The muscles which are required for mastication are known as the muscles of mastication, These muscles help mainly in the movement of the mandible and not the maxilla as maxilla is an integral part of the skull and the mandible being the only movable bone in the skull.

There are many muscles which help in the process of mastication but the main muscles which take part in the process are :

  • Masseter muscle
  • Temporalis
  • Lateral Pterygoid
  • Medial Pterygoid

Now let us discuss in brief about each of these muscles:

Masseter Muscle: It is one of the muscles which helps in the process of mastication

In humans, the masseter is the second most efficient masticatory muscle. Its origin and insertion make it very useful for the movements of the jaw and for applying good bite force for mastication.

The masseter muscle extends from the zygomatic arch to the ramus and body of the mandible. The fibers of this muscle are broad, extending from the region of the second molar on the surface of the mandible to the surface of the ramus.The muscle is divided into 2 parts

  • Superficial
  • Deep

The main function of masseter muscle is

  • Elevation of the mandible
  • lateral movements of the mandible for efficient chewing and grinding of the food
  • unilateral chewing
  • Retraction of the mandible

Blood supply:

  • Masseteric artery .

Nerve supply:

  • Massetric nerve.

Temporalis muscle

Temporalis Muscle: This is the muscle which helps in elevation of the mandible, It is one of the muscles of mastication. It is large shaped in appearance and covers the Temporal area of the skull.

Origin and Insertion:

  • From the Parietal bone of the skull and is inserted on the coronoid process of the mandible.

Arterial supply:

  • The Deep Temporal artery supplies the large muscle.

Nerve Supply:

  • Trigeminal nerve( this nerve has been associated with being the cause of Headache and migrane.

Functions:

  • Elevation of the mandible
  • Retraction of the mandible.
  • Crushing of food between the molars.

Lateral Pterygoid and medial pterygoid muscle.

Lateral Pterygoid Muscle: This is a small muscle which also helps in the mastication process. It is divided into 2 heads:

Inferior head: Originates from Pterygoid process. Insertion in the Mandible.

Superior head: Originates from Sphenoid bone. Insertion in the  Articular disc.

Nerve Supply:

  • Pterygoid branch of Trigeminal nerve.

Arterial supply:

  • Pterygoid branch of Maxillary artery.

Functions:

  • Depresses the mandible and protrudes it forward for opening of the jaw.

Medial Pterygoid muscle: It is a thick muscle of mastication.

Origin and Insertion :

  • It Arises from the deep head the lateral pterygoid plate, and from the maxillary tuberosity.
  • Insertion is seen on the Medial angle of the Mandible.

Arterial supply:

  • Pterygoid branch of Maxillary artery.

Nerve Supply:

  • Mandibular nerve through the medial pterygoid.

Functions:

  • Elevates the mandible,
  • Closes the jaw,
  • Helps in side to side movement.

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