I have found in my massage practice in York that many people can have tension in their jaw. It is surprising how tight the muscles in this area can become. A gentle massage around the face generally, with a focus on the temples can be a very welcome part of a tension releasing massage.
The body in very interlinked. As such, the neck and shoulders can influence tension in the jaw, and vice-versa. This is just one illustration of how massage should be looked on as a holistic treatment.