The Risorius muscle is a facial muscle located in the cheek area that extends from the corner of the mouth to the zygomatic bone. It is responsible for pulling the corners of the mouth laterally, resulting in a smile-like expression.

The muscle is used in a variety of facial expressions, including expressions of happiness, amusement, and pleasure. It also plays a role in regulating the position and movement of the lips and cheeks during speech and eating. The importance of the Risorius muscle lies in its role in maintaining proper facial expression and communication. By controlling the position and movement of the corners of the mouth, it can help to convey various emotions and facilitate effective communication. It also plays a role in proper oral function, particularly in helping to regulate the movement of food and drink during eating and drinking.

Dysfunction of the risorius muscle can lead to various issues, including difficulty speaking and eating, as well as difficulty conveying certain emotions through facial expressions. It can also contribute to sagging skin in the lower face and the development of wrinkles around the mouth.