachii". </P> <Ul> <Li> Animation . Close up . Long head . Lateral head . Medial head . </Li> <Li> <P> Still image . Anterior view . </P> </Li> <Li> <P> Muscles on the dorsum of the scapula, and the Triceps brachii . </P> </Li> <Li> <P> Triceps and biceps . </P> </Li> <Li> <P> Movement of biceps and triceps when arm is flexing </P> </Li> </Ul> <Li> Animation . Close up . Long head . Lateral head . Medial head . </Li> <Li> <P> Still image . Anterior view . </P> </Li>

Triceps brachii insert on the olecranon process of the ulna and can act to