The left side of the neck tendon pain may be caused by cold or poor posture, not a disease, such as long-term pain, need to be alert to the local muscle, fascia lesions, cervical spondylosis, etc.. 1. Cold or poor posture: poor posture of the neck for a long time or the left side of the neck by the cold stimulation, can lead to the left side of the neck tendon pain, and is not the cause of disease. Daily attention to maintain a reasonable posture of the neck, avoiding cold, the symptoms can be gradually relieved. 2. Muscle and fascia lesions: If the left side of the neck has localized muscle strains, strain injuries or fascial inflammation, it is usually easy to trigger the symptoms of localized tendon pain, and may even affect the strength of the local muscles. 3. Cervical spondylosis: If the posture is poor for a long time, it will induce cervical spondylosis, which will easily affect the structure of the cervical spine, resulting in the symptoms of pain in the left side of the neck, and may even produce the problem of cervical spine activity restriction. The left side of the neck tendon pain may also be caused by other reasons, if the symptoms of the left side of the neck tendon pain is more obvious and lasts for a long time, you need to consult a doctor as soon as possible, through the physical examination, ultrasound and magnetic resonance and other tests to make a clear diagnosis, targeted treatment.