Which muscle aids in frowning by pulling the corners of the mouth down?

The muscle that aids in frowning by pulling the corners of the mouth down is the triangularis. This muscle is located at the corners of the mouth and is primarily responsible for depressing the lips, which creates a frowning expression. When the triangularis contracts, it effectively lowers the corners of the mouth, resulting in a downward movement characteristic of a frown. Understanding the function of this muscle is important in esthetics, as it can influence facial expressions and overall appearance in cosmetic treatments.

In contrast, the other muscles listed serve different purposes. The risorius, for example, primarily pulls the mouth's corners sideways, contributing to smiling rather than frowning. The masseter is a muscle involved in chewing by elevating the jaw. The temporalis also supports the jaw, particularly in its movements, but does not directly affect the corners of the mouth. Knowing the specific functions of these muscles is vital for estheticians who may be assessing facial aesthetics or planning treatments.