The muscles of mastication are a group of muscles around the temporomandibular joint. They are responsible for the movements at the mentioned joint, so they are also responsible for moving the lower jaw.

The muscles of mastication participate in moving the mandible during eating and speaking. They assist while chewing and grinding the food. Therefore, these muscles also participate in opening and closing the mouth.

The muscles of mastication are subdivided into two groups - primary or main and secondary or accessory muscles. Each person has four pairs of primary masticatory muscles and several accessory muscles. These muscles elevate, depress, protrude and retract the mandible, as well as provide side-to-side movements.

Note: The accessory muscles anatomically are not classified as the muscles of mastication, but they assist the primary muscles and are involved in the mastication process.

The primary muscles of mastication include:

The accessory muscles are:

In prosthetic dentistry, these muscles define the borders and peripheral extensions, and knowing the basics of the masticatory system is a requirement for prosthodontists.

Humans chew approximately 15 times from the moment the food enters the mouth until it is swallowed. Masticatory muscles have a shorter contraction time compared to the most of the muscles in the body, and they do not get easily tired.

Besides the classification described above, all these muscles can be divided into several more subdivisions depending on their function.

Muscles that close the jaws (elevators) are:

Muscles that open the jaws (depressors) include the following:

Lateral pterygoid (lower head)
Digastric (anterior belly)
Mylohyoid
Geniohyoid

Muscles that protrude the jaw are as follows:

Masseter
Medial pterygoid
Lateral pterygoid (lower head)
Digastric
Temporalis

Muscles providing jaw retrusion are:

Temporalis
Digastric
Lateral pterygoid (lower head)

Muscles providing side-to-side movements of the lower jaw include the following:

Masseter
Temporalis
Medial pterygoid
Lateral pterygoid

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Muscles of mastication