Chewing is coordinated by the cerebellum, located at the rear of the head in the posterior fossa. This is a part of the central nervous system. Thin wires connect the jaw muscles with the lower lobe of the cerebellum. The control pulses to the muscles are of electro-chemical nature.
The cheek muscles are also controlled by the cerebellum. This lobe is situated in the top of the cerebellum.
When the jaw muscles contract, the cheek muscles should extract. The coordination therefore is known as the “coho-sinc-lock-pulse”. And there is the week point. This pulse is controlled by the “afflectus sensualis”, a large number of neurons, positioned in the mucous membrane. When food is very tasty, or when you are very hungry, then you produce a lot of mucus fluid. There is a risk that the neurons lose their ability to register the overpressure and under pressure in your mouth, so the “coho-sinc-lock-pulse” can corrupt.
When both your jaw muscles and your cheek muscles contract simultaneously, you will bite in your cheek.
Something like that can happen with your lips.
When . . . maybe it is better I stop. Actually I haven’t the faintest idea what I am talking about.