GIF-based FACS guide with isolated action units (AUs), proper FACS nomenclature, & corresponding muscle labels.
*See AU 11 & AU 23 for rare reference shots of nasolabial furrow deepener & lip tightener.
—- S E C T I O N G U I D E —-
eyebrows & forehead
– inner brow raiser (AU1) / frontalis, pars medialis
– outer brow raiser (AU2) / frontalis, pars lateralis
– brow lowerer (AU4) / varied
eyes & cheeks
– upper lid raiser (AU5) / levator palpebrae superioris
– cheek raiser (AU6) / orbicularis oculi, pars orbitalis
– lid tightener (AU7) / orbicularis oculi, pars palpebralis
nose & middle face
– nose wrinkler (AU9) / levator labii superioris, alaeque nasi
– upper lip raiser (AU10) / levator labii superioris
– nasolabial furrow deepener (AU11) / zygomaticus minor
lip corner elevators & pinchers
– lip corner puller (AU12) / zygomaticus major
– sharp lip puller (AU13) / levator anguli oris
– dimpler (AU14) / buccinator
real & faux lip depressors
– lip corner depressor (AU15) / depressor anguli oris
– lower lip depressor (AU16) / depressor labii inferioris
– chin raiser (AU17) / mentalis
orbicularis oris
– howler mouth (fAUx8) / orbicularis oris
– lip funneler (AU22) / orbicularis oris
– lip tightener (AU23) / orbicularis oris
– lip presser (AU24) / orbicularis oris
– lips suck (AU28) / orbicularis oris
eyebrows & forehead
stills
click tabs for GIFs & further info
AU1 – inner brow raiser
frontalis, pars medialis
for a deeper dive on AU1:
- The Secret Life of Inner Brow Raiser
- This post and video will walk you through the variations in inner brow raiser and how to identify each person’s unique inner brow raising style – including your own!
- (If you are not a subscriber, the free version of this video is on YouTube)
- Inner Brow Raiser Deep Dive
- This post covers fundamental features of inner brow raiser.
- It also goes over common misconceptions regarding inner brow raiser and how to recognize incorrect inner brow raiser references. (Spoiler alert: There are a lot of them.)
- Frontalis Variation
- This post covers under-researched topics in frontalis muscle structure.
- It covers anatomical differences of the frontalis muscle and how these differences look as well as what implications they may have in the areas of:
- face tracking
- mocap
- EMG recording
- FACS-based facial coding
- Compare AU1 to a full brow raise (1+2). Observe image below.
AU2 – outer brow raiser
frontalis, pars lateralis
for a deeper dive on AU2:
- In the context of AU1 vs. AU2: The Secret Life of Inner Brow Raiser (If you are not a subscriber, the free version of this video is on YouTube)
- While this post and video is primarily focused on AU1 (inner brow raiser), there is valuable information on AU2 here as well.
- Frontalis Variation
- This post covers under-researched topics in frontalis muscle structure.
- It covers anatomical differences of the frontalis muscle and how these differences look as well as what implications they may have in the areas of:
- face tracking
- mocap
- EMG recording
- FACS-based facial coding
- Compare AU2 to a full brow raise (1+2). Observe image below.
AU4 – brow lowerer
corrugator supercilii, procerus, depressor supercilii
for a deeper dive on AU4:
-
- The 3 muscles that make up AU4 can move independently.
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- corrugator supercilii
- depressor supercilii
- procerus
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- The 3 muscles that make up AU4 can move independently.
1. corrugator supercilii
GIF above shows posed. isolated (or mostly isolated) corrugator supercilii activation at mild/medium intensity.
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- tends to push the brows toward each other
- can be referred to as “knitting” the brows
- causes vertical wrinkles above the nose
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2. depressor supercilii
GIF above shows spontaneous. isolated (or mostly isolated) depressor supercilii activation at mild intensity.
GIF above shows posed. isolated (or mostly isolated) depressor supercilii activation at mild/medium intensity. NOTE 1: In the posed version, I was unable to symmetrically activate depressor supercilii, and it is dominant on the left side (screen right). NOTE 2: In the posed version, I activate nostril compressor, which accounts for the movement on the lower parts of the nose. Please ignore this movement, as it is not a part of depressor supercilii movement. Reference the spontaneous pose to see action without added movement from nostril compression.
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- technically considered an eye muscle
- debated whether this muscle is its own distinct muscle or part of orbicularis oculi
***Many surgeons, dermatologists, ophthalmologists, and plastic surgeons argue strongly that depressor supercilii is a distinct muscle with its own movement. I’m with them on this one.
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3. procerus
GIF above shows posed full brow raise (frontalis) + procerus activation. I cannot activate procerus without strong corrugator supercilii unless I raise my brows. Even in this example, besides the full brow raise, there appears to be mild to moderate intensity depressor supercilii and potentially mild corrugator supercilii; however, the strongest and most obvious AU4 action here comes from procerus, which you can observe creating U-shaped wrinkles in the medial area of the forehead. When occurring without brow raise, procerus wrinkles are typically straight and horizontal.
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- technically considered a nasal muscle
- tends to push the down the medial portion of the brows, above the nose
- causes horizontal wrinkle above nasal root
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GIFs
AU1 – inner brow raiser
AU2 – outer brow raiser
AU4 – brow lowerer
* * *
still images
eyes & cheeks
stills
click tabs for GIFs & further info
AU5 – upper lid raiser
levator palpebrae superioris
AU6 – cheek raiser
orbicularis oculi, pars orbitalis
for a deeper dive on AU6:
AU7 – lid tightener
orbicularis oculi, pars palpebralis
for a deeper dive on AU7:
AU5 – upper lid raiser
AU6 – cheek raiser
AU7 – lid tightener
nose & middle face
If you are not familiar with the infraorbital triangle and the nasolabial furrow: You should be. Below are some lower face actions I feel are very influential to the infraorbital triangle. 
stills
click tabs for GIFs & further info
AU9 – nose wrinkler
levator labii superioris, alaeque nasi
for a deeper dive on AU9:
- Breaking Down Nose Wrinkler
- Facial coding notes from video of nose wrinkler with:
- AU4 – brow lowerer
- AU6 – cheek raiser
- AU7 – lid tightener
- AU10 – upper lip raiser
- AU15 – lip corner depressor
- AU17 – chin raiser
- If you do not have subscription access, you can view the video without the notes here.
- Facial coding notes from video of nose wrinkler with:
AU10 – upper lip raiser
levator labii superioris, caput infraorbitalis
AU11 – nasolabial furrow deepener
zygomaticus minor
lip corner elevators & pinchers
stills
click tabs for GIFs & further info
AU12 – lip corner puller
zygomaticus major
AU13 – sharp lip puller
levator anguli oris
If you are confused by the similarities between AU12 and AU13, please review the image below, and if you are further confused, I made a YouTube video to highlight the differences: Watch here 🙂 
AU14 – dimpler
buccinator
NOTE:
I have coined two differentiations of the dimpler action: y-axis dimpler and z-axis dimpler. I have done so, because the existing FACS facial actions do not effectively encompass the depth of expression possible to achieve from the buccinator muscle (the muscle behind AU14).
There are two types of dimplers that I have observed:
1) y-axis dimpler – involving outer portions of the lip corners compressing against each other in a vertical plane
2) z-axis dimpler – involving the inner mouth portions of the lip corners pushing against the teeth and inner cheeks
(y-axis dimpler)
* * *
(z-axis dimpler)
real & faux lip depressors
stills
click tabs for GIFs & further info
AU15 – lip corner depressor
depressor anguli oris
AU16 – lower lip depressor
depressor labii inferioris
The above photo illustrates AU16 at a low-moderate intensity. The photo below shows AU16 at a moderate-high intensity. Note how the shape of AU16 gets more square-shaped and lateral as the movement of depressor labii inferioris gets stronger.
AU17 – chin raiser
mentalis
orbicularis oris
stills
click tabs for GIFs & further info
AU28 – lips suck: coming soon
fAUx8 – howler mouth **
orbicularis oris**
ATTENTION: THE FOLLOWING IS A DEVIATION FROM CLASSIC FACS.
While FACS is great, it doesn’t cover everything. To fill in the gaps, I will be building a set of actions coined faux AUs, “fAUx” for short. Anything labeled “fAUx” signifies that I have either altered an existing FACS code or have defined a new action.
In this specific case, I have altered the definition of an existing FACS code, AU8 – “lips toward each other” – and have redefined it as fAUx8 – “howler mouth.” fAUx8 is named after the howler monkey’s constricted mouth shape formed during their signature howling.
fAUx8 is the sphincter-like contraction of the lips while the jaws are open or when the lips are forced open by the presence of another action. The degree to which the jaw or lips are open will affect the look of fAUx8. The greater the opening, the more room for contraction and higher intensity fAUx8. When opening is subtle, so is the intensity for fAUx8.
* low intensity *
* medium intensity *
* high intensity *
______________
AU8 vs. fAUx8
The following is the true FACS description of AU8:
“ This AU designates an AU 24 action when the lips are parted with an AU 25, and usually the jaw is lowered with a 26 or 27. The lips are pulled towards each other, and would press together if the lips were closed. A trace of lip narrowing may also occur in this action.
A. Appearance Changes due to AUs 8+25
1. The upper lip is pulled down towards the lower lip, but not pulled back over the teeth (that would be AU 28).
2. The lower lip is pulled up towards the upper lip.
3. The lips are not closed. AU 8 must be scored as 8+25, usually with 26 or 27.
4. There may be some lip narrowing but not lip tightening (AU 23).
5. It is possible, although not common, for 8 to affect only one lip. If it is totally absent in one lip, score as T8 (top lip) or B8 (bottom lip).
6. If you score 8 as either T or B, you cannot also score 8 as unilateral. There is no image of AU 8+25 but there is a video example of 8+26. “
And this is the official FACS example of AU8 proper:
why I created fAUx8
I’ve always felt that AU8 was much too vague in both demonstration and definition. In demonstration, the Ekman pose is not very clear, and no other visual examples are provided in the AU8 section of the FACS Manual. In definition, AU8 is framed as an in-between shape – a precursor to AU24 – without its own identity.
AU8 has so much more potential and should not be relegated to exist as AU24’s shadow. The creation of fAUx8 allows for a more specific action with a stronger end shape.
The parts of AU8 that have been retained in fAUx8 include the following:
- the upper lip is still pulled down toward the bottom lip (and still not over the teeth)
- the lower lip is still pushed up toward the top lip
- there still may be lip narrowing – especially at higher intensities – not due to AU23 (lip tightener) **However, it would be near impossible to spot AU23 in a full strength fAUx8.
- it is still possible for fAUx8 to occur in just the top or bottom lip
The former restrictions of AU8 have been removed from fAUx8 to allow for new properties:
- at high intensities, the lips may touch
- AU25 does not have to be present in order to score fAUx8 **However, some degree of jaw dropping is necessary.
fAUx8 – closest to original AU8
fAUx8 max – breaking the rules of original AU8
AU22 – lip funneler
orbicularis oris
AU23 – lip tightener: 2 types
orbicularis oris, pars marginalis
ATTENTION: THE FOLLOWING IS A DEVIATION FROM CLASSIC FACS.
This 2-type distinction is a deviation from official FACS. Only “type 1: 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.
There is currently no representation for any action like “type 2: vertical type” in the FACS Manual. Such omission is a prime example of lost potential for orbicularis oris.
The advancement of tech and entertainment demands more than original FACS can offer. Implementing this new configuration will allow for more flexibility in recreating and interpreting facial actions, especially as they pertain to speech. (Please contact me facetheFACS@melindaozel.com if interested in viseme consultation.)
type 1: horizontal type
***
ATTENTION: THE FOLLOWING IS A DEVIATION FROM CLASSIC FACS.
type 2: vertical type
First GIF shows coordinated vertical tightening in top and bottom lip. Second GIF shows staggered vertical tightening, beginning with the bottom lip then with the top.
Though I am placing “type 2” in the family of lip tightener, the vertical type commands a different description than the horizontal type; therefore, original FACS guidelines must not be used when interpreting vertical type lip tightener.
It should also be noted that many unvetted reference sources mistakenly display lip tightener as a combo shape: “type 2: vertical type” + lip pucker. This incorrect representation is made quite frequently due to the ease of misinterpretation and difficulty to voluntarily perform the lip tightener action in isolation (either in horizontal or vertical form).
TYPE 2: VERTICAL TYPE DESCRIPTION:
- tightening of the lips, directed toward a vertical center
- top and bottom lip may tighten independently
- top lip may be brought down by vertical tightening
- bottom lip may be brought slightly up
- lips may be open or closed
- lip corners may be brought slightly inward – however when this inward motion occurs, always consider the presence of of the incisivus muscles (involved with AU18, lip pucker), which draw the lip corners medially
Please observe the following to distinguish the difference between “vertical type” alone vs. “vertical type” + lip pucker.
This GIF begins with “type 2: vertical type.” Midway through, the incisivus muscles are added, drawing the lip corners medially, forming a combo of: vertical lip tightener + lip pucker.
__________________________
For more information on original FACS lip tightener / “type 1: horizontal type,” please see the post attached below.
AU24 – lip presser
orbicularis oris
AU28 – lips suck
orbicularis oris
More upper face references HERE. 
Eyebrow combination references HERE.
| AU | Description | Facial Muscle(s) |
Example GIFs |
For AUs 1-17, see tabs above |
This FACS cheat sheet is under construction. |
For old FACS Cheat Sheet, click here |
|
| 18 | lip pucker | incisivii labii superioris and incisivii labii inferioris |
 |
| 20 | lip stretcher | risorius w/ platysma |  |
| see orbicularis oris | section for funneler | tightener & presser | |
| 25 | lips part | depressor labii inferioris or relaxation of mentalis, or orbicularis oris |
 |
| 26 | jaw drop | masseter, relaxed temporalis and internal pterygoid relaxed |
 |
| 27 | mouth stretch | pterygoids, digastric |  |
| 28 | lip suck | orbicularis oris |  |
| 45 | blink | relaxation of levator -palpebrae superioris; orbicularis oculi, pars palpebralis |  |
| 46 | wink | relaxation of levator palpebrae superioris; orbicularis oculi, pars palpebralis |
 |
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