The corrugator supercilii is a small, narrow muscle located in the eyebrow region of the face above the medial end of the eyebrow. It extends from the frontal bone to the skin of the eyebrow. The corrugator supercilii muscle is responsible for pulling the eyebrows downward and medially, causing vertical wrinkles between the eyebrows. This muscle is often associated with the expression of anger, worry, or confusion. The corrugator supercilii muscle is innervated by the temporal branch of the facial nerve (cranial nerve VII) and works in conjunction with other facial muscles to produce a range of facial expressions. Dysfunction or weakness of the corrugator supercilii muscle can lead to difficulties with facial expressions, such as the ability to furrow the eyebrows.