Action Units
Upper Face
AU1 — Inner Brow Raiser
- Muscles
- frontalis — medial frontalis
- Appearance
- Inner corners of the eyebrows lift, raising short vertical wrinkles above the nose bridge.
- Drill cue
- Worry brows: raise only the inner ends.
AU2 — Outer Brow Raiser
- Muscles
- frontalis — lateral frontalis
- Appearance
- Outer corners of the eyebrows lift, arching the brow and widening the eye laterally.
- Drill cue
- Lift just the outer end of each brow, like a skeptical arch.
AU4 — Brow Lowerer
- Muscles
- corrugator-supercilii, depressor-supercilii, procerus
- Appearance
- Brows pull down and together, producing vertical furrows between the brows and a lowered, bulging brow ridge.
- Drill cue
- Frown brows: pull the brows down and toward the nose.
AU5 — Upper Lid Raiser
- Muscles
- levator-palpebrae-superioris
- Appearance
- Upper eyelids lift, exposing more sclera above the iris for a widened, alert or startled look.
- Drill cue
- Open the eyes wide without raising the eyebrows.
AU6 — Cheek Raiser
- Muscles
- orbicularis-oculi — orbital part of orbicularis oculi
- Appearance
- Cheeks raise, crow's-feet wrinkles appear at the outer eye corners, and the lower eyelid bunches slightly.
- Drill cue
- Squint gently from the cheeks up, not the lids down — the genuine-smile eye crinkle.
AU7 — Lid Tightener
- Muscles
- orbicularis-oculi — palpebral part of orbicularis oculi
- Appearance
- Eyelids tighten and narrow around the eye without the cheek-raising crinkle of AU6.
- Drill cue
- Narrow the eyes by tightening the lids, as if scrutinizing something.
Lower Face
AU9 — Nose Wrinkler
- Muscles
- levator-labii-superioris-alaeque-nasi, nasalis
- Appearance
- Skin over the nose bridge bunches into wrinkles as the nostril and upper lip lift.
- Drill cue
- Wrinkle the nose like smelling something bad.
AU10 — Upper Lip Raiser
- Muscles
- levator-labii-superioris
- Appearance
- Upper lip raises, deepening the nasolabial furrow and exposing the upper teeth.
- Drill cue
- Raise the upper lip only, baring the upper teeth without smiling.
AU11 — Nasolabial Furrow Deepener
- Muscles
- zygomaticus-minor
- Appearance
- The upper portion of the nasolabial furrow deepens slightly as the muscle draws the skin medial to the mouth corner upward.
- Drill cue
- Lift the upper lip a touch just beside the nose, deepening the crease from nose to mouth corner without a full smile.
AU12 — Lip Corner Puller
- Muscles
- zygomaticus-major
- Appearance
- Mouth corners pull up and back into a smile, deepening the nasolabial fold.
- Drill cue
- Smile by pulling the corners up and out toward the ears.
AU13 — Sharp Lip Puller
- Muscles
- levator-anguli-oris
- Appearance
- Mouth corners sharply lift straight up, producing a tighter, more pointed smile than AU12.
- Drill cue
- Lift the corners straight upward, sharp and narrow, not outward.
AU14 — Dimpler
- Muscles
- buccinator
- Appearance
- Mouth corners tighten inward, pulling the cheek against the teeth and creating a dimple.
- Drill cue
- Pull the corners in toward the teeth, like a wry, tight-lipped smile.
AU15 — Lip Corner Depressor
- Muscles
- depressor-anguli-oris
- Appearance
- Mouth corners pull downward, giving the mouth a frowning, inverted-U shape.
- Drill cue
- Pull the corners of the mouth straight down, like holding back tears.
AU16 — Lower Lip Depressor
- Muscles
- depressor-labii-inferioris
- Appearance
- Lower lip pulls down and slightly out, exposing the lower teeth.
- Drill cue
- Pull the lower lip down and out, showing the bottom teeth.
AU17 — Chin Raiser
- Muscles
- mentalis
- Appearance
- Chin skin bunches and wrinkles as the lower lip pushes up and out into a pout.
- Drill cue
- Push the lower lip up into a pout, wrinkling the chin.
AU20 — Lip Stretcher
- Muscles
- risorius, platysma
- Appearance
- Mouth corners stretch straight sideways, flattening the lips into a grimace.
- Drill cue
- Stretch the mouth straight sideways, like showing clenched teeth in fear.
AU21 — Neck Tightener
- Muscles
- platysma
- Appearance
- Neck skin tenses into visible vertical bands, and the mouth corners drag downward.
- Drill cue
- Tense the neck as if bracing for impact, letting it pull the jaw down.
AU23 — Lip Tightener
- Muscles
- orbicularis-oris
- Appearance
- Lips narrow and tighten against the teeth without fully disappearing.
- Drill cue
- Tighten the lips into a thin, firm line.
AU24 — Lip Pressor
- Muscles
- orbicularis-oris
- Appearance
- Lips press firmly together, flattening and slightly disappearing.
- Drill cue
- Press the lips together firmly, as if suppressing a comment.
Mouth Opening
AU25 — Lips Part
- Muscles
- orbicularis oris / depressor labii inferioris relaxation
- Appearance
- Lips separate slightly, revealing a gap between them without a dropped jaw.
- Drill cue
- Let the lips relax open just enough to show a sliver of teeth.
AU26 — Jaw Drop
- Muscles
- masseter, temporalis — jaw drop from relaxation of masseter/temporalis plus gravity, not active elevation
- Appearance
- Jaw drops open under relaxed control, parting the teeth.
- Drill cue
- Let the jaw drop open, relaxed, like mild surprise.
AU27 — Mouth Stretch
- Muscles
- lateral pterygoids and digastric (deep, not surface muscles)
- Appearance
- Mouth stretches wide open, jaw dropped to its full extent.
- Drill cue
- Open the mouth as wide as it will go, like a big yawn.