129. TMJ Dysfunction – A PT Refresher

Hey guys. Welcome to PTs Snacks podcast. This is Kasey, your host, and if you are tuning in for the very first time, what you need to know is that this podcast is meant for physical therapists and physical therapist students who are looking to grow your fundamentals in bite side segments of time. In this episode, we are gonna cover more about the anatomy of the temporomandibular joint. We're gonna talk about the most common TMJ disorders, how we assess for it, and then

next week we'll talk more about treatment strategies on the TMJ. Now side note, a lot of times. TMD is used to refer to temporal mandibular dis joint disorders or disorders. But for this episode, we're gonna refer to it mainly as TMJ. So let's get started. When we are thinking about the anatomy of the temporomandibular joint, it is made up primarily of the mandible or lower jaw, the temporal bone, and the articular disc. I think maybe just 'cause I'm a nerd.

This joint is so cool because it's a glioma arthrodial joint. I'm gonna say that again. Gli mo arthrodial joint. That is a combination of hinge and gliding movements. So hinge gliss and gliding do. Movements. This is actually possible because it's divided by an articular disc into two separate joint spaces. So in the inferior joint space, this allows for rotation. So being able to hinge and close. Whereas the superior joint space enables translation.

So sliding forward during wide opening, this is important because this dual compartment design allows for a smooth controlled motion when chewing, speaking and yawning. So dysfunction in one or both of these areas can really affect movement quality and cause pain and limitation. When we are looking at our key supporting structures beyond the joint, we have our muscles. The main stars are our masser, temporalis, medial and lateral OIDs.

For our ligaments, we have our temporomandibular ty mandibular and S Pheno mandibular ligaments. It is innervated by the auricular, temporal and esoteric nerves from the mandibular vision of the trigeminal nerve. So that's V three. And then our blood supply is from superficial, temporal and maxillary arteries from the

external carotid. So looking at these structures it's not. It can be easy to see why TMJ issues can also refer to the ear, the temple, the neck or the head, and how pain can actually be either local or systemic. So let's cover what the most common TMJ disorders are. And then we'll dive into how to assess for the different ones. TMD can include a large range of conditions. Three of the most common will cover our myofascial pain, disc displacement and joint degeneration.

So when we dive into number one. Myofascial pain, this is probably gonna be the most common, and it's usually triggered by overuse of the jaw muscles from clenching, bruxism, or stress which can also cause people to clench their jaw. And it's often linked to poor posture, anxiety, or fibromyalgia. And I don't always talk about posture a lot, but if you think about a forward head position that does change the mechanics of your joint a little bit, you can try it yourself.

Now, with this condition, we are treating the muscle, not just the joint. So we need to look into why the muscle itself is causing this pain and look into maybe if some stress management or postural retraining or essential here or working on postural strength essentially for disc displacement. For disc displacement, we have disc displacement with reduction and without reduction.

So what this means is that sometimes when people are having this type of pain and their disc is reducing, it means that when they're opening, closing their mouth, the disc actually slips back into place when opening, causing a clicking or popping. Whereas without reduction, the disc kind of stays displaced and it can result in locking or limited opening. So with reduction, you have the clicking and popping. You may have full range of motion, just might not feel good.

And then with reduction, the disc is displaced near more likely to have limitations in range of motion. Now number three is joint degeneration or arthritis. So this patient can present with crepitus, stiffness, and joint pain. It could be related to osteoarthritis or rheumatoid arthritis. Now there are obviously other diagnoses to keep in mind. This is meant to be a short episode, but some of those conditions include inflammatory conditions like synovitis or capsulitis.

Someone can have congenital or developmental. Anomalies of course. And then mystic

satory, muscle disorders like spasms or contractures can occur. Or sometimes motor control can play a role in it. How someone is opening their jaw, moving weird, whether that's impacted because they've been having pain or from something else. So something to keep in mind.

Now when that patient is walking in your door and they're complaining about jaw pain, we do need to make sure that we are also doing the essentials and not just going right to their jaw because at the TMJ, a lot of times the cervical can be heavily involved or other components, other body regions that are nearby. And we also need to make sure that it's actually musculoskeletal as well, so that if it is not, they are going to a more appropriate provider.

But some questions that can help you to narrow in on the TMJ include if asking if they have any clicking locking, or trouble opening or closing that could potentially suggest. Disc displacement. If they're having any morning pain or clenching, like they wake up and they're like, oh my goodness, my jaw's killing me. That could indicate bruxism or nighttime muscle overuse. And a lot of times these patients have probably already been asked by their.

Dentist if they grind their teeth at night or may have been recommended, a mouth guard. So that's something that you could ask about too. And then headaches, ear symptoms or neck pain can often be referred from TMJ or posture related tension. Obviously we also need to screen out those causes from other things too. And then stress levels, stress can really drive parafunctional habits and muscle overload and understanding If.

There's something that has changed in that patient's life relative to about the time when they started experiencing those symptoms can be really helpful. Did they just switch to the night shift or have they been working overtime or, fill in the

blank. Those are something that can be helpful to talk through and see if that person also wants to see a specialist to help them with their stress levels or depending on what the cause of it is. Now, hopefully you've also ruled out other underlying causes from nearby joints. I can refer to this too, but with our objective tests, this is a chance for us to really rule in on if this is a TMJ issue and if it's more related to our active tissues.

Like our muscles are more of our passive tissues, like our joint, the disc, et cetera. So we need our exam to be able to reflect. How to differentiate between these two, are we bringing it on with only passive things or only active things? Or is there overlap? If they've had pain for a long period of time, there's probably multiple types of tissues that are a little aggravated. But what is the root underlying cause that you can best tell based on their exam and also their patient history?

So even starting off with screen out the joints that are nearby, but we wanna look at their mandibular range of motion. So I'm gonna review the normal ranges because it's not really always a very common joint that we see. So for mandibular opening, the normal range is 40 to 50 millimeters, and that's measured between the upper and lower central incisors. Functional opening though is about 3 35 millimeters.

So we say functional in that it's enough for them to be able to eat and speak and all those sorts of things. Or if you don't have a goniometer to measure this two to three finger widths vertically on top of vertically is a good, quick functional screen. Maybe just let your patient know what you're doing or have them do it with their fingers just to. Side note there. Now lateral deviation is the normal range, so it draws moving side to side, eight to 12 millimeters to each side.

You're measuring from the midline at rest to the point of maximum deviation, not from one side fully to the other. Right now, limited lateral deviation can help us indicate if they have a joint capsule. Now if they have limited lateral deviation, this can help us to maybe see if they have some sort of joint capsule restriction, dis displacement without reduction or muscle imbalance especially with media lateral tiggo dysfunction.

So you should be accumulating this knowledge in your head as you're looking through them. Protrusion where the lower teeth pass in front of the upper teeth, the normal range is six to nine millimeters. So if they're limited in this, we can see that also with disc displacement, without reduction, arthritic exchanges or posterior capsule tightness and retraction, the opposite direction is gonna be normal range more three to four millimeters.

So if they're limited in this, which is pretty hard to see, three, three to four millimeters is not. A huge amount but could indicate anterior disc issues or anterior capsule or muscular tightness. Now, if you are seeing asymmetry, as I mentioned in lateral excursion or reduced protrusion, you can have put disc displacement on your radar, especially if it's accompanied by clicking or deviation. If the motion is globally restricted. Maybe think more about joint degeneration or muscle guarding.

'cause we don't tend to have degeneration just on one side or like one side of our jaws having muscle tightness, right? Palpation and joint sounds can help guide movement. So joint sounds as in, can you hear clicking? You can even break out your stethoscope and put it on their jaw to better see, hear. That might indicate dis displacement with reduction or are they having any crepitus, degenerative changes, palpating. So this can help to just measure irritability of those muscles.

With specifically the masseter, the temporal temporalis, the lateral tego. You might have to do intraorally or you will have to do intraorally. Now. Note if they're having referral patterns to the ear temple or the jaw with these they, these can just be helpful to rule in or rule out if those, if you're suspicious of some sort of muscular involvement and they don't seem to be irritated or at all might be good to still look into other areas of potential causes.

Now the bite test or Popsicle stick test, that's what I remember most from PT school. But it's actually pretty helpful. So what you do is you take a Popsicle stick or some people use like a cotton ball, and you'll have the patient bite down on one side. So if they're experiencing pain on the same side as the Popsicle stick or whatever they're biting down on, it's more indicative of muscular involvement.

Whereas pain on the opposite side of where they're biting down can be indicative of joint or disc involvement. So this just better helps us to differentiate between what tissue type is involved more. You can also do a joint loading compression test where you apply an upward posterior force on the mandible. A positive meaning it doesn't feel good would suggest intraarticular irritation or resisted movements. So you can muscle test there. The muscles around the TMJ for.

Protraction opening lateral lateral deviation, et cetera, and see if that reproduces their pain or if they're having weakness or mechanical block, meaning they just can't even get into that range passively or actively potential joint or disc issue. And of course you wanna assess their cervical si spine. Look at their range of motion mobility post if they

have. They live in a forward head posture. So this is just commonly cited as a position that can exasperate TMJ load. And if you're concerned about nerve involvement, there's something called a fostex sign. You tap anterior to their ear over the facial nerve, and then twitching suggests neurogenic or systemic issues. So differential diagnoses. So these are things that you need to keep in mind that are not necessarily TMJ issues.

For one, if they're experiencing facial pain, maybe rule out trigeminal neuralgia, sinusitis or salivary gland issues, oral facial pain, rule out dental abscesses or tooth eruption best that you can at least headaches rule out. Headaches differentials can include migraines, cluster headaches, or temporal arteritis and ear symptoms, otitis media, barotrauma and eustachian dysfunction.

You may want to refer this patient to a max maxillofacial surgeon if there is severe dysfunction, if they're failing conservative care or

they have a history of trauma. Especially for things like worsening or persistent pain, if they have trius or jaw lock, cranial nerve deficits, weight loss, or systemic illness, or they're experiencing asymmetry, like unilateral hearing loss, new tinnitus, vestibular issues, things of that matter. Now, we will cover treatment next week, but by this episode, just as a recap, know that.

It's important to have a basic understanding of the, what's unique about this anatomy, the common diagnoses that we'll see, and some takeaways for questions that you can ask in assessments in your exam to help you differentiate what the root of the problem is. So if you would like to take a deeper dive, there is a med bridge course. If you have a Med Bridge subscription on temporomandibular disorders by Bill Garrett. If you don't know who Med Bridge is, they are a, an online CCU company.

They actually sponsor this podcast, but they have thousands of online courses, webinars, specialty exam prep, all on an app, and there are giving listeners over a hundred dollars off their year subscription. So if you like big discounts and you like to learn. Just check out the promo code in the show notes. But other than that, I hope this was helpful to you. And if you have any questions, feel free to reach out at pt Snacks podcast@gmail.com.

If you'd like to support the show, there's a link below. But I hope you guys have a great rest of your day, and until next time.