What is the principal function of the INTRINSIC (capsular and temporomandibular) ligaments of the temporomandibular joint?

Correct answer: A. Passive restriction of mandibular border movements

• A. CORRECT. The INTRINSIC ligaments — the joint CAPSULE and the TEMPOROMANDIBULAR (lateral) ligament — are PASSIVE restraints. They contain no contractile tissue and do not participate in movement; they simply define the outer limit of mandibular border movement, preventing excessive inferior, posterior and lateral displacement of the condyle. The TM ligament in particular has an outer oblique portion that limits rotational opening and an inner horizontal portion that limits posterior condylar displacement, thereby protecting the retrodiscal tissues.
• B. Passive suspension of the mandible is attributed to the EXTRINSIC (accessory) ligaments — the STYLOMANDIBULAR and SPHENOMANDIBULAR ligaments — not the intrinsic ones.
• C. Protrusive translation is produced by the LATERAL PTERYGOID muscle and guided by the bony contour of the articular eminence and the disc; ligaments only limit the endpoint of that excursion.
• D. Elevation of the mandible is performed by the MUSCLES of mastication — masseter, temporalis and medial pterygoid. Ligaments are non-contractile and can never actively move a joint.

Note: Divide the TMJ ligaments cleanly: INTRINSIC = capsule + temporomandibular (lateral) ligament, both true functional restraints. EXTRINSIC/ACCESSORY = sphenomandibular (attaches to the lingula; a landmark for the IAN block) and stylomandibular. All of them are passive; none of them move the joint.