First things first. TMJ stands for Temporo-Mandibular Joint. When referring to TMJ pain, this usually means pain at the temporo-mandibular joint. TMJ pain can also be labelled TMD or TMJD meaning temporo-mandibular dysfunction/disorder or temporo-mandibular joint dysfunction/disorder respectively. Ok, so for the rest of this article I will use TMJ to mean the joint and TMJD to mean the dysfunction or pain. People will often just say they have TMJ (meaning pain), but technically if someone says “I have TMJ” you could easily say, “yes, and so does every other human and most mammals (i think)”, as this just means they have a temporo-mandibular joint. But that is being really pedantic and annoying… moving right along.
TMJD is a very common condition that we treat all the time. It would be one of the most common reasons people come to our clinic. Jaw clenching and grinding tend to be the most common causes of this pain and as most people clench or grind in their sleep at night, they usually don't have a sense of why they are getting pain in the first place.
TMJD can be debilitating and at its worst can mean you can't chew solid food without pain. There are many different causes and some underlying issues that can be at the root cause, making this a tricky injury to treat and manage.
Let’s start with the basics. What is the TMJ? This is where the temporal bone (side of the skull) meets the mandible (jaw bone). Where the mandible and temporal bones come together is a synovial joint. This joint actually has a disc just like our spine. This disc absorbs pressure as without this disc the pressure of chewing food would damage this joint.
The skull or cranium is actually made up of 8 bones. These bones are held together with sutures or connective tissue when we are born, to help the skull be more malleable so the head can fit through the birth canal. The sutures then fuse at around the age of 2 to become one solid bone. The 8 cranial bones are the ethmoid bone, frontal bone, occipital bone, parietal bone, sphenoid bone and 2 temporal bones (see picture).
The muscles of the jaw: