Something I've noticed more and more with training/treating is some seriously poor jaw positioning in clients. Whether it's just resting posture or the middle of a big lift, people go thru some weird jaw movements: flaring it wide open, biting down hard and grinding, protracting the jaw forward, or just being slack-jawed. Besides weirding people out, it indicates that we are lacking a strategy for maintaining a stable, centered jaw position over the upper cervical spine which is critical for movement integrity, neural output, and resolving neck or jaw pain including headaches. Essentially, the system is looking for stability and finding it in dysfunctional positions.
We know that head position can actually influence pelvic tilt such that a forward head or looking up during a lift promotes an anterior pelvic tilt and an overextended lumbar spine - which is why we should NOT cue athletes to "look up" during squats or deadlifts. I previously wrote that mouth breathing can destabilize the cervical spine and certainly it affects jaw position. Developmentally, motor control is learned from proximal to distal and from head to toe (i.e., we learn to move the jaw before the lips and tongue; control the head before the arms). The ability to keep the head in midline is a prime example of developmental progress. So by accessing a developmental or primitive pattern and setting the jaw (including the tongue) into a stable position, we can better access the nervous system and promote adaptation and improve output.
So what is the stable position of the jaw?
The mandible attaches to the temporal bone like a boat to a dock - it's floating around in there rather than anchored like the hip, for example. What this means is it's a joint that requires loads of stability and motor control for optimal function.
Ultimately, the jaw is not optimally stabilized if we do not have full cervical range in all planes while maintaining the lips sealed, jaw slightly open, and the tongue at the roof of the mouth. Having that tongue position really optimizes and integrates the whole system.
Check out the video below for a few ideas on improving upper cervical spine mobility and jaw positioning. These are also clutch for tension-type headaches.
Not having the basics of jaw positioning (including the tongue) just won't cut it and will lead to alterations in the nervous system, spinal control, and power generation.