The trapezius muscle is a large diamond shaped muscle in your back and neck. It helps with shoulder and neck movements. This muscle is often over worked due to poor posture, such as sitting in front of a computer. This muscle is also a common ” stress” muscle where people have their shoulders hunched up to their ears. As a result trigger points in the upper traps are very common. These points refer pain into the temple and behind the ear. Upper trap trigger points are a common cause or headaches.