The muscles of mastication are the four paired skeletal muscles which allow us to bite and chew the food we eat so that we can swallow it. They are located on the postero-lateral aspect of face and head. They arise from different parts of the base of cranium, stretching from the sphenoid, temporal, maxilla, and zygomatic bone all the way down to be inserted into the mandible (lower jaw). They are all innervated by different branches that originate from the same nerve: the trigeminal nerve (CN V), and they are supplied with oxygenated blood by arterial branches that arise from the maxillary and external carotid artery.
The Muscles of Mastication
1) Masseter Muscle. It is made up of two portions; a superficial and a deep part. They originate from the zygomatic arch and are inserted into the ramus of mandible. It raises and protrude the lower jaw as it is the main muscle of chewing.
2) Temporalis Muscle. It is the broadest of them all, occupying the temporal fossa and it gets inserted into the coronoid process of mandible. It raises the mandible.
3) Lateral Pterygoid Muscle. It arises from the greater wing of sphenoid bone and it is inserted into the articular capsule of mandibular joint. It pulls the mandible to the contralateral side.
4) Medial Pterygoid Muscle. It takes origin from the walls of pterygoid fossa (sphenoid bone) and it gets inserted into pterygoid tuberosity of mandible. It also displaces the mandible to the contralateral side. It raises the lower jaw as well.
In the two images shown below, you can see the muscles of mastication.
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| In this picture, the masseter was cut away to expose the lateral pterygoid and the medial pterygoid muscle. |