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The orbicularis oris muscle, also known as musculus orbicularis oris, is a complex, multi-layered muscle that encircles the mouth and forms the majority of the lips. It is responsible for pulling the lip tissue centrally, allowing for actions such as eating, drinking, whistling, and kissing. The muscle consists of two parts: a larger peripheral part and a smaller marginal part. The peripheral portion, also called the extrinsic portion, originates from the modiolus, arising from the fibers of the buccolabial muscles that attach to it. The orbicularis oris muscle is not a simple sphincter muscle, but rather it is composed of numerous strata of muscular fibers surrounding the mouth.
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What You'll Learn
- The orbicularis oris muscle is a complex, multi-layered muscle
- It controls the shape and movement of the lips
- It is composed of two parts: a larger peripheral part and a smaller marginal part
- The muscle is responsible for actions such as eating, drinking, whistling, and kissing
- It is not a true sphincter, but is composed of four independent quadrants
The orbicularis oris muscle is a complex, multi-layered muscle
The orbicularis oris muscle is derived from the second branchial arch and is composed of intrinsic and extrinsic muscles of the lip. It is not a true sphincter muscle, as it is composed of four independent quadrants that interlace and give only the appearance of circularity. It is also not a simple sphincter muscle like the orbicularis oculi. Instead, it consists of numerous layers of muscular fibers surrounding the mouth but running in different directions. Some of the fibers are derived from other facial muscles inserted into the lips, while others are proper to the lips. The orbicularis oris muscle is a powerful muscle with only a thin layer of fat protecting it, making it susceptible to repetitive force.
The orbicularis oris muscle develops from two embryonic laminae: the mandibular lamina, which differentiates into the lower fibers of the muscle, and the infraorbital lamina, which develops into the upper fibers. The main blood supply to this muscle is from the facial artery, specifically the superior labial branch and inferior labial branch. It also receives a blood supply from the maxillary artery and the superficial temporal artery via their transverse facial branch. The nerve supply to the orbicularis oris muscle comes from the buccal and mandibular branches of the facial nerve, which is derived from the second pharyngeal arch.
The orbicularis oris muscle is part of the buccolabial group, a large group of muscles responsible for facial expressions. It works alongside other muscles such as the levator anguli oris, levator labii superioris alaeque nasi, zygomaticus major, and risorius to control the shape and movements of the lips. These muscles help to elevate the angle of the mouth and produce various facial expressions, such as anger and sadness. The orbicularis oris muscle may be regarded as a single muscle anatomically, but functionally, it appears to consist of different parts that act either independently or together with other facial muscles.
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It controls the shape and movement of the lips
The orbicularis oris muscle is a complex, multi-layered muscle that encircles the mouth and forms the majority of the lips. It is responsible for controlling the shape and movement of the lips. This muscle is part of a large group of muscles of facial expression called the buccolabial group. The buccolabial muscles that provide fibres for the peripheral portion of the orbicularis oris include the levator anguli oris, depressor anguli oris, buccinator, risorius and zygomaticus major muscles. Most of the fibres that comprise the orbicularis oris originate from the buccinator muscle.
The orbicularis oris muscle has two parts: a larger peripheral part and a smaller marginal part. The peripheral portion, also called the extrinsic portion, originates from the modiolus, which is a dense fibromuscular nodule at the angle of the mouth. The marginal part of the orbicularis oris muscle arises from the labial sides of the modiolus of angulus oris. The uppermost and lowermost fibres of the peripheral portion pass into the superior and inferior labial areas, respectively. The inner labial part of the muscle arises from the vermillion line.
The fibres from the marginal part of the orbicularis oris muscle course round into their respective upper and lower labial areas, attaching to the surfaces of the maxilla and mandible, as well as to the labial part at the vermillion line. The fibres from the labial part extend into the submucosa of the lips and extend laterally to the base of the modiolus of angulus oris. Overall, the orbicularis oris muscle compresses and protrudes the lips, enabling actions such as eating, drinking, whistling, kissing, and forming words during speech.
The orbicularis oris muscle is derived from the second branchial arch and is composed of intrinsic and extrinsic muscles of the lip. It is not a true sphincter muscle, as was once thought, as it is composed of four independent quadrants that interlace and give only the appearance of circularity. The muscle fibres run in different directions, with some fibres derived from other facial muscles inserted into the lips and some fibres proper to the lips.
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It is composed of two parts: a larger peripheral part and a smaller marginal part
The orbicularis oris muscle is a complex, multi-layered muscle that encircles the mouth and forms the majority of the lips. It is composed of two parts: a larger peripheral part and a smaller marginal part.
The peripheral portion, also known as the extrinsic portion, originates from the modiolus, which is a dense fibromuscular nodule at the angle of the mouth. The uppermost and lowermost fibres of this portion pass into the superior and inferior labial areas, respectively. The marginal part arises from the labial sides of the modiolus of angulus oris and its fibres course into the upper and lower labial areas, attaching to the surfaces of the maxilla and mandible.
The orbicularis oris muscle is responsible for pulling the lip tissue centrally, allowing for actions such as eating, drinking, whistling, and kissing. It also closes, protrudes, and compresses the lips, facilitating speech and various facial expressions.
The muscle is derived from the second branchial arch and consists of intrinsic and extrinsic muscles of the lip. It is not a true sphincter, as it is composed of four independent quadrants that interlace and give the appearance of circularity. The deep fibres of the muscle act as a constrictor and are responsible for the sphincteric action of the mouth.
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The muscle is responsible for actions such as eating, drinking, whistling, and kissing
The orbicularis oris muscle is a complex, multi-layered muscle that encircles the mouth and forms the majority of the lips. It is responsible for pulling the lip tissue centrally, allowing for actions such as eating, drinking, whistling, and kissing.
The orbicularis oris is composed of intrinsic and extrinsic muscles of the lip. It has two parts: a larger peripheral part and a smaller marginal part. The peripheral portion, also called the extrinsic portion, originates from the modiolus—a dense fibromuscular nodule at the angle of the mouth where most buccolabial muscles attach. The marginal part arises from the labial sides of the modiolus of angulus oris.
The orbicularis oris is part of the buccolabial group, a group of muscles of facial expression. These muscles control the shape and movements of the lips, such as closing, protruding, and compressing them. This facilitates speech and helps produce various facial expressions, such as anger and sadness.
The muscle is derived from two embryonic laminae: the mandibular lamina, which differentiates partially into the lower fibres of the muscle, and the infraorbital lamina, which develops into the upper fibres of the muscle. The main blood supply to the orbicularis oris comes from the facial artery, specifically the superior labial branch and inferior labial branch. It also receives supply from the maxillary artery and the superficial temporal artery.
The orbicularis oris is a powerful muscle with only a thin layer of fat protecting it. It is susceptible to the breakdown of tissue due to repetitive force, such as drinking through a straw, kissing, or sun exposure.
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It is not a true sphincter, but is composed of four independent quadrants
The orbicularis oris muscle is a complex, multi-layered muscle that encircles the mouth and forms the majority of the lips. It is not a true sphincter, but is composed of four independent quadrants that interlace and give only an appearance of circularity. The muscle is responsible for pulling the lip tissue centrally, allowing for actions such as eating, drinking, whistling, and kissing. It also closes, protrudes, and compresses the lips, facilitating speech and various facial expressions.
The orbicularis oris muscle has two parts: a larger peripheral or extrinsic portion and a smaller marginal or inner labial part. The peripheral portion originates from the modiolus, a dense fibromuscular nodule at the angle of the mouth, and arises from the fibers of several buccolabial muscles that attach to it. These include the levator anguli oris, depressor anguli oris, buccinator, risorius, and zygomaticus major muscles. The uppermost and lowermost fibers of the peripheral portion pass into the superior and inferior labial areas, respectively.
The marginal part of the orbicularis oris muscle arises from the labial sides of the modiolus of angulus oris. Its fibers course round into their respective upper and lower labial areas, attaching to the surfaces of the maxilla and mandible, as well as to the labial part at the vermillion line. The fibers from the labial part extend into the submucosa of the lips and laterally to the base of the modiolus of angulus oris.
The orbicularis oris muscle is derived from the second branchial arch and consists of intrinsic and extrinsic muscles of the lip. It is supplied by several arteries, including the superior and inferior labial, infraorbital, and transverse facial arteries. The muscle receives nerve supply from the buccal and mandibular branches of the facial nerve.
The orbicularis oris muscle is not a simple sphincter muscle like the orbicularis oculi. While it encircles the orifice of the mouth, its fibers run in different directions, giving it a unique structure and functionality. The muscle is composed of numerous strata of muscular fibers, some derived from other facial muscles inserted into the lips, and some proper to the lips themselves. A significant number of fibers are derived from the buccinator muscle, forming the deeper stratum of the orbicularis oris.
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Frequently asked questions
The Orbicularis Oris muscle is a complex, multi-layered muscle that encircles the mouth and forms the majority of the lips. It is responsible for controlling the shape and movement of the lips, including closing, protruding, compressing, and pulling the lips centrally.
The Orbicularis Oris muscle is composed of intrinsic and extrinsic muscles of the lip and consists of two parts: a larger peripheral part and a smaller marginal part. The peripheral portion arises from the modiolus, with fibres from five buccolabial muscles attaching to it. The marginal part arises from the labial sides of the modiolus of angulus oris, while the inner labial part arises from the vermillion line.
The Orbicularis Oris muscle is responsible for various functions, including closing the mouth, puckering the lips, and facilitating speech and facial expressions. It is also used in playing brass and some woodwind instruments.
The Orbicularis Oris muscle develops embryonically from two laminae: the mandibular lamina, which forms the lower fibres of the muscle, and the infraorbital lamina, which forms the upper fibres. Its main blood supply is from the facial artery, particularly the superior and inferior labial branches.
