A tendon pain in the left shoulder and neck may be caused by long-term fixed posture, exercise fatigue and other physiological reasons, or may be caused by cervical spondylosis, cervical-shoulder syndrome and other pathologic factors. 1. Physiological reasons: the left shoulder and neck area has the trapezius muscle, lateral border of the sternocleidomastoid muscle, scapularis muscle and other soft tissue structures, if the body is in a fixed position for a long time, it may cause the tension or spasm of these soft tissue structures, and the symptoms of a tendon pain in the left shoulder and neck. Inadequate warm-up before exercise or a large amount of exercise, may also appear in the above soft tissue fatigue, the above symptoms. 2. Pathological factors: Degenerative lesions of the cervical spine or long-term chronic strain injury may induce cervical spondylosis and cervical-shoulder syndrome, which may cause the left cervical and shoulder myofascial muscles to be in a compensatory state for a long period of time, or cause compression of the nerves that innervate the left cervical and shoulder region, which may cause the symptoms of pain in a tendon of the left shoulder and neck. The symptoms of left shoulder and neck tendon pain alone sometimes can not accurately determine the cause, but also need to be combined with the characteristics of the medical history, other test results to make an accurate judgment, it is recommended to clarify the cause of the disease under the guidance of a doctor, and comply with the doctor’s instructions to standardize the treatment.