Trapezius Muscle Anatomy and Function

Model of the human body showing trapezius muscle
Model of the human body showing trapezius muscle. SCIEPRO/Science Photo Library/Getty Images

Unless you're vigilant about it, work - and life - in the 21st century can be all but devoid of movement.  While this has its conveniences, there are drawbacks, as well.  For one, muscles that remain inactive for most of the day are much more likely to go into spasm.

The upper trapezius muscle - which is the one located at the tops of your shoulders - is particularly prone to this type of tension.  Check it for yourself: How well can you move your shoulders up and down (especially down,) and do you have pain at the top of either shoulder, or both?

 If your should movement is limited and/or there's pain in that area, you may have an upper trapezius muscle in spasm.  (Fortunately, the solution tends to be pretty easy - exercise.)

But the trapezius doesn't stop there.  This large shoulder and upper/mid back muscle has 3 parts, described below.  It's just that the upper part is the one most of us are familiar with - because we tend to get pain, limitation and/or trigger points there.

The Three Parts of the Trapezius Muscle

The trapezius muscle is divided into 3 areas:

  • upper fibers
  • middle fibers
  • lower fibers.

The significance of this division lies in the variety of functions the trapezius performs.

Functions of the Trapezius Muscle

The functions of the trapezius muscle are:

  • to move the shoulder blade in toward the spine
  • to rotate the shoulder blade so that the topmost part of the upper arm faces up
  • to move the shoulder blade up and down
  • to bring the head and neck in a backward direction
  • to rotate and side bend the neck
  • to assist in breathing

How the Trapezius Affects the Neck (Especially for You Office Workers)

Because the trapezius muscle works to move the neck in several directions, its degree of tightness or looseness affects neck flexibility. For people who work at desks and computers, or who spend many hours driving, the upper trapezius is the muscle on top of your shoulder that becomes very sore and painful.

The Trapezius Muscle as a Breathing Muscle

The trapezius is an accessory breathing muscle. This means that it helps open up the small amount of breathing room in the upper chest area. For back and neck pain management, it is best not to rely on the trapezius alone, as this will produce shallow breathing. The most primary and powerful breathing muscle, the diaphragm, also a muscle of posture, affects a large volume of breathing space all the way up and down the torso.

Tight Trapezius Muscles Love a Good Massage

Although the trap muscles tend to get very tight for most people, they tend to respond well to massage. An added perk is that they are located such that you can reach your own. Try a self-massage on your trapezius muscle.


Kendall, Florence, McCreary, Elizabeth Kendall, Provance, Patricia Geise. Muscles Testing and Function 4th ed. Williams and Wilkins. Baltimore, Maryland, 1993.

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