- What is the temporomandibular joint?
- What is the function of the temporomandibular joint?
- Where is the TMJ located?
- What problems can the TMJ cause?
The TMJ (Articulatio temporomandibularis) allows the movements of the lower jaw against the upper jaw and the chewing and crushing of food in the oral cavity. The temporal bone forms the joint socket with the mandibular fossa, in which the condyle (caput mandibulae) of the lower jaw sits movably. Read all important information about the temporomandibular joint: anatomy, function, important diseases and injuries!
What is the temporomandibular joint?
The temporomandibular joint consists of the condyle, the acetabulum, a joint hump, a joint disc and the joint capsule.
The condyle (caput mandibulae) on the articular process of the lower jaw has a cylindrical shape and is covered on the front by cartilage. Above it, in the joint cavity surrounded by an articular capsule, is a cartilaginous disc (Discus articularis). It divides the joint cavity into two sections.
As an acetabulum, the fossa mandibularis of the temporal bone acts. It is covered in the anterior area by cartilage. In front of her lies the small articular tubercle (tuberculum articulare ossis temporalis).
The great mobility of the temporomandibular joint is made possible by the joint capsule, which consists of elastic fibers and connective tissue. It is so wide and flaccid that the lower jaw can even "dislocate" (luxate) without it tearing.
The temporomandibular joint in newborns and the elderly
The socket is flat in newborns. In edentulous old people flat socket and articular tubercle increasingly from. The opening and closing of the mouth then takes place exclusively via a hinge movement.
What is the function of the temporomandibular joint?
The movements of the temporomandibular joint are primarily used for chopping and chewing food.
The temporomandibular joint is quite complicated in its mechanics, as it is to be understood as a combination of two joints: A lower joint (discomandibular hinge joint) and an upper joint (discotemporales sliding joint) together cause a kind of "rotary gliding". The right and left temporomandibular joint always work together.
When the jaw is closed and no chewing movements are performed, the teeth do not touch. The condyle is then together with the discus in the anterior part of the joint pit and on the back of the joint bump.
The opening and closing of the mouth is a combination of a hinge and a sliding movement. It begins with a hinge movement where the discus slides forward on the articular tubercle and the angle of the jaw moves backwards, with no articulation of the teeth. When closing the mouth, the reverse movement takes place. This hinge movement is provided by the lower (discomandibular) hinge joint.
Slide or slide movement
The forward and backward sliding of the lower jaw takes place in the upper (discotemporal) sliding joint under the guidance of the teeth. Here, the discus with the condyle slides forward on the articular tubercle. In this movement of the temporomandibular joint, the condition, the shape and the position of the teeth play a role. In case of a strong overbite, the joint must first be opened a little, so that the incisors of the lower jaw can be guided past those of the upper jaw.
Sideways or grinding movements
For sideways or Mahlbewegungen also the teeth are involved. Here, the one condyle rotates about a vertical axis in the socket, the other one rotates forward on the articular tuberosity, causing the rows of teeth on this side to diverge. The chin is moved to the opposite side. The movements take place alternately in the two temporomandibular joints.
Where is the TMJ located?
The temporomandibular joint is the articulated connection between the temporal bone - a large, paired bone on the lateral cranial wall - and the arched lower jaw.
What problems can the TMJ cause?
Arthritis of the temporomandibular joint is the result of damage to the articular cartilage. This can result from multiple "dislocation" (dislocation), injury or inflammation of the temporomandibular joint. During the - painless - opening of the mouth, the lower jaw deviates to the healthy side (Bonnet position). During the opening of the mouth occurs a typical joint cracking.
The temporomandibular joints can cause headache, backache, tinnitus or other discomfort. For poorly fitted dental fillings or crowns, teeth grinding, stress or crooked posture permanently damage the temporomandibular joints. This causes the masticatory muscles to cramp, which can send painful signals to all sorts of parts of the body. One then speaks of a temporomandibular joint syndrome (TMG syndrome = temporomandibular joint syndrome).
If the condyle moves in front of the articular tuberosity when the mouth is very wide open, it can lead to a jaw lock - the mouth can not be closed.In the opposite case, the mouth can not be opened in a so-called jaw clamp.
The TMJ Can be broken in the face in case of a fall or a blow.