Table 2 Selected single action units from the Facial Action Coding System (FACS) [41];
From: Imitation and recognition of facial emotions in autism: a computer vision approach
AU number | FACS name | Muscles |
|---|---|---|
AU01 | Inner Brow Raiser | Frontalis, Pars Medialis |
AU02 | Outer Brow Raiser | Frontalis, Pars Lateralis |
AU04 | Brow Lowerer | Depressor Glabellae; Depressor Supercilli, Corrugator |
AU05 | Upper Lid Raiser | Levator Palpebrae Superioris |
AU06 | Cheek Raiser | Orbicularis Oculi, Pars Orbitalis |
AU07 | Lid Tightener | Orbicularis Oculi, Pars Palebralis |
AU09 | Nose Wrinkler | Levator Labii Superioris, Alaeque Nasi |
AU10 | Upper Lip Raiser | Levator Labii Superioris, Caput Infraorbitalis |
AU11* | Nasolabial Furrow Deepener | Zygomanic Minor |
AU12 | Lip Corner Puller | Zygomatic Major |
AU14** | Dimpler | Buccinator |
AU15 | Lip Corner Depressor | Triangularis |
AU16* | Lower Lip Depressor | Depressor Labii |
AU17 | Chin Raiser | Mentalis |
AU20 | Lip Stretcher | Risorius |
AU22* | Lip Funneler | Orbicularis Oris |
AU23 | Lip Tightener | Orbicularis Oris |
AU24* | Lip Pressor | Orbicularis Oris |
AU25 | Lips Part | Depressor Labii, or Relaxation of Mentalis or Orbicularis Oris |
AU26 | Jaw Drop | Masetter; Temporal and Internal Pterygoid Relaxed |
AU27* | Mouth Stretch | Pterygoids; Digastric |
AU28** | Lip Suck | Orbicularis Oris |