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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