The depressor septi is a small, triangular muscle located in the nose region of the face. It extends from the maxilla bone to the nasal septum, the cartilage separating the two nostrils. The muscle is responsible for pulling the nasal septum downward and to the side, which can cause the nostrils to flare slightly. The depressor septi muscle works in conjunction with other facial muscles to produce certain facial expressions, such as snarling or sneering. The depressor septi muscle is innervated by the buccal 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 depressor septi muscle can lead to difficulties with speech, eating, and facial expressions, such as flaring the nostrils or wrinkling the nose.