The orbicularis oris lies between the skin and the mucous membrane of the lips. It consists of a bundle of muscle fibers that surround the mouth and extends upward to the septum of the nose and downward to the region between the lower lip and chin. These muscular fibers are partially derived from other facial muscle that are inserted into the lips. The orbicularis oris pulls the lips against the teeth and causes lips to close and pucker, as when kissing.
