The temporomandibular joint is an important joint of the skull, which is essential for all daily functional activities of the mouth, such as speaking, eating, and singing. It is a very special joint, one of the few joints in the human body with an articular disc (other familiar joints are the knee joint, which has a meniscus), and is the only joint in the body that requires bilateral joint linkage (this is a very important point, where many problems arise). It has a very heavy workload, every time you open and close your mouth, it needs to be involved, every time you chew, it brings different sizes of pressure, every time you laugh, it has to run back and forth to match the degree of mouth opening, it and the teeth and tongue are good friends, they rest together, work together, of course if one of them is sick and uncomfortable, the other two are likely to be affected. The temporal bone of the skull and the condyles of the mandible form this joint, and there are joint discs between them to play the role of buffer, because we are walking upright, unlike other animals, so many joints in the human body have done the corresponding evolutionary adaptation to this change, the human spine has several bends, the average dispersion of each vertebra and intervertebral discs when standing The temporomandibular joint relies on the joint disc to produce forward sliding when opening the mouth, increasing the degree of mouth opening. Our daily jaw movements can be as shown above, including opening the mouth, closing the mouth, extending the jaw forward, retracting the jaw, and tilting the jaw to one side, and during these movements, the TMJ is in motion. All joint movements on the human body are driven by muscle contractions. The movement of the jaw is the involvement of our masticatory muscle system, including: the occlusal, temporal, bicipital, internal pterygoid, and external pterygoid muscles, while there are many ligaments and joint capsules around the joint to limit excessive and incorrect movements of the joint. So when there is a problem or disease in the power muscles and the limiting ligaments and joint capsule, the joint will move incorrectly, which is one of the pathogenesis of TMJ disorder that everyone is concerned about. This will be described in another article “What Doctors Say: A Brief Discussion of TMJ Disorders”. The movements of our jaws on a daily basis can include those shown above, including opening the mouth, closing the mouth, extending the jaw forward, retracting the jaw, and tilting the jaw to one side, and during these movements, the temporomandibular joint is moving. All joint movements on the human body are driven by muscle contractions. The movement of the jaw is the involvement of our masticatory muscle system, including: the occlusal, temporal, bicipital, internal pterygoid, and external pterygoid muscles, while there are many ligaments and joint capsules around the joint to limit excessive and incorrect movements of the joint. So when there is a problem or disease in the power muscles and the limiting ligaments and joint capsule, the joint will move incorrectly, which is one of the pathogenesis of TMJ disorder that everyone is concerned about. This will be described in another article “What Doctors Say: A Brief Discussion of TMJ Disorders”. The above diagram can let us know that when opening and closing the mouth, the condyle of the mandible will slide forward and backward in a wide range, as I said earlier, this is an important and necessary movement of this joint. Does it seem to move differently on both sides? Does the bone seem to bounce and make a loud sound when you open it? Does it seem like it will feel stuck when you open it? Does it seem like it’s not only stuck but also hurts when it’s opened wide? Does it seem like the two sides move separately when opening? Does it seem like there is a rubbing sound and some pain here when it opens wide? All of you reading this article are patients, and these are the most common manifestations of TMJ disorder. Let’s go inside the joint and see what’s going on inside the joint. Inside the joint we can see that the articular disc divides the TMJ into the upper temporal bone and the upper articular surface of the articular disc to form the superior articular cavity, and the condyle of the mandible and the lower articular surface of the articular disc to form the inferior articular cavity. When we open the mouth about one finger size (1cm), it is mainly the condyle and the lower articular surface of the articular disc that do the rotation and slight rolling. When continuing to open wide, the articular disc and condyle come forward together and the superior articular surface of the articular disc slides a great deal against the temporal bone. Next, let’s look at the complete process from closed mouth to open and closed again. 1 is when the mouth is closed, 4-5 is when the mouth is completely wide open, and you can see that the articular disc and condyle slide forward a lot. 8-1 is when the mouth is closed again, and the condyle and articular disc return backward to their resting position. It is the pterygoid muscle, which is a very important muscle in the front, that drives the condyles and discs to slide forward, and it is the joint capsule around the joint that restricts and maintains the discs in the correct position inside the joint. Irreducible? Well, today we have brought you a brief introduction to our TMJ, and I think you have a preliminary understanding, and I hope it will increase your basic understanding when you look at other TMJ disorder articles.