The main symptom of hyperfunction of the extra-pterygoid muscles is popping and over-opening. When the popping occurs on one side, the opening pattern is skewed toward the healthy side at the end of the opening; when there is popping on both sides, the opening pattern is not skewed or skewed toward the side of the weaker contraction of the extrapin. The main manifestation of extrinsic pterygoid spasm is pain and restriction of opening, and the mechanism causing pain and restriction of opening is extrinsic pterygoid spasm. On examination, the opening is moderately restricted, the opening degree is 2-2.5 cm, the passive opening degree is greater than the natural opening degree, and the lower jaw is biased to the affected side when opening. There is pressure pain on the corresponding face of the external pterygoid muscle (at the lower Guan point and above the posterior maxillary tuberosity), but there is no redness or swelling, and there is no pressure pain in the joint area. 3. Myofasciitis Myofasciitis is mostly caused by mental stress, overload of the masticatory muscles, trauma, and cold stimulation. The nature of the pain is persistent dull pain with pressure points, which are called trigger points when the pressure points are sensitive. The opening is mildly restricted, and the passive opening can be opened to the normal range, but there is pain. 4. reversible articular disc displacement reversible articular disc displacement opens and closes the mouth with a popping sound. The mechanism is that when the articular disc is in forward displacement, the transverse crest of the condyle hits the posterior edge of the posterior band of the articular disc during the opening movement and rapidly moves forward and then upward, while the articular disc recoils backward, thus restoring the normal structural relationship between the condyle and the articular disc. In the open-jaw type, the affected side is favored before the onset of the popping, and returns to the midline after the popping. x-ray (Schuyler’s position) shows narrowing of the posterior joint space, and arthrography or MPI can confirm anterior displacement of the joint disc. If pterygoid spasm or synovitis is present, the symptoms are associated with it.5. Irreducible disc displacement Irreducible disc displacement has a typical history of joint popping, followed by a history of intermittent joint locking, and then the popping disappears and the opening is limited. On clinical examination, the opening is limited, the lower jaw is tilted to the affected side during opening, and the joint area is painful; on passive opening examination, the opening cannot be increased; on X-ray (Hüllerian), the posterior joint space is narrowed; on arthrography or MPI, the anterior displacement of the joint disc can be confirmed.6. Dilatation of the joint capsule with loosening of the joint disc attachment is similar to the symptoms of pterygoid extrinsic muscle hyperfunction, and the opening is too large, which may be accompanied by chronic synovitis. Arthrography can confirm the dilatation of the joint capsule with loosening of the joint disc attachment.7. Localized joint pain occurs during synovitis joint movement, and the pain increases with increased joint loading in the posterior and superior direction. If there is fluid in the joint cavity, there may be mild swelling in the joint area and an inability to bite closely with the ipsilateral posterior teeth. Arthrogryposis is clinically difficult to differentiate from synovitis, but the pressure points are mainly on the lateral side of the joint capsule, which helps in the diagnosis.8. The main symptoms of ruptured and perforated joint discs in osteoarthrosis are polyphonic crushing sounds and open-ended distortion at any stage of jaw movement. The main symptom of condylar bone degeneration is continuous friction sounds in opening and closing mouth movements. Arthrography reveals superior and inferior cavity traffic; radiographs reveal sclerosis, destruction, cystic changes, osteophytes, and osteophytes in the joint bone.