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Orbicularis oris muscle, also known as musculus orbicularis oris is a complex, multi-layered muscle which attaches through a thin, superficial musculoaponeurotic system to the dermis of the upper lip and lower lip and serves as an attachment site for many other facial muscles around the oral region.[1] This muscle may be regarded as a single muscle anatomically, but functionally it appears to consist of different parts that act either independently or together with other facial muscles.[2] It has neither a bony or tendinous origin. Earlier, some authors were of the opinion that this muscle is a sphincter muscle as it encircles the orifice of the mouth. But, this theory was discarded as research found that fibers of this muscle run in different directions rather than running in a uniformly circular manner.