If you have jaw tightness that interferes with your ability to chew or talk, it’s time to get it checked out. Tight jaw muscles can be diagnosed by a physical exam performed by your doctor, dentist, or physical therapist. If further TMJ issues are suspected, you might also need an X-ray, CT (computed tomography) scan, or an MRI (magnetic resonance imaging). Once the underlying cause of your symptoms is clear, treatment can begin.