Final answer:
The orbicularis oris muscle is located around the mouth and is responsible for moving the lips, important for facial expressions, speech, and eating. Related facial muscles include the orbicularis oculi, which closes the eyes, and the occipitofrontalis, which moves the scalp and eyebrows.
Step-by-step explanation:
The orbicularis oris muscle is situated in the region of the mouth, encircling the lips. It functions as a circular muscle or sphincter, which means that when it contracts, it can decrease the size of the oral opening. This muscle action is crucial for various facial expressions and movements such as puckering the lips for whistling or kissing. It is heavily involved in the articulation of speech and the management of foods and liquids within the mouth.Another related muscle is the orbicularis oculi, which is a circular muscle that surrounds each eye. The contraction of this muscle allows us to close our eyes. Meanwhile, the occipitofrontalis muscle is responsible for movements of the scalp and eyebrows. The frontal belly of this muscle lies on the forehead, while the occipital belly is near the back of the head. The two bellies are connected by a broad tendon known as the epicranial aponeurosis, or galea aponeurosis.These muscles are not just functional; they also have aesthetic and communicative significance, as represented by the cultural significance of gestures like kissing and expressions such as smiling or frowning.