Muscle · Shoulders

Triceps brachii

Musculus triceps brachii

The three-headed muscle filling the back of the upper arm and the only significant extensor of the elbow — everything you push away from you goes through it. Two of its heads arise from the humerus, but the long head comes off the shoulder blade, so it also helps pull the arm backward and steadies the shoulder when you press overhead. All three converge on a single strong tendon that anchors onto the point of the elbow.