What Is the Temporomandibular Joint?

Temporomandibular joint is also called "temporomandibular joint" or "mandibular joint". It consists of the mandibular head, the mandibular fossa of the temporal bone, and the joint nodules. The left and right synthesize a joint joint, which deals with mouth opening and closing and chewing movements. The joint capsule is loose and the sides are strengthened by the medial and lateral ligaments. The joint disc in the capsule is oval and consists of fibrocartilage, divided into anterior, middle and posterior parts. The upper part is saddle-shaped, with an anterior concavity and convexity, corresponding to the convex and concave contours of the joint nodules and the mandibular fossa; the inferior concavity is directly opposite the mandibular head, the peripheral edge is connected to the joint capsule, and the leading edge is connected to the external wing tendon passing through the joint capsule. The joint disc divides the joint cavity into upper and lower halves. The sphenoid mandibular ligament (sphenoid spine to mandibular tongue) and styloid mandibular ligament (styloid process to mandibular angle) are reinforced outside the joint.

Temporomandibular joint is also called "temporomandibular joint" or "mandibular joint". It consists of the mandibular head, the mandibular fossa of the temporal bone, and the joint nodules. The left and right synthesize a joint joint, which deals with mouth opening and closing and chewing movements. The joint capsule is loose and the sides are strengthened by the medial and lateral ligaments. The joint disc in the capsule is oval and consists of fibrocartilage, divided into anterior, middle and posterior parts. The upper part is saddle-shaped, with an anterior concavity and convexity, corresponding to the convex and concave contours of the joint nodules and the mandibular fossa; the inferior concavity is directly opposite the mandibular head, the peripheral edge is connected to the joint capsule, and the leading edge is connected to the external wing tendon passing through the joint capsule. The joint disc divides the joint cavity into upper and lower halves. The sphenoid mandibular ligament (sphenoid spine to mandibular tongue) and styloid mandibular ligament (styloid process to mandibular angle) are reinforced outside the joint.

Chinese name

Temporomandibular joint

Foreign name

articulatio mandibularis OR Temporomandibular Joint (TMJ)

Activity method

Left and right side linkage

Features

Stability and multidirectional mobility

Location

Maxillofacial

Make up

Sphenoid mandibular ligament, styloid mandibular ligament

Temporomandibular joint movement mechanism

The mandibular joint allows the mandible to be raised, lowered, advanced, retracted, and laterally moved. In the activities of opening and closing, the mandible head rotates along the frontal axis passing through the mandible head in the mandibular joint cavity, and the mandible appears to descend and lift up. During anterior and posterior movements, the joint disc and the mandible head slide in an arc around the frontal axis located in the joint nodule in the upper joint cavity. Lateral motion is the vertical axis rotation of the mandibular head in the lower joint cavity in situ, while the contralateral mandibular head and the joint disc move forward in the upper joint cavity. The upper and lower incisor margins can reach a distance of 50 to 60 mm when the mouth is opened, and move about 10 mm when moving forward and sideways. When extremely open, the mandibular head can even slide before the joint nodule, enter the infratemporal fossa, and become anterior dislocation. When resetting, press the left and right molars with your thumbs and press down. At the same time, lift the crotch, pull the mandibular head down, cross the joint nodule, and then push it back up, and put the mandibular head back into the mandibular socket.

Temporomandibular Joint Imaging Structure

On plain X-ray films, the joint disc is not visualized and the joint space is significantly widened. Generally, the structure of the joints is observed by lateral projection, the performance of the joints is compared with the closed and open positions, and the structure of the joint discs and capsules are observed by angiography.

1. Temporomandibular joint lateral position. The temporomandibular joint is located in front of the external ear door and overlaps the base of the occipital bone and the petrocone, so it is easy to see that some people have unclear visualization. Generally, the circular contour of the small head of the lower jaw can be traced up along the posterior edge of the lower jaw branch. In addition, from the tip of the rock cone forward, a strip-shaped zygomatic arch shadow can be seen. The lower edge of the mandible corresponding to the mandibular head is markedly concave to form the mandibular fossa. Sometimes the mandibular fossa appears as a section shadow, which is an axial shadow at the top of the mandibular fossa. The upper and lower edges of the cross-section shadow are dense cortex and the middle layer is cancellous. The temporomandibular joint is formed between the mandibular small head and the mandibular joint fossa, and there is a transparent joint space with a thickness of about 2mm.

2. Temporomandibular joint closed. This projection position is basically lateral, but the tube is moved forward by an angle of 25 ° to 30 °. Because of the oblique X-ray, the image of the rock cone moves down, so the temporomandibular joint is clearly developed, and the mandibular fossa and joint nodules are often sectioned. The lower head of the lower jaw corresponds to the joint socket to form a joint. The surface of the joint gap is smooth, the gap width is basically the same in all aspects, and the left and right sides should be the same.

3. Temporomandibular joint opening. On the normal temporomandibular joint opening film, the mandibular small head has moved forward below the joint nodule, the mandibular body turned down, and the mandibular angle moved later. Comparing the closed-mouth images, we can see that the normal temporomandibular joint moves forward under the joint nodules when the temporomandibular joint is opened, and the mandibular head retracts into the mandibular fossa when the mouth is closed. This movement is more clearly seen on X-ray television recordings.

Temporomandibular Joint Related Diseases and Treatment

The diseases that mainly involve temporomandibular joint surgery include temporomandibular joint dislocation, tumor, infection, ankylosis, congenital or developmental deformity, condylar hypertrophy, and the problem of dealing with the structural relationship of the temporomandibular joint.

1. The treatment methods for temporomandibular joint disorders are mainly conservative treatments, including hot compresses, physical therapy, closure, acupuncture, medication, pads, and other treatments. Surgical treatment of temporomandibular joint disorders mainly includes joint injection therapy, joint irrigation treatment, arthroscopy, joint disc reduction, joint disc perforation repair, joint disc resection, joint disc replacement, condylar resection, High condylar resection, condylar planing, joint nodule excision, joint nodule heightening, temporomandibular arthroplasty, total joint replacement, etc.

2. Condylar fractures are common clinical maxillofacial fractures, accounting for about 45% of mandibular fractures. Controversial or surgical treatment has been controversial. Treatment of condylar fractures with the patient's age (children under 12 years of age are not suitable for surgery), the type of fracture (such as simply divided into the chin, sacral neck and sub-sacral fractures), the evaluation of the treatment effect (such as the temporomandibular joint Function, occlusion relationship, facial shape) and so on. However, conservative treatment is difficult to achieve anatomical reduction, and is prone to complications such as joint degeneration, facial asymmetry, and wrong. Surgical treatment can achieve anatomical reduction, quickly restore joint function, and reduce discomfort caused by long-term intermaxillary fixation. Especially with the popularization of the application of solid internal fixation, the scope of indications for surgical treatment has been expanded.

3. The surgical methods for the surgical treatment of temporomandibular joint ankylosis include: fissured arthroplasty, various interposition arthroplasty (interposition includes autologous tissue, allogeneic tissue, artificial materials, etc.) and joint reconstruction (including ribs, rib cartilage) Transplantation, mandibular ascending branch inversion, coracoid process transplantation, ascending branch moving up to reconstruct joints, distraction osteogenesis, artificial joints, etc.).

4. The congenital malformation of the temporomandibular joint is caused by abnormal embryonic development, and the main causes are teratogenicity caused by genetic, environmental, viral, infection, and chemical drugs. Part of the condyles are underdeveloped or the condyles are missing. Surgical treatment is mainly used to replace the missing condyles by osteochondral transplantation, distraction osteogenesis, or total joint reconstruction to form a nearly normal joint structure. Orthognathic surgery was used to make the bilateral mandibular ascending branches symmetrical or reconstruct the height of the lower third of the face. The treatment of condylar hyperplasia is mainly surgical treatment, and the timing of surgical treatment should be based on the specific conditions of the lesion.

Related clinical technologies

The complexity of the structure and function of the temporomandibular joint makes its reconstruction one of the biggest challenges facing surgeons. Artificial temporomandibular joint is one of the important methods of temporomandibular joint reconstruction. It is mainly suitable for temporomandibular joint ankylosis, comminuted fracture of condyles that cannot be fixed, temporomandibular joint tumors, advanced intraarticular disorders and some congenital craniofacial syndrome Caused by dysplasia of the temporomandibular joint. The artificial temporomandibular joint is designed to improve the function of the temporomandibular joint, reduce pain, and prevent serious complications. In oral and maxillofacial surgery, the artificial temporomandibular joint has the advantages of being able to imitate normal anatomical morphology, fit with the host, do not require additional materials, and can perform functional training immediately after surgery. Prosthetic materials play a vital role in the development of the artificial temporomandibular joint. Good design and reliable fixation are essential conditions for the artificial temporomandibular joint to perform its functions. Of course, the study of joint biomechanics is also essential. Essential. With the rapid development of related disciplines such as materials science, joint biomechanics, and manufacturing technology, artificial temporomandibular joints have made many advances in implant materials and design of joint prostheses. With the development of artificial temporomandibular joint, its application is becoming more and more widespread.