Masseteric fascia

The masseteric fascia is a dense fibrous layer derived from the deep cervical fascia that invests the masseter muscle on the lateral surface of the face. It forms part of the parotid0masseteric fascia complex.

Location and Attachments

The masseteric fascia extends superiorly from the inferior border of the zygomatic arch to the angle and inferior border of the mandible. Anteriorly, it blends with the buccal fascia over the buccinator muscle and overlies the buccal fat pad, finally blending with the epimysium of the buccinator muscle. Posteriorly, it is continuous with the parotid fascia, and superiorly, it connects with the temporal fascia across the zygomatic arch. Inferiorly, it merges with the investing layer of the deep cervical fascia.

Superficial and deep layers

Some texts describe the masseteric fascia splitting into superficial and deep layers that invest the masseter, with its deep layer becoming continuous with the pterygoid fascia surrounding the pterygoid muscles.

Anatomical relationships

• The masseteric fascia forms the outer capsule of the masseter muscle, separating it from the overlying subcutaneous tissue and facial muscles.

• It often divides into superficial and deep laminae, which enclose the parotid duct, facial vessels, and buccal branches of the facial nerve as they cross the masseter.

• Medially, it is continuous with the pterygoid fascia, collectively forming the masticator space that encloses the masseter, pterygoid muscles, and ramus of the mandible.

Relation to the Superficial Musculoaponeurotic system (SMAS) and Facial Muscles

The masseteric fascia lies deep to the superficial musculoaponeurotic system (SMAS) and platysma in the parotid–masseteric region. It provides the deep investing surface of the SMAS, anchoring it to the zygomatic arch and mandible, and acting as a gliding plane for facial movement. Through its continuity with the parotid, temporal, buccal, and cervical fasciae, it forms a continuous fascial network linking the muscles of facial expression (platysma, buccinator, zygomaticus) to the muscles of mastication (masseter and pterygoids).

Functional and clinical significance

The masseteric fascia supports and compartmentalizes the parotid–masseteric region, provides passage for neurovascular structures, and maintains the facial contour. It is a key surgical plane in facelift (SMAS) and parotid surgeries and helps define the masticator space, a potential site for deep facial infections.

Summary of Key Points