The most common type of headache is a tension or muscle contraction.
最常见的头痛类型是紧张或肌肉收缩。
2
But when the emotion that leads to stiffening the lip is more intense, and involves strong muscletension, facial feedback may heighten emotional response.
但是当导致嘴唇僵硬的情绪变得更加强烈，并导致肌肉强烈绷紧时，面部表情反应就可能会增强情绪反应。
3
Laughter is a pressure valve which releases muscletension.