Table of Contents
- Orbicularis Oris
- Orbicularis Oris Action
- Orbicularis Oris Origin And Insertion
- Orbicularis Oris Anatomy and Clinical Significance
- Lesson Summary
The muscles of the face work together to carry out a variety of functions, including facial expressions and the motions associated with eating and talking. Referred to scientifically as the labium oris, the lips are especially important in terms of expression, talking, and eating. While movement of the lips is controlled by a number of different muscles and structures, the primary muscle responsible for the action and function of the lips is the orbicularis oris.
As implied by the origin of this muscle's name, the orbicularis oris is circular in shape (derived from the Latin word orbicularis) and surrounds the mouth (the Latin word oris). Surrounding the lips and comprised of muscle fibers running in several directions, the orbicularis oris consists of two main layers, a deep and a superficial layer sometimes referred to as the pars marginalia and the pars superficialis. Each layer possesses somewhat different sites of origin and insertion. However, both layers of the orbicularis oris consist of muscle running horizontally from one corner of the mouth to the other.
Innervation refers to the nerve supply for a particular muscle, tissue, or structure. Innervation allows muscles to contract and perform the movements associated with a structure. The orbicularis oris muscle is innervated by the motor branch of the facial nerve. The facial nerve is derived from cranial nerve VII (CN VII) and consists of five branches. The buccal and mandibular branches specifically innervate the orbicularis oris. The orbicularis oris receives its primary blood supply from the facial artery, which supplies blood to other structures and muscles of the face.
The main function of the orbicularis oris is to enable the mouth to close. However, the orbicularis oris also facilitates other types of movements associated with talking, kissing, eating, or making facial expressions such as anger. The orbicularis oris often works in conjunction with other muscles of the lips such as the levator labii, zygomaticus, and depressor labii muscle groups in order to carry out these movements.
What does the orbicularis oris muscle do? The main action of the orbicularis oris is to close the mouth via contraction of the muscle fibers. Parts of the muscle can also be isolated in order to perform other types of movements, such as puckering and pouting. Movement of the lips via the orbicularis oris also helps to form the different sounds associated with speech.
The orbicularis oris possesses a number of important functions pertaining to speech, eating, and facial expressions. The deep layer of the orbicularis oris primarily functions as a sphincter for the mouth by constricting the lips when the muscle fibers contract. Contraction of this layer is also important for humans when chewing or swallowing foods and liquids, as well as when kissing, whistling, or playing musical instruments such as the trumpet, flute, or clarinet. The superficial layer facilitates fine motor movements associated with speech. For example, the orbicularis oris helps to control the contact made between the lips and the teeth in order to form different vowel and consonant sounds.
All muscles possess points of origin and insertion that enable the muscle fibers to perform actions related to the movement of different structures of the body. Most muscles originate and insert onto bony structures, with the origin occurring on the stable bone of a joint and the insertion located on the more mobile bone of a joint. A joint refers to the location where two or more bones meet. The orbicularis oris is unique because it lacks direct connections to bony structures. However, some individuals can possess anatomical variations in which several fibers of the orbicularis oris originate from the upper jaw (or maxilla) or the lower jaw (or mandible).
The deep layer possesses its origin on the modiolus, a structure made from fibrous connective tissue located at each corner, or side, or the mouth. The modiolus represents at attachment site for several muscles of the face, including the orbicularis oris. The fibers of the deep layer then curl in upon themselves to contribute to the formation of the vermilion, the pink or red part of the lips upon which lip balm, lip gloss, or lipstick is sometimes applied. The general insertion points for the deep layer consist of the upper and lower lips.
The origin of the superficial layer is derived from the muscle fibers of the other facial muscles, such as the depressor anguli oris, as well as the levator labii, and zygomaticus muscle groups. Fibers from the superficial layer then insert onto the dermis of the lip, or the superficial layer of skin located on the lips. As with the deep layer, the superficial layer of the orbicularis oris inserts in general onto the upper and lower lips. The levator labii superioris muscle, in particular, represents a long muscle that inserts onto the orbicularis oris.
As discussed earlier in this lesson, the orbicularis oris represents a ring of muscle fibers located around the mouth. In addition to contributing to the fleshy and dermal portions of the lips, the orbicularis oris also provides the muscles fibers needed for speaking, swallowing, and eating. Due to the importance of of the orbicularis oris to the overall actions of the mouth and the face in general, dysfunction of this muscle is associated with several clinical conditions.
For example, damage to the motor branches of the facial nerve, which innervates the orbicularis oris along with other muscles of the face, can result in facial palsy, in which the muscles of the mouth droop and sag. This can result in drooling and difficulty with eating and swallowing. Cleft palate represents another condition affecting the orbicularis oris. In infants born with cleft palate, openings or splits form in the upper palate, or roof of the mouth, as well as the upper lip. When the upper lip is affected, the structure of the orbicularis oris is often impacted. Surgical treatment typically restores the structural integrity and function of the orbicularis oris in order to enable the infant to properly close his/her mouth.
The orbicularis oris represents a ring-shaped muscle surrounding the mouth in humans. The muscle is comprised of two layers, a deep and a superficial portion. The deep layer is primarily responsible for the closure of the lips and mouth, while the superficial layer controls the fine motor movements associated with facial expressions and speech. The deep layer originates from the modiolus, a fibrous structure located at each corner of the mouth, while the superficial layer originates from the muscle fibers of other muscles associated with facial expression, such as the levator labii and zygomaticus muscle groups. Both muscles insert onto the upper and lower lips.
In a majority of people, the orbicularis oris possesses no bony attachments. However, In some individuals, several fibers from the orbicularis oris may originate from the upper jaw (maxilla) and the lower jaw (mandible). The orbicularis oris possesses a number of important functions in humans, including its primary function as the sphincter for the mouth. In addition to closing the mouth, the orbicularis oris facilitates movements associated with kissing, whistling, or playing instruments such as the flute or clarinet. Moreover, the orbicularis oris provides fine motor movements associated with the formation of vowel and consonant sounds during speech and with facial expressions such as anger.
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The primary function of the orbicularis oris is to serve as the sphincter that controls the closure of the mouth. This is accomplished via the contraction of the deep layer of the orbicularis oris.
The orbicularis oris controls the movement of the lips, and therefore is essential for closing the mouth when eating or swallowing. The orbicularis oris also contributes to the fine motor movements associated with speech and facial expression.
The orbicularis oris possesses a number of important functions in humans. These functions include swallowing, eating, closing the lips, whistling, kissing, and playing instruments such as the flute or clarinet.
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