Muscle · Neck

Upper trapezius

Pars descendens musculi trapezii

The upper trapezius is the sloping muscle you can take hold of between the side of the neck and the point of the shoulder. It runs from the back of the skull and the ligament down the back of the neck out to the outer third of the collarbone, which means it does two jobs at once: it lifts the shoulder girdle — the shrug — and, working with the other side, helps hold the head up. That dual role is why it is usually the first muscle to complain about a desk, a phone, a heavy bag or a stressful week. It is also one of the accessory breathing muscles, recruited whenever breathing becomes shallow and high in the chest. Momentum's system treats tightness here as a symptom rather than the problem: the upper trapezius tends to be compensating for a lower trapezius and serratus anterior that are not doing their share.