| Muscles of mastication | |
|---|---|
 Mandibular division of the trigeminal nerve | |
| Details | |
| Nerve | Mandibular nerve |
| Identifiers | |
| Latin | musculi masticatorii |
| MeSH | D008410 |
| TA98 | A04.1.04.001 |
| TA2 | 2104 |
| FMA | 74060 |
| Anatomical terms of muscle | |
The four classicalmuscles of mastication elevate themandible (closing the jaw) and move it forward/backward and laterally, facilitating biting and chewing. Other muscles are responsible for opening the jaw, namely thegeniohyoid,mylohyoid, anddigastric muscles (thelateral pterygoid may play a role).
The muscles are:
In humans, themandible, or lower jaw, is connected to thetemporal bone of the skull via thetemporomandibular 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.
Unlike most of the otherfacial muscles, which are innervated by thefacial nerve (orCN VII), the muscles of mastication are innervated by thetrigeminal nerve (orCN V). More specifically, they are innervated by themandibular branch, orV3. The mandibular nerve is both sensory and motor.
Embryologically, the muscles of mastication are all derived from the firstpharyngeal arch.
Themuscles of facial expression, on the other hand, are derived from the second pharyngeal arch.
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] | Origin | Insertion |
|---|---|---|---|
| Masseter | Elevates mandible (closes mouth and aids chewing) | Zygomatic arch | Mandible (coronoid process andramus) |
| Temporalis | Elevates and retracts mandible (closes mouth; pulls lower jaw in/backward) | Temporal bone | Mandible (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 ofsphenoid 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 oflateral pterygoid plate andpalatine bone Superficial head: tuberosity ofmaxilla | Mandible (medial ramus below themandibular foramen) |
This article incorporatestext available under theCC 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.
