development of orofacial region

8/3/2019 Development of Orofacial Region

1/36

DEVELOPMENT OFDEVELOPMENT OF

OROFACIAL REGIONOROFACIAL REGION

Oral HistologyOral Histology

Dent 206Dent 206


2/36

Folding of the embryoFolding of the embryo


3/36

Branchial ArchesBranchial Arches

Buccopharyngeal membraneBuccopharyngeal membraneruptures @ 21 daysruptures @ 21 days Stomodeum (primitive mouth)Stomodeum (primitive mouth)

Branchial (pharyngeal) pouchesBranchial (pharyngeal) pouches

Branchial (pharyngeal) cleftsBranchial (pharyngeal) clefts

Branchial (pharyngeal) archesBranchial (pharyngeal) arches


4/36

Branchial archesBranchial arches

28 days26 days

28 days32 days


5/36


Embryologic basis of all the differentiatedEmbryologic basis of all the differentiatedstructures of the head and neckstructures of the head and neck

5 pairs of branchial arches appear on day 225 pairs of branchial arches appear on day 22

Correspond to the primitive vertebrae gillCorrespond to the primitive vertebrae gillbarsbars

On either side of the pharyngeal foregutOn either side of the pharyngeal foregut

Each arch consists of 3 layersEach arch consists of 3 layers

Outercovering of ectodermOutercovering of ectoderm

Innercovering of endoderm,Innercovering of endoderm,

Middle core of mesenchyme.Middle core of mesenchyme.

Arches are separated further intoArches are separated further into

External, ectodermExternal, ectoderm--lined pharyngeal cleftslined pharyngeal clefts

Internal, endodermInternal, endoderm--lined pharyngeal poucheslined pharyngeal pouches


6/36


First stages of a recognizable face at the end ofFirst stages of a recognizable face at the end ofthe third weekthe third week

Frontal nasal process (cephalic portion of theFrontal nasal process (cephalic portion of theneural tube)neural tube)


Over weeks, the arches grow differentially andOver weeks, the arches grow differentially and

obliterate plates/grooves to give rise to the faceobliterate plates/grooves to give rise to the face Each arch gives rise to a cranial nerve, musclesEach arch gives rise to a cranial nerve, muscles

and cartilage/boneand cartilage/bone


7/36


Each branchial arch hasEach branchial arch has

Skeletal elementsS

keletal elements

Nervous elementsNervous elements

Muscular elementsMuscular elements

Vascular elementsVascular elements


8/36

Skeletal elementsSkeletal elements

First archFirst arch Meckels cartilageMeckels cartilage

Anterior partAnterior part

Doesnt form the body of theDoesnt form the body of the

mandiblemandible

Act as a scaffold for the body ofAct as a scaffold for the body of

the mandible to form at its lateralthe mandible to form at its lateral

aspectaspect

Disappears finallyDisappears finally

Middle partMiddle part

Anterior malleolar ligamentAnterior malleolar ligament

Sphenomandibular ligamentSphenomandibular ligament

Dorsal endDorsal end -- MalleusMalleus

Pterygoquadrate barcartilagePterygoquadrate barcartilage

IncusIncus


9/36


10/36

Skeletal elementsSkeletal elements

Second archSecond arch

Reicherts cartilageReicherts cartilage

Dorsal endDorsal end -- StapesStapes

RemainderRemainder

Styloid processStyloid process andand stylohyoid ligamentstylohyoid ligament

Hyoid boneHyoid bone except greater hornexcept greater horn

Third archThird arch -- Greater horn of hyoidGreater horn of hyoid

Fourth to sixth archesFourth to sixth arches Thyroid, cricoid &Thyroid, cricoid &

arytenoid cartilagesarytenoid cartilages


11/36

Nervous elementsNervous elements

First archFirst arch

Trigeminal nerve (V)Trigeminal nerve (V)

Second archSecond arch Facial nerve (VII)Facial nerve (VII)

Third archThird arch

Glossopharungeal (IX)Glossophar

ungeal (IX)

Fourth to sixth archesFourth to sixth arches

Vagus nerve (laryngealVagus nerve (laryngeal

branches)branches)


12/36

Muscular elementsMuscular elements

First archFirst arch Muscles innervated byMuscles innervated by trigeminal nervetrigeminal nerve

Muscles of masticationMuscles of mastication

Anterior belly of digastricAnterior belly of digastric

MylohyoidMylohyoid

Tensor tympaniTensor tympani

Tensor veli palatiniTensor veli palatini


13/36

Muscular elementsMuscular elements Second archSecond arch

Muscles innervated byMuscles innervated by facial nervefacial nerve Muscles of facial expressionMuscles of facial expression

Posterior belly of digastricPosterior belly of digastric

Third archThird arch Muscles innervated byMuscles innervated byglossopharyngealglossopharyngeal

nervenerve Palatopharyngeus musclePalatopharyngeus muscle

Fourth to sixth archesFourth to sixth arches Muscles innervated by the pharyngeal branchMuscles innervated by the pharyngeal branch

ofofVagusVagus nervenerve

All muscles of the pharynx exceptAll muscles of the pharynx exceptpalatopharyngeuspalatopharyngeus

All muscles of the soft palate except tensorAll muscles of the soft palate except tensorveli palatiniveli palatini

Muscles innervated by the laryngealMuscles innervated by the laryngealbranches ofbranches ofVagusVagus nervenerve

Intrinsic laryngeal musclesIntrinsic laryngeal muscles

Extrinsic laryngeal musclesExtrinsic laryngeal muscles


14/36


Each archEach arch right & left aortic arch vesselright & left aortic arch vessel

Leads from the heartLeads from the heart

Ascends dorsally to the face, brain & posterior region ofAscends dorsally to the face, brain & posterior region of

the bodythe body

Third arch vessel becomes prominent to take over the facialThird arch vessel becomes prominent to take over the facial

region of the first tworegion of the first two common carotid arterycommon carotid artery

Fourth arch vesselFourth arch vessel dorsal aortadorsal aorta

Blood supply for neck& faceBlood supply for neck& face Before weeksevenBefore weekseven internal carotidinternal carotid

After weeksevenAfter weekseven external carotidexternal carotid


15/36



16/36

Pharyngeal pouchesPharyngeal pouches

Tongue formationTongue formation Appears @ 32 daysAppears @ 32 days

Develops fromDevelops from Swellings from 1Swellings from 1stst arch (anterior 2/3s)arch (anterior 2/3s)

Lateral swellingsLateral swellings Tuberculum imparTuberculum impar

Swelling from 3Swelling from 3rdrd (posterior 1/3)(posterior 1/3) Copula/Hypobranchial eminenceCopula/Hypobranchial eminence

Overgrows 2Overgrows 2ndnd archarch

Swelling from 4Swelling from 4thth arch (extremearch (extreme

posterior)posterior) EpiglottisEpiglottis

Sulcus terminalisSulcus terminalis

Foramen cecumForamen cecum Thyroglossal ductThyroglossal duct

Thyroid glandsThyroid glands


17/36

Innervation of the tongueInnervation of the tongue Anterior 2/3sAnterior 2/3s

SensorySensory First arch nerve (trigeminal throughFirst arch nerve (trigeminal through

lingual nerve)lingual nerve)

TasteTaste Facial nerve through chordaFacial nerve through chorda

tympanitympani

Glossopharyngeal (Vallate papillaeGlossopharyngeal (Vallate papillaemigration)migration)

MotorMotor Hypoglossal nerve XII (muscles ofHypoglossal nerve XII (muscles of

the tongue are from myotomes ofthe tongue are from myotomes ofmetotic somites)metotic somites)

Posterior 1/3Posterior 1/3 Sensory and tasteSensory and taste

Third arch nerve (glossopharngeal)Third arch nerve (glossopharngeal)

Extreme posteriorExtreme posterior Sensory and tasteSensory and taste

Fourth arch nerve (SuperiorFourth arch nerve (Superiorlaryngeal nerve)laryngeal nerve)


18/36

Development of the faceDevelopment of the face

Growth ofGrowth of

Maxillary processesMaxillary processes

Mandibular pro

cessesMandib

ular pro

cesses

Frontonasal processFrontonasal process

47 days


19/36

Development of the faceDevelopment of the face

Face forms around stomodeumFace forms around stomodeum

Buccopharyngeal membrane ruptures @ 21Buccopharyngeal membrane ruptures @ 21

daysdays Mesodermal processesMesodermal processes

Nasolacrimal ductNasolacrimal duct


20/36


21/36

Frontonasal process (unpaired)Frontonasal process (unpaired)

Nasal placodesNasal placodes

Nasal pitNasal pit -- nostrilsnostrils

Medial nasal swellings (togetherMedial nasal swellings (together -- Intermax

illaryIntermax

illarysigment)sigment)

Mid portion of the noseMid portion of the nose

Philtrum ofupper lipPhiltrum ofupper lip

Primary palatePrimary palate lateral nasal swellingslateral nasal swellings

Alae of the noseAlae of the nose


22/36


23/36

11stst arch processes (paired)arch processes (paired)

Maxillary processesMaxillary processes

Much of the maxillaMuch of the maxilla

Lateral parts ofupper lipLateral parts ofupper lip

Mandibular processesMandibular processes

MandibleMandible

Lower lipLower lip


24/36


25/36

Nasolacrimal ductNasolacrimal duct

Forms between lateral nasal swellings andForms between lateral nasal swellings and

maxillary processmaxillary process


26/36


27/36


28/36

PalatePalate

Starts @ 6 weeksStarts @ 6 weeks

Primary palatePrimary palate

Secondary palateSecondary palate

Palatine processesPalatine processes

11stst they are verticallythey are verticallyorientedoriented

Tongue in betweenTongue in between

Horizontal reorientationHorizontal reorientation

Fusion with primary palateFusion with primary palate

Fusion with ea

ch other

Fusion with ea

ch other

Fusion with nasal septumFusion with nasal septum

Palate completed by 60Palate completed by 60daysdays


29/36


30/36


31/36

CleftsClefts


32/36

Development of the maxillaDevelopment of the maxilla

MaxillaMaxilla Membranous ossificationMembranous ossification

2 ossification centres2 ossification centres

Maxilla properMaxilla proper

Ossification starts at 40 daysOssification starts at 40 days

Maxillary sinusMaxillary sinus

PremaxillaPremaxilla

Ossifies later than maxillaOssifies later than maxilla

ProcessesProcesses

FrontalFrontal

ZygomaticZygomatic

PalatinePalatine

Medial & lateral alveolarMedial & lateral alveolarplatesplates


33/36

Development of the mandibleDevelopment of the mandible

Development of bodyDevelopment of body

Development of ramusDevelopment of ramus


34/36

Development of bodyDevelopment of body

Membranous ossificationMembranous ossification

Close association with Meckels cartilageClose association with Meckels cartilage

Ossification starts atOssification starts at 7 weeks7 weeks At the site where mental nerve branches offAt the site where mental nerve branches off

Continues around IANContinues around IAN

Alveolar processAlveolar process

Symphasis mentiSymphasis menti Fuses at 1Fuses at 1ststpostnatal yrpostnatal yr


35/36

Development of ramusDevelopment of ramus

EndochondralEndochondralossificationossification

CondylarcartilageCondylarcartilage

Appears at 11 weeksAppears at 11 weeks Growth until 21 yrsGrowth until 21 yrs

Coronoid cartilageCoronoid cartilage 14 weeks14 weeks

Replaced by boneReplaced by bonebefore birthbefore birth


36/36

Mandiblular unitsMandiblular units

UnitsUnits

CondylarCondylar

BodyBody

AngularAngular forms informs inresponse toresponse to

Medial pterygoidMedial pterygoid

MasseterMasseter

CoronoidCoronoid forms informs inresponse to temporalisresponse to temporalis

AlveolarAlveolar

Forms in response to teethForms in response to teeth

development of orofacial region

Documents