The orbicularis oris may also contract with the mouth open. Either lip may tighten without the other, as in the speaking mouth (A), where only the upper lip is tensed.
Another action of orbicularis oris is pursing the lips. This is the work of specialized fibers called incisivis that pull the mouth corners together, shortening the lips and pushing them outward. The lips pushed out from the face create a sharp shadow below (A).
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