There are several possible causes of pain from the left shoulder to the left side of the neck: first, cervical spondylosis, when cervical spondylosis compresses the nerve root, it can radiate to the shoulder and cause pain in the neck and shoulder, then early physical examination, early cervical spine X-ray, CT, nuclear magnetic to early diagnosis and treatment. Second, myofasciitis. Patients with myofasciitis can also have pain on the inside of the scapula as the first symptom, which can radiate to the ipsilateral shoulder and neck and cause pain in the neck and shoulder. Third, shoulder joint disease, when the shoulder joint has frozen shoulder or rotator cuff tear, it can also appear the pain and discomfort of one side of the neck to the shoulder, then it is necessary to check the MRI of the shoulder joint for early diagnosis and early treatment.