Which muscle's primary action is to elevate the nostrils and upper lip?

The muscle responsible for elevating the nostrils and upper lip is the Quadratus labii superioris. This muscle plays a significant role in facial expressions, particularly those associated with emotions such as disgust or surprise. It is located on the side of the face and extends from the upper jaw to the lip, allowing it to pull the upper lip upward as well as elevate the nostrils when it contracts. This action is important for portraying various emotional states and facilitating expressions that rely on the movement of the upper facial features.

The other muscles mentioned do not share this specific function. The Orbicularis oculi is primarily involved in controlling the movement of the eyelids, while the Auricularis anterior is related to the movement of the ear. The Quadratus labii inferioris primarily acts to lower the lower lip. Each of these muscles has distinct actions focused on different areas of facial expression, illustrating the specialized functions of muscle groups in the face. Thus, understanding the role of the Quadratus labii superioris in elevating the nostrils and upper lip is crucial for comprehending facial anatomy and expressions.