It is just too easy to blame the upper trapezius for our neck soreness, tightness, and pain. But these muscles may be getting a bad reputation that is unjustified. Like most muscles in our body, the upper traps do not just become tight without any provocation or underlying reason.
What is your upper trapezius?
The upper trapezius is the upper portion of the complete trapezius muscle, which includes a middle and lower portion with each section having a different action. The upper traps are responsible for upward rotation and elevation of the shoulder blade as we raise our arms. Injuries to the neck and shoulder can increase the activation of this muscle to compensate normal movements due to the injury.
Where is the pain coming from?
With injuries to the neck or shoulder your upper traps can work overtime as they try to either help protect the neck or help you lift your arm when other injured muscles are too weak or injured to do so. This can be a common reason that your upper traps become tight or painful. A common misconception is that posture can cause this muscle to be tight and 
painful. This is not entirely true. When you sit with poor posture, forward head and rounded shoulders most often seen with prolonged computer use, you are placing a lot of stress on the spine and nerves that run through the shoulder (see picture to left). Over time the nerves in the neck and/or shoulder can be stretched to their limit and begin to cause you pain. Well, those nerves are running from your neck, under your upper trap, and through your shoulder. This can cause pain anywhere along the path of the nerve but most commonly it causes symptoms beneath your upper trap. You might think the upper trap is the culprit because it sits on top of those nerves, but instead look to your posture and the nerves that become affected by it.
What should I do about it?
The first thing you should do if you have pain in the upper traps is correct your posture. Make sure your head is on top of your shoulders and not in front of them, pull your shoulders back and quit reaching for the keyboard (pull the keyboard close to you), and sit upright. Bringing the monitor up to eye or head level will also help. If you are sitting there saying that you don’t sit on a computer all day and still have the pain…. How often do you use your phone or a tablet and in what posture are you in when you use them? That could also be placing you in the same posture as someone who does work on a computer all day. Second thing you can do is try stretching. Do this by grabbing the edge of your chair with one hand and then leaning away with your body and head in the opposite direction of the hand that is holding the chairs. You should feel a pull through your neck and upper traps. Hold this for 20 seconds and repeat with the other side. You should be performing this throughout the day.
If you think you have the best posture, don’t use any electronic device for hours on end, have been doing the stretches, and nothing seems to work, then you may have other reasons for pain in that area. Visit a physiotherapist and see what the underlying cause may be for your discomfort.