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Muscles of Mastication

Musculi masticatorii

For medical students2 min readUpdated 2026-10-10

The muscles of mastication (musculi masticatorii) are a group of four paired muscles responsible for the movements of the mandible. They share a common embryonic origin and unified innervation via the mandibular nerve ($V_3$), working in a coordinated fashion to execute complex chewing actions, including elevation, depression, protrusion, retrusion, and lateral excursion of the jaw.

GroupComprises 4 paired muscles that move the mandible
InnervationMandibular nerve ($V_3$)
TMJLateral pterygoid fibers insert into the articular disc and joint capsule
Blood supplyBranches of the facial, maxillary, and superficial temporal arteries

Masseter and Temporalis Muscles

These two muscles are located more superficially and play a vital role in jaw closure.

  1. Masseter Muscle (m. masseter)

This powerful muscle originates from the zygomatic arch (arcus zygomaticus). It inserts onto the lateral surface of the mandibular ramus and a specialized bony landmark, the masseteric tuberosity (tuberositas masseterica). Function: Its primary action is powerful elevation of the mandible (closing the jaw). Additionally, the superficial fibers assist in protrusion (advancing the jaw forward). Blood supply: Supplied by branches of the masseteric artery (a. masseterica) and facial artery (a. facialis).

  1. Temporalis Muscle (m. temporalis)

This broad, fan-shaped muscle originates within the temporal fossa (fossa temporalis). Its muscle fibers converge inferiorly to insert onto the coronoid process of the mandible (processus coronoideus). Function: Like the masseter, the temporalis elevates the mandible. In addition, its posterior fibers perform the opposite movement to protrusion—retrusion (pulling the retracted jaw backward). Blood supply: Provided by the deep temporal arteries (aa. temporales profundae) and superficial temporal artery (a. temporalis superficialis).

Pterygoid Muscles

The pterygoid muscles are located in the deeper compartments of the facial skeleton and are responsible for both elevation and complex lateral movements of the jaw.

  1. Medial Pterygoid Muscle (m. pterygoideus medialis)

This muscle originates from the pterygoid fossa (fossa pterygoidea). From there, fibers travel downward and backward to insert onto the pterygoid tuberosity (tuberositas pterygoidea) on the medial surface of the mandibular angle. Function: Its primary action is elevation of the mandible. Blood supply: Supplied by numerous branches of the maxillary artery (a. maxillaris).

  1. Lateral Pterygoid Muscle (m. pterygoideus lateralis)

This muscle has a complex origin and unique insertion. It arises from the roof of the infratemporal fossa (fossa infratemporalis) and the lateral pterygoid plate. Its fibers insert characteristically into the capsule and articular disc of the temporomandibular joint (TMJ), as well as the pterygoid fovea on the neck of the mandibular condyle. Function: Bilateral contraction protrudes the mandible. Unilateral contraction produces laterotrusion (side-to-side or grinding movement of the jaw to the opposite side). Blood supply: Like the medial pterygoid, it receives blood from branches of the maxillary artery (a. maxillaris).

Functional Summary (Biomechanics)

To facilitate learning, the actions of the masticatory muscles are categorized by movement type:

Frequently asked questions

Which muscles are responsible for depression of the mandible?

Depression of the mandible is performed by several suprahyoid muscles acting as antagonists to the elevators:

  • Mylohyoid muscle — forms the floor of the oral cavity.
  • Geniohyoid muscle.
  • Digastric muscle — utilizing both anterior and posterior bellies.
  • Stylohyoid muscle.
  • Lateral pterygoid muscle (assists during early opening).

For effective jaw opening, the hyoid bone must be stabilized by the infrahyoid musculature.

Which specific motor branches does the mandibular nerve supply to the masticatory muscles?

The mandibular nerve (n. mandibularis, $V_3$) gives off several dedicated motor branches to the muscles of mastication after exiting the skull via the foramen ovale:

  • Masseteric nerve (n. massetericus).
  • Deep temporal nerves (nn. temporales profundj).
  • Medial and lateral pterygoid nerves (nn. pterygoidei medialis et lateralis).
What fascial layers invest the muscles of mastication?
  • Masseteric fascia (fascia masseterica) covers the masseter muscle, attaching superiorly to the zygomatic arch and continuous posteriorly with the parotid fascia.
  • Temporal fascia (fascia temporalis) covers the temporalis muscle, attaching to the superior temporal line above and splitting into superficial and deep layers as it attaches to the zygomatic arch.
Which muscles elevate the mandible?

Mandibular elevation is primarily driven by three muscles: the masseter (m. masseter), temporalis (m. temporalis), and medial pterygoid (m. pterygoideus medialis).

Which muscle inserts into the TMJ capsule and articular disc?

The lateral pterygoid muscle (m. pterygoideus lateralis) sends fibers directly into the capsule and articular disc of the temporomandibular joint.

What is protrusion, and which muscles perform it?

Protrusion is the anterior sliding of the lower jaw. It is executed by the lateral pterygoid muscle and the superficial fibers of the masseter muscle.

What is the primary blood supply to the pterygoid muscles?

Both the medial and lateral pterygoid muscles are vascularized by branches of the maxillary artery (a. maxillaris).

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