If you have jaw pain, you have probably heard the term “TMJ” used to describe both the joint and the problem. But TMJ and TMD are not the same thing. Understanding the difference matters because it affects how your condition is diagnosed and treated. Both fall under the broader field of TMJ and orofacial pain.

TMJ: The Joint.

TMJ stands for temporomandibular joint. It is the joint itself, not a disease or disorder. Everyone has two TMJs, one on each side of the head, right in front of the ears. These joints connect your lower jaw (mandible) to your skull (temporal bone).

Your TMJ is a sliding hinge joint. A small disc of cartilage sits between the two bones. Muscles, ligaments, and tendons surround the joint and control its movement. You use your TMJ every time you open your mouth, chew, talk, or yawn.

TMD: The Disorder.

TMD stands for temporomandibular disorder (sometimes written as temporomandibular disorders, since there are multiple types). TMD refers to the medical conditions that affect the TMJ and the muscles that control jaw movement.

When people say “I have TMJ,” they usually mean “I have TMD,” meaning something is wrong with their jaw joint or muscles. Saying you have TMJ is like saying you have knee when you mean you have a knee injury. The joint itself is not the problem. The disorder affecting the joint is the problem.

In short
Everyone has a TMJ. Not everyone has TMD.

Why the Distinction Matters.

This is not just a matter of terminology. The distinction matters for diagnosis and treatment because TMD is not one condition. It is a group of conditions that fall into two main categories:
01

Myogenous TMD (Muscle-Related)

The pain comes from the muscles that move your jaw. These muscles can become tight, sore, or develop trigger points. Causes include teeth grinding, stress, poor posture, and overuse. Myogenous TMD is the more common type and often responds well to treatments like oral appliances, Botox, trigger point injections, and physical therapy. Learn more about myofascial pain →
02

Arthrogenous TMD (Joint-Related)

The pain comes from inside the jaw joint itself. This can happen when the disc slips out of position (disc displacement), when arthritis develops in the joint, or when the joint is injured. Arthrogenous TMD often causes clicking or popping sounds and may require different treatment approaches, including regenerative therapies like PRP or prolotherapy.
Many patients have both types at the same time. An orofacial pain specialist can tell the difference through a thorough exam and, when needed, imaging tests. The right diagnosis guides the right treatment.
Treatments page for South Bay TMJ non-surgical TMJ and orofacial pain care

The Diagnostic Standard: DC/TMD.

The international standard for diagnosing TMD is called the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). This system gives doctors a clear framework for identifying which type of TMD a patient has. It separates muscle-related problems from joint-related problems and provides specific criteria for each.

At South Bay TMJ, Sleep, Headache & Orofacial Pain Institute, our board-certified specialists follow the DC/TMD framework. This ensures your diagnosis is accurate and your treatment targets the actual source of your pain.

What You Can Do.

If you think you have a TMJ disorder, the most important step is getting an accurate diagnosis from a specialist who understands all the different types of TMD. A thorough evaluation can determine whether your pain is coming from the muscles, the joint, or both, and guide a treatment plan that addresses the real cause.

Do not settle for a generic diagnosis of “TMJ.” Ask your provider what type of TMD you have and what is driving it. That specificity makes all the difference in treatment outcomes. Learn what to expect as a new patient →