Which structure is NOT considered part of the temporomandibular joint?

• A. Articular disc
• B. Lateral pterygoid muscle
• C. Articular eminence
• D. Stylomandibular ligament

Answer: (D)

The temporomandibular joint is a combined articulation between the mandible and the temporal bone, with structures like the articular disc and the articular surfaces (the condyle and the articular eminence) forming the joint itself, all enclosed by a joint capsule and supported by intrinsic ligaments. The articular disc sits between the condyle and the articular eminence, enabling smooth opening and closing of the jaw. The articular eminence is part of the temporal bone and directly participates in shaping the joint’s movement, so it belongs to the TMJ.

The lateral pterygoid muscle, while crucial for moving the jaw and guiding the disc and condyle during function, is a muscle of mastication and not a structural component of the joint itself. The stylomandibular ligament, on the other hand, is an extrinsic ligament that extends from the styloid process to the mandible outside the joint capsule, providing external support rather than forming part of the TMJ’s internal structure. Therefore, the structure not considered part of the temporomandibular joint is the stylomandibular ligament.