Face the FACS
Facial Expressions in Art, Science, & Technology
Facial Action Coding System (FACS) Cheat Sheet
A visual reference guide for the Facial Action Coding System (FACS), featuring action units (AUs) and their corresponding musculature.
NOTE: The former “cheat sheet” is available to premium members here: “FACS Study Guide.”
FACS name
muscle name
expression reference
AU1 – inner brow raiser
frontalis (the medial portion)
AU2 – outer brow raiser
frontalis (the lateral portion)
AU4 – brow lowerer
corrugator supercilii, depressor supercilii, and/or procerus
AU5 – upper lid raiser
levator palpebrae superioris
AU6 – cheek raiser
orbicularis oculi (the orbital portion)
AU7 – lid tightener
orbicularis oculi (the palpebral portion)
AU8 – lips toward each other
orbicularis oris
AU9 – nose wrinkler
levator labii superioris alaeque nasi (+ usually depressor supercilii and/or procerus)
AU10 – upper lip raiser
levator labii superioris
AU11 – nasolabial furrow deepener
zygomaticus minor
AU12 – lip corner puller
zygomaticus major
AU13 – sharp lip puller
levator anguli oris
AU14 -dimpler
buccinator
y-axis type
z-axis type
NOTE: y-axis and x-axis dimplers are not FACS-official terms. Learn why I’ve coined these distinctions here.
AU15 – lip corner depressor
depressor anguli oris
AU16 – lower lip depressor
depressor labii inferioris
AU17 – chin raiser
mentalis
AU18 – lip pucker
incisivus labii inferioris & incisivus labii superioris
NOTE 1: Incisivus labii superioris and incisivus labii inferioris are considered accessory bands to the orbicularis oris muscle.
NOTE 2: Lip pucker typically co-activates vertical lip tightener (as seen in this example).
AD19 – tongue show
it depends**
NOTE: “AD” refers to “action descriptor.” An action descriptor is basically a less fleshed out action unit (AU). ADs differ in that they function more as event descriptors. In this case, AD19 – tongue show, simply means the tongue is protruding in a notable way beyond typical protrusion for speech, eating, breathing, etc. For a deep dive into tongue actions and tongue-related muscles, book a mini course on tongue movements and tongue anatomy.
AU20 – lip stretcher
risorius
NOTE: Risorius is one of the most variable facial muscles in humans. Depending on the study, it has been reported missing in anywhere from 1-94% of research subjects. Risorius is narrow and difficult to locate; so it is possible that this discrepancy in statistics is partly inflated due to methodological study errors. For more on anatomical variation, book a studio lecture on facial muscle diversity.
AU21 – neck tightener
platysma
NOTE: You may see some AU20 – lip stretcher in the AU21 – neck tightener example and vice versa. This concurrence is due to a close relationship between the risorius and platysma muscles.
AU22 – lip funneler
orbicularis oris (peripheral portion)
AU23 – lip tightener
orbicularis oris (marginal portion)
horizontal type
vertical type
NOTE: This 2-type distinction is a deviation from official FACS. Only “horizontal type” qualifies as lip tightener in original FACS. I have chosen to divide lip tightener into two types, because the lips tighten in distinct manners. The muscle behind both movements, orbicularis oris, possesses rich variation in fiber directionality; such directional variation yields more potential actions for orbicularis oris than have thus far been documented. The distinction of horizontal vs. vertical lip tightening proves especially useful when breaking down speech. For speech references, visit the Viseme Cheat Sheet.
AU24 – lip presser
orbicularis oris (marginal portion)
AU25 – lips part
it depends**
NOTE: In FACS, AU25 – lips part, refers to the state of the lips being parted. This parting can be caused by any action that separates the lips – e.g. relaxation of mentalis, relaxation of orbicularis oris, contraction of other muscles, etc.
AU26 – jaw drop
masseter, relaxed temporalis and relaxed internal pterygoid
AU27 – mouth stretch
pterygoids, digastric
AU28 – lips suck
orbicularis oris (marginal and peripheral portions)
NOTE 1: AU17 – chin raiser appears during the in-between steps. I cannot perform this action without assistance from AU17 during the transition to the final pose. Mentalis appearance during lips suck is likely the case for many others as well.
NOTE 2: Jaw drop is almost always required for lips suck.
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