The tongue is not just taste organ, it also holds many other wonderful secrets. It is the main method of diagnosis in Traditional Chines Medicine, the analysis of the size, colour, texture and coatings determine the energetic state and health of the body as a whole.
Even in Tai Chi it is revered as a major grounding tool, placed on the hard pallet (the roof of the mouth just behind the teeth) it calms the mind and helps to focus Yin and Yang - this point is where the Yin meridians meet with Yang Meridians. Placing the tongue at this point with a relaxed tongue root and jaw supports the lungs and also the TMJ. Doing this throughout the day while working, or putting on your make up, cleansing or whenever you aims to re-set the yin/yang state.
More than this the tongue is the end point of on of the anatomy trains - the deep front line, shown below:
Lines of fascia throughout the body are long ribbons of connective tissue, if one part is affected it will impact that whole line. The Deep front line impacts the lungs, abdomen, hips and knees. The tongue and jaw muscles have a major influence on these fascial connections , so poor breathing and tension in the jaw and tongue can reach all the way down to the fascia in the feet and legs. If you have any discomfort along those lines, look at the tongue exercise above as well as organic breathing techniques.
Here is a great breathing exercise called the Lions Breath which aids the lungs, tongue, jaw and of course the Deep front Line!