MR Imaging of the TMJ: A Pictorial Essay

Chris Roth, MD; Robert J. Ward, MD; Scott Tsai, MD; Wendy Zolotor, MD; Richard Tello, MD, MSME, MPH

Disclosures

Appl Radiol. 2005;34(5):9-16. 

In This Article

Abstract and Introduction

Magnetic resonance imaging (MRI) is now the primary modality for the evaluation of the temporomandibular joint (TMJ). With the use of careful technique with dedicated coils and high spatial resolution, MRI provides exquisite tissue contrast for visualizing the soft tissue and periarticular structures of the TMJ.

Magnetic resonance imaging (MRI) has replaced computed tomography (CT) and arthrography as the primary modality in the evaluation of the temporomandibular joint (TMJ). Direct visualization of the disk afforded by MRI is a distinct advantage over arthrography.[1] Despite the superior resolution of CT and limited visualization of cortical bone by MRI, most osseous pathology is accurately depicted.[2] Intra-articular abnormalities are readily visible on MRI images, providing further information not available with other imaging modalities.[3]

The TMJ is a ginglymoarthrodial (hinge and glide) articulation with some degree of diathrosis (free motion) formed by the mandibular condyle and glenoid fossa of the temporal bone[4] (Figure 1). Within this synovial joint is a fibrous disk or meniscus that divides the joint into superior and inferior compartments that do not communicate unless disk integrity is compromised. The biconcave disk has 3 functional segments: A thick posterior band that is separated from the anterior band by the thin intermediate zone. Multiple ligamentous attachments provide disk stability. Posteriorly, the bilaminar zone attaches the disk and capsule to the condyle and temporal bone. Laterally, the disk is continuous with an unnamed ligament attaching to the neck of the condyle. The superior belly of the lateral pterygoid muscle inserts into the anterior portion of the disk.

Drawing of normal temporomandibular joint showing normal relationship between temporal fossa, disk, and mandibular condyle. (A) A closed-mouth sagittal image shows mandibular condyle articulating with temporal fossa. The disk is at the 11 o'clock position. (B) An open-mouth sagittal image illustrates normal translation of disk and condyle. The condyle is positioned at the apex of the articular eminence

The surrounding supporting ligamentous structures are the temporomandibular, sphenomandibular, and stylomandibular ligaments. The temporomandibular ligament provides lateral support extending from the zygomatic process of the temporal bone to the condylar neck. The sphenomandibular and stylomandibular ligaments provide medial support coursing from the spine of the sphenoid bone to the lingual of the mandibular foramen and from the styloid process to the mandibular ramus, respectively. No discrete ligaments are normally observed anteriorly or posteriorly around the joint.

The relationships of the structures of the TMJ change with mouth position. When the mouth is closed, the disk is positioned at approximately 11 o'clock with respect to the mandibular condyle; the posterior segment of the disk caps the apex of the mandibular condyle. As the jaw opens, the disk remains between the condyle and the articular eminence as the condyle translates anteriorly. The thin intermediate zone of the disk is interposed between the condyle and the articular eminence in the fully open mouth position (Figure 2).

A 20-year-old woman with a normal temporomandibular joint. (A) A closed-mouth sagittal T1-weighted image shows a normal relationship of the mandibular condyle (large arrow), the disk (small arrow) at the 11 o'clock position, the temporal fossa (arrowhead), and the articular eminence (curved arrow). (B) Open-mouth sagittal T1-weighted image shows normal translation of the disk (small arrow) and condyle (large arrow) at the apex of the articular eminence (arrowhead).

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