Topics

Topic

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Articular disc of temporomandibular joint

The articular disc of the temporomandibular joint (TMJ) is a key fibrocartilaginous structure that separates the mandibular condyle from the temporal bone within the joint space. It plays a vital role in smooth jaw movement, cushioning, and load distribution during mastication and speech. Proper assessment of the disc is crucial in evaluating TMJ disorders, especially using advanced imaging modalities such as MRI.

Synonyms

  • TMJ articular disc

  • Mandibular disc

  • Temporomandibular disc

  • Interarticular disc

Anatomical Features

  • Biconcave fibrocartilaginous structure

  • Divides the TMJ into superior (meniscotemporal) and inferior (meniscomandibular) compartments

  • Anteriorly attaches to the joint capsule and lateral pterygoid muscle

  • Posteriorly attaches to the bilaminar zone (retrodiscal tissue)

  • Central portion is avascular and thinner; peripheral areas are thicker and more vascular

Functions

  • Absorbs and distributes mechanical loads during jaw movement

  • Facilitates smooth articulation between the mandibular condyle and temporal bone

  • Stabilizes the condylar head within the glenoid fossa

MRI Appearance

On Proton Density (PD) Sequence

  • The articular disc appears as a low-signal (dark) biconcave structure

  • Clearly demarcated between the high-signal synovial fluid of the joint compartments

  • Helpful for assessing disc position (normal, anterior displacement, perforation)

On Short Tau Inversion Recovery (STIR) Sequence

  • Disc remains low signal intensity, distinct from surrounding tissues

  • STIR is sensitive for detecting joint effusion and inflammation, with effusion appearing hyperintense (bright) and disc as a dark structure

  • Useful for identifying associated soft tissue edema and pathology

MRI images

Articular disc of temporomandibular joint