Orbicularis oris muscle

Orbicularis oris muscle
Orbicularis coris
Orbicularis oris.jpg
Latin musculus orbicularis oris
Gray's subject #108 384
Origin Maxilla and mandible
Insertion    Skin around the lips
Artery
Nerve cranial nerve VII, buccal branch of the facial nerve
Actions It is sometimes known as the kissing muscle[1][2] because it is used to pucker the lips.

In human anatomy, the orbicularis oris muscle is the sphincter muscle around the mouth. "Orbicularis Oris is a complex of muscles in the lips that encircle the mouth; until recently it was misinterpreted as a sphincter, or circular muscle, but it is actually composed of four independent quadrants that interlace and give only an appearance of circularity."[3]

It is also one of the muscles used in the playing of all brass instruments and some woodwind instruments.

This muscle closes the mouth and puckers the lips when it contracts.

Contents

Anatomy

The Orbicularis oris is not a simple sphincter muscle like the Orbicularis oculi; it consists of numerous strata of muscular fibers surrounding the orifice of the mouth but having different direction.

It consists partly of fibers derived from the other facial muscles which are inserted into the lips, and partly of fibers proper to the lips.

Of the former, a considerable number are derived from the Buccinator and form the deeper stratum of the Orbicularis.

Some of the Buccinator fibers—namely, those near the middle of the muscle—decussate at the angle of the mouth, those arising from the maxilla passing to the lower lip, and those from the mandible to the upper lip.

The uppermost and lowermost fibers of the Buccinator pass across the lips from side to side without decussation.

Superficial to this stratum is a second, formed on either side by the Caninus and Triangularis, which cross each other at the angle of the mouth; those from the Caninus passing to the lower lip, and those from the Triangularis to the upper lip, along which they run, to be inserted into the skin near the median line.

In addition to these there are fibers from the Quadratus labii superioris, the Zygomaticus, and the Quadratus labii inferioris; these intermingle with the transverse fibers above described, and have principally an oblique direction.

The proper fibers of the lips are oblique, and pass from the under surface of the skin to the mucous membrane, through the thickness of the lip.

Finally, there are fibers by which the muscle is connected with the maxillæ and the septum of the nose above and with the mandible below.

In the upper lip these consist of two bands, lateral and medial, on either side of the middle line; the lateral band m. incisivus labii superioris arises from the alveolar border of the maxilla, opposite the lateral incisor tooth, and arching lateralward is continuous with the other muscles at the angle of the mouth; the medial band m. nasolabialis connects the upper lip to the back of the septum of the nose.

The interval between the two medial bands corresponds with the depression, called the philtrum, seen on the lip beneath the septum of the nose.

The additional fibers for the lower lip constitute a slip m. incisivus labii inferioris on either side of the middle line; this arises from the mandible, lateral to the Mentalis, and intermingles with the other muscles at the angle of the mouth.

Clinical significance

Newborn babies are occasionally born without one or both sides of this particular muscle resulting in a slight droop to the affected side of the face.

Additional images

References

  1. ^ "orbicularis oris muscle". TheFreeDictionary : Mosby's Dental Dictionary, 2nd edition. 2008. http://medical-dictionary.thefreedictionary.com/orbicularis+oris+muscle. Retrieved 2010-10-03. 
  2. ^ "Muscles - Facial". BBC : Science & Nature : Human Body & Mind. http://www.bbc.co.uk/science/humanbody/body/factfiles/facial/frontalis.shtml. Retrieved 2010-10-03. 
  3. ^ Saladin, "Anatomy & Physiology: The Unity of Form and Function". 5th edition. McGraw Hill. Page 330

External links

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.


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Look at other dictionaries:

  • orbicularis oris muscle — musculus orbicularis oris …   Medical dictionary

  • Orbicularis oculi muscle — Latin musculus orbicularis oculi Gray s subject #106 380 …   Wikipedia

  • orbicularis oris — ōr əs n, pl orbiculares oris a muscle made up of several layers of fibers passing in different directions that encircles the mouth and controls most movements of the lips (as compressing, closing, or pursing movements) …   Medical dictionary

  • Orbicularis oris — Musculus orbicularis oris Ursprung Ober und Unterkiefer Ansatz Haut der Lippe Funktion Zusammenziehen der Mu …   Deutsch Wikipedia

  • pars labialis musculi orbicularis oris — [TA] labial part of orbicularis oris muscle: the part of the muscle whose fibers are restricted to the lips …   Medical dictionary

  • pars marginalis musculi orbicularis oris — [TA] marginal part of orbicularis oris muscle: the part of the muscle whose fibers blend with those of adjacent muscles …   Medical dictionary

  • orbicularis oris — ˈōrə̇s noun (plural orbiculares oris) Etymology: New Latin, literally, orbicularis of the mouth : a muscle made up of several layers of fibers passing in different directions that encircles the mouth and controls most movements of the lips (as… …   Useful english dictionary

  • Depressor anguli oris muscle — Depressor anguli oris Scheme showing arrangement of fibers of Orbicularis oris. (Triangularis labeled at bottom right.) …   Wikipedia

  • M. orbicularis oris — Musculus orbicularis oris Ursprung Ober und Unterkiefer Ansatz Haut der Lippe Funktion Zusammenziehen der Mu …   Deutsch Wikipedia

  • Musculus orbicularis oris — Ursprung Ober und Unterkiefer Ansatz Haut der Lippe Funktion …   Deutsch Wikipedia

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