Topography and location of the depressor anguli oris muscle with a reference to the mental foramen

Abstract

The labiomandibular fold (LMF) is the area of the face that extends from the mouth corner to the mandibular border, and its prominence tends to increase with age. The LMF can be formed by the medial or lateral border of the depressor anguli oris (DAO). The aim of this study was to demonstrate the topographical anatomy between the DAO and mental foramen, thereby providing critical information for the safest and most effective site at which to inject botulinum toxin type A (BTX-A). Thirty-four hemifaces from Korean adult cadavers were dissected. The maximum width between the medial borders of the bilateral DAO, parallel to the intercheilion horizontal line, was 59.9 +/- 4.6 (mean +/- SD) mm below the lower lip. The minimum width between the medial borders of the attachment of bilateral DAO was 29.7 +/- 4.8 mm at the mandibular border. The mental foramen was located in the middle third from the cheilion to the mandibular border in 28 cases (90.3%), and it was mostly confined within the DAO muscle coverage in 21 cases (67.7%). The buccal branch of the facial nerve entered through the middle third of the lateral border of DAO and then distributed. Concomitantly, the marginal mandibular branch of the facial nerve entered through the lower third of the lateral border of DAO in 17 cases (60.7%). These results represent additional reference data for identifying the position of the mental foramen on the facial skin, and will be useful for providing criteria for the most effective site for injecting BTX-A when treating the LMF.

Lower-face and neck antiaging treatment and prevention using onabotulinumtoxin A: the 2010 multidisciplinary French consensus - part 2

“…As a result, the amount of dental display may be diminished and the Cupid’s bow may also flatten 7 . An anatomo‐morphological study showed that the optimum injection point is situated at the inferior third of the DAO, below the mental foramen 21 . Adjunction of onabotulinum to the usual filler treatment relaxes the DAO, allowing the opposing and normokinetic zygomaticus muscles to elevate the mouth corners, giving the face a more natural balance 6,17 .…”

“…7 An anatomo-morphological study showed that the optimum injection point is situated at the inferior third of the DAO, below the mental foramen. 21 Adjunction of onabotulinum to the usual filler treatment relaxes the DAO, allowing the opposing and normokinetic zygomaticus muscles to elevate the mouth corners, giving the face a more natural balance. 6,17 Furthermore, this prolongs the effect of fillers by preventing repeated molding caused by regular movements.…”

A Retrospective and Anatomical Study Describing the Injection of Botulinum Neurotoxins in the Depressor Anguli Oris

“…This led the authors to suggest that botulinum toxin injection in the lower third of the depressor anguli oris below the mental foramen would have a lower risk of direct neurovascular needle damage to the mental nerve emerging from the mental foramen. 14 A further cadaver study of 21 South Asian adults (42 hemifaces) examined the topography of facial muscles at the oral commissure. 16 The results showed that a fan-shaped area located less than 45 degrees lateral and less than 30 degrees medial to the modiolus was the safest and most effective depressor anguli oris injection site.…”

“…The labiomandibular fold can be formed by the medial or lateral border of the depressor anguli oris. 14 It is defined superiorly by cutaneous insertion of the depressor anguli oris at the labiomandibular crease and inferiorly by the mandibular ligament. Both-the dynamic movement of the depressor anguli oris and the natural aging process relative to these fixed cutaneous points-create the appearance of the labiomandibular fold.…”

Mandibular Rim Trilogy with Botulinum Toxin Injection: Reduction, Projection, and Lift

“…10 The hypercontraction of this broad, thin muscle results in lower face ptosis. The depressor anguli oris 11 originates from the mandible and inserts into the angle of the mouth, which causes the downward motion of the mouth corners, resulting in a sad and frustrated expression.…”