What is the primary function of the corrugator supercilii muscle?

The primary function of the corrugator supercilii muscle is to move the eyebrows down and inward. This action is typically associated with frowning or displaying a furrowed brow, which can convey emotions such as anger or concentration. The muscle is located just above the orbit and is responsible for creating vertical lines between the eyebrows when it contracts.

In contrast, raising the eyebrows is primarily performed by the frontalis muscle, while closing the eyelids involves the orbicularis oculi. Smiling is attributed to several muscles, including the zygomaticus major and minor, which are not related to the corrugator supercilii's function. Understanding the specific role of the corrugator supercilii helps clarify how facial expressions are nuanced by different muscles and their actions.