When the neck is turned, or when flexion and extension, rotation inside click click click click, it means that the cervical spine has degenerative changes, there are three main factors: 1, cervical vertebral osteophytes, including the cervical vertebral body of the anterior and posterior edges of the osteophytes, the hook vertebral joint of the upper and lower edges of the hyperplasia, intervertebral small joint of the upper and lower synapses, etc., the hyperplastic bone spurs in the cervical spine flexion and extension, rotation, ring rotation activities in the process of mutual friction, it will emit 2, calcification of the collar ligament, if the collar ligament calcification, that is, the ligament inside the bone, the cervical spine in flexion and extension, rotation activities, calcified bone and ligament friction between each other will make a sound. 3, the back side of the neck ligaments, tendons, fascia, muscles and other soft tissue strain, in the activity will also make a loud sound.