The mentalis muscle is a paired central Skeletal muscle of the lower lip, situated at the tip of the chin.
Structure
The mentalis muscle originates from the mental protuberance of the
mandible near the midline.
It inserts into the
soft tissue and
skin of the
chin.
Function
The mentalis muscle causes a weak upward-inward movement of the
soft tissue complex of the
chin.
This raises the central portion of the
Lip.
In the setting of lip incompetence (the upper and lower lips not touching each other at rest), the contraction of the mentalis muscle can bring temporary but strained oral competence.
In conjunction with the orbicularis oris muscle (for the upper lip), the mentalis muscle allows the lips to "pout". Externally, contraction of the mentalis muscle causes Wrinkle and Dimple of the Human skin on the chin, as used in expressions of doubt or displeasure.
Clinical significance
The mentalis muscle can be easily assessed using ultrasound.
Geniospasm
Geniospasm is a
genetic disorder movement disorder of the mentalis muscle.
It involves repetitive contraction of the muscle, with episodes lasting between seconds and hours.
Certain medications may be used to treat it, such as
haloperidol and
Benzodiazepine.
Injection of
botulinum toxin (to temporarily
Paralysis the muscle) may be more effective.
Cosmetics
The mentalis muscle may be partially paralysed using botulinum toxin to reduce
wrinkling of the skin of the chin.
This may be done for cosmetic purposes.
== Additional images ==
. Mentalis is indicated by the red circle at left.]]
