Tendon of triceps brachii

The triceps brachii tendon is the distal tendinous structure of the triceps brachii muscle, responsible for transmitting force from the muscle to the olecranon process of the ulna, enabling elbow extension.

The triceps brachii tendon is formed by contributions from all three muscle heads—long, lateral, and medial. The tendon is composed of a thick intramuscular tendon (between the long and medial heads) and a thinner superficial aponeurosis (from the lateral and medial heads), with the intramuscular tendon curving medially to laterally and inserting broadly onto the proximal and lateral facets of the olecranon via fibrocartilage. The superficial aponeurosis merges distally with the aponeurosis of the anconeus muscle.

At the insertion, the medial head has a distinct, deep insertion that is mainly muscular at its distal extent, while the long and lateral heads form a conjoined superficial tendon. Histologically, these structures are confluent at the olecranon, resulting in a single, broad tendon footprint.