FACS & Video References FOREHEAD & BROW AREA INNER BROW RAISER - AU1 Contraction of the medial section of the frontalis muscle. https://vimeo.com/743099798 FULL BROW RAISE - AUs 1+2 COMBO: inner brow raiser + outer brow raiser Contraction of the full frontalis muscle (both medial and lateral portions).https://vimeo.com/743090941 BROW LOWERER - AU4 Contraction of corrugator ... Read more