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Depressor anguli oris muscle

Facial muscle that depresses the corner of the mouth during frowning

Field	Value
Name	Depressor anguli oris
Latin	musculus depressor anguli oris
Image	Gray381.png
Caption	Scheme showing arrangement of fibers of Orbicularis oris (triangularis labeled at bottom right).
Image2	Depressor anguli oris.png
Caption2	Muscles of the head, face, and neck (labeled as triangularis near chin).
Origin	Tubercle of mandible
Insertion	Modiolus of mouth
Action	Depresses angle of mouth
Blood	Facial artery
Nerve	Marginal mandibular branch of the facial nerve

The depressor anguli oris muscle (triangularis muscle) is a facial muscle. It originates from the mandible and inserts into the angle of the mouth. It is associated with frowning, as it depresses the corner of the mouth.

Structure

The depressor anguli oris arises from the lateral surface of the mandible. Its fibers then converge. It is inserted by a narrow fasciculus into the angle of the mouth. At its origin, it is continuous with the platysma muscle, and at its insertion with the orbicularis oris muscle and risorius muscle. Some of its fibers are directly continuous with those of the levator anguli oris muscle, and others are occasionally found crossing from the muscle of one side to that of the other; these latter fibers constitute the transverse muscle of the chin.

The depressor anguli oris muscle receives its blood supply from a branch of the facial artery.

Nerve supply

The depressor anguli oris muscle is supplied by the marginal mandibular branch of the facial nerve.

Function

The depressor anguli oris muscle is a muscle of facial expression. It depresses the corner of the mouth, which is associated with frowning.

Clinical significance

Paralysis

Damage to the marginal mandibular branch of the facial nerve may cause paralysis of the depressor anguli oris muscle. This may contribute to an asymmetrical smile. This may be corrected by resecting (cutting and removing) the depressor labii inferioris muscle, which has a more significant impact on smiling.

Hypoplasia/aplasia

Underdevelopment (hypoplasia) or complete absence (aplasia) of the depressor anguli oris can occur. Similarly to paralysis, individuals with these conditions will have an asymmetric smile. These conditions are rare, and develop at or before birth (congenitally).

Additional images

File:Depressor anguli oris animation small.gif|Position of depressor anguli oris muscle File:Gray176.png|Mandible, outer surface, side view File:Gray508.png|The arteries of the face and scalp

References

(2004-09-01). "Depressor labii inferioris resection: an effective treatment for marginal mandibular nerve paralysis". British Journal of Plastic Surgery.
(13 November 2020). "Hypoplasia: Where it can occur, causes, effects, and treatment options".

Info: Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

muscles-of-the-head-and-neck facial-muscles

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