Pain over the top of the shoulder can be muscular in origin. The Upper Fibres of Trapezius (UFT) – which originates from the spinous processes and ligaments of the neck and proceeds downward and outward to be inserted into the back border of the collar bone. An injury to the ACJ can easily cause a protective strain of the UFT or you can have an UFT strain without any ACJ involvement causing your symptoms. The neck joints and musculature around it can commonly refer pain to the top of the shoulder as well, making this quite a complex area of the body to treat. The differentiation between the two will be made by your Chartered Physiotherapist at WPB.