Modiolus: where the mouth corner muscles meet
- Muscle
- Highlighted area
Quick facts
- Definition
- A fibromuscular node lateral to the corner of the mouth, where several muscles of expression cross and attach.
- Location
- Slightly lateral and usually slightly above the oral commissure, on each side.
- Muscles
- Orbicularis oris, buccinator, zygomaticus major, levator anguli oris, risorius, depressor anguli oris and platysma fibers.
- Function
- Coordinates the movement of the mouth corner in speech, smiling and chewing.
- Relevance in HOF
- Helps explain downturned corners, smile asymmetry after toxin and the anatomy of mouth corner filler.
- In Harmy
- The area corresponds to the Mouth Corner point of the marking.
The modiolus is a fibromuscular node located slightly to the side of the corner of the mouth, where several muscles of facial expression cross, interlace and attach. It is not an isolated muscle, but a condensation of muscle fibers and fibrous tissue that works as a mobile anchoring point. It coordinates the movement of the oral commissure when smiling, speaking and chewing, which makes it a central piece in the anatomy of the mouth corners.
Where is it and how do you recognize it?
The modiolus sits on each side, slightly lateral and usually slightly above the commissure. You can feel it by holding the cheek near the corner of the mouth between the thumb, inside, and the index finger, outside: with the mouth relaxed, a denser point can be felt, which becomes firm when the person contracts the surrounding muscles. Position and height vary between people and between sides.
Which muscles meet at the modiolus?
| Muscle | Direction of force at the mouth corner |
|---|---|
| Orbicularis oris | Closes and protrudes the lips |
| Buccinator | Compresses the cheek against the teeth and pulls the corner back |
| Zygomaticus major | Up and out, in the smile |
| Levator anguli oris | Up |
| Risorius | Sideways |
| Depressor anguli oris | Down |
| Platysma (fibers) | Down and out |
The result of the movement depends on the balance between these forces. The smile, for example, is the sum of the lift by the zygomatics and levators with the action of those that pull sideways.
Why does the modiolus matter in HOF?
- Downturned mouth corners: when the force of the depressor anguli oris predominates and support in the area decreases, the modiolus and the commissure drop, which adds to the marionette lines. The topic is covered in botulinum toxin in the depressor anguli oris.
- Asymmetric smile after toxin: because many muscles arrive at the same point, diffusion of botulinum toxin to a neighboring muscle can alter the smile. See asymmetric smile after toxin.
- Mouth corner filler: the area is mobile and heavily used in speech and chewing, which influences the choice of product and the tendency toward displacement or palpability. The procedure is covered in mouth corner filler.
How does it show up in the assessment?
- At rest: position of the commissure relative to the line between the lips and symmetry between the sides.
- Spontaneous and forced smile: shows where each corner is pulled and whether there is muscular asymmetry.
- Speech: reveals movements that a posed smile hides.
- Palpation: firmness and position of the modiolus on each side.
- Toxin history: previous injections in the area change the balance of forces.
Also called: modiolar node, modiolus, mouth corner node.
Frequently asked questions
What is the modiolus of the mouth?
It is a meeting point of muscles beside the corner of the mouth, made of interlaced muscle fibers and fibrous tissue. The muscles that raise, lower, pull sideways and close the mouth attach to it, which is why it coordinates the movement of the commissure.
Which muscles form the modiolus?
The orbicularis oris, buccinator, zygomaticus major, levator anguli oris, risorius, depressor anguli oris and platysma fibers are generally cited. The contribution of each varies between people.