BY Dr. D.V.S. REVATH VYAS

1ST MDS

DEVELOPMENT OF FACE AND DEVELOPMENT OF FACE AND JAWSJAWS

ORIGIN OF HUMAN EMBRYO GERM LAYERS BRANCHIAL ARCHES, CLEFTS AND POUCHES

AND THEIR DERIVATIVES STAGES OF CRANIOFACIAL GROWTH DEVELOPMENT OF LOWERTHIRD FACE DEVELOPMENT OF MIDDLE THIRD FACE DEVELOPMENT OF UPPER THIRD FACE DEVELOPMENTAL ANAMOLIES.

OUTLINE OF MY PRESENTATION

Human prenatal development begins with process involving in ovarian cycle and fertilization Fertilization occurs in fallopian tube Fertilized ovum undergoes cleavage to form series of divisions to form blastocyte which further gives rise to tissues and organs.

ORIGIN OF HUMAN EMBRYO

10 lunar months Three phases

First – GERMINAL PHASE -- from fertilization 2 weeks largely cellular proliferation, migration and some

differentiation

Second – EMBRYONIC PHASE – from 2nd week 2nd month Largely the differentiation of all major internal and external

organ Morphogenesis

Very vulnerable stage

Third – FETAL STAGE – from 2nd month to birthLargely a matter of growth and maturation

Prenatal development

FORMATION OF GERM LAYERS

At a very early stage the embryo proper acquire to form 3 layered disc called as

embryonic disc.3 layers are ectoderm ,mesoderm and the

endoderm.

• Blastocyst increases in size by proliferation• A blastocoel or blastocyst cavity forms between the inner cell

mass and the trophoblast• Differentiation of the inner cell mass ES cells begins• Results in the formation of a bilaminar embryonic disc comprised

of two cell layers• Two layers are called an upper epiblast (ectoderm, mesoderm,

endoderm) and a lower hypoblast (extraembryonic endoderm)• Above this disk is an upper amniotic cavity and a lower yolk sac

(primitive hematopoietic organ for the embryo/fetus)• Trophoblast also begins to differentiate to form a primitive placenta• The embryo connects to the developing placenta through a stalk

• The bilaminar embryonic disk converts into a trilaminar Disk of

ectoderm, mesoderm, endoderm (gastrulation)

• Formation of the primitive streak within the embryonic Disc critical to this formation

• Migration of epiblast cells through the primitive streak Towards the hypoblast – eventually creates three tissue layers called the Germ layers1. Ectoderm2. Mesoderm3. Endoderm

DEVELOPMENT OF NEURAL CREST CELLS

•At the time of neural tube closure a unique

population of cells separate from

• the crest fold they are called as neural crest

cells.These have great

migrating capacity.They are ectodermal in

origin but they also exhibit property of

mesenchymal tissue so they are also called as

ectomesenchymal cells.

In the head and neck region the cells give rise to facial process ,branchial arches and their cartilages , bone cells, ganglia of autonomic nervous system.

Also contribute to the formation of embryonic connective tissue of facial origin includes dental structures like dentin cementum and pulp.

DERIVATIVES OF NEURAL CREST CELLS

development of a head fold is critical to the formation of

the primitive oral cavity folding results in the formation

of the primitive oral cavity = stomatodeum

separated from the developing and expanding gut by a buccopharyngeal membrane (or oropharyngeal membrane)

BRANCHIAL ARCHES• 1,2, 3 and 4 arch are well developed in

humans.•1and 2 extend into the midline.

•Mandibular arch is 1 st to develop located just below the stomodium.

•Hyoid arch is 2 nd to develop.The tissue bordering the stomodium gets

elongated due to the series of mesodermal thickenings in the wall of the cranial most part of

foregut called as branchial arches.

CLEFT --- ECTODERMARCH --- MESODERMPOUCH --- ENDODERM

First arch(mandibular arch) derivatives

Cartilage – meckel’s cartilage Muscles – muscles of mastication, mylohyoid, tensor

tympani, tensor palatini, anterior belly of digastric, part of temporal bone

Bones – maxilla, mandible, malleus, palatine bone, part of

temporal bone Nerve supply – mandibular nerve Blood supply – maxillary artery Ligment – sphenomandibular ligament (remenent)

Cartilage – reicherts cartilage Muscles –stapedius, stylohyoid, muscles of facial

expression, platysma, auricular muscle, occipito frontalis, posterior belly of digastric

Bones – smaller cornua and superior part of hyoid, styloid process, stapes

Nerve supply – facial (seventh) nerve Blood supply - stapedial artery Ligment – stylohyoid ligament (remenent)

Second arch (hyoid arch) derivatives

Muscles - stylopharyngeus Bones – greater cornua of hyoid and inferior

part of it Nerve supply – glossopharyngeal (ix) nerve Blood supply - right and left common

carotids

Third arch derivatives

Muscles – all the Muscles of pharynx (except stylopharyngeus), all the Muscles of soft palate (except tensor palatini), cricothyroid

Nerve supply -

Fourth arch derivatives

Sixth arch derivatives

After the development of arches in the region of neck ,a series of grooves are formed ,they are ectodermal clefts.

Clefts of 1 and 2 arches - external acoustic meatus 2 ,3,4 and 6th arch - cervical sinus

Cervical sinus gives swelling in the region of neck along the anterior border of the sternocledomastoid musle forming branchial cyst

Branchial cyst opening into surface forming branchial sinus.

Rarely opens into the lumen of pharynx in the tonsillar region.

Fate of ectodermal clefts.

1st pouch Ventral part obliterated to form tongue

I. Dorsal part of 1st and 2nd pouch together form diverticulum called as tubo-tympanic recess

II. Distal part gives rise to auditary tube

Fate of endodermal pouches

2nd pouchVentral part - tonsilDorsal part -tubotympanic recess3rd pouch - inferior parathyroid gland and

thymus4th pouch - superior parathyroid glands 5th pouch (ultimobranchial pouch)Is seen for brief period during development Incorporated with 4th pouch forming caudal

pharyngeal complex

CLINICAL COMMENT • From the initial development each cranial

arch has specific cranial nerves associated with it.

• The nerve and musculature of each arch merge together and follow defined

pathway to their functional position.• These events are closely regulated

genetically during development.

STAGES OF CRANIOFACIAL DEVELOPMENT

• The prenatal craniofacial growth develops in 3 stages.

• The period of ovum fertilisation to 2weeks.

• The period of embryo -2weeks to 8weeks.

• The period of foetus -8weeks till birth.

face and related structure begins to develop during 4 th week of iu life

During this time the rapidly growing brain of embryo bulges over the oropharanangial membrane and developing heart

Facial development depends on 5 process which surrounds the primitive mouth .

They are The frontonasal process.Paired maxillary processPaired mandibular process

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The face is divided into upper third middle third lower third

Growth of mandibular arch Formation of lower soft tissues Formation of lower hard tissues.

DEVELOPMENT OF LOWER THIRD OF FACE

After formation of stomodeum 2 bulges appear inferior to primitive mouth they are mandibular process.

Consist of core of mesenchymal cells formed from neural crest cells.

They migrates from facial region Covered by ectoderm externally and

endoderm internally.

GROWTH OF MANDIBULAR ARCH

Development of body of mandible is continued ,bone formation markedly increases the size of mandible with development of alveolar process surrounding tooth germ.

Paired mandibular process fuse to form mandibular arch .

Future mandibular arch give rise to lower face ,lower lip and lower teeth.

Mesoderm of this arch gives rise to 1. Muscles of mastication2. Palatal musles 3. Supra hyoid muscles4. tongue

5-6 th week muscle cell begin to differentiate and orient towards their origin and insertion

7th week muscle cell enlarge and begins to migrates ,gets differentiated into massetter medial pterygoid ,lateral pterygoid and temporalis..

10 th week muscle mass becomes well organised bilaterally nerves from 5th cranial nerve are incorporated early in these muscles.

Initially grows intramembranously but subsequent growth is related to appearance of secondary cartilage .

It is preceded by appearance of rod of cartilage called as meckels cartilage.

It extends from cartilagenous otic capsule in the region of developing ear to a midline symphysis.

GROWTH OF MANDIBLE

1. Extends towards the midline lie in close relationship with opposite side.

2. 2plates are separated by fibrous tissue to form symphysis.

When tooth reaches bell stage ,bone comes closely related to form alveolus.

Inner wall resorption occurs –indicated by howship lacunae

Outer wall bone deposites-indicated by osteoblast lining osteoid.

Developing teeth lie in trough of bone.Later teeth are separated by interdental septa

with development of root.Interradicular bone develops in multirooted teeth.

Mapped out as condensation of fibrocellular tissue that is continued developing along with body of mandible.

Further there is backward spread of ossification.

Appear on10-14 th week of iu. They are Condylar cartilage Coronoid cartilage and Symphyseal cartilage.

Appear on 12th week iuRapidly forms cone shaped occupies most of the

developing ramus Cartilage converted to bone by endocondrial

ossification.By 20th week iu only thin layer of cartilage

remain in the condylar headDirection and amount of condylar growth is

related to the change in mandibular position.

Appears 4th month iu Surrounds anterior border and top of coronoid

process.They are transitory growth cartilage.symphyseal cartilage2 in no Appear as connective tissue at 2 ends of meckles

cartilage.Obliterates with in 1 year of life.

Gives rise to incus and malleus Spine of spenoid. sphenomandibular ligament Anterior ligament of malleus.

Develops at 12 th week iu . Develops intramembranously Forms mesenchymal lining between developing

mandibular condyle below and temporal bone above.

Forming upper and lower joint cavities Intervening mesenchyme becomes interarticular

disc.

Joint capsule develops from condensation of mesenchyme

At birth mandibular fossa is flat No articular eminence is seen Becomes prominent only after eruption of

deciduous dentition.

During 4th week of iu frontonasal process forms as bulging of tissue in the upper facial area at most cephalic end of the embryo.

It gives rise to fore head bridge of nose primary palate nasal septum.

They are rounded areas of specialised thickened ectoderm on the outer surface of the embryo

Found at developing sense organ 2lens placode –on eiter side forming future eye 2otic placode –on eiter side forming future inner

ear 2 nasal placodes on anterior portion of frontonasal

process forming olfactory cells.

At 4th week iu Placode gets submerged forming

depression called as nasal pits Deepening of pits produces nasal sac Grows internally towards brainOronasal membrane separates nasal and

stomodeumIts disintegration brings nasal and oral

cavities in communication in the primary conchae posterior to primary palate

At the same time superior middle and inferior conchae also develop.

Middle portion of tissue forms medial nasal process

Fuse to form middle portion of nose root to apex Center portion of upper lip and philtrumInternal portion medial nasal process grows

inferiorly forming intermaxillary segment and premaxillary segment

Involved in the formation of upper incisors primary palate and nasal septum

Outer portion of nasal pit are lateral nasal process ,give rise to ala and side of nose.

Fusion of lateral nasal and medial nasal and maxillary process give rise to nares and nostrils.

AT 4TH WEEK IU adjacent swelling forms from increased growth of mandibular arch

Grows superiorly and anteriorly on each side of stomodeum

Maxillary process give rise to upper lip ,cheeks ,secondary palate posterior portion of maxilla ,maxillary canines and posterior teeth zygomatic bone and part of temporal bone.

Develops from connective tissue around the oral cavity of embryo.

Appears during 2nd month of iu. Formed from the centers which are not

preceeded by cartilage.

Development of maxilla

5 centers are External/malar - forms bone outside the infra

orbital canal and zygomatic process Inner/orbitonasal - forms inner part of the

floor of the orbit the frontal process and wall of the antrum.

Palatine center - forms posterior3/4th of palate .

Nasal center – situated between frontal process and canine tooth .

Incisive center – added to form premaxilla which forms front part of alveolus which carries incisor teeth .

By 10th week bone consist of 2 portion ,maxilla proper and premaxilla.

The term palate refers to tissue interposed between oral cavity and nasal cavity

Develops from 1medial palatine process 2lateral palatine process

Formed from 2 different embryonic structures.Primary palate and secondary palate.Hard and soft tissue of palate are formed between

5th -12th week

1. Formation of primary palate 2. Formation of secondary palate 3. Completion of palate

Formation of intermaxillary segment Arised as a result of fusion of 2 medial nasal

processes IMS Is a wedge shaped mass,extends deep into

nasal pits on stomodeum , develops into floor of nasal septum

IMS gives rise to primary palate Serves as partial separation between nasal and

oral cavities

IMS gives rise to I. Premaxillary portion of maxillaII. Anterior 1/3rd of final and definate palate III. Small portion of hard palate anterior to incisive

foramen

6th week iu bilateral maxillary process gives rise to 2 palatal shelves /lateral palatine processes

Grows inferiorly deep inside the stomodeum in a vertical direction on both sides of developing tongue.

Unknown shelf elevating force shifts direction of palatal shelves from vertical to superior direction .Thus shelves move horizontally.

2 palatal sheves elongates move towards each other to form secondary palate.

Secondary palate gives rise to I. Posterior 2/3rd of hard palate maxillary canines

and posterior teethII.Soft palate and uvula

Secondary palate meets posterior portion of primary palate

Fuse to form hard and soft palate

Starts rapidly during 8th week Primary center is near infraorbital foramen Posterior of hard palate ossifies from single

ossification center of palatine bone Completes at 12th week iu In posterior most region ossification does not

occur forming soft palate Mesenchyme from 1 n 2nd branchial arches

migrate to form palatal muscles.

A small paired nasopalatine canal persist near median plane of mature hard palate at the site of junction of primary and secondary palate this canal is represented by incisive foramen in mature palate

1.MICROGLOSSIA

2.AGLOSSIA

3.MACROGLOSSIA

4.ANKYLOGLOSSIA

5.BIFID TONGUE5.BIFID TONGUE

Median rhombhoid glossitisMedian rhombhoid glossitis

CLEFT LIP

CLEFT PALATE

Bifid uvula

JAMES .K.AVERY MOOR PERSAUD B.K.BERKOVITZ MARY BATH BELOGH INDERBIR SINGH

REFERANCE

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