Head and neck muscles (chewing, facial, and throat muscles)

Superficial part of masseter

Musculus masseter, pars superficialis

Origin

Zygomatic process of the maxilla and the anterior two-thirds of the zygomatic arch

Insertion

Angle of the mandible and the lower part of the ramus of the mandible

Function

Powerful elevator of the lower jaw (jaw closing/biting), with a slight protrusive component

Innervation

Masseteric nerve, branch of the mandibular nerve (V3, trigeminal nerve)

Movement & chain

Works together with temporalis and medial pterygoid as the main elevator of the mandible during chewing.

Palpation

Easily felt as a thickening just in front of the ear when clenching the jaws together.

Clinical

Often hypertrophic with bruxism (teeth grinding) and a commonly used injection site for botulinum toxin in jaw clenching or a square jawline.

Segmental innervation

Motor via the trigeminal nerve (V3); no spinal segment.

In clinical practice

Standard palpation site when examining for temporomandibular dysfunction and bruxism.

Region in the model

Head and neck muscles (chewing, facial, and throat muscles)