What is the main function of the sphenomandibular (medial) ligament?

• A. Maintains tension during jaw opening and closing
• B. Stabilizes the TMJ during lateral movements
• C. Limits posterior movement of the mandible
• D. Prevents anterior dislocation of the jaw

Answer: (A)

The sphenomandibular ligament acts as a passive check ligament for the mandible. It runs from the spine of the sphenoid to the lingula of the mandible and primarily limits excessive opening of the jaw, helping to stabilize the mandible as it moves. This is why it’s described as maintaining tension during jaw movement—especially when the mouth opens wide—providing a restraining influence that prevents too much downward translation. Other ligaments around the TMJ have different primary roles, such as restricting posterior movement, stabilizing during lateral shifts, or limiting protrusion, so this ligament’s main job is the restraint and passive support during opening.