Anatomy & Histology · single question
Where is ELASTIN found in the Temporomandibular Joint (TMJ)?
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Correct answer: D. Articular disc
The articular disc of the TMJ is composed of dense fibrocartilage (type I collagen). The extracellular matrix of the articular disc contains BOTH type I collagen AND elastin fibers. The elastin provides the disc with resilience and elasticity, allowing it to return to its shape after deformation during jaw movement. The articular surfaces of the TMJ (glenoid fossa and mandibular condyle) are covered by fibrocartilage (NOT hyaline cartilage, as in other joints).
- A. CORRECT. The TMJ articular disc contains type I collagen AND elastin in its fibrocartilage extracellular matrix.
- B. Incorrect. The sphenomandibular ligament is composed of dense collagen fibers — not elastin. It is an accessory ligament of the TMJ.
- C. Incorrect. The glenoid fossa and articular eminence are covered by fibrocartilage — the cartilage itself is primarily collagen, not elastin-rich.
- D. Incorrect. The TMJ does not have typical 'articular cartilage' (hyaline) — it has fibrocartilage. Elastin is specifically identified in the disc, not the bony articular surfaces.
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