Topics

Topic

design image
Masseter muscle (Superficial part)

The masseter muscle (superficial part) is a powerful, quadrilateral muscle of mastication located on the lateral aspect of the mandible. It plays a crucial role in elevating the mandible and closing the jaw, contributing to chewing movements. As one of the primary muscles of mastication, it is easily palpable and can be visualized through various imaging modalities, providing essential information for diagnosis and treatment of maxillofacial pathologies.

Synonyms

  • Musculus masseter (superficialis)

  • Superficial layer of masseter

  • Superficial masseter

Function

  • Elevation of the mandible (jaw closure)

  • Assists in protrusion of the mandible

  • Plays a key role in mastication (chewing)

Origin

  • Zygomatic process of the maxilla

  • Inferior border and medial surface of the anterior two-thirds of the zygomatic arch

Insertion

  • Angle of the mandible

  • Lower lateral surface of the ramus of the mandible

Nerve Supply

  • Mandibular division of the trigeminal nerve (cranial nerve V3)

  • Specifically, via the masseteric nerve

Arterial Supply

  • Masseteric branch of the maxillary artery

  • Facial artery (minor contribution)

Venous Drainage

  • Masseteric vein

  • Drains into the pterygoid venous plexus

MRI Appearance

  • T1-weighted: Intermediate to slightly hyperintense compared to adjacent soft tissues

  • T2-weighted: Normal muscle demonstrates relatively low signal intensity, but increased signal may indicate edema or pathology.

  • STIR (Short Tau Inversion Recovery): Low signal intensity in normal muscle; marked hyperintensity in cases of edema, inflammation, or myositis

CT Appearance

  • Appears as a well-defined, homogeneously dense soft tissue structure on the lateral side of the mandible

  • Borders clearly demarcated from the subcutaneous fat and bone

MRI images

Masseter Muscle (Superficial Part) mri axial image -img-00000-00000