The answer is that they share a common root cause, which is the unique anatomy of the throat (oral pharynx) of human species. It is an intersection between the breathing passage from the nostrils to the lungs and the food passage from the mouth to the stomach. This allows us to breathe through our mouths, speak and enunciate through movements of our tongue and still swallow through the tongue. It also allows the tongue to enter and fully or partially block the throat, including the airway. This is most immediately threatening human survival.
My articles in Your Health Magazine (YH) since 2007 have addressed many aspects of this in their explanation of how OSA is jaw-tongue-throat relationship to airway patency, which is anatomical and it therefore, exists round-the-clock. It is associated with anatomic balance of the body as seen in “ease” of swallowing, speaking and breathing. It also impacts and is impacted by physiology and biochemistry in modifying and/or compensating for compromised airway anatomy at any point in time and over time.
I have discussed, how through the study of “Oral Systemic Balance” Farrand C. Robson, D.D.S. has observed the three ways the body compensates for impaired oral functions of speaking, swallowing and breathing. They are:
An increased state of “fight or flight” as adrenaline like affects
Postural changes that often appear to be characterized by forward head posture
Clenching and grinding of the teeth, this leads to most TMJ symptoms.
In my YH articles since 2008, I addressed the postural compensation and its musculo-skeletal impact upon the whole body. I even provided, for a reader, a way to personally observe these compensations as the force themselves to stand in an ideal posture, while awake (daytime apnea) as, most often their swallowing, speaking and breathing became more difficult, adrenaline-type “stress” sensations increased and how jutting their mandible (lower-jaw) as far forward as possible, pulling the tongue forward from the back of the throat provides some relief.
From this, all three compensations are observable; especially, how the body posturally adapts to provide more room behind the tongue and the back of the throat and supporting vertebral column to ensure adequate airflow, thus survival.
The long term impact of three dimensional compromises in ideal body posture upon the musculo-skeletal pain, however, I have not shared my perspective upon its impact upon the elliptically not-spherically shaped weight bearing joints of the body and the incidence of knee and hip surgery leading to joint replacement that also appears to be increasing in prevalence in “modern” society associated with “posture”.
I believe that cooperation between dental, orthopedic surgery, physical therapy and chiropractic researchers can bring this information to light and lead to integrated care that reverses this trend.