Zygomaticus major muscle

The zygomaticus major is a muscle of the human body. It is a muscle of facial expression which draws the angle of the mouth superiorly and posteriorly to allow one to smile. Like all muscles of facial expression, the zygomatic major is innervated by the facial nerve (the seventh cranial nerve), more specifically, the buccal and zygomatic branches of the facial nerve.
Structure.
The zygomaticus extends from each zygomatic arch (cheekbone) to the corners of the mouth.
Function.
It raises the corners of the mouth when a person smiles. Usually a single unit, Dimples are caused by variations in form. It is thought that dimples are caused by bifid zygomaticus major muscle.