The orbicularis oris is an integral facial muscle of expression composed of two distinct parts: the orbicularis oris superior, and the orbicularis oris inferior. These muscles are of particular importance, as they form the main sphincter muscles of the lips. This allows the lips to close and narrow the opening of the mouth.
The orbicularis oris is a flat muscle that originates from the maxilla and from the other muscles of the cheek, and inserts onto the skin and mucous membrane of the lips.
The primary action of this muscle is to close the lips by narrowing the oral opening, a movement of particular importance in many facial expressions. The action of the orbicularis oris can be further broken down into other more exact types of movements, such as pouting, whistling, and allowing for proper articulation during speech.
The orbicularis oris is innervated by the buccal branches of the facial nerve.
Blood supply of the orbicularis oris is provided by the superior and inferior labial branches of the facial artery.
In considering the orbicularis oris, it is important to know that it is a flat muscle, which means that it is thin in comparison to the other facial muscles it is connected to. This thinness allows for a greater control of the lips in order to create various expressions. For example, the orbicularis oris can help to create a “scowl”expression, as well as the more common smile or frown.
The orbicularis oris is further distinguished from other facial muscles by its ability to resist contraction without the use of the other facial muscles. This characteristic allows the orbicularis oris to remain contracted, providing facial expressions that last longer than those created by other facial muscles. It is also important to note that proper contraction of this muscle also allows for articulation of words, as the lips will need to be slightly opened for the air to escape during speaking.
The orbicularis oris is a unique and important muscle of facial expression. It originates from the maxilla and other muscles of the cheek, inserts onto the skin and mucous membrane of the lips, and is innervated by the buccal branches of the facial nerve. It is responsible for closing the lips to narrow the oral opening, allowing for more controlled facial expressions and improved articulation during speech. The thinness of the orbicularis oris allows for greater control of the lips, and its resistance to contraction allows for longer lasting facial expressions. When considering the importance of a facial muscle of expression, the orbicularis oris should not be overlooked.
