The temporomandibular joint, or TMJ, is the articulation between the condyle of the mandible and the squamous portion of the temporal bone.
The condyle is elliptically shaped with its long axis oriented mediolaterally,The articular surface of the temporal bone is composed of the concave articular fossa and the convex articular eminence
The MENISCUS is a fibrous, saddle shaped structure that separates the condyle and the temporal bone. The meniscus varies in thickness: the thinner, central intermediate zone separates thicker portions called the anterior band and the posterior band. Posteriorly, the meniscus is contiguous with the posterior attachment tissues called the bilaminar zone. The bilaminar zone is a vascular, innervated tissue that plays an important role in allowing the condyle to move foreward. The meniscus and its attachments divide the joint into superior and inferior spaces. The superior joint space is bounded above by the articular fossa and the articular eminence. The inferior joint space is bounded below by the condyle. Both joint spaces have small capacities, generally 1cc or less.
Normal TMJ Function
When the mouth opens, two distinct motions occur at the joint. The first motion is rotation around a horizontal axis through the condylar heads. The second motion is translation. The condyle and meniscus move together anteriorly beneath the articular eminence.
In the closed mouth position, the thick posterior band of the meniscus lies immediately above the condyle. As the condyle translates forward, the thinner intermediate zone of the meniscus becomes the articulating surface between the condyle and the articular eminence. When the mouth is fully open, the condyle may lie beneath the anterior band of the meniscus.
Imajing of TMJ
:Transcranial:the only radiograph in diagnostic position of TMJ
Transpharengeal:in semi opened position with no superimposition from skull
:Reverse town:in opened position shows high fracture of condyle.
transorbital:mediolateral planeshowing condyle + condylar neck
submentovertix: needed b/f CT & MRI for correcting position
CT: in case of cyst &tumors ,resorbtion ,etc
conventional tomography : allow for diagnostic position view.
Soft tissue by using:
Arthrography to see the disc indirectly
is not used extensively anymore since noninvasive MR imaging has replaced it.
MRI:to see the disc directly in coronal &sagittal views
Normal function of TMJ
Abnormalities of TMJ
abnormalities include develpmental,pain dysfunction syndrome,disc displacement,Trauma,&Tumors
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شكراً لكل من شدوي ، فصول،أوبتي
لمواصلة مابدأناه ولكي تكتمل الصورة لتكون أوضح وأسهل للقارىء
Temporomandibular joint Disorders or Temporomandibular joint syndrome
Trauma is divided into microtrauma and macrotrauma. Microtrauma is internal, such as bruxism (grinding the teeth) and clenching (jaw tightening). This continual hammering on the temporomandibular joint can change the alignment of the teeth. Muscle involvement causes inflammation of the membranes surrounding the joint. Teeth grinding (bruxism) and clenching are habits that may be diagnosed in people who complain of pain in the temporomandibular joint or have facial pain that includes the muscles involved in chewing (myofascial pain). Macrotrauma, such as a punch to the jaw or impact in an accident, can break the jawbone or damage the disc
Like other joints in the body, the jaw joint is prone to undergo arthritic changes. These changes are sometimes caused by breakdown of the joint (degeneration) or normal aging. Degenerative joint disease causes a slow progressive loss of cartilage and formation of new bone at the surface of the joint. Cartilage destruction is a result of several mechanical and biological factors rather than a single entity. Its prevalence increases with repetitive microtrauma or macrotrauma, as well as with normal aging. Immunologic and inflammatory diseases contribute to the progress of the disease.
Rheumatoid arthritis causes inflammation in joints and can affect the TMJ, especially in children. As it progresses, the disease can cause destruction of cartilage and erode bone, deforming joints. It is an autoimmune disease involving the antibody factor against immunoglobulin G (IgG). Chronic rheumatoid arthritis is a multisystem inflammatory disorder with persistent symmetric joint inflammation.
TMJ Syndrome Symptoms
Pain in the facial muscles and jaw joints may radiate to the neck or shoulders. Joints may be overstretched. You may experience muscle spasms from TMJ syndrome. You may feel pain every time you talk, chew, or yawn. Pain usually appears in the joint itself, in front of the ear, but it may move elsewhere in the skull, face, or jaw.
TMJ syndrome may cause ear pain, ringing in the ears (tinnitus), and hearing loss. Sometimes people mistake TMJ pain for an ear problem, such as an ear infection, when the ear is not the problem at all.
sounds, such as clicking, grating, and/or popping. Others may also be able to hear the sounds. Clicking and popping are common. This means the disc may be in an abnormal position. Sometimes no treatment is needed if the sounds give you no pain.
the face and mouth may swelling on the affected side.
The jaw may lock wide open (then it is dislocated), or it may not open fully at all. Also, upon opening, the lower jaw may deviate to one side. You may find yourself favoring one painful side or the other by opening your jaw awkwardly. These changes could be sudden. Your teeth may not fit properly together, and your bite may feel odd.
You may have trouble swallowing because of the muscle spasms.
Headache and dizziness may be caused by TMJ syndrome. You may feel nauseous or vomit
Examination of TMJ
examination of joint
Tenderness to palpation
Pain in or in front of the ear is a common reason for a patient to seek treatment. A tenderness to palpation implies inflammation, generally as a result of acute or chronic trauma.
A finger should be placed in the immediate pre-auricular area, gently applying pressure on the lateral pole/head of the condial while the jaw is closed. The level of pain and discomfort on each side should be assessed and compared.
The little finger should also be placed in the external auditory meatus, and pressure gently applied forwards
There are 2 types of joint sound to look out for: Clicks - single explosive noise
Crepitus - continuos 'grating' noise
A joint click probably represents the sudden distraction of 2 wet surfaces, symptomatic of some kind of disc displacement. The diagnosis of a joint click, and therefore treatment, varies on whether the click is left, right or bilateral, painful or painless, consistent or intermittent. The timing of a click is also significant: a click heard later in the opening cycle may represent a greater degree of disc displacement.
Clicks may frequently be felt as well as heard, though they are not normally painful.
Crepitus is the continuous noise during movement of the joint, caused by the articulatory surfaces of the joint being worn. This occurs most commonly in patients with degenerative joint disease.
The joint sounds should be listened to with a stethoscope, preferably a stereo one, as the two sides can be more easily compared.
Range of motion
This is the only truly measurable parameter, as the others are more subjective. It is just as important to record jaw movement as a means to assess the rate and degree of improvement as it is to determine the severity of symptoms.
Movements to be measured are:
Incisal opening - pain free limit
Incisal opening - maximum (forced)
Lateral mandibular excursions
Mandible deviations on pathway of opening
The incisal opening is measured from the upper incisal tip to the lower, with the patient first of all opening to the limit of their comfortable, pain free range. This is then compared to the normal range of motion Normal Range of motion Vertical
Their maximum (forced) limit is also recorded. It is important to determine whether a limitation of vertical movement is due to pain or a physical obstruction. If it is pain, then it may be a muscular problem, if an obstruction, then disc displacement is most likely.
The lateral movement should be measured from mid-line to mid-line, the patient moving the mandible to their maximum extent, from one side to the other.
When the jaw is opened, the path it follows should of course be straight and consistent. Deviations from the norm are either lasting or transient, and are all suggestive of internal derangements of different sorts.
Lasting deviations are caused by the joint on one side not moving as far as on the other. If the movement is consistent but off centre(i.e. a straight diagonal pathway), this may due to adhesions within the joint. If the movement is normal till just before the maximum range, when a lateral deviation occurs, this may be due to anterior disc displacement without reduction (if the overall range of opening is reduced).
Transient deviations occur when the joints are moving as far but at different rates. This is often caused by disc displacement with reduction.
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