Claim: The Orbicularis oris muscle is a completx group of muscles in the lips that encircles the mouth and is composed of four independent quadrants that interlace and give only an appearance of circularity.
Evidence: In human anatomy, the orbicularis oris muscle is a complex of muscles in the lips that encircles the mouth. It is a sphincter, or circular muscle, but it is actually composed of four independent quadrants that interlace and give only an appearance of circularity.