Temporomandibular Joint Dysfunction… Where do we start?!
Such a small joint, but so much to understand and consider when assessing and treating this presentation.
I hear from so many of you that the TMJ is just so complex and difficult to work with, and many people will simply refer on, not knowing how to approach it clinically. Not surprisingly really, as there is generally very little attention paid it in most undergraduate programs.
However, if you are like me and you find this region to be fascinating and have spent considerable time trying to understand it at a deeper level, then you’ll know there are some key facts and concepts that will help you make sense of it more often than not.
Today’s article, will be part 1 in a series on TMJ. There is so much to explore in this presentation, so lets make it bite sized portions (pun intended).
Let’s start with some basics.
How do the various muscles of the jaw impact movement and positioning?
It is important to remember that the mandible moves in the same way as any other bone in the body… muscles pull on it. So let’s look at in the same way.
Each muscle that acts on the jaw has the ability to draw the mandible in one or more specific directions. When we consider movement assessment, we simply look at how the jaw opens and closes (repeatedly) and we look for asymmetry or unusual movement patterns.
Get the patient to open and close their mouth fully 15 or more times. This number of repetitions will start to cause some fatigue, which will highlight any issues.
Often a deviation in one direction or another will give us a clue as to which muscle(s) will be hypertonic or shortened.
A major difference between the jaw and the rest of the body is that asymmetrical movement has the potential to create greater problems at that joint than it does in other areas, and much faster.
One bone, with two separate articulations (left and right side temporomandibular joints) means that any movement that is less thank ideal, has the potential to create unwanted stress and irritation on related joint structures on both sides.
So, to help us try to reverse engineer which muscle(s) are potentially causing the asymmetrical movement of the jaw, we have to consider the functions of each.
Below is a list of the primary drivers of movement at the TMJ along with their actions…
Masseter – Elevation, protraction (ipsilateral excursion)
Temporalis – Elevation, retraction (ipsilateral excursion)
Medial Pterygoid – Elevation, protraction (contralateral excursion)
Lateral Pterygoid – Depression, protraction (contralateral excursion)
Digastric – Depression (when infrahyoid muscles hold the hyoid bone in place)
Geniohyoid – Depression
Platysma – Depression
To give you an example, if you observe that your patient opens their mouth and the jaw deviates to the left at full opening/depression, then this may be due to:
➡️ Hypertonic left masseter
➡️ Hypertonic left temporalis
➡️ Hypertonic right medial pterygoid
➡️ Hypertonic right lateral pterygoid
It may be that one or several of the above muscles are at play in this scenario.
Another example could be that when opening the jaw, you notice that it translates forward more than it should be (protraction), in which case it could be:
➡️ Hypertonic Masseter bilaterally
➡️ Hypertonic medial or/and lateral pterygoid bilaterally
So how do we find out for sure? Again, we go back to our basics.
We palpate the tissue to determine if it feels tight, if it contains taught bands or trigger points or if it is painful.
While this form of assessment is not 100% reliable, it does form part of the data gathering and when used in conjunction with the movement assessment, we can start to build case for our working diagnosis.
The next step is to use palpation during movement assessment.
This helps us further confirm what we are seeing and what we are feeling.
You may also discover that you can identify to a greater degree which movement problems are present and which tissues are working the hardest.
Once we have formed a clinical picture of the presentation and determined which soft tissues are at play, we can then, yep you guessed it! go back to the basics and use the soft tissue therapy techniques such as massage, trigger point therapy, dry needling, MET, positional release, etc to address the hypertonic muscles.
The next bit is key and so often overlooked.
IMMEDIATELY after you have applied your treatment intervention, reassess the patient’s movement and ask about their pain.
If you have applied the appropriate treatment, you should see and improvement right away. It may not completely resolve the issue, but it should modify it somehow.
But remember, lots of things can reduce pain, and sometimes they are not the thing that will be part of the solution. So, consider the treatment results in the same way that you consider your assessment findings, they form part of the data set that we use as part of the care plan.
Before I leave you, I want to emphasise that pain in the TMJ is like pain anywhere in the body. It is multifactorial and there is likely other non-mechanical factors at play, especially if it is a chronic presentation.
So this article should serve to simply give you one component to focus on, and over time we’ll build on this theme and equip you with more tools to assess, treat and manage TMJ dysfunction.
For those of you who are interested specifically in Dry Needling for TMJ pain, ACE also holds a Dental Dry Needling Course. While this course is designed as an introductory course in dry needling for Dentists, any practitioner already trained in dry needling is also welcome to attend. Details HERE.