Muscles of mastication
Mandibular division of the trigeminal nerve.
Details
Nervemandibular nerve
Identifiers
Latinmusculi masticatorii
MeSHD008410
TA98A04.1.04.001
TA22104
FMA74060
Anatomical terms of muscle

The four classical muscles of mastication elevate the mandible (closing the jaw) and move it forward/backward and laterally, facilitating biting and chewing. Other muscles are responsible for opening the jaw, namely the geniohyoid, mylohyoid, and digastric muscles (the lateral pterygoid may play a role).

Structure

The muscles are:

In humans, the mandible, or lower jaw, is connected to the temporal bone of the skull via the temporomandibular joint. This is an extremely complex joint which permits movement in all planes. The muscles of mastication originate on the skull and insert into the mandible, thereby allowing for jaw movements during contraction.

Each of these primary muscles of mastication is paired, with each side of the mandible possessing one of the four.

Innervation

Unlike most of the other facial muscles, which are innervated by the facial nerve (or CN VII), the muscles of mastication are innervated by the trigeminal nerve (or CN V). More specifically, they are innervated by the mandibular branch, or V3. The mandibular nerve is both sensory and motor.

Development

Embryologically, the muscles of mastication are all derived from the first pharyngeal arch.

The muscles of facial expression, on the other hand, are derived from the second pharyngeal arch.

Function

The mandible is the only bone that moves during mastication and other activities, such as talking.

While these four muscles are the primary participants in mastication, other muscles help with the process, such as those of the tongue and the cheeks.

Prime mover Movement[1] [2]OriginInsertion
Masseter Elevates mandible (closes mouth and aids chewing) Zygomatic archMandible (coronoid process and ramus)
Temporalis Elevates and retracts mandible (closes mouth; pulls lower jaw in/backward) Temporal boneMandible (coronoid process and ramus)
Lateral pterygoid Depresses?, protracts, laterally moves mandible (opens mouth?; pushes lower jaw out/forward; moves lower jaw side to side) Superior head: infratemporal surface of greater wing of sphenoid bone

Inferior head: lateral pterygoid plate of sphenoid bone

 Mandible; temporo-mandibular joint
Medial pterygoid Elevates, protracts, laterally moves mandible (closes mouth; pushes lower jaw out/forward; moves lower jaw side-to-side) Deep head: medial surface of lateral pterygoid plate and palatine bone

Superficial head: tuberosity of maxilla

 Mandible (medial ramus below the mandibular foramen)

Clinical significance

References

  1. ↑  This article incorporates text available under the CC BY 4.0 license. Betts, J Gordon; Desaix, Peter; Johnson, Eddie; Johnson, Jody E; Korol, Oksana; Kruse, Dean; Poe, Brandon; Wise, James; Womble, Mark D; Young, Kelly A (June 28, 2023). Anatomy & Physiology. Houston: OpenStax CNX. 11.3 Axial muscles of the head, neck and back. ISBN 978-1-947172-04-3.
  2. ↑ Hansen, John T. (2010), "HEAD AND NECK", Netter's Clinical Anatomy, Elsevier, pp. 349–445, retrieved 2024-01-08
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