Orbicularis oris muscle

In human anatomy, the orbicularis oris muscle is a complex of muscles in the lips that encircles the mouth.Until recently, it was misinterpreted as a sphincter, or circular muscle, but it is actually composed of four independent quadrants that interlace and give only an appearance of circularity.Muscles of head and neckMuscles of the head, face, and neckScheme showing arrangement of fibers of orbicularis oris In human anatomy, the orbicularis oris muscle is a complex of muscles in the lips that encircles the mouth.Until recently, it was misinterpreted as a sphincter, or circular muscle, but it is actually composed of four independent quadrants that interlace and give only an appearance of circularity. It is also one of the muscles used in the playing of all brass instruments and some woodwind instruments. This muscle closes the mouth and puckers the lips when it contracts. The orbicularis oris is not a simple sphincter muscle like the orbicularis oculi; it consists of numerous strata of muscular fibers surrounding the orifice of the mouth, but having different direction.It consists partly of fibers derived from the other facial muscles which are inserted into the lips, and partly of fibers proper to the lips. Of the former, a considerable number are derived from the buccinator and form the deeper stratum of the orbicularis.