Steven Moore's blog http://taichiheartwork.blogspot.com/ is well worth reading and provides an insight into tai chi as a spiritual path. Steven is a former student of John Kells and now resides in Israel.
One of his posts reminds us that the jaws are the hips of the head.
Just as we relax the hips, so we should also relax the jaws to let go of tension that we hold in the head. Focus on the lower jaw hinges,soften and relax.
Let the feeling cascade downwards. Play with it.