MUSCLE OF MASTICATION

Riddhi Dave

MUSCLE OF MASTICATION There are main FOUR muscle which are

involved in mastication. 1) TEMPORALIS 2) MASSETER 3) LATERAL PTERYGOID 4) MEDIAL PTERYGOID

MUSCLE ATTEACHMENT TO THE MANDIBLE

TEMPORALIS MUSCLE

INTRODUCTION Temporalis muscle is fan shape muscle. It fills the temporal fossa.

ORIGIN Temporal fossa excluding the zygomatic

bone. Temporal fascia.

FIBERS Anterior fibers run vertically. Middle fibers run obliquely. Posterior fibers run horizontally. All converge and pass through gap deep to

zygomatic arch.

INSERTION Margins and deep surface of coronoid

process. Anterior border of ramus of mandible.

NERVE SUPPLY Two deep temporal branches from

anterior division of mandibular nerve.

ACTION Elevates mandible Helps in side to side grinding movement Posterior fibers retract the mandible

MASSETER MUSCLE

INTRODUCTION It is quadrilateral in shape. It is antigravity muscle. It covers the lateral surface of ramus of

mandible, and it has two layers.

ORIGIN Superficial layer(largest) :- from anterior

2/3 rd of lower border of zygomatic arch and adjoining zygomatic process of maxilla.

Deep layer(small) :- from deep surface of zygomatic arch.

FIBERS Superficial fibers pass downwards and

backwards at 45 degree. Deep fibers pass vertically downwards.

INSERTION Superficial layer :- into lower part of

lateral surface of ramus of mandible. Deep layer :- into rest of the ramus of

mandible.

NERVE SUPPLY Masseteric nerve

ACTION Elevates the mandible to close the

mouth for bite.

LATERAL PTERYGOID

INTRODUCTION Short , conical muscle. It has two heads upper and lower head.

ORIGIN Upper head(small) :- from infratemporal

surface and crest of greater wing of sphenoid bone.

Lower head(larger) :- from lateral surface of the lateral pterygoid plate.

FIBERS Fibers run backward and laterally and

converge for insertion.

INSERTION Pterygoid fovea on the anterior surface

of neck of mandible. Anterior margin of articular disc and

capsule of TMJ.

NERVE SUPPLY Nerve to lateral pterygoid branch of

mandibular nerve.

ACTION Depresses mandible to open mouth with

suprahyoid muscle. Lateral and medial pterygoid protrude

mandible. Right lateral and medial pterygoid

muscle turn the chin on left side as part of grinding movements.

MEDIAL PTERYGOID

INTRODUCTION It is a quadrilateral muscle. It has small superficial and large deep

muscle.

ORIGIN Superficial head :- from tuberosity of

maxilla and adjoining bone. Deep head :- from medial surface of

lateral pterygoid plate.

FIBERS Fibers run downwards , backwards and

laterally.

INSERTION Roughened area on the medial surface of the

angle and adjoining ramus of mandible, below and behind the mandibular foramen and mylohyoid groove.

NERVE SUPPLY Nerve to medial pterygoid which is a branch of

the main trunk of mandibular nerve.

ACTION Elevates the mandible Protrude the mandible Right lateral and medial pterygoid muscle turn

the chin on left side as part of grinding movements.

RELATIONS OF MEDIAL PTERYGOID MUSCLE SUPERFICIAL RELATIONS Lateral pterygoid plate Lingual nerve Inferior alveolar nerve

DEEP RELATIONS Tensor veli palatini Superior constictor of pharynx Styloglossus