= Orbicularis oris muscle
The <orbicularis oris muscle> is a complex of <skeletal muscle> fibres around the mouth that closes and shapes the <lips>. Its contraction can press the <lips> together or project them forward. Compare sealing the mouth while holding water with rounding the <lips> to whistle: both use the same muscular region to change the outlet's shape. The visible <lip> includes other <tissues> besides the <muscle> that moves it.<Anatomy and Physiology 2e by J. Gordon Betts and others>[Section 11.3, Muscles That Create Facial Expression, figures 11.7–11.8]{ref}
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