The risorius and the buccinator muscles assist in the retraction of the lips, as well as support entrapment of air within the oral cavity.是什么意思_The risorius and the buccinator muscles assist in the retraction of the lips, as well as support entrapment of air within the oral cavity.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句