Pain in the preauricular region is one of the common clinical flank pains. Its main cause is pain in the temporomandibular joint area, which is often mostly caused by inflammation, in addition to neurogenic, osteoarthrosis and trauma to the temporomandibular joint. 1. Acute synovitis The synovial membrane of the temporomandibular joint covers the inner surface of the joint at the beginning, including below the upper part of the joint disc. However, with the advent of function, the synovial membrane only lined the inner surface of the joint capsule and the upper and lower part of the bilabial area. Histologically, it is divided into cellular intima and subintima. Electron microscopic subsurface synovial cells are divided into two types, A and B. Type A cells are rich in Golgi apparatus, vesicles, and vesicles, and their main function is phagocytosis; type B cells have a large number of rough endoplasmic reticulum, nucleoprotein bodies, and their main function is to synthesize hyaluronidase, etc. The main functions of synovial membrane are; phagocytosis, synthesis, immunity, regulation, etc. When the synovial membrane is inflamed, the main manifestation is pain, especially a positive “posterior push test”. 2.Temporomandibular joint capsule The TMJ capsule is a capsule of connective tissue that is attached around the joint, wrapping around the entire joint, sealing the joint cavity and forming two joint cavities through the joint disc. The capsule is generally described as loose, referring to the upper part of the joint capsule, which is the upper part of the joint capsule. The inferior capsule, the lower part of the joint capsule, is fused with the internal and external ligaments of the articular disc and is tougher. The joint capsule is inflamed for various reasons, resulting in a large amount of inflammatory exudate, which contains many inflammatory factors and causes pain. The clinical manifestation is “painful movement” of the temporomandibular joint. The pain is present with both “open and closed mouth movements” and “local touch”, and is accompanied by symptoms of restricted mouth opening. 3.Temporomandibular arthritis Temporomandibular arthritis, a condition of the joint between the jaw and the ear, is also a common source of pain. By placing your fingers in front of the ear canal on either side and opening your mouth wide, you can hear a sound similar to cracking. Symptoms of TMJ are very common. They include localized joint pain, ear pain, headache, noise and pain during chewing, and are accompanied by pain in various muscles. The degree of opening the mouth is limited and sometimes there is difficulty in swallowing food. 4, rheumatoid arthritis This disease is an inflammatory, progressive, symmetric and destructive joint disease. The general examination is positive for rheumatoid factor and imaging with bone destruction images. 5.Temporomandibular joint injury Often there is a clear history of trauma, and the clinical diagnosis is relatively clear. 6.Temporomandibular joint tumor Most commonly seen in progressive pain, with a tendency of gradual aggravation; clinical examination and imaging examination can find “occupying lesions” and images of bone destruction in the condyle or joint fossa, which can cause mouth opening restriction. 7.Trigeminal neuralgia or auriculotemporal neuralgia The pain is paroxysmal, electric shock-like or cutting-like pain. The pain occurs mostly in the daytime and is rare at night. Oral carbamazepine or oxcarbazepine is effective. 8, otogenic pain, such as otitis media, is usually diagnosed by consultation with an otolaryngologist. The treatment plan is carried out by an otolaryngologist. 9.Mumps Various types of mumps have changes under the earlobe, parotid ducts or saliva. It can also be caused by systemic infectious diseases such as measles and scarlet fever. 10. Stromal hyperostosis In addition to pain and abnormal sensation in the pharynx during swallowing, it can often cause pain in the posterior condylar region as well as the posterior region of the joint, the retroauricular region and neck involvement pain during opening and chewing. x-ray examination can easily confirm the diagnosis. In addition, there is also pain due to compression of nerves by intracranial lesions of various causes, which often requires consultation with a neurosurgeon.