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.
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. 
