Dev of Fac - Palakk

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DEVELOPMENT OF FACE- II

PRESENTED BY

DR.PALAKK AGGARWALM.D.S 1ST YEAR

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CONTENTSCONTENTS1. Introduction2. Neural crest cells and derivatives3.

Branchial arches and pouches4. Development of lower lip5. Development of upper lip6. Development of nasal passages7. Development of palate

8. Development of cheeks9. Development of eye10. Development of tongue11. Development of maxilla and mandible12. Bibliography



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INTRODUCTION

Much of the face is derived from Neural Crest cells.

There is appearance of various prominances on the dorsalsurface of head end around the primitive oral cavity.

Development of different structure take place

simultaneously.The growth of the bones continues even after foetal life.



Neural crest cells

y The neural tube is formed from the ectoderm overlying thenotochord .

y As the neural tube grows, neural crest cells are formed inthem.

y They can be distinguished differentiating and separatingat the crest of the neural folds, hence named neural crest

cellsy Cells have capacity to migrate and differentiate.y They differentiate to form most of the connective tissue of

the head

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Derivatives of NCC

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Cranial NCCNervous system DerivativesNeurons including Sensory ganglia

Sympathetic

ParasympatheticNeuroglial cellsSchwann cells

Skeletal system

BA cartilagesBones including Maxilla, palatine, facialcomplex, vault



Derivatives of Cranial NCCy Connective tissue component of:

y Vascular & dermal smooth msy Odontoblast, pulpy Corneal endothelium & stromay Melanocytes, melanophoresy Pigment cellsy Secretory cells:

carotid body Type I cellscalcitonin producing cells

y Cranial musculaturey Adenohypophysisy Lingual glandsy Thymusy thyroid & parathyroid





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PHARY NGE AL POUCHES A ND GR OOVES

y Intervening between the archesexternally are pharyngealgrooves.

y The lining of pharyngealgrooves surface ectoderm.

y Each ectodermal pharyngealgroove corresponds with eachendodermal pharyngeal pouch with a layer of mesodermalmesenchyme .



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PHYRANGEAL POUCHES AND GROOVES

y The first pharyngeal groove persists, while its ventral end isobliterated, its dorsal end deepens to form the externalacoustic meatus

y The 2nd ,3rd and 4th pharyngeal groove become obliteratedby the caudal overgrowth of second pharyngeal arch (hyoidoperculum), which provides a smooth contour to the neck



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Structures present in each arch are:-

y A skeletal element (cartilage that later may form bone)

y Striated muscle supplied by the nerve of the arch.

y An arterial arch.



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Numbe r :-

y t first t ere are six arc es t t e fift arc isa ears as

s as it is f r e .



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FI RST PHARYNGEAL ARCH

Ma i lar arc

y 1 t 5t ays st c ce ti .

y It is rec rs r f t axillary a a i lar ja s aa r riately s t e lateralas ects f t e st at e .



Ear ossiclesI cus & Malleus

An terior li ame n t of malleusSphe n oma nd ibular li ame n t

MECKLE S C AR TI A GE.

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FI RST PHARYNGEAL ARCH





Nerve

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Mandibular nerve

Chorda tympani



Muscles

Tenso r l ti

Tenso r tym n i Mylo hy o id

An te rio r b e lly of dig s tric

Mu s cl es of m s tic ti on

Is t rch

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SECOND PHARYNGEAL ARCH

y H yoid arch

y 45 to 48 th days of post conception.

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REICH ERT S CARTILAGE

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SECOND PHARYNGEAL ARCHMuscles

stapedius stylohyoid

Posterior

bell of d i astric

Musclesof face&Occipito-fro n talis

Plat sma , A uricularmuscles





TH IR D PHARY NGE AL AR CH

y Cartilage of this arch

y Muscle - stylopharyngeus

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greater horn andcaudal part of the

hyoid bone



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THIRD PHARYNGEAL ARCH

NERVE INNERVATION sensory innervation by theglossopharyngeal nerve

ARTERY of this arch contributes to the commoncarotid artery and part of internal carotid arteries



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THIRD PHARYNGEAL ARCH



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FOURTH PHARYNGEAL ARCH

y Cartilage of 4 th pharyngeal arch probably formsthe thyroid cartilage .

The arch muscle develops into-cricothyroidconstrictors of pharynxpalatopharyngeuslevator veli palatiniuvular muscles of soft palatePalatoglossus muscle of tongue



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FOURTH PHARYNGEAL ARCH

Nerve

Artery

left side forms thearch of aorta.

right subclavianand

brachiocephalicarteries.

superior laryngeal



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F IF TH PHARY NGE AL AR CH

y The fifth arch, a transitory structure .

y It disappears almost as soon as it forms.

y It leaves no permanent structural elements.



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SIXTH PHARY NGE AL AR CH

y Cricoid &arytenoid cartilages of the larynx .

y orms the intrinsic muscles of the larynx .

y NERVE INNERVATION - recurrent laryngeal branch of vagus nerve .



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Cartila es of the archesCartilage o f 1 st arch Incus and malleus.

C artilage of 2 nd arch Stapes, styloid process,stylohyoid ligament, smaller cornu of hyoid bone, superior part of body of hyoid bone





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NERVES AND MUSCLES OF THE ARCHES

AR CH NER VE OF THE AR CH MUSCLE OF THE AR CH

FIRST MANDIBULAR Muscles of mastication,Mylohyoid, Anterior belly of Digastric, Tensor tympani,Tensor palate

SECOND F ACIAL Muscles of face, Occipito-frontalis, Platysma,Stylohyoid, Posterior belly of Digastric, Stapedius,

Auricular muscles.

TH IRD GLOSSOPH ARYNGEAL Stylopharyngeus.

FOURTH SUPERIOR LARYNGEAL Muscles of pharynx.

SIXTH RECURRENT LARYNGEAL Muscles of larynx



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1 st Endodermal pouch - Diverticulum calledtubotympanic recess. The

middle ear and auditorytube develop f rom it.

2nd Endodermal pouch - Palatine tonsil.



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3 rd Endodermal pouch - In f erior parathyroid glandand thymus.

4 th Endodermal pouch - Superior parathyroid gland.



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DEVELOPMENT OF F A CE

In tro ductio n :-y The basic morphology of the face and mouth is created

between the 4th and 10th weeks by the development and

fusion of the five prominences:- An unpaired F ro n to n asal process .Two Maxillar swellings and two Mand ibularswellings of the 1st pharyngeal arches.

y

TheB

ucco phar ng eal membra n e breaks down to formthe opening of the oral cavity at about 27th day.



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y

Mand ibular arch plays an important role in thedevelopment of Naso-maxillary region.

y Mandibular arch of both sides form the lateral wall of thestomatodeum.

y Maxillary process grows ventro-medio-cranial to the main

part of the mandibular arch which is now calledMand ibular process .

M andibular arch gives off a bud at the dorsal endcalled the Maxillary process .



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y

Thus at this stage, Stomato deum is overlapped :-1. Above by Frontal process2. Below by Mandibular process3. On either side by Maxillary process



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y The ectoderm overlying the fronto-nasal process showsbilateral localize d thicke n ing s above the stomatodeunknown as Nasal placo des

Developme n t of Nose



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y In the 6th week, ectoderm at the centre of each n asalplaco de in vagin ates to form the oval Nasal pits .

y Formation of the nasal pits divide the frontonasal processinto :-

y Med ial n asal process.y Lateral n asal process .



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DEVELOPMENT OF NASAL PASSAGES

y The Nasal passages are formed by the deepening of thenasal pits.

y At the end of the 6th week, the deepening nasal pits fuse toform a single, enlarged, ectodermal nasal sac lyingsuperoposterior to the intermaxillary process .

y From the end of the 6th week to the beginning of the 7th week, the floor and posterior wall of the nasal sacproliferate to form a thickened, platelike fin, or keel, of ectoderm separating the nasal sac from the oral cavity known as Nasal fi n .



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y Vacuoles develop in the fin and fuse with the nasal sac,thus enlarging the sac and thinning the fin to a thinmembrane called Oro n asal membra n e , which separatesthe sac from the cavity.

y The membrane ruptures during the 7th week to form anopening called the Primar choa n a .



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DEVELOPMENT OF LOWER LIP

y The right and the left mandibular processes grow towardseach other and fuse in the midline to form the Lower lip

and Lower jaw .



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DEVELOPMENT OF THE UPPER LIP

y Each maxillary process now grows medially and fuses, first with the lateral nasal process.

y

The medial and lateral nasal process also fuse with eachother. In this way , n asal pits are cut off from thestomato deum.



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y Maxillary process undergoes considerable growth.y Stomatodeum is now bounded above by the

Upper lip which is derived as follows :-1. Meso dermal basis of the lateral part of the lip is

formed from the Maxillar process. The overlyingskin is derived from ectoderm covering this process .

2. By the 10th week, the mesodermal basis of the median

part (philtrum) of the upper lip is formed by theIn termaxillar process.



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y The maxillary process, overgrows this mesoderm to meetthat of the opposite maxillary process in the midline. As aresult, the ski n of the e n tire lip is i nn ervate d b theMaxillar n erves.



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DEVELOPMENT OF CHEEK

y After formation of the upper lip and lower lip, mouth(stomatodeum) is very broad.

y

In its lateral part, it is bounded by the maxillary processabove and mandibular process below.

y These processes und er go pro gressive fusio n to form the

cheeks .



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DEVELOPMENT OF THE E Y Ey The region of the eye is first seen as an ectodermal

thickening, the Len s placo de , which appears on the ventro-lateral side of the developing forebrain, lateral andcranial to the nasal placode.

y The nasal placode sinks below the surface and is eventually cut off from the surface ectoderm.

y The developing eyeball produces a bulging in this situation.



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y The bulgings of the eye are first directed laterally and lie inthe angles between the maxillary processes and lateralnasal processes.

y With the narrowing of the frontonasal process they cometo face forwar d .

y The eyelids are formed from the folds of the ectoderm thatare formed above and below the eyes, and by mesodermenclosed within the folds.



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Developme n t of Ear

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External ear is f ormed around theFirst ectodermal cle f t

A series o f mesodermal thickenings

known as hillocks or tubercles appear on the1 st & 2 nd arches where they join this cle f t and f orms the auricle



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An terior two-thir d of the to ng ue

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First arch f orms

a median swelling

Tuberculum impar or

Median tongue bud

Lateral lingualSwellings

Or Distal tongue buds



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y Anterior 2/3 rd - 1. tuberculum impar2. two lingual swellings.

y Posterior 1/3 rd - 1. cranial part of thehypobranchial eminance. 2. Third

arch mesoderm.y Posterior most part - fourth arch



y

Immediately behind thetuberculum impar, theepithelium proliferates toform a downward growth( thyroglossal duct) from which the thyroid glanddevelops.

y The site of thisdownward growth is

marked by a depressioncalled the foramencaecum

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Musculature of the to ng ue

y All the muscles of the tongue are derived from theM otomes of the occipital somites except thePalato glossus

y Palatoglossus is innervated by the Phar ng eal plexus of the Va gus n erve

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Nerve suppl of the to ng ue

An terior two-

thir d of the to ng uey Sensory receptors

Ling ual bra n ch of ma nd ibular d ivisio n

of tri gemi n al n erve

y Taste buds Chor dat mpa n i except the Vallate papillae

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Posterior o n e-thir d of the to ng ue

Vallate papillae and general sensory are supplied by the Glossophar ng eal n erve

Posterior most of the to ng ue

Superior lar ng eal bra n ch of Va gus n erve

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Development of Palate

y Initially a common oro-nasal cavity occurs which isbounded anteriorly by the primary palate and is

mainly occupied by the developing tongue

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The me d ial n asal processes&

fro n to n asal process

Primary palate

mi dd le portio n of upper lip

an terior portio n of maxilla

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F rom each maxillar process, a platelike shelves grows me d iall , k n own

as palatal shelvesF ro n to- n asal process becomesNarrow a nd forms n asal septum

P rimitive palate

7 th week

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Horizontal section

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y After the seventh week of development, the tongueis withdrawn from between the palatal shelves,

which now elevate and fuse with each other abovethe tongue and with the primary palate

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B i d i 7 8 k &



Formation of Secondary Palate

Each palatal palate fuses with the primar palate

The two palatal processesfuse with each other i n themi d lin e(be gin s an teriorland procee ds posteriorl )

The me d ial e dg es of thepalatal processes fuse withthe free lower e dg e of n asal

septum

B egins during 7-8 weeks &completes around 3 months

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Ossificatio n of the palate -

y Ossification of the palate occurs from the 8th week of theintra-uterine life.

y Mesenchymal condensation in the ventral portion of thesecondary palate undergoes in tramembra n ousossificatio n to form the bo ny har d palate .

y In the dorsal potion of the secondary palate, m y ogen icmese n ch y me co nd en ses to give rise to the musculatureof the soft palate .

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PR EN A T AL EMB RY OLOG Y OF M A NDI B LEyy Earlier it was thought that mandible develops fromEarlier it was thought that mandible develops from

endochondralendochondral bone formation because of the closebone formation because of the closeapproximation of approximation of Meckel sMeckel s cartilagecartilage

yy Now, its proved that mandible develops as a separate entity,Now, its proved that mandible develops as a separate entity,lateral tolateral to Meckel sMeckel s cartilage by cartilage by intramembranousintramembranous boneboneformationformation

Meckel s cartila ge has a close positio n al relatio n shipto the developi ng ma nd ible but makes n o co n tributio n to it

It exte nd s from the cartila gin ous otic capsule to themi d lin e or s y mph y sis a nd provi des a template

for gui d ing the growth of the ma nd ible

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y First structure to develop in mandible is Mand ibulard ivisio n of the tri gemi n al n erve

A single ossi f ication centre for each half of the mandible arises in the 6th week of the intra-uterine life in the region o f thebi f urcation o f in f erior alveolar nerveinto mental and incisive branches on

the lateral aspect of

meckel¶s cartilage

Sixth week

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An terior sprea d of bo n e forms a trou gh thatcon tai n s lateral a nd me d ial plates that u n ite

be n eath the i n cisive n erve

This trou gh exte nd s to the mi d lin e to come i n close approximatio n with the similar trou gh

forme d in the a d joi n ing ma nd ibular process

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The two ossificatio n cen tres remai n separate d atthe ma nd ibular s y mph y sis u n til shortl y after

birth.

This trou gh is soo n con verte d in to a ca n al asbo n e forms over the n erve, joi n ing the me d ial& lateral plates

Similarl y , the posterior sprea d of the bo n e forms agutter which later co n verte d in to a ca n al thatcon tai n s in ferior alveolar n erve

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Medial and lateral alveolar plates of bone develop in relationto forming tooth germs (occupying a secondary trough of bone)

This trough is partitioned so that teeth come to occupy individual compartments, which finally is totally enclosedby growth of bone over the tooth germ

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Spread of the ossification continues dorsally and ventrally

Forms the B ody and the R amus of themandible

As ossification continues

Meckel s cartilage become surrounded andinvaded by bone.

Ossification stops at the site to form theMand ibular li ng ula

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B y tenth week, rudimentarymandible is f ormed

Further growthuntil birth

Condylar

cartilage

Coronoid

cartilage

Symphyseal

cartilage

Muscular

attachments

Secondarycartilages

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Condylar cartilage Appears during 12 th week

Converted quicklyinto bone

by endochondral ossi f ication

B y 20 th week, only a thin layer

o f cartilage remainsin the condylar head

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Coronoid cartilageAppears at

4th

month

Disappears longbe f ore birth

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Symphyseal cartilages Two i n n umber

A ppear i n the

conn ective tissueB etwee n the two e nd sof meckel s cartila ge

Obliterate d withi n thefirst y ear after birth

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yy Trough will be formed to accommodate the infraorbital nerve and laterTrough will be formed to accommodate the infraorbital nerve and laterit will hold the teethit will hold the teethyy From this trough, a downward extension of bone forms the alveolarFrom this trough, a downward extension of bone forms the alveolar

plate which will accommodate the maxillary teethplate which will accommodate the maxillary teethyy Ossification also spreads to palatine processes to form hard palateOssification also spreads to palatine processes to form hard palateyy Malar / zygomatic cartilageMalar / zygomatic cartilage secondary cartilage also contributes to thesecondary cartilage also contributes to the

development of maxilladevelopment of maxilla

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y The body of maxilla is relatively small because maxillary sinus has not developed

y The sinus forms during the sixteenth week as a shallowgroove on the nasal aspect of the developing maxilla

y At birth, the sinus is still a rudimentary structure about thesize of a small pea

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B IB LIOG RAPHY

James K. Avery. Oral Development & H istology.Inderbir Singh, G.P.Pal . Human Embryology.7 th ed: McMillan India Ltd :2001: 110-124,136-151

Geoffrey H . Sperber.Craniofacial development. H arcourtPublishers Limited;2001:51-66,103-139Thomas Sadler.Langman s Medical embryology.9 th Ed:Lippincott Williams & Wilkins;2003:96-105

Ten cate .Oral histology:development, structure andfunction. 7 th ed: Mosby;2007 :223-245



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Dev of Fac - Palakk