“TMD” and “TMJ” are two acronyms often used interchangeably. In actuality, they refer to different — though related — terms. Let’s figure out what each means.

The temporomandibular joint (TMJ) is a hinge-like joint that connects your lower jaw to your skull. You have a pair of these joints. They can be found on either side of your head in front of your ears.

Temporomandibular joint disorder (TMD), sometimes also referred to as TMJD, is a group of conditions that happen when your TMJ becomes inflamed or painful.

Sometimes, people might call this disorder “TMJ” because it relates to the TMJ joint. But because this creates confusion, it’s best to separate these two terms and refer to the health condition as “TMD” or “TMJD.”

Your TMJ is shaped like a sliding hinge that allows your jaw to open and close and move from side to side.

Several mechanisms work together to help your TMJ function smoothly and without pain.

First, the parts of your bones that form the joint are covered with cartilage, a flexible connective tissue. Second, these bones are separated by a shock-absorbing disc also made of cartilage. Third, the joint is filled with a thick, lubricating liquid called synovial fluid.

With the help of many muscles in your face and head, TMJ makes it possible for you to:

  • chew
  • suck
  • swallow
  • speak
  • change your facial expression
  • breathe
Conditions that may cause TMJ, such as teeth grinding and stressShare on Pinterest
Conditions that may cause TMJ, such as teeth grinding and stress. Illustration by Antonio Jimenez.

Because your TMJ is so complex, there can be many ways it can be damaged. Damage to the TMJ that causes pain, discomfort, or inflammation results in TMD.

TMD can affect one or both sides of your face. Symptoms can be temporary or last years. The condition may be common in women — according to a 2018 study, women are twice as likely as men to develop TMD.

According to the National Institutes of Health, the symptoms of TMD may include:

  • pain in your jaw, face, neck, shoulder, or back
  • stiffness in the muscles of the jaw
  • limited movement or locking of the jaw
  • clicking or popping in the TMJ
  • changes in how your upper and lower teeth fit together
  • headaches
  • earaches or ringing in the ears (tinnitus)

According to 2022 research, the most frequent causes of TMD are:

  • overuse of your chewing muscles, which can happen if you:
  • misaligned bite (for example, underbite or overbite)
  • anxiety and stress
  • damage to your lower jawbone from injury or dental issues
  • wear and tear on the cartilage, for instance, due to arthritis
  • damage to the disc inside your TMJ
  • structural jaw differences present at birth

The causes of TMD are often unclear.

Seek medical attention if you have any of the symptoms of TMD, especially if you:

  • have persistent pain
  • have discomfort
  • have inflammation in your jaw
  • cannot open or close your jaw completely

Dentists most often diagnose and treat TMD, but your primary care professional will be able to help you as well.

Treatment of TMD varies based on the following factors:

  • the specific cause of your TMD
  • your age
  • your general health
  • how long you’ve been living with your TMD symptoms
  • your opinion and preferences

Treatment of TMD may include:

Learn more about treatment options for TMD.

Although the terms “TMJ” and “TMD” are often confused, they refer to different — though related — things.

“TMJ” refers to the temporomandibular joint, a hinge-like joint that connects your lower jaw to your skull. “TMD” is a condition that affects the TMJ, and it stands for temporomandibular joint disorder.

TMD occurs when there’s damage to your TMJ. It often causes severe, persistent pain, discomfort, and inflammation.

Make sure to speak with your dentist or primary care professional if you suspect you have TMD. Many treatment options can help you find relief from this condition.