In myofascial TMD, what primarily limits range of motion?

• A. Muscle tightness.
• B. Disc displacement.
• C. Bone fracture.
• D. Nerve compression.

Answer: (A)

Muscle tightness from hypertonic jaw muscles is the main reason jaw range of motion is limited in myofascial TMD. When the masticatory muscles (like masseter, temporalis, and pterygoids) develop taut bands and trigger points from clenching or overuse, they resist stretching and movement and cause pain with function. This muscular guarding reduces how wide the mouth can open and how freely the jaw translates, even if the joint structures themselves are intact. Disc displacement can cause locking or pain in other TMD subtypes, but in the myofascial form the primary limiter is the muscle tightness. Bone fracture would present with acute injury and instability, and nerve compression isn’t the usual driver of ROM limitation in this context.