+++
Historical Perspective
++
Treatment of the temporomandibular joint (TMJ) was first described in Egyptian papyri 4,000 years ago and the technique currently used for reducing TMJ dislocation was developed by the ancient Greeks.1 However, the construct of TMJ disorders was first introduced in the 1930s, when James Costen, an otolaryngologist, put forth the theory that pain in the muscles of mastication, facial pains, headaches, ringing in the ears, and numerous other symptoms originated in the TMJ. Disorders of the TMJ were presumed to be caused by dental malalignment, occlusal disharmonies, and missing teeth—the implication being that TMJ disorders were dental problems, best treated with structural corrections. This view survived for half a century; but in the last 30 years, the discussion of TMJ-related problems has taken a very different turn. Occlusal factors have been all but abandoned as a major cause of symptoms and current treatment guidelines generally do not recommend invasive interventions and structural changes.2
+++
Causes of TMJ Disorders
++
TMJ disorders have been attributed to a variety of causes, but in recent years the focus has shifted away from the TMJ as the sole cause of the symptoms previously attributed to this joint. Structures outside the TMJ, including the joints and muscles of the cervical spine, are now recognized as common sources of symptoms. An example of the changing emphasis is a decreasing concern with diseases and dysfunctions. The discussion is shifting away from presumed mechanical or structural problems toward a focus on symptoms; consequently, symptoms associated with TMJ disorders are now most commonly referred to simply in terms of craniofacial pain or orofacial pain.3
++
The TMJ is a compound synovial joint between the mandible and the cranium. This joint is considered a part of a larger functional unit, the craniomandibular system, encompassing the TMJ, the cranium, and the cervical spine.
++
The osseous components of the TMJ consist of two surfaces, covered with fibrocartilage, and an interposed articular disk. The osseous components are (1) the anterior part of the mandibular fossa of the temporal bone, and the articular eminence anterior to it, and (2) the condyle of the mandible (Fig. 8-1). The anatomy of the joint is described here in the sagittal, coronal, and axial planes:
++
Sagittal plane: The temporal articular surface covers the anterior slope of the fossa and the articular eminence; the mandibular (condylar) cartilage primarily covers the anterosuperior condyle. Note that both these osseous surfaces are convex; the disk makes up their lack of congruence (see Fig. 8-1).
Coronal plane: The mandibular fossa, concave in the coronal plane, articulates with the medial side of the convex condyle only (Fig. 8-2).
Axial (horizontal) plane: The mediolateral dimension of the condyle is greater than the anteroposterior dimension, giving the condyle an ...