MUSCLES OF MASTICATION

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Muscles of mastication. These muscles originates from the skull and insert into the mandible, only mandible moves during mastication and other activities. Four muscles are the primary participants in mastication, and other accessory muscles

Each of these primary muscles of mastication is paired

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Temporalis muscle

Masseter muscle

Lateral pterygoid

Medial pterygoid

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Suprahyoid muscles

Digastric

Stylohyoid

Mylohyoid

Geniohyoid

Infrahyoid muscles

Sternohyoid

Thyrohyoid

Omohyoid

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Jaw elevators

Masseter

Temporalis

Medial pterygoid

Jaw depressor

Lateral pterygoid

Anterior digastric

geniohyoid

mylohyoid

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Insertion, margins and deep surfaces of coronoid process of mandible.

Blood supply,

Arterial supply- superficial temporal artery

Venous drainage- superficial temporal vein

Innervation, deep temporal branches from anterior division of mandibular nerve

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Elevation of mandible

Retraction of mandible

Posterior fiber draw the mandible backwards after it has been protruded

It contribute in side to side grinding movement

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superficial;

origin; from zygomatic process of maxillaand anterior 2/3 of lower border of zygomatic arch

Insertion; into lower part part of lateral surface of ramus of mandible

Middle layer, it originate from the anterior 2/3 of the deep surface and posterior 1/3 of lower border of the zygomatic arch and insert into middle part of ramus

Deep layer, it originate from the deep surface of zygomatic arch and insert into upper part of the ramus and into the coronoid process

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Supplied by masseteric artery branch of maxillary artery

Venous drainage through masseteric vein

Innervation; masseteric nerve branch of mandibular nerve

Functions

Elevation of the mandible

Lateral movements of the mandible for efficient chewing and grinding of the food

Unilateral chewing

Retraction of mandible

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Origin; upper head originate from the infratemporal surface and crest of greater wing of sphenoid bone, lower head originate from lateral pterygoid plate

Insertion. Two heads converge into a tendon which attaches to the neck of the mandible

Innervation. Pterygoid branch of trigeminal nerve

Blood supply, pterygoid branch of maxillary artery, ascending palatine artery.

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Depress the mandible to open mouth

Lateral and medial pterygoid of both sides contract to protrude the mandible

When contract alternatively produce chewing movements

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Medial pterygoid muscle. This is quadrangular muscle having a small superficial head and a large deep head which forms the major part of muscle. It is located inferiorly to the lateral pterygoid

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Origin, superficial head from the maxillary tuberosity, deep head from medial surface of lateral pterygoid plate and part of palatine bone

Insertion, into the medial angle of mandible

Blood supply

Lingual vein

Innervation, branch of mandibular nerve

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Elevate the mandible

Closes the jaw

Helps in side to side movements

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