The trapezius muscle is often a neglected body part and it should not be, it performs three functions, the “superior region” supports the weight of the arm, the “intermediate region” retracts the scapulae and the “inferior region” is the ascending part of the trapezius which rotates and depresses the scapulae, however many times people don’t work them out.
Some of the best bodybuilders on the planet had well-developed trapezius muscles which obviously made a better overall visual effect of their physique
Having big traps gives you the look of more mass and strength plus it helps make the shoulders more pronounced. If you have a well developed upper body without traps it can make your overall body structure look week.
If you want to have a well-rounded physique it is important to develop the trapezius muscle, it can highlight the back more and give you that Christmas tree effect making the upper body structure including the back thicker and more robust.
Having a well-developed trapezius also adds enhancement to the deltoids and shoulder muscle. It's not hard to develop the trapezius and it is one of those exercises that can be performed on the same day when doing shoulders and can be incorporated into that workout.
If you have never exercised your trapezius you will want to start off slow, so beginners can start off with three basic exercises and gradually move on to more advanced training for full development.
For beginners the exercise that directly targets the trapezius is the shoulder shrug which can be performed with dumbbells or a barbell using moderate weight, the Barbell is better at helping keep your arms straight.
To perform you simply shrug your shoulders upward, hold for a few seconds then release, the second exercises is performing an upward lift or rowing motion with a barbell lifting only your arms inverted “please see video below” up to your chin and then dropping back down, the third exercise is the two arm overhead barbell press.
A more advanced trapezius exercise can be performed as mentioned before when working out shoulders, my three favorite exercises are the upward lift, barbell shrugs and rear raises using the a smith machine, you may also want to perform behind the head presses which incorporate the shoulder and the trapezius at the same time.
Warming up first to prevent injury
I know some people who have not warmed up properly which has caused discomfort and even a pinched a nerve. When performing trap exercises it is very important to start off with light weight to loosen up the shoulders which you can do with shrugs to avoid injury and prevent discomfort when moving on to heavier weight.