Along the way he identified a particular type of smile that engages both the zygomatic major and the orbicularisoculi - muscles that raise the corners of the mouth and cheeks, respectively.
根据这种方法，他辨识到一种特别的微笑方式，位于颧骨和眼轮眶肌间的肌肉分别带动嘴角和脸颊肌肉提起。
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And they mean it: they smile with their eyes (a contraction of the orbicularisoculi facial muscles), not just their mouths.