Sadness is the only expression in which the zygomatic minor (A) appears. Like the other two branches of the sneering muscle, it thickens the upper lip (middle and below); unlike them it does nothing to the nose. Its most characteristic sign is the "floating" wrinkle (B). In the most intense action the cheeks begin to swell, a side effect of the full contraction of the orbicularis oculi around the eye.
Three interacting forces stretch and compress the mouth. The strongest action is that of the risorius/platysma (A), making the lips taut as it widens the mouth. The hook-shaped cords beside the mouth corner are the signature wrinkle of the triangularis (B), but its downward pull isn't as strong as the pull outward. The action of the mentalis (C) balls up the chin (creating the sharp crease [D] ) and pushes the lips together. Compressed lips do not bow upward (as happens in open-mouthed cry), but lower lip begins to turn outward instead.
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