The muscles of the mouth are a group of muscles that are responsible for moving the lips and forming speech sounds. One of these muscles is the orbicularis oris muscle (m. orbicularis oris). It is located around the mouth and is involved in the formation of a smile, the expression of emotions and the articulation of sounds.
The orbicularis oris muscle consists of two parts: the upper (superior portion) and the lower (inferior portion). The upper part of the muscle starts from the base of the nose and goes into the upper lip, and the lower part starts from the lower jaw and goes into the lower lip.
The function of the orbicularis oris muscle is to maintain the shape of the lips, smile formation, and articulation. It is also involved in chewing and swallowing. When the upper part of the muscle contracts, the mouth opens, and when the lower part contracts, it closes.
With pathology of the orbicularis oris muscle, problems with the articulation of sounds, such as a lisp, burr and other speech defects, may occur. Drooping of the corners of the mouth may also occur, which is associated with impaired muscle function.
Treatment for the orbicularis oris muscle may include massage, physical therapy, lip and tongue exercises, and injections of Botox or other medications. In some cases, surgery may be required.