muscles of mastication 2

7/29/2019 Muscles of Mastication 2

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MUSCLES OF MASTICATION

SEBY J GARDENS


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CONTENTS Introduction

Embryological development Masticator space Origin, Course, Insertion, Relation Muscles

of Mastication

Fascia- Masseteric, Temporalis, Pterygoid Mandibular sling Buccinator Muscle Nerve supply

Blood supply Actions & Group actions Applied Anatomy Conclusion

References


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INTRODUCTION


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EMBRYOLOGICAL DEVELOPEMENT

Mesoderm of the 1st Branchial Arch


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MASTICATOR SPACE(PARVIZ)

CONTENTS

4 Muscles of Mastication

Ramus & Posterior portion of body ofMandible

Fascia Masseteric , Pterygoid,

Temporalis


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MASSETER

Quadrilateral / Rectangular Covers lateral surface of Ramus of

mandible

3 superimposed layers, that blendanteriorly. (PARVIZ JANFAZA)


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ORIGIN,

MOST ANTERIOR FIBRESarises as a thick aponeurosis

= Maxillary process of zygomaticbone(GRAYS)

SUPERFICIAL (largest)

= anterior 2/3lower border, Zygomatic Arch


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ORIGIN,

MIDDLE= anterior 2/3 posterior 1/3

deep surface & lower borderzygomatic arch

DEEP

= posterior 1/3deep surfacezygomatic arch


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Course of masseter

Superficial layer passes downwards&backwards at an angle of 45 degree

Middle & Deep Layer pass vertically

downwards


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INSERTION,

SUPERFICIAL, = posterior lower ,lateral surface, Ramus

&

angle of mandible MIDDLE = central part,

lateral, Ramus

DEEP = upper , lateral,Ramus&

lateral surface,CoronoidProcess


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Middle & Deep layers together constitutethe deep part of the masseter,

refd to in the NOMINA ANATOMICA( MacDougall ,1955 );

they form a cruciate muscle

(GRAYS)


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RELATIONS,

SUPERFICIAL - Skin- Platysma- Risorius

- Zygomatic Major- Antr part,Parotid Gland- Parotid duct

- Facial n, terminal brs- Transverse Facial vessels


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DEEP - Ramus- Lower part of Temporalis

- Massetric n & a ,reach the deep surface of m. bypassing through the Dorsal part ofMandibular Incisure

ANTERIORLY - Buccinator- Buccal n

POSTERIORLY Parotid gland


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PAROTID MASSETERIC FASCIA

Covers Masseter (except,as its deep upperportion. Here there is a communication withfascial planes associated with the insertion of

temporalis m.)

&splits to invest ParotidGland

Attaches, Zygomatic archLower border of Mandible

Continues, Investing Cervical Fascia overSternocleidomastoid m,


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Extends deep & fuses with, Fascia ofPosterior Belly of Digastric m. as

Stylomandibular ligament.

Encircles, anteriorly- Ramus

deep- Medial Pterygoid m.

Fuses with, dense&tough superficial

fascia covering parotid gland. Irregularsepta into the gland.


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TEMPORALIS

Fan shaped Fills Temporal Fossa

ORIGIN,

Bones forming Temporal fossa (excludingzygomatic bone)

Temporal Fascia (deep surface)


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Course,

Antr fibres- vertically downwards Postr fibres horizontally forwards

Intermediate obliquely

-------- converge to form a tendon

(TEMPORALIS TENDON) &pass thr gap b/w Zygomatic arch and sideof the skull


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INSERTION,

Coronoid Process,= deep (medial) surface +

= margins (apex, anterior & posteriorborder)

Ramus,anteromedial aspect, nearly to the

last molar tooth

(GOSLING)


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RELATIONS,

SUPERFICIAL -Skin-Auricularis anterior

-Auricularis superior

-Temporal branch-Facial n-Zygomatico temporal nerve

-Superficial temporal a & v-Galea aponeurotica

-Zygomatic arch-Masseter m


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DEEP,-Temporalis fossa

-Lateral pterygoid m-Superficial head, medial pterygoid m

-Buccinator m

-Maxillary artery-Deep temporalis n

-Buccal vessels & n


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TEMPORAL FASCIA

The most cranial extension of the DeepCervical Fascia

Thick Fibrous Aponeurotic sheets, coversTemporalis

Supr, single layered

Superior Temporal Line

Infr, splits into 2 layers

inner&upper lips, upper bor, Zygo arch.

Gap b/w 2, - Zygomatic br.of Superficial Temporal a.

- Zygomaticotemporal n.

Continues, Masseteric Fascia


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Relations, Temporal Fascia

SUPERFICIAL- 1.Skin2.Auricularis AnteriorAuricularis Superior (gives origin to)

3.Superficial Temporal a & v4.Auriculo-temporal N5.Facial N temporal br

6.Galea Aponeurotica (Epicranial Aponeurosis)

DEEP (gives origin to) superficial fibers of Temporalis


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LATERAL PTERYGOID

2 heads upper, small_ lower, large

ORIGINUPPER HEAD. = Infratemporal surface

= Infratemporal crest of

Greater Wing of Sphenoid

LOWER HEAD = Lateral surface of

Lateral Pterygoid Plate


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Course,

Both heads converge &

run Backwards_laterally


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INSERTION,

Pterygoid Fovea (a depression),

on Anterior surface, Neck of

mandible Anterior margin of,

Articular disc &

Capsule of TMJ


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INSERTION,

Pterygoid Fovea (a depression),

on Anterior surface, Neck of

mandible Anterior margin of,

Articular disc &

Capsule of TMJ

Relations


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Relations

key muscle of the region,because its relationsprovide a fair idea about the layout of structurein Infratemporal Fossa

SUPERFICIAL 1.Ramus2.Maxillary a3.Tendon of temporalis

4.Masseter


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1.Deep head of Medial Pterygoid m. 2.Sphenomandibular Ligament

3.Middle Meningeal a 4.Mandibular n

DEEP


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STRUCTURES EMERGING AT THE UPPER BORDER

1.Masseteric n

2.Deep Temporal n

STRUCTURES EMERGING AT THE LOWER BORDER

1.Lingual n

2.Infr.Alveolar n

3.Middle Meningeal aSTRUCTURES PASSING THROUGH THE GAP

BETWEEN 2 HEADS 1.Maxillary a

2.Mandibular n, Buccal br

Pterygoid Plexus Of Veins Surround The Lateral

Pterygoid


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MEDIAL PTERYGOID

Quadrilateral Muscle 2 heads Superficial, small

Deep, large


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ORIGIN

Superficial- Tuberosity of Maxilla

- Grooved surface (Lateral aspect)of

Pyramidal process,Palatine bone Deep - Medial surface,Lateral Pterygoid Plate

- adjoining part of Pyramidal

process,Palatine Bone


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course

Incline obliquely,run Downwards_Backwards_Laterally


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INSERTION

as a strong tendinous lamina,

Roughened area on the Medial surface

of Angle adjoining part of Ramus

below Mandibular Foramen

behind Mylohyoid Groove


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RELATIONS

SUPERFICIAL (upper part)- seperates LateralPterygoid

Lateral Pterygoid Plate

Lingual NerveInf.Alveolar NerveSuperficial (lower part)seperates Ramus

Lingual Nerve

Inf. Alveolar NerveMaxillary ArterySphenomandibular Ligament


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DEEPSuperior Constrictor- anteriorly,tendinous band

i.e. Pterygomandibular Raphecrossed by, Styloglossus m

Stylopharyngeus mStylohyoid ligament

Glossopharyngeal n.Gap b/w upper border of superior constrictor & base of skull

Tensor palati

Levator palatiAnterior to Tensor palati,

Medial Pterygoid plate(I. Singh)


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PTERYGOID FASCIA

Encases both Pterygoid muscles and attaches tothe Stylomandibular Ligament

Between the sphenoid spine and the lingula ofthe mandible facial condensation to form thesphenomandibular ligament

The terminal part of this facia between thesphenoid spine and the posterior margin of thelateral pterygoid muscle is called thepterygospinous ligament


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MANDIBULAR SLING

Mac Conaill (1975) the most superficialfibres of masseter are continuous at the

lower border of the mandible with theattachment of the medial pterygoid m.

The attachments of the medial pterygoid

& the masseter muscle provide a muscularsling that suspends the angle of the of thejaw.


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They provide a functional articulation b/w themaxilla & mandible,with the TMJ acting as aguide

When the jaw opens or closes, the mandiblemoves along a center of rotation created by theattachment of the sling & the sphenomandibular

ligament


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Buccinator muscle

Which assists in chewing by helping ( tokeep food b/w upper & lower teeth) &

(away from the cheeks) Is not classified as Muscle of Mastication

as it does not move the mand

(Mc Minns )


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MOTOR NERVE INNERVATIONS,

5TH

Cranial Nerve, Mandibular br.

Masseter- -Masseteric N

Temporalis- -Antr & Postr DeepTemporal N

Lat.Pterygoid -N to Lat.PterygoidMed.Pterygoid- N to Med. pterygoid


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Blood Supply

MAXILLARY ARTERY

(second part)


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ACTION, MASSETER

Elevation

Protrusion / Protraction( by, Anterior fibres )


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ACTION, TEMPORALIS

Elevation

Retraction

( by, Posterior horizontal fibres )


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ACTION, LATERAL PTERYGOID

Depression

ProtrusionSide to Side Movement


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ACTION, MEDIAL PTERYGOID

Elevation

ProtrusionSide to Side Movement

ACCESSORY MUSCLES OF


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MASTICATIONDigastric

GeniohyoidMylohyoid

Bi h i f th


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Biomechanics of the

MASTICATORY SYSTEM

( Hannam )


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Applied Anatomy_Surgical Implications


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To Conclude.

REFERENCES


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REFERENCES, Parviz, Surgical Anatomy of the head n neck, 2001,

Lippincott.

Peter L Williams, Grays Anatomy, 38th 1995, ChurchillLivingstone,

Gosling, Human Anatomy- Color atlasa&text, 3rd ed1996, Mosby-Wolfe.

R.M.H.McMinn, Functional & Clinical Anatomy, 1995,Mosby.

P.H.Abrahams, McMinns color atlas of Human Anatomy,5th 2003, Mosby.

Y.Ide, Anatomical Atlas of the TMJ, 1991, Quintessence.

Inderbir Singh, TB orf Anatomy, 2nd

1999, Jaypee. B.D. Chaurasias, Human Anatomy vol III, 3rd 1999, CBS. W.E.McDevitt, Functional Anatomy of the Masticatory

System, 1989, Wright


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Thank you

muscles of mastication 2

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