《黄帝内经·灵枢·经脉》
唇舌是肌肉的根本，经脉不能滋养肌肉，肌肉就不滑润；肌肉不滑润，人中部就会肿满；人中肿满，就会出现口唇外翻；口唇外翻，就是肌肉先死的征象。
脉不荣则肌肉软，肌肉软则舌萎人中满，人中满则唇反，唇反者肉先死。
The lips and tongue are the foundation of the muscles; if the meridian cannot nourish the muscles, the muscles will not be smooth; if the muscles are not smooth, the middle part of the face will be swollen; when the philtrum is swollen, the lips will appear everted; everted lips are a sign of the death of muscles.