The common causes of pain in the shoulder muscles are periarthritis, shoulder joint trauma and cervical spondylosis, as follows: 1. Periarthritis: In middle-aged and elderly patients with periarthritis, there will be limited movement of the shoulder joint and they will not be able to move normally for a long time, the muscles around the shoulder joint will spasm and tense, and pain symptoms will occur. 2. Trauma to the shoulder joint: If the shoulder joint is fractured or dislocated, it can cause reflex pain. 3.Cervical spondylosis: Neurogenic cervical spondylosis can cause radioactive pain in the neck and shoulder, and at the same time, the patient will have limited cervical movement, and the degree of nerve compression can be found by MRI. Therefore, there are several common causes of pain in the shoulder muscles. After early diagnosis and active treatment, the shoulder muscle pain symptoms can be relieved quickly. Patients should also pay attention to maintenance in general to avoid lesions in the above areas to prevent shoulder muscle pain symptoms from occurring.