Ear Pain Due to TMJ (Jaw Joint) Disorders


The temporomandibular joint or TMJ is the
joint that allows jaw movement to occur. It is located immediately in front of the
ear canal shown by the green arrow. Both the ear canal and TMJ share a common
boney wall and as such, TMJ disorders can often cause significant ear pain leading some
patients to think they may have an ear infection even though none is present. In order to understand ear pain due to TMJ
disorders, one first needs to understand how the joint looks and moves when it works normally. Within the TMJ capsule, there is an articular
disc made of cartilage that allows for both vertical as well as horizontal movement. The disc and jawbone are attached to the lateral
pterygoid muscle anteriorly that contract to allow jaw opening. Retrodiscal tissue attaches behind the disc
and has many nerve endings. The first 2 centimeters of jaw opening is
due to a purely rotational movement of the jawbone with respect to the articular disc. When the mouth opens wider than 2 centimeters,
the jawbone and articular disc both move in a coordinated fashion forward and down along
the articular eminence of the skull and out of the joint socket. Overall, this movement is called translation. The most common TMJ disorder that results
in ear pain is due to articular disc displacement. The most common displacement position of the
disc is anteriorly such that when the mouth opens, the jawbone pulls the disc forward
thereby not only stretching the retrodiscal tissue even further than normal but also pinching
it. Because retrodiscal tissue contains many nerve
endings, ear pain may occur from both being overly stretched as well as pinched in between
the two bones. Furthermore, there is more bone on bone movement
which may cause further discomfort. The displaced articular disc also prevents
smooth forward movement of the jawbone due to its abnormal position. In order for the mouth to open fully, the
jawbone has to jump over the back end of the displaced articular disc causing a clicking
or popping sound along with causing pain. When the mouth closes, the jawbone comes back
off the disc and onto the retrodiscal tissue resulting in another pop and click with associated
pain. The medical term for this condition is called
“disc displacement with reduction.” Over time, the jawbone stays behind the dislocated
articular disc without being able to jump onto the disc pad. At this point, the popping and clicking disappears,
but the mouth-opening is limited and the ear pain becomes substantial. At this point, the jaw is considered to be
in a locked position. This condition is called “disc displacement
without reduction.” Fortunately, this TMJ disorder resolves spontaneously
over time when the retrodiscal tissue undergoes scar change and denervation. Functionally, at this point, it replaces the
normal articular disc and is now called a “pseudo-disc”.

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