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What is the Mentalis?

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  • Written By: Dee S.
  • Edited By: Jenn Walker
  • Last Modified Date: 18 November 2016
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The mentalis is a muscle located directly below the lower lip, near the chin tip. It is responsible for raising the lower lip. Since it works to wrinkle the chin and push the lower lip out, it is often called as the pouting muscle. Someone who exaggerates her expression of displeasure or sadness will most likely use this muscle. Although most people go through life without giving much thought to their mentalis, some people are plagued with medical conditions and disorders that greatly affect this muscle.

The mentalis does not usually pose a problem for most people, but there are a few disorders and conditions that may require medical attention. For example, geniospasms, a rare genetic disorder, may affect the mentalis muscle. With geniospasms, the chin and lower lip quiver involuntarily and repeatedly. Geniospasms are usually brought on by stress, usually beginning in childhood.

Luckily, when the mentalis is affected by geniospasms, there are medical procedures that can be used to control the spasms. Specifically, injections of botulinum toxin A, known by the brand name Botox®, work well. As a result of the injections, the muscle is paralyzed, but the facial expressions are not impaired and the speech is not impeded. Botox® is one of the most cost effective, least painful, and quickest methods to treat the problem. However, all options should be considered because there are side effects to Botox®, as well, including pain, headache or upset stomach.

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Some people may opt to have cosmetic surgery to alter the size or shape of their chin. If the chin is made smaller, the procedure is called mentoplasty. If the chin is made larger, it is called genioplasty. In either case, the mentalis muscle is detached during the surgery and may then become damaged or incorrectly reattached. As a result, Botox® has proven to be useful to treat the symptoms of the damaged muscle.

In some cases, the mentalis is strained due to a chin deformity. In those cases, a surgeon may recommend a chin implant or filling the chin with fat. The chin implant and the addition of fat typically work to reduce the strain on the muscle.

A specialist should be contacted before undergoing any chin surgery. Mentalis and chin deformities are rather uncommon, but surgery can alter speech and appearance of the affected individual. Surgery is not always necessary, but it may become the best option. A second medical opinion may be warranted in some cases, especially if alternatives to surgery are available.

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anon284892
Post 3

I injected Botox into my chin. As a result the midsection of the lower lip is pulled down. I am still able to pucker. The fault is visible when I talk or smile. The left side still covers the bottom teeth like normal and the right side shows both upper and lower teeth. Recommendations? Please help.

anatapeia
Post 2

The mentalis (chin muscle) is a peculiar and quite amazing little muscle. Its two claims to fame are that its the only muscle that attaches to bone in the lower face, and that its capable of 'dual action'.

The mentalis is actually a pair of anvil-shaped muscles, which attach to the bone side by side, at two small points below the central lower lip (two little dimples can sometimes be seen here).

Its shorter fibers extend upwards to intermesh with the orbicularis oris (ringing the mouth), while its longer lower fibers splay out over the chin bone, forming the bulk of the pad.

The labiomental fold (crease below the lip) is an extraordinary feat of muscular architecture. It is capable

of transferring fine transformative movement through it, to regions above and below.

The firm anchoring of the muscles to the bone, enables the paired mentalis to lever against this producing a flow of movement in varied direction, but predominantly up or down. The mentalis is therefore said to be capable of dual action.

Its lower fibers may contract pushing the chin and lip up (e.g. pouting lip), or its upper fibers may contract pulling the chin and lip down (e.g. retracted lip). There is a degree of muscle tension constantly present in the mentalis, and this enables the lower lip to rise against gravity. No bone or cartilage holds up the lip. The mentalis does all the work here.

The action of the mentalis upon the lower lip is indirect, and the chin and lip are considered one anatomical unit.

The surprising thing is that the mentalis isn't too fussy about what it levers against. A chin implant may provide a firm bolster for this levering action, even where the muscle has been detached.

However, if the chin implant has to be removed for any reason, the detached mentalis will have nothing to lever against, and the labiomental fold may distort, and contort upon itself in function The emptied implant pocket (capsule) below on the chin, can sometimes add to the confusion as it may bunch up and furrow producing a 'prune chin' effect.

A firm grasp of the anatomy is essential for any surgeon operating in the region of the mentalis. The intraoral approach entails dissection of this unique and talented little muscle. Respectful repair is a must for those who insist on doing so.

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