It’s really sort of amazing how complicated the working of the jaw is and how little we even think about chewing and swallowing until something goes wrong.
I became interested in the temporomandibular joint (TMJ) and its related dysfunctions a couple of years ago when my mother took a really bad fall. She got a concussion that, fortunately, recovered well. But they almost ignored the fact that she had severely damaged both her teeth and her jaw. Since then, she’s been having troubles with her jaw brought on by the trauma of the fall.
The temporomandibular joint (TMJ) is the junction of the skull and the jaw.
It’s a very complicated hinge. When you are chewing, the skull stays still and only the mandible (jawbone) is moving.
Furthermore, the act of chewing is not simply a ‘chomp-chomp’ straight up-and-down bite, as you would see in an alligator or crocodile. In most mammals, including humans, the mandible not only goes up-and-down, but both forward-and-backwards and side-to-side.
Try it now. It’s quite remarkable. The TMJ is a very subtle and complicated joint.
It allows you to chew your food efficiently and, with the help of your tongue, pass food at various levels of processing to teeth with the appropriate shape and function (incisors for cutting, bicuspids for shearing, and molars for crushing, grinding and shearing.) For this to happen properly, you need to coordinate multiple muscles that engage in chewing as well as a healthy TMJ.
When things go wrong
It is not a huge surprise that when things go wrong with this joint and/or its related nerves and muscles that it can become quickly problematic.
The phrase ‘temporomandibular joint dysfunction’ (TMJD) is a bit like ‘migraine’ in that they are both sort of ‘catch-all’ categories: a dozen or more causes with a single name.
With TMJD there is a whole suite of ailments that result in similar symptoms making diagnosis tricky. TMJD can be caused by problems with circulation (temporal arteritis), arthritis in the joint, congenital problems with the joint, physical damage to the joint (like my mom’s), misalignment of the teeth, teeth grinding while asleep, even irritation of the nerves passing near the joint. The list is extensive. The bone in the skull or jaw, condylar surfaces, ligaments, muscles, or nerves associated with the TMJ can become damaged or inflamed.
In previous posts, we have discussed the trigeminal nerve (Cranial Nerve V) broadly and seen how irritation of the second branch of the trigeminal nerve (maxillary nerve) can lead to bouts of chronic pain and one strategy that helps in many cases (the SPG block).
What I had hoped to focus on in this brief article was involvement of the third branch of the trigeminal nerve in the generation of chronic pain. The third branch subdivides further into the auriculotemporal branch (around the ear and across the temples), and the masseteric branch (around the masseter muscle, the muscle that runs from the zygomatic arch (cheek bone) and the rear of the jaw.
However, as unsatisfying it may seem, an exhaustive review of the sensory nerves involved in the generation of TMJD is beyond the scope of this blog post. So, I am handing you off to three excellent articles on TMJD:
- National Institute of Dental and Craniofacial Research.
- Michigan Medicine at the University of Michigan .
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