Upper TrapeziusDescending Part of Trapezius

backPars descendens musculi trapezii

The upper trapezius is the slope of muscle from the back of your neck to the point of your shoulder. It lifts the shoulder — the shrug — and it is what most people mean when they say traps.

Upper Trapezius highlighted on an anatomical figure, from behind.
Where it sits, from behind.

These are the fibres that run down from the base of the skull and the back of the neck and attach outward onto the collarbone. They are the visible part of the trapezius: the slope between neck and shoulder that thickens noticeably on people who lift.

Its familiar job is the shrug. Lift your shoulders toward your ears and this is what does it. Because the fibres also run forward onto the collarbone rather than onto the shoulder blade itself, it pulls the shoulder up and slightly backward, which is why a shrug performed with the shoulders rolling forward feels different from one performed straight up.

There is a technical point worth stating plainly because it is where a lot of confusing writing comes from. The upper trapezius does not attach to the shoulder blade at all — it attaches to the collarbone, and the collarbone is joined to the shoulder blade at the tip of the shoulder. So its effect on the shoulder blade is indirect, transmitted through that joint. Some texts describe it as elevating the scapula and others as elevating the clavicle. Both descriptions are describing the same thing.

It also has a second life as a neck muscle. With the shoulder anchored, it tips the head back and to the side, which is why the upper trapezius and the neck are so often discussed together.

Training notes

Shrugs are the direct movement and they need less complication than they usually get. Straight up and straight down, a pause at the top, and enough range that the shoulders genuinely finish lower than they started. Rolling the shoulders adds motion that the muscle is not producing.

The upper traps also get substantial work from anything heavy held in the hands. Farmer's carries, heavy deadlifts and rack pulls all load them isometrically for long stretches, which is why lifters who never shrug often have well-developed upper traps anyway.

The persistent myth here is that big upper traps cause or reveal bad posture. They do not. The imbalance worth caring about is training the upper fibres without training the middle and lower fibres, because those are the ones holding the shoulder blade back and down against a day spent reaching forward.

Upright rows are often prescribed for the upper traps and are a mediocre choice for them: much of the load goes to the deltoid, and the position the shoulder is taken into is one many people find uncomfortable at heavier weights. A shrug and a lateral raise separately cover what an upright row is trying to combine.

Anatomy

Origin
  • External occipital protuberance and the medial third of the superior nuchal line
  • Nuchal ligament
  • Spinous process of the seventh cervical vertebra
Insertion
  • Posterior border of the lateral third of the clavicle
Actions
  • Elevates the shoulder girdle — the shrug
  • Contributes to upward rotation of the scapula by pulling up on the outer end of the clavicle
  • Extends and side-bends the neck when the shoulder is held still
Innervation
Accessory nerve (CN XI), with sensory fibres from C3–C4

Exercises

Antagonists

Synergists