TMJ ANATOMY

Temporo mandibular joint 

Keywords; tmj anatomy, trigeminal neuralgia, chiropractic help, jaw joint exercises, migraine headaches.

This page is not designed to be a highly academic tour of this complex joint; however it is a difficult topic that has had chiropractors scratching their heads. The sensory nucleus of the large nerve that supplies the jaw is located in the cervical spine, and hence the strong connection between migraine headache, neck and facial pain. 

It will give you some insights if you can struggle with the anatomy, and provide some understanding of how the temporo mandibular joint cancause severe

• Facial pain 
• Migraine headaches 
• Referral to the upper neck
• Tinnitus or ringing in the ears

It is also the joint that contributes to a complex and extremely painful condition called trigeminal neuralgia. You can go to our TMJ ear pain page for more information.

Shall we sully forth on our TMJ anatomy tour? It will help you understand any jaw joint symptoms you may be having and how it can cause such misery. 

Two cranial structures form the joint.

• The temporal bone lies on the side of your head. It has a neat little socket into which the jawbone fits.
• The mandible is the anatomical name of the jawbone.

Hence temporo mandibular and then, of course, joint to get TMJ. 

TMJ anatomy

The pterygoid pocket is a cul de sac behind the upper molars; it can be very painful.

This picture is taken from a book called Grays Anatomy. Come back later and take a short tour about this amazing man. A real pioneer. Click here for more about Henry Grays Anatomy tour.

Notice the mandible has two prongs.

1. The posterior prong (hidden in the picture above behind some ligaments which hold the jawbone firmly in place) fits snuggly into a hollow in the Temporal bone, just in front of the ear.
2. The anterior prong is for the attachment of the Temporalis muscle, the main biting muscle. See how much leverage this gives the Temporalis muscle which covers the side of the head? - hence its awesome power.

TMJ muscles

Notice two features in this second picture of our temporo mandibular joint anatomy tour.

The actual joint, where the posterior prong fits into a socket in the temporal bone.

The three muscles that slam the jaw closed.

1. The huge flat temporalis muscle that is attached to the other prong (or condyle), and another jaw closer,
2. the masseter muscle.
3. The third, the internal pterygoid we'll come to later.

A very powerful trio, strong enough to bite your own finger off! Literally. As we will see in due course, these muscles can contribute to your headache and facial pain, and neck pain if the temporo mandibular joint is not functioning as it should.

You will discover four primary jaw muscles on your tmj anatomy tour. They open, close, protrude and move the jaw sideways, enabling you to talk, chew, and swallow, kiss and many other things we do with our mouths. We'll come to the fourth muscle in due course.

There are three kinds of tmj anatomy pain:

1. Primary muscle pain is not really common but overuse, as in chewing gum or in South Africa, biltong, in association with disc malfunction can commonly causes jaw pain, facial pain headache and sometimes neck pain.

If the jaw joints are functioning optimally then muscle overuse is not usually a problem. But if the jaw joints are not moving in sinc then the more you chew, the greater the problem.

The important feature on this leg of our TMJ anatomy tour is the disc, ormeniscus as it is known, that rides in the joint, which functions as a moving shock absorber between the condyle and the fossa, or, socket, separating the two bony structures.

It's unique, quite different to any other joint in the body. As you open your jaw, the condyle first rotates and then slides forward in the fossa.

When the disc malfunctions, often after the jaw has been opened too wide, or taken a blow as in a punch, then it gives the familiar clicking and popping sound so often associated with temporo mandibular joint pain.

Please, please, do not slap your child's face, your spouse, even your enemy. You may just cause them a life time's temporo mandibular joint anatomy pain.

Joint related pain may occasionally result from inflammation, as in rheumatoid arthritis, but more usually from degeneration of the tissues within the temporo mandibular joint. 

This wear and tear in the joint, and dislocation of one of the menisci, are the two most common joint disorders of the temporo mandibular joint. The two joints then no longer work together in harmony causing facial pain, jaw joint pain and migraine headache. And, upper neck referred pain. 

Note two things here. How the condyle (posterior prong) sits in its fossa, and the position of the normal disc. See how the disc is attached another very important muscle, the lateral pterygoid? Because of this attachment to the disc, this muscle can become supremely, exquisitely, extremely painful.

This is the muscle that opens the jaw, pulling the condyle forwards out of its fossa, protected by the disc from grinding bone on bone. Used on one side only, it moves the jaw from side to side when chewing the cud. Juggle your jaw from side to side - that's the Lateral Pterygoid you are using. Now protrude the jaw, push it forwards. That's the two Lateral Pterygoids working together. See in the next picture how the condyle has slid forwards out of its fossa? That's normal.

Dislocated disc (meniscus)

Notice in the next picture how the disc has been displaced forwards. This is definitely not normal. Should you now open your jaw there will be a popping sound as the disc pops back behind the prong of the jawbone (the condyle). When this happens repeatedly the disc starts to wear, and sets up a pain pattern in the muscles around the jaw joint.

Try placing the pads of your index fingers in your ear, and slowly open your mouth. Do they open nicely together? Any clicks or pops?

Often patients are terrified of words like disease and degenerationsometimes used in describing this wear-and-tear process. No need, it's no different to your hair turning grey. What is now clearly recognised in the literature though is that, untreated, joint malfunctions, or fixations as we call them, lead to unnecessary, premature degeneration. Every time the displaced disc has to pop over the condyle, it is probably equivalent in terms of wear and tear to 100 openings of a healthy jaw.

Nerve pain or Trigeminal Neuralgia

This information about the jaw joint, its position, clicking and pain is then fed back to the brain via the largest cranial nerve, theTrigeminal nerve which supplies the face and has a spinal nucleus deep in the neck. This is how the pain from a clicking jaw causes facial pain, and can be referred to the neck. It's the reason why TMJ sufferers also usually have upper neck pain.

This facial pain can be very severe and is sometimes set off by a stimulus a slight as brushing the cheek or a breath of wind.

See that long black structure in the picture below? (in the next pic it's highlighted in green). That is the huge trigeminal nucleus extending right down into the spinal cord in the neck.

Facial Pain

It's called the TRI-geminal nerve, because it has three different sensory branches, seen here in green, blue and brown, supplying primarily the face, teeth, sinuses and TMJ. It is by far the largest cranial nerve.

Whilst I don't want to overdo the complexity of TMJ anatomy, this next slide will show you how the TMJ can cause neck pain, perhaps CAUSE subluxations, and how subluxations in the cervical spine can make the TMJ vulnerable to injury.

On the right hand side you have the four functions of the Trigeminal nerve. Focus only on the one labelled "Pain and Temperature". If you follow it along the "Spinal Trigeminal Tract" you will see that its sensory nucleus (called the "Spinal Trigeminal nucleus") is right down in the neck. From there a dark-coloured tract reaches up into the sensory cortex of the brain (those two dark arrows) where the pain is perceived.

So, noxious pain and temperature signals from the TMJ feed right down into the neck, where they meet up with other nerves from the neck, swapping messages. Pain!

Enough, right! Well done, you're a perseverer!

There's nothing simple about the human body. Nothing! and certainly not the TMJ anatomy. "Fearfully and wonderfully made" as one great surgeon named his book. Amen!

I said there are four jaw muscles. The fourth, the Internal Pterygoid is also a jaw closer. I include it here, partly for completeness, but also so that you can see the four branches of the Trigeminal nerve in situ. One motor branch to the muscles of the jaw, and three sensory nerves (labelled 1st Div, 2nd and 3rd). See the proximity of the nerve to the Internal Pterygoid muscle? This is why jaw muscle pain can so readily become intense nerve pain.

For anatomy students only: See the tiny branches supplying the Tensor Tympani muscle in the inner ear (dampens overly loud sounds) and the Tensor Veli palatini muscle that has two vital functions: in swallowing it helps raise the soft palate so food doesn't enter the sinuses, and opens the auditory tube, allowing for equalising the pressure between the inner ear and the outside air. Vital for example when driving up a steep hill, or ascending in an aeroplane. That pop in the ear... Tensor Veli Palatini doing its job.

So, the very complex fifth cranial nerve, the Trigeminal nerve, is almost continuously in use in chewing, speaking, swallowing, hearing and bringing sensory information from the teeth, face, jaw joints to the brain. 

Tinnitus 

Not a pain, but there is an irritating condition, sometimes it becomes extreme, ringing in the ears, that is common and sometimes associated with vertigo, and sometimes a result of a TMJ anatomy problem. But not usually, alas. But if you have crackling sounds, pain and stiffness coming from your jaw, then your tinnitus MAY be coming from the TMJ. May. If there is hearing loss, then Meniere's disease also needs to be considered.
Vertigo, similar to but not quite the same as dizziness, is a dreadful condition that we will consider elsewhere at Chiropractic Help.

Chiropractic Help

Like all other chronic joint conditions there is no real permanent cure for TMJ anatomy wear and tear. An acute pain or click which has just begun, correctly addressed should pass over, and the trick is not to allow it to become chronic. Like any other condition, once you know it's not going to get better on its own, then it's better to contact the relevant health professional sooner rather than later.

Not unlike the neck and back, good care of chronic TMJ pain aims at reducing the ache, restoring normal function, and avoiding known factors that provoke symptoms; like biting a whole apple and chewing gum.

The pain and dysfunction is often temporary, lasting a few days or weeks, even a month or two perhaps, so adventurous surgery which cannot be reversed should only be contemplated when all else has failed. Your first port of call, of course should be your chiropractor.

I have done no research in my practice, but I would guess at least 75 percent of patients have good to excellent results with chiropractic treatment of the TMJ.

What will your chiropractor do? Firstly a good history of how the pain or clicking started, how long it's been there, what aggravates it and so on; whether you are getting headaches, and any of the sharp stabbing pain associated with trigeminal neuralgia. Are there any definite sinus symptoms?

Then there will be an examination of the TMJ anatomy, and your neck. Treatment will include mobilising the joint, treating any active trigger points, and stretching of the muscles and joint capsule.

So, what's the good news? This is a very treatable condition. You don't have to live with TMJ anatomy pain for months.

Is there any bad news? If the pterygoids have active trigger points, they can only be reached from inside the mouth, and the treatment may be wretchedly painful, sometimes lasting a few days. Hang in with your chiroprator, that too will pass. It's very effective.

What can you do for yourself? Are there any jaw exercises for TMJ? An ice block rubbed directly on the painful spot, followed by moist heat; do it in the shower.  Now that you've taken your TMJ anatomy tour, you know where to find these muscles, right? Gently massage them. Your chiropractor will give you some stretches and, for more tips about TMJ exercises, scroll down.

If appropriate, your chiropractic treatment may include cervical spine adjustments too, if there are associated fixations. For more about the neck adjustments, scroll down to neck pain treatment.

For an interesting case from the coalface, click on this link and scroll down to Mrs Hol. 

There is a tool for self treatment of the internal pterygoid muscle; I regret I've seen no research on how effective it is, but you might like to try it