<prompt> Facial N. stimulation during testing of nerve indicated by contraction of muscleTemporalisMasseterSternoleidomastoidOrbicularis oris  <response>: The orbicularis oris muscle is a sphincter muscle that encircles the mouth.It lies between the skin and the mucous membranes of the lips, extending upward to the nose and down to the region between the lower lip and chin.It is sometimes called the kissing muscle because it causes the lips to close and pucker. 