Yvonne, a 38-year-old housewife and mother of three, complains that she has a hard time closing her jaws. In fact, she says that she is unable to close her mouth completely. She says that this started 2 days ago when she opened her mouth really wide and yawned, right after she had just woken up. After she yawned, she noticed that she had an impossibly hard time closing her mouth. When she visited the dentist, he diagnosed her with TMJ or temporomandibular joint dislocation(TMD).
The temporomandibular joint is found on the anterolateral area of the cranium, “both sides of the head”, within the cheek area. This is a joint found right below the temporal bone, which is a part of the cranium/skull, “the group of bones found on the upper part of the head, specifically above the mouth”. Aside from this, the joint is found on top of the super lateral area, “on the upper right and left area” of the mandible, “the bone composing the lower jaw”. It is located in the anteroinferior area of the external acoustic meatus, “front of the lower part of the ear”.
Basically, a joint is an area where two or more bones articulate, “make contact” with each other. These are constructed to ensure proper movement and mechanical support. The TMJ is a type of ball-and-socket joint, where one bone has a condyle(ball) “a type of elevation within the bone which is round in shape”, which fits perfectly in a fossa(socket) “a type of hollow depression” in the other bone which penetrates through it.
Therefore, this joint is a synovial joint, a joint with a type of fibrous capsule around a synovial cavity containing synovial fluid, “a type of fluid providing lubrication” between the articulating bones, allowing free movement. When a person opens their mouth wide, the “ball”, condyle, moves out of the socket, and moves forward”. And, normally, moves back to place when one closes her mouth. In the case of the temporomandibular joint the condyle is found on the mandible, literally called the “condyle of mandible”. This condyle articulates with a fossa within the temporal bone specifically called the arcus zygomaticus.
The dislocation is caused by the condyle of the mandible moving too far forward. When one opens their mouth too wide, the condyle suffers disarticulation, “gets stuck on a position where it is not supposed to be in”. It is disarticulated in a “slight elevation” or bony prominence. This prominence is known as the articular eminence. When this happens, the condyle will not be able to move back to its usual place. Most of the time, this happens when the ligament, “the tissues connecting the two bones and keeping them in place”, are loose or weak. When these are loose, they allow the bones to move past the articular eminence.
Once the condyle surpasses the articular eminence, it will not be able to go back to its usual positon. In addition, the muscles surrounding the joint often go into spasm “a sudden involuntary continuous muscular contraction” which effectively keeps the condyle in the dislocated position.
The dislocation will remain in its disarticulated position, until it is treated by moving the joint back to place. To treat it, the person must be given an injection of a local anaesthesia, “a type of anaesthesia which would only affect a small area”. When this anaesthesia is applied on the body part which requires attention, it is benumbed, “experiences a loss of sensation”. Afterwards, the patient will be prescribed muscle relaxants, “loosens the muscle spasm”.
This is given intravenously, “into a vein in the patient’s arm”. In rare cases, the person has to be given general anaesthesia in the operating room to have the disarticulation corrected. To do this, wires or elastics are placed in between the superior, “upper”, and inferior, “lower” molars to ensure that the jaw’s movements are limited. The doctor or dentist then pulls the posterior portion of the lower jaw inferiorly” downward”, while the distal portion, “the tip”, of the chin is pulled superiorly “upwards”. The attending physician then guides the ‘ball’ into the ‘socket’.
For a recovery period lasting several days, Yvonne will be advised to avoid hard-to-chew food such as meats, candies, ice cubes, etc, and those that will require her to depress her lower jaw too low, “open her mouth wide”. In fact, Yvonne will be on a soft or liquid diet for several days.
Bibliography
Snell, R.S. (2008) Clinical Anatomy by Regions. 8th ed. London, Sage.
Clemente, C.D. (1997) Anatomy. 4th ed. Los Angeles, California, Lippincott, Williams, & Wilkins.
Shorey, C.W. & Campbell, J.H. (2000) Dislocation of the temporomandibular joint Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology. Indianapolis, Indiana University. Vol 89: 662-668.