Triceps Brachii Muscles

The triceps brachii has three heads (connective immovable muscle) and is the only muscle on the back of the upper arm. It connects the humerus (upper arm bone) and the scapula (shoulder blade) to the ulna (longest of the forearm bones) and is the primary extensor of the elbow. The three heads are the "lateral," the "medial," and the "long head."