The bone pain on the side of the ear when the mouth does not open wide may be a normal physiological reaction, but it does not exclude the pathological reaction caused by temporomandibular arthritis, temporomandibular joint disorder and other pathological reasons. 1. The bone pain on the side of the ear when the mouth does not open wide may be the patient’s joint ankylosis and muscle spasm after long-term mental tension. Or the cold environment leads to poor synovial fluid mobility in the joint cavity, poor lubrication and so on. General rest can be relieved, is a normal physiological reaction. 2. The bone pain on the side of the ear when the mouth is not wide open may also be caused by temporomandibular arthritis. Generally the initial symptom of pain is joint popping, i.e., clicking, and then joint pain occurs, and its main symptoms are localized joint pain, ear pain, headache, pain when chewing, and will be accompanied by a variety of buccal muscle pain, the degree of opening the mouth will be limited, and sometimes there is difficulty in swallowing food. 3. Temporomandibular joint disorders may also lead to pain in the bones by the ears when the mouth is not open. For example, if the patient’s teeth are deviated, atresia, deep overjet, deep cover, etc., the uneven force on the teeth and the tightness of the bite at night may cause the above symptoms. To summarize, the causes of pain in the bone next to the ear when the mouth is not wide open are many and complex, and it is recommended that the patient go to the hospital for consultation and treatment.