Table 1. Description of AUs and its locations corresponding to different emotions by Ekman and Friesen [20].

Emotions	Action Units (AU’s)	FACS Name	Muscular Basis
Happiness	AU6	Cheek Raiser	Orbicularis oculi (pars orbitalis)
	AU12	Lip Corner Puller	Zygomaticus major
Sadness	AU14	Dimpler	Buccinator
	AU15	Lip Corner Depressor	Depressor anguli Oris (also known as triangulation)
Surprise	AU12	Lip Corner Puller	Zygomaticus major
	AU5B	Upper Lid Raiser	Levator palpebrae superioris, superior tarsal muscle
	AU26	Jaw Drop	Masseter; relaxed temporalis and internal pterygoid
Fear	AU12	Lip Corner Puller	Zygomaticus major
	AU4	Brow Lowerer	Depressor glabellae, depressor supercilii, corrugator supercilii
	AU5	Upper Lid Raiser	Levator palpebrae superioris, superior tarsal muscle
	AU7	Lid Tightener	Orbicularis oculi (pars palpebralis)
	AU20	Lip Stretcher	Risorius platysma
	AU26	Jaw Drop	Masseter; relaxed temporalis and internal pterygoid
Disgust	AU9	Nose Wrinkler	Levator labii superioris alaeque nasi
	AU15	Lip Corner Depressor	Depressor anguli oris (also known as triangularis)
	AU16	Lower Lip	Depressor labi inferioris
Anger	AU4	Brow Lowerer	Depressor glabellae, depressor supercilii, corrugator supercilii
	AU5	Upper Lid Raiser	Levator palpebrae superioris, superior tarsal muscle
	AU7	Lid Tightener	Orbicularis oculi (pars palpebralis)
	AU23	Lip Tightener	Orbicularis oris