Muscle · Head

Orbicularis oris

Musculus orbicularis oris

The muscle of the lips. Despite the name it is not a simple ring: most of it is made of fibres arriving from the surrounding facial muscles, which converge on a dense knot at each corner of the mouth and then sweep across the lips, plus a smaller set of its own fibres. It closes, purses and protrudes the lips and presses them against the teeth, which makes it essential to speech, whistling, and keeping food and drink in the mouth — the reason its failure is socially and functionally costly out of all proportion to its size.