Masseter muscle: function, hypertrophy and toxin

The masseter is the main muscle of chewing. It sits on the side of the face, from the zygomatic arch to the angle of the mandible, and is easy to feel with the fingers when the person clenches the teeth. Its function is to raise the mandible and generate force for biting and chewing.

Why does it matter in facial harmonization?

The volume of the masseter directly influences the width of the lower third and the shape of the jaw angle. When the muscle is hypertrophied, the face tends to look squarer around the angle. Hypertrophy can be constitutional or associated with clenching and grinding of the teeth, and it can also cause pain and muscle fatigue.

In the assessment, it is worth distinguishing what is muscle, what is bone and what is fat or parotid gland. Palpating the masseter while the patient clenches the teeth helps with this reading, and investigating the functional cause may require a dental assessment.

What options involve the masseter?

Botulinum toxin in the masseter is a recognized use, both for reducing hypertrophy and as part of managing clenching. Doses, injection points and intervals are the decision of the licensed professional, after assessment. Unwanted effects described include fatigue when chewing, smile asymmetry from spread and, in cases of excessive blocking, a hollow on the side of the face.

The front border of the masseter is also an anatomical landmark: the facial artery crosses the mandible just in front of it, which matters in jawline filler. When hyaluronic acid is used, hyaluronidase should be available.

In Harmy

The Jawline point in the marking represents filler in the area. Masseter reduction with toxin has no dedicated point in the app.

Also called: masseter, chewing muscle.