The FACS Study Guide

A visual guide to the Facial Action Coding System (FACS)

A comprehensive visual guide to facial action units (AUs), plus additional motions not covered in FACS (marked #notFACS). Learn about each AU and its corresponding muscle(s) through animated GIFs, images, and descriptions.

Open any action for video, notes, and further reading.

32 actions · 7 regions ·

Brows Eyes & cheeks Nose & middle face Lip corners Depressors Lips Jaw

Eyebrows & forehead

AU1 inner brow raiser

frontalis (medial)

AU2 outer brow raiser

frontalis (lateral)

AU4 brow lowerer

corrugator supercilii, procerus, depressor supercilii

#notFACS ears up & back

auricular muscles (see NOTES)

AU1 - inner brow raiser GIF - FACS - Facial Action Coding System

AU1

inner brow raiser

frontalis, pars medialis

Compare AU1 to a full brow raise (1+2). Observe image below.

AU1 - inner brow raiser vs. full brow raise static image - FACS - Facial Action Coding System

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

AU2 - outer brow raiser - frontalis, pars lateralis GIF

AU2

outer brow raiser

frontalis, pars lateralis

Compare AU2 to a full brow raise (1+2). Observe image below.

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

Eyes & cheeks

AU5 upper lid raiser

levator palpebrae superioris (LPS)

AU6 cheek raiser

orbicularis oculi (orbital)

AU7 lid tightener

orbicularis oculi (preseptal, palpebral)

AU45 blink

orbicularis oculi (palpebral) + LPS relaxation

AU46 wink

orbicularis oculi**

#notFACS open-eyed blink

orbicularis oculi (pretarsal, palpebral)

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.