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GOOD MORNING
“If there were some deep principle that drove
organic systems towards living systems, the
operation of the principle should easily be
demonstratable in a test tube in half a
morning. Needless to say, no such
demonstrahttp://chellescorner.com/wp-
content/uploads/2011/06/New-
Beginnings.jpgtion has ever been given.
Nothing happens when organic materials are
subjected to the usual prescription of showers
of electrical sparks or drenched in ultraviolet
light, except the eventual production of a
system”
Sir Fred Hoyle
GOOD MORNING
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GROWTH AND
DEVELOPMENT
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CONTENTS
Introduction
Definitions
Fundamentals of development
Stages of growth
Prenatal growth
Development of face
Theories of growth
Conclusion
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INTR0DUCTION
• Growth is a complex and spectacular process
involving various steps from one-celled stage to
complete formation of body of living organism and
the variations that occur in this complex
process,has been the subject of fascination since
long.
• Growth is the raw material in the orthodontic
treatment ,without changes in the craniofacia;l
morphology, no occlusion can be improved .
• Wide variability of expressions .www.indiandentalacademy.com
Definitions
• Growth is an increase in size
-TODD
• Development is all the naturally occurring
unidirectional changes in life of an
individual from its existence as a single
cell to its elaboration as a multifunctional
unit terminating death.
• -MOYERS
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FUNDAMENTALS OF DEVELOPME
• PATTERNING: Initial axial specification of embryo from
(head to tail) through segmentation.
INVOLVES: 3
cells
functions,shapes & rates of turnover
compartmentized
differentiate or remain constant
INDUCTION
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Homeobox genes
(180 nucleotide base pairs)
regulatory molecules
(growth factors,retinoic acids)
cell surface receptors
regulate the expression
COMPETANCY,DIFFERENTIATION
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Stages of growth
“He who sees things grow from the beginning will
have the finest view of them”
-Aristotle
• Prenatal growth
• Post natal growth
• Maturity
• Oldage
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Prenatal growth
Includes
Proliferation period (1st 7 days)
Embryonic period (next 7 weeks)
Fetal period (next 7 calendar
months)
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Proliferative period
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Gametogenesis
Sperm (23) ovum(23)
fertilisation
ZYGOTE(46)
CLEAVAGE
(uterine tube)
24 HOURS
30 HOURS
Proliferative period
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3 DAYS
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Morula
Space
(between the central Blastomeres)
filled with the fluid
Trophoblast embryonic mass
(Placenta) (embryo)
BLASTOCYST
4 – 5 DAYS
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FLOWS FREELY IN UTERINE SECRETIONS FOR 2 DAYS
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IMPLANTATION
(upper part of uterus in posterior wall)
Trophoblast
(Rapid division and differentiation)
Cytotrophoblast syncitiotrophoblast
UTEROPLACENTAL CIRCULATION
Embryonic endoderm
(inner cell mass)
6th DAY
7th DAY
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Embryonic period
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Embryonic period
Spaces between trophoblast coalesce
slit like amniotic cavity
Bilaminar embryo
Epiblast Hypoblast
(ectoderm &mesoderm) (endoderm)
8TH DAY
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9TH DAY
Embryonic pole: Lacunar stage(embryotroph)
Abembryonic pole: extracoelomic membrane(hypoblast)
around the cavity – PRIMITIVE YOLK SAC
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10 – 12th DAY
Interstitial implantation - in the endometrium
Extra embryonic coelom
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13TH DAY
Secondary yolk sac
Chorionic cavity
Prechordal plate
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3rd WEEK –
TRILAMINAR DISC
3 germ layers established
Primitive node
Primitive pit
Ectoderm &
endoderm
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 Primitive streak
 Invagination- 15TH DAY
 Invaginated cells of epiplast –
endoderm
 Cells remaining in epiblast -
ectoderm
 Cells in between - mesoderm
Primitive
knot
PRESOMITE
EMBRYO
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Future mouth
& head region
Oropharyngeal
membrane
communication
between yolk sac and
amniotic cavity
17TH DAY
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End of 4th WEEK
Notochordal plate
Definitive
notochord
Neurocentric
canal obliterates
END OF GASTRULATION
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Embryonic ectoderm over notochord
Thickens
Neural plate(neuro ectoderm)
Neural fold, neural tube
Neural crest
(affinity with epithelium lost-
neural crest cells )
18TH DAY - NEURALATION
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Derivatives of neural crest cells
• Connective tissue and bones of face &skull
• Cranial nerve ganglia
• Odontoblasts - dentin
• C cells of thyroid
• Spinal ganglia
• Sympathetic chain
• Parasympathetic ganglia of GIT
• Adrenal medulla
• Glial cells,schwann cells
• Arachnoid and piamater
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• 20th DAY- MESODERM
Thickening of intraembryonic mesoderm
Somites -
sclerotome,myotome,dermatome
Intraembryonic coelom- pericardial
pleural and peritonial cavities (2nd
month)
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Mesodermal derivatives
Paraxial mesoderm – Somitomeres
• Muscle(smooth,cardiac,skeletal)
• Extra ocular muscles &muscles of tongue
• Connective tissue,dermis of skin
• Bone,cartilage
• Blood & lymph vessels(angioblasts)INS IN THE 5TH WEEK
BLOOD FORMATION -
BEGINS IN THE 5TH WEEK
• Duramater
• Testes, ovaries
• Dental sac (PDL,cementum,
alveolar bone)
• Intermediate mesoderm – urogenital structures
• Lateral mesoderm – serous
membranes(pericardial,pleural,peritoneal)
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ENDODERM – END OF 1ST MONTH
VENTRAL SURFACE OF EMBRYO
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• Epithelial lining of: Gastrointestinal tract
• Trachea, bronchi, lungs
• Biliary apparatus
• Urinary bladder, urethra
• Vagina
• Auditory tube & Middle ear cavity
• Parenchyma of Liver & Pancreas
• Submandibular gland & Sublingual gland
• Thyroid & Parathyroid
DERIVATIVES
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HIGH LIGHTS Of EMBRYONIC PERIOD
4TH WEEK:
• Branchial apparatus appear
• Fore brain- prominent elevation on the
head
• Otic pits & inner ear primordia
• Lens placodes & leg buds
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5TH WEEK
MINOR CHANGES
Cranial growth increases(brain)
Fore limb differentiation
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6TH WEEK
• Fore limbs,wrist,elbow,future
fingers(finger rays)
• External auditory meatus
• Retinal pigment & eye
• Cervical flexure
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7TH WEEK
• Decreased communication between yolk
sac & gut
• Limbs further develop
• The brain is now functioning
• Ears now functioning to
provide a sense of balance
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8TH WEEK
• Tail bud dissapears
• Finger & toes apparent
• Head – erect - ½ the size of embryo
• Eyelids formed
• Umbilical cord size decreased
Five weeks of embryonic period
– most critical
Major portion of the face is
developed www.indiandentalacademy.com
Fetal period
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FETAL PERIOD – 9th week till birth
9-12 WEEKS
• Face broadens
• Ears low set
• Eyes widely low set
• Upper limb reaches
the final length
• Lower limbs still
developing
• External genetalia distinguishable- sex of the
fetus can be determinedwww.indiandentalacademy.com
13- 16 WEEKS
• Growth is rapid
• Head is smaller than the body
• Lower limbs well developed
• Skeletal ossification begins
(clear radiographs seen)
• Scalp hair begins
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16- 20 WEEKS
• Growth is slow
• Lower limbs – final length
• Fetal movements are felt by mother
• Fatty secretions and brown fat by fetus -
protection
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21 – 25 WEEKS
• Lean and well proportionate body
• Gains weight
• No subcutaneous fat-
skin wrinkles
• Immature respiratory system
- die if born premature
• Other organs –
well developed
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26-29 WEEK
• Subcutaneous fat – developed
• Eyes reopen
• Hair well developed
• Respiratory system
mature enough
• CNS- controls temperature
& breathing
• Premature fetus survives
at this stage
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35-38 WEEKS
• Body is plump(well rounded)
• Lanugo hair(5 mon fetus hair)
disappears
• Fetus is ready for birth
• Crown – rump length - 360 mm
(top of the head – crown,
Bottom of buttocks – rump)
• Fetus weight – 3400gm
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Time of birth:
• Approx. 266 days after fertilization(38
weeks)
or
280 days(40 weeks) from onset of last
menstrual period.
so gestation period is - 9 months
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DEVELOPMENT OF FACEMESENCHYME FOR HEAD FORMATION-
1.Paraxial mesoderm(somites &
somitomeres)
2.Lateral plate mesoderm-
3.Neural crest
4.Ectodermal placodes
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Branchial apparatus
• Comparable to fish embryo with gills.
consists-
1.Branchial arches – mesoderm &neural crest cells
2.Branchial grooves- ectoderm
3.Branchial pouches- endoderm
4.Branchial membranes
groove
groove
pouch
pouch
Arch
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Branchial arches
Develop during the late somite period
i.e. 4th week I.U
The mesoderm of the ventral foregut
region gets segmented
Six distinct bilateral mesenchymal
swellings
BRANCHIAL ARCHES
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4th week
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BASIC ANATOMY OF AN ARCH
Consists
• Cartilage component :
Adapt to form Bony,
Cartilagenous or
Ligamentous structures
• Muscle component:
Give rise to special visceral
muscles composed of striated
muscle fibers.
• Vascular component:
Provides necessary blood supply
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• Nerve component :
Nerve fibers of special cranial nerves
Enter mesoderm of branchial arches
Initiate muscle development in the
mesoderm
Migrate and adapt to the branchial arches
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ARCH
1ST
(MANDIBULAR
ARCH)
2ND
(HYOID ARCH)
SKELETAL ELEMENT
• MECKEL’S CARTILAGE
• INCUS,MALLEUS
• ANTERIOR MANDIBLE
• ZYGOMATIC BONE
• PALATINE BONE
• PART OF TEMPORAL
BONE
• SPHENOMANDIBULAR
LIGAMENT
• DORSAL PART OF
MAXILLA
• STAPES
• STYLOID PROCESS
• SMALLER CORNU OF
HYOID
• SUPERIOR PART OF BODY
OF HYOID
NERVE
MANDIBULAR
NERVE (V3)
FACIAL
NERVE(VII)
MUSCLE
• MUSCLES OF
MASTICATION
• ANTERIOR BELLY
OF DIGASTRIC
• TENSOR
TYMPANI
• TENSOR PALATI
• MYLOHYOID
• MUSCLES OF
FACIAL
EXPRESSION
• PLATYSMA
• STYLOHYOID
• POSTERIOR BELLY
OF DIGASTRIC
• STAPEDIUS
• AURICULAR
MUSCLES
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By the time that the
anterior neuropore
closes,
Human Age:27 days
the first and Second
pharyngeal arches
are evident.
I ARCH
II ARCH
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ARCH
III ARCH
IV ARCH
SKELETAL ELEMENT
• GREATER CORNU
OF HYOID
• LOWERN PART OF
BODY OF HYOID
CARTILAGES OF
LARYNX
NERVE
GLOSSO
PHARYNGEAL
(IX)
SUPERIOR
LARYNGEAL
MUSCLE
STYLOPHARYNGEUS
• ALL MUSCLES OF
PHARYNX EXCEPT
STYLOPHARYNGEUS
• ALL MUSCLES OF
PALATE EXCEPT
TENSOR VELI PALATI
• CRICOTHYROID
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• The first, second,
third and fourth
arches are visible
externally. The sixth
arch does not form an
external elevation.
Human Age: Fifth week
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• Anomalies associated with branchial arches
• Deficient development of the branchial arches result in
syndromes according to the arch involved.
• First arch syndromes :
- Agnathia
- Microstomia
- Treacher Collins syndrome (mandibular dysostosis)
- Pierre Robin syndrome (micrognathia+cleft palate
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• Branchial pouches
Branchial arches on endodermal surface
are craniocaudally by pharyngeal
pouches.
4 well defined pouches .
5th rudimentary.
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POUCHES
I POUCH
II POUCH
III POUCH
IV POUCH
V POUCH
(ULTIMOBRANCHIAL
POUCH)
DERIVATIVES
PHARYNGOTYMPANIC TUBE
MIDDLE EAR CAVITY
TYMPANIC ANTRUM
TONSIL
TUBOTYMPANIC RECESS
INFERIOR PARATHYROID GLANDS
THYMUS
SUPERIORPARATHYROID GLANDS
PARAFOLLICULAR CELLS OF THYROID
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PHARYNGEAL GROOVES & PHARYNGEAL POUCHESwww.indiandentalacademy.com
Branchial grooves
The regions between the pharyngeal
arches are termed pharyngeal grooves
PHARYNGEAL
GROOVE
I PHARYNGEAL
GROOVE
II,III,IV PHARYNGEAL
GROOVE
DERIVATIVES
EXTERNAL AUDITORY MEATUS
CERVICAL SINUS
Branchial membrane
Major component of branchial apparatus
from which the skeletal of both muscular and
vascular systems are derived
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DEVELOPMENT OF FACE
• Development of the head depends upon
inductive activities of 2 organizing
centers
-- Prosencephalic centre
-- Rhombencephalic centre
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• Prosencephalic organizing center :
-- Derived from prechordal mesoderm
that migrates from the primitive
streak.
-- Situated at the rostral end of the
notochord below the fore brain.
-- Induces the formation of :
 Visual apparatus
 Inner ear apparatus
 Upper third of face
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• Rhombencephalic organizing center :
-- Caudal in relation to the Prosencephalic
centre.
Induces the formation of:
-- Middle and lower third of the face.
-- Middle and external ears.
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Oral development in embryo is demarcated extremel
early in life by the appearance of
prechordal plate (14th day) + Endoderm
Thickening
Oropharyngeal Membrane
OROPHARYNGEAL MEMBRANE
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Oropharyngeal membrane – temporary bilaminar
membrane
Functions as:
1. Site of junction of ectoderm and
endoderm.
2. Demarcates the stomodeum from the rest.
i.e; initial demarcation of the future mouth
Rapid development of the cranial portion than
the caudal portion - charecteristic of orofacial
development – DIFFERENTIAL GROWTH
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 At 5- 7 week of IU - from 5 primordia surrounding the
primitive oral pit
I frontal process –above oral pit – upper face
2 maxillary processes - lateral pit oral pit
- cheeks &upper lip
2 mandibular prominence – below oral pit
-mandibular(lower face)
From neural crest ectomesenchyme
Late 4TH WEEK
Facial prominences –– upper part of stomodeum
Maxillary prominences- lateral to stomodeum
Mandibular prominences- caudal to stomodeum
first prominences of the face
FACE
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Thickenings on either side of FNP
(Nasal placodes)
Invaginate
(nasal pits)
Ridge (nasal prominences)
Lateral and medial nasal prominences
5TH WEEK
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• Next, is the union of the facial prominences
by either of the 2 developmental events.
1. Merging of the frontonasal, maxillary
and mandibular prominences.
OR
2. Fusion of the central maxillonasal components.
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• Merging - completed as a result of proliferation of the
underlying mesenchyme into the intervening grooves.
• The above is guided by the disintegration of the
contacting surface epithelium b/w the processes
termed as Nasal fin
• Failure of normal disintegration of nasal fin
Due to:
1. Cell death
2. Mesenchymal
transformation
Leads to cleft of upper lip and
anterior palate
(Due to prevention of merging
of mesenchyme of max. and
medial nasal processes)
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• Midline merging of median nasal prominences
forms
 Philtrum of upper lip
Median tubercle.
Tip of the nose.
Primary palate
• Post. Merging of Medial nasal processes
Median primary palate
Premaxilla
Future site of 4 upper incisors
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• Midline merging of the paired
mandibular prominences
Lower jaw + Lower lip
-- First to get definitely established
• Lateral merging of maxillary and
mandibular prominences.
Commisures of mouth
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Maxillary prominences- increase in size
Grow medially and compress the MNP
Cleft between MP and MNP lost
MNP & MP fuse
upper lip & jaw
Lower lip & jaw –
2 mandibular processes
merge in the midline
UPPER LIP & JAW
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• Union of
the medial nasal
prominence with
the lateral nasal
prominence and
maxillary
prominence is
required for
normal
development of
the upper lip.
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NASOLACRIMAL DUCT & LACRIMAL SAC
MP & LNP seperated by deep furrow
nasolacrimal groove
Ectoderm in the floor
of the groove forms cord
Canalisation
Nasolacrimal duct
Upper end widens- lacrimal sac
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CHEEKS AND MAXILLA
Cord detaches
MNP & LNP merges
NLD runs from medial corner
of eye to inferior meatus of
nasal cavity
MP ‘s enlarges
Cheeks & maxillawww.indiandentalacademy.com
NOSE
Formed from 5 prominences
• Frontal prominence-bridge of the nose
• Merged MNP’s – crest & tip
• LNP’S-side (alae) of the nose
• Nasal pits – anterior nares
• Cartilage nasal capsule-
septum & nasal conchae
• Blind sacs of deepened
nasal pits (disintegrate)
-posterior nares www.indiandentalacademy.com
VOMERONASAL ORGAN
Ectoderm invasion into median nasal
septum from nasal fossae
Vomeronasal organ (Jacobson,s organ)
Vestigial blind pouches-
chemosensory
- pheromone receptor in adulthood
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EAR - 6TH WEEK
1.Internal ear
Hind brain induction of surface ectodermal cells
Elongates into thick otic placode
Invaginates into pit
Internal ear
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2.External ear
1ST Brachial groove
-- External acoustic meatus
Develops in neck region as
6 auricular hillocks
i.e; the mesoderm of the 1st and 2nd
Branchial arches
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3.Middle ear
1st pharyngeal pouch (endoderm lined)
-tympanic cavity &auditory tube
Ossicles –
1st arch- malleus & incus
2nd arch- stapes
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EYE
Localised thickenings of epithelium on sides of
head (between FNP & MP)
lens placodes
(future eyes)
Lateral growth of fore head
lateral expansion of face
Eyes thus positioned more anteriorly
5th WEEK
6TH WEEK
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TONGUE
End of 4th week
I,II,III arches &muscles from occipital myotomes
Anterior 2/3rd :
Median triangular elevation in the floor of
the primitive pharynx anterior to foramen caecum
Median tongue bed (Tuberculum Impar)
Mesenchyme of the 1st arch on
either side of median tongue bed.
2 distal tongue beds (lateral lingual swellings)
.
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Posterior 2/3rd :
 II branchial arch – venteromedial part fuses
COPULA
 III & IV arches – venteromedial parts- caudal to copula
HYPOBRANCHIAL EMINENCE
 Cranial part of hypobranchial eminence overgrows copula
posterior 2/3rd of tongue
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• The first arch
contributes to the
surface of the
anterior two-thirds
of the tongue, while
the third arch
contributes the
posterior one-third
• The fourth
arch contributes to
the epiglottis.
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• Line of fusion Anterior and posterior parts
Terminal sulcus
• Lymphatics ,blood vessels & musculature –
occipital myotomes
• Connective tissue – branchial arch mesoderm
Papillae:
• Circumvallate papillae- 2-5 mon IU
• Fungiform & filiform papillae – 2-5 weeks IUwww.indiandentalacademy.com
MAXILLA
4TH WEEK IU –
mesenchyme of 1st branchial arch
Centre of ossification
Angle where anterosuperior dental nerve
to given off from infraorbital nerve
Bone spreads form a trough:
Posteriorly: - Below the orbit toward the developing
zygoma
Anteriorly: - Towards the future incisor region
Superiorly: - To form the frontal process
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• Lateral alveolar plate: downward extension
from the trough
• Medial alveolar plate:junction of maxillary
process & main body of maxilla around
tooth germs
• Secondary cartilage- zygomatic or malar
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PALATE:
The palate develops in 2 parts . viz;
1.The primary palate
2.The secondary palate
Formed by maxillary processes and frontonasal
process.
Primary palate
medial nasal process
small triangular, median part of the palate
primary palate.
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• The medial nasal
prominences contrib
ute the tissues that
will form the
anterior part of the
palate, the primary
palate (circled).
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• Secondary palate:
parts of the maxillary processes
extend laterally on either side of the tongue
MP’s grow medially
Palatal shelves
Union is prevented by - presence of the tongue.
shelves grow vertically down
Tongue developing from the occipital myotomes initially
occupies the entire oronasal cavity
7th WEEK
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Descends of the tongue in to the oral cavity
elevation of the palatal processes from a
vertical to a horizontal plane
fuse in the midline around the 9th week of
I.U.L.
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• Complete tongue obstruction over a time specific
period
• Intrinsic shelf- elevating force – accumulation &
hydration of hyaluronic acid
• Rapid differential mititic growth
• Biochemical transformations in physical consistenc
of connective tissue matrix if shelves
• Alteration in the cranial flexure
CAUSES for rapid elevation of palatal shelves
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Fusion of palate:
Entire palate does not contact and fuse at the same
time
Initial contact
 In the region of the secondary palate
 Just posterior to the anterior or primary palatine
processes
 Continues both anteriorly and posteriorly to this
point.
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A process of “merging” which result in the
medial space
Anterior palatal suture and the foramen
remain in the post natal period
evidence of the early existence of primary
and secondary palate.
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CLEFT LIP & PALATEwww.indiandentalacademy.com
• At about 6th week of I.U. life – from 1st arch –
meckel’s cartilage.
• Makes little contribution towards the
development of the mandible
• Provides a template for subsequent development
of the mandible.
MANDIBLE
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• 7th week of I.U. life,
• a centre of ossification appears lateral to
the meckel’s cartilage.
• From this centre, bone formation spreads
rapidly backwards, forwards & upwards
around inferior alveolar nerve & its
terminal branches.
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• Trough of bone extends to the midline,
where it comes into close approximation
with a similar trough formed in the
adjoining mandibular processes.
• The two separate centers of ossification
remain separated at the mandibular
symphysis until shortly after birth
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Ramus of the mandible
Rapid spread of ossification posteriorly into
the mesenchyme of the first arch
Turning away from meckels cartilage
Point of divergence (lingula)
By 10 weeks the rudimentary mandible is
formed almost entirely by membranous
ossification www.indiandentalacademy.com
SECONDARY CARTILAGES - 3
10th & 14th week of I.U. life.
condylar , coronoid and symphysial cartilage
Condylar cartilage
12 weeks IU
Cone like mass occupies developing ramus
Endochondral ossification
Condyle almost formed (20 weeks)
Thin cartilage remains on the condylar headswww.indiandentalacademy.com
Condylar cartilage
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coronoid cartilage
4 month
anterior border and the top of the condylar process
between the two ends of meckels cartilage
obliterated within the first year of birth
The neural, alveolar and
muscular elements and
growth are assisted by
the development of these
secondary cartilages
www.indiandentalacademy.com
DEVELOPMENT OF FACIAL FEATURES
• Due to differential growth by increase in breadth of
MNP,LNP AND MP’s
• 7th week –face acquires more of human appearance
-medial part increases in anterior direction
-mouth merges at an angle & limit to size
(large at 5th week)
• As vertical height increases – nose increases in
length
so eyes & nose- not in same horizontal
plane
• Eyes move from lateral aspects to front as orbits
grow-protrusion as in 7th & 8th weeks decreases
www.indiandentalacademy.com
• Orbital cavities attain adult size by 7 years
Mandible
• Initially small-compared to upper face
• 7-12th week-normal /more rapid face
• Later-smaller than maxilla
Changes in facial
features critically
seen from 5th to
7th weeks
www.indiandentalacademy.com

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Embrology

  • 2. GOOD MORNING “If there were some deep principle that drove organic systems towards living systems, the operation of the principle should easily be demonstratable in a test tube in half a morning. Needless to say, no such demonstrahttp://chellescorner.com/wp- content/uploads/2011/06/New- Beginnings.jpgtion has ever been given. Nothing happens when organic materials are subjected to the usual prescription of showers of electrical sparks or drenched in ultraviolet light, except the eventual production of a system” Sir Fred Hoyle GOOD MORNING www.indiandentalacademy.com
  • 4. CONTENTS Introduction Definitions Fundamentals of development Stages of growth Prenatal growth Development of face Theories of growth Conclusion www.indiandentalacademy.com
  • 5. INTR0DUCTION • Growth is a complex and spectacular process involving various steps from one-celled stage to complete formation of body of living organism and the variations that occur in this complex process,has been the subject of fascination since long. • Growth is the raw material in the orthodontic treatment ,without changes in the craniofacia;l morphology, no occlusion can be improved . • Wide variability of expressions .www.indiandentalacademy.com
  • 6. Definitions • Growth is an increase in size -TODD • Development is all the naturally occurring unidirectional changes in life of an individual from its existence as a single cell to its elaboration as a multifunctional unit terminating death. • -MOYERS www.indiandentalacademy.com
  • 7. FUNDAMENTALS OF DEVELOPME • PATTERNING: Initial axial specification of embryo from (head to tail) through segmentation. INVOLVES: 3 cells functions,shapes & rates of turnover compartmentized differentiate or remain constant INDUCTION www.indiandentalacademy.com
  • 8. Homeobox genes (180 nucleotide base pairs) regulatory molecules (growth factors,retinoic acids) cell surface receptors regulate the expression COMPETANCY,DIFFERENTIATION www.indiandentalacademy.com
  • 9. Stages of growth “He who sees things grow from the beginning will have the finest view of them” -Aristotle • Prenatal growth • Post natal growth • Maturity • Oldage www.indiandentalacademy.com
  • 10. Prenatal growth Includes Proliferation period (1st 7 days) Embryonic period (next 7 weeks) Fetal period (next 7 calendar months) www.indiandentalacademy.com
  • 12. Gametogenesis Sperm (23) ovum(23) fertilisation ZYGOTE(46) CLEAVAGE (uterine tube) 24 HOURS 30 HOURS Proliferative period www.indiandentalacademy.com
  • 14. Morula Space (between the central Blastomeres) filled with the fluid Trophoblast embryonic mass (Placenta) (embryo) BLASTOCYST 4 – 5 DAYS www.indiandentalacademy.com
  • 15. FLOWS FREELY IN UTERINE SECRETIONS FOR 2 DAYS www.indiandentalacademy.com
  • 16. IMPLANTATION (upper part of uterus in posterior wall) Trophoblast (Rapid division and differentiation) Cytotrophoblast syncitiotrophoblast UTEROPLACENTAL CIRCULATION Embryonic endoderm (inner cell mass) 6th DAY 7th DAY www.indiandentalacademy.com
  • 18. Embryonic period Spaces between trophoblast coalesce slit like amniotic cavity Bilaminar embryo Epiblast Hypoblast (ectoderm &mesoderm) (endoderm) 8TH DAY www.indiandentalacademy.com
  • 20. 9TH DAY Embryonic pole: Lacunar stage(embryotroph) Abembryonic pole: extracoelomic membrane(hypoblast) around the cavity – PRIMITIVE YOLK SAC www.indiandentalacademy.com
  • 21. 10 – 12th DAY Interstitial implantation - in the endometrium Extra embryonic coelom www.indiandentalacademy.com
  • 22. 13TH DAY Secondary yolk sac Chorionic cavity Prechordal plate www.indiandentalacademy.com
  • 23. 3rd WEEK – TRILAMINAR DISC 3 germ layers established Primitive node Primitive pit Ectoderm & endoderm www.indiandentalacademy.com
  • 24.  Primitive streak  Invagination- 15TH DAY  Invaginated cells of epiplast – endoderm  Cells remaining in epiblast - ectoderm  Cells in between - mesoderm Primitive knot PRESOMITE EMBRYO www.indiandentalacademy.com
  • 25. Future mouth & head region Oropharyngeal membrane communication between yolk sac and amniotic cavity 17TH DAY www.indiandentalacademy.com
  • 26. End of 4th WEEK Notochordal plate Definitive notochord Neurocentric canal obliterates END OF GASTRULATION www.indiandentalacademy.com
  • 27. Embryonic ectoderm over notochord Thickens Neural plate(neuro ectoderm) Neural fold, neural tube Neural crest (affinity with epithelium lost- neural crest cells ) 18TH DAY - NEURALATION www.indiandentalacademy.com
  • 28. Derivatives of neural crest cells • Connective tissue and bones of face &skull • Cranial nerve ganglia • Odontoblasts - dentin • C cells of thyroid • Spinal ganglia • Sympathetic chain • Parasympathetic ganglia of GIT • Adrenal medulla • Glial cells,schwann cells • Arachnoid and piamater www.indiandentalacademy.com
  • 29. • 20th DAY- MESODERM Thickening of intraembryonic mesoderm Somites - sclerotome,myotome,dermatome Intraembryonic coelom- pericardial pleural and peritonial cavities (2nd month) www.indiandentalacademy.com
  • 30. Mesodermal derivatives Paraxial mesoderm – Somitomeres • Muscle(smooth,cardiac,skeletal) • Extra ocular muscles &muscles of tongue • Connective tissue,dermis of skin • Bone,cartilage • Blood & lymph vessels(angioblasts)INS IN THE 5TH WEEK BLOOD FORMATION - BEGINS IN THE 5TH WEEK • Duramater • Testes, ovaries • Dental sac (PDL,cementum, alveolar bone) • Intermediate mesoderm – urogenital structures • Lateral mesoderm – serous membranes(pericardial,pleural,peritoneal) www.indiandentalacademy.com
  • 31. ENDODERM – END OF 1ST MONTH VENTRAL SURFACE OF EMBRYO www.indiandentalacademy.com
  • 32. • Epithelial lining of: Gastrointestinal tract • Trachea, bronchi, lungs • Biliary apparatus • Urinary bladder, urethra • Vagina • Auditory tube & Middle ear cavity • Parenchyma of Liver & Pancreas • Submandibular gland & Sublingual gland • Thyroid & Parathyroid DERIVATIVES www.indiandentalacademy.com
  • 33. HIGH LIGHTS Of EMBRYONIC PERIOD 4TH WEEK: • Branchial apparatus appear • Fore brain- prominent elevation on the head • Otic pits & inner ear primordia • Lens placodes & leg buds www.indiandentalacademy.com
  • 34. 5TH WEEK MINOR CHANGES Cranial growth increases(brain) Fore limb differentiation www.indiandentalacademy.com
  • 35. 6TH WEEK • Fore limbs,wrist,elbow,future fingers(finger rays) • External auditory meatus • Retinal pigment & eye • Cervical flexure www.indiandentalacademy.com
  • 36. 7TH WEEK • Decreased communication between yolk sac & gut • Limbs further develop • The brain is now functioning • Ears now functioning to provide a sense of balance www.indiandentalacademy.com
  • 37. 8TH WEEK • Tail bud dissapears • Finger & toes apparent • Head – erect - ½ the size of embryo • Eyelids formed • Umbilical cord size decreased Five weeks of embryonic period – most critical Major portion of the face is developed www.indiandentalacademy.com
  • 39. FETAL PERIOD – 9th week till birth 9-12 WEEKS • Face broadens • Ears low set • Eyes widely low set • Upper limb reaches the final length • Lower limbs still developing • External genetalia distinguishable- sex of the fetus can be determinedwww.indiandentalacademy.com
  • 40. 13- 16 WEEKS • Growth is rapid • Head is smaller than the body • Lower limbs well developed • Skeletal ossification begins (clear radiographs seen) • Scalp hair begins www.indiandentalacademy.com
  • 41. 16- 20 WEEKS • Growth is slow • Lower limbs – final length • Fetal movements are felt by mother • Fatty secretions and brown fat by fetus - protection www.indiandentalacademy.com
  • 42. 21 – 25 WEEKS • Lean and well proportionate body • Gains weight • No subcutaneous fat- skin wrinkles • Immature respiratory system - die if born premature • Other organs – well developed www.indiandentalacademy.com
  • 43. 26-29 WEEK • Subcutaneous fat – developed • Eyes reopen • Hair well developed • Respiratory system mature enough • CNS- controls temperature & breathing • Premature fetus survives at this stage www.indiandentalacademy.com
  • 44. 35-38 WEEKS • Body is plump(well rounded) • Lanugo hair(5 mon fetus hair) disappears • Fetus is ready for birth • Crown – rump length - 360 mm (top of the head – crown, Bottom of buttocks – rump) • Fetus weight – 3400gm www.indiandentalacademy.com
  • 45. Time of birth: • Approx. 266 days after fertilization(38 weeks) or 280 days(40 weeks) from onset of last menstrual period. so gestation period is - 9 months www.indiandentalacademy.com
  • 46. DEVELOPMENT OF FACEMESENCHYME FOR HEAD FORMATION- 1.Paraxial mesoderm(somites & somitomeres) 2.Lateral plate mesoderm- 3.Neural crest 4.Ectodermal placodes www.indiandentalacademy.com
  • 47. Branchial apparatus • Comparable to fish embryo with gills. consists- 1.Branchial arches – mesoderm &neural crest cells 2.Branchial grooves- ectoderm 3.Branchial pouches- endoderm 4.Branchial membranes groove groove pouch pouch Arch www.indiandentalacademy.com
  • 48. Branchial arches Develop during the late somite period i.e. 4th week I.U The mesoderm of the ventral foregut region gets segmented Six distinct bilateral mesenchymal swellings BRANCHIAL ARCHES www.indiandentalacademy.com
  • 50. BASIC ANATOMY OF AN ARCH Consists • Cartilage component : Adapt to form Bony, Cartilagenous or Ligamentous structures • Muscle component: Give rise to special visceral muscles composed of striated muscle fibers. • Vascular component: Provides necessary blood supply www.indiandentalacademy.com
  • 51. • Nerve component : Nerve fibers of special cranial nerves Enter mesoderm of branchial arches Initiate muscle development in the mesoderm Migrate and adapt to the branchial arches www.indiandentalacademy.com
  • 53. ARCH 1ST (MANDIBULAR ARCH) 2ND (HYOID ARCH) SKELETAL ELEMENT • MECKEL’S CARTILAGE • INCUS,MALLEUS • ANTERIOR MANDIBLE • ZYGOMATIC BONE • PALATINE BONE • PART OF TEMPORAL BONE • SPHENOMANDIBULAR LIGAMENT • DORSAL PART OF MAXILLA • STAPES • STYLOID PROCESS • SMALLER CORNU OF HYOID • SUPERIOR PART OF BODY OF HYOID NERVE MANDIBULAR NERVE (V3) FACIAL NERVE(VII) MUSCLE • MUSCLES OF MASTICATION • ANTERIOR BELLY OF DIGASTRIC • TENSOR TYMPANI • TENSOR PALATI • MYLOHYOID • MUSCLES OF FACIAL EXPRESSION • PLATYSMA • STYLOHYOID • POSTERIOR BELLY OF DIGASTRIC • STAPEDIUS • AURICULAR MUSCLES www.indiandentalacademy.com
  • 54. By the time that the anterior neuropore closes, Human Age:27 days the first and Second pharyngeal arches are evident. I ARCH II ARCH www.indiandentalacademy.com
  • 55. ARCH III ARCH IV ARCH SKELETAL ELEMENT • GREATER CORNU OF HYOID • LOWERN PART OF BODY OF HYOID CARTILAGES OF LARYNX NERVE GLOSSO PHARYNGEAL (IX) SUPERIOR LARYNGEAL MUSCLE STYLOPHARYNGEUS • ALL MUSCLES OF PHARYNX EXCEPT STYLOPHARYNGEUS • ALL MUSCLES OF PALATE EXCEPT TENSOR VELI PALATI • CRICOTHYROID www.indiandentalacademy.com
  • 56. • The first, second, third and fourth arches are visible externally. The sixth arch does not form an external elevation. Human Age: Fifth week www.indiandentalacademy.com
  • 57. • Anomalies associated with branchial arches • Deficient development of the branchial arches result in syndromes according to the arch involved. • First arch syndromes : - Agnathia - Microstomia - Treacher Collins syndrome (mandibular dysostosis) - Pierre Robin syndrome (micrognathia+cleft palate www.indiandentalacademy.com
  • 58. • Branchial pouches Branchial arches on endodermal surface are craniocaudally by pharyngeal pouches. 4 well defined pouches . 5th rudimentary. www.indiandentalacademy.com
  • 59. POUCHES I POUCH II POUCH III POUCH IV POUCH V POUCH (ULTIMOBRANCHIAL POUCH) DERIVATIVES PHARYNGOTYMPANIC TUBE MIDDLE EAR CAVITY TYMPANIC ANTRUM TONSIL TUBOTYMPANIC RECESS INFERIOR PARATHYROID GLANDS THYMUS SUPERIORPARATHYROID GLANDS PARAFOLLICULAR CELLS OF THYROID www.indiandentalacademy.com
  • 60. PHARYNGEAL GROOVES & PHARYNGEAL POUCHESwww.indiandentalacademy.com
  • 61. Branchial grooves The regions between the pharyngeal arches are termed pharyngeal grooves PHARYNGEAL GROOVE I PHARYNGEAL GROOVE II,III,IV PHARYNGEAL GROOVE DERIVATIVES EXTERNAL AUDITORY MEATUS CERVICAL SINUS Branchial membrane Major component of branchial apparatus from which the skeletal of both muscular and vascular systems are derived www.indiandentalacademy.com
  • 62. DEVELOPMENT OF FACE • Development of the head depends upon inductive activities of 2 organizing centers -- Prosencephalic centre -- Rhombencephalic centre www.indiandentalacademy.com
  • 63. • Prosencephalic organizing center : -- Derived from prechordal mesoderm that migrates from the primitive streak. -- Situated at the rostral end of the notochord below the fore brain. -- Induces the formation of :  Visual apparatus  Inner ear apparatus  Upper third of face www.indiandentalacademy.com
  • 64. • Rhombencephalic organizing center : -- Caudal in relation to the Prosencephalic centre. Induces the formation of: -- Middle and lower third of the face. -- Middle and external ears. www.indiandentalacademy.com
  • 65. Oral development in embryo is demarcated extremel early in life by the appearance of prechordal plate (14th day) + Endoderm Thickening Oropharyngeal Membrane OROPHARYNGEAL MEMBRANE www.indiandentalacademy.com
  • 66. Oropharyngeal membrane – temporary bilaminar membrane Functions as: 1. Site of junction of ectoderm and endoderm. 2. Demarcates the stomodeum from the rest. i.e; initial demarcation of the future mouth Rapid development of the cranial portion than the caudal portion - charecteristic of orofacial development – DIFFERENTIAL GROWTH www.indiandentalacademy.com
  • 67.  At 5- 7 week of IU - from 5 primordia surrounding the primitive oral pit I frontal process –above oral pit – upper face 2 maxillary processes - lateral pit oral pit - cheeks &upper lip 2 mandibular prominence – below oral pit -mandibular(lower face) From neural crest ectomesenchyme Late 4TH WEEK Facial prominences –– upper part of stomodeum Maxillary prominences- lateral to stomodeum Mandibular prominences- caudal to stomodeum first prominences of the face FACE www.indiandentalacademy.com
  • 68. Thickenings on either side of FNP (Nasal placodes) Invaginate (nasal pits) Ridge (nasal prominences) Lateral and medial nasal prominences 5TH WEEK www.indiandentalacademy.com
  • 69. • Next, is the union of the facial prominences by either of the 2 developmental events. 1. Merging of the frontonasal, maxillary and mandibular prominences. OR 2. Fusion of the central maxillonasal components. www.indiandentalacademy.com
  • 70. • Merging - completed as a result of proliferation of the underlying mesenchyme into the intervening grooves. • The above is guided by the disintegration of the contacting surface epithelium b/w the processes termed as Nasal fin • Failure of normal disintegration of nasal fin Due to: 1. Cell death 2. Mesenchymal transformation Leads to cleft of upper lip and anterior palate (Due to prevention of merging of mesenchyme of max. and medial nasal processes) www.indiandentalacademy.com
  • 71. • Midline merging of median nasal prominences forms  Philtrum of upper lip Median tubercle. Tip of the nose. Primary palate • Post. Merging of Medial nasal processes Median primary palate Premaxilla Future site of 4 upper incisors www.indiandentalacademy.com
  • 72. • Midline merging of the paired mandibular prominences Lower jaw + Lower lip -- First to get definitely established • Lateral merging of maxillary and mandibular prominences. Commisures of mouth www.indiandentalacademy.com
  • 73. Maxillary prominences- increase in size Grow medially and compress the MNP Cleft between MP and MNP lost MNP & MP fuse upper lip & jaw Lower lip & jaw – 2 mandibular processes merge in the midline UPPER LIP & JAW www.indiandentalacademy.com
  • 74. • Union of the medial nasal prominence with the lateral nasal prominence and maxillary prominence is required for normal development of the upper lip. www.indiandentalacademy.com
  • 75. NASOLACRIMAL DUCT & LACRIMAL SAC MP & LNP seperated by deep furrow nasolacrimal groove Ectoderm in the floor of the groove forms cord Canalisation Nasolacrimal duct Upper end widens- lacrimal sac www.indiandentalacademy.com
  • 76. CHEEKS AND MAXILLA Cord detaches MNP & LNP merges NLD runs from medial corner of eye to inferior meatus of nasal cavity MP ‘s enlarges Cheeks & maxillawww.indiandentalacademy.com
  • 77. NOSE Formed from 5 prominences • Frontal prominence-bridge of the nose • Merged MNP’s – crest & tip • LNP’S-side (alae) of the nose • Nasal pits – anterior nares • Cartilage nasal capsule- septum & nasal conchae • Blind sacs of deepened nasal pits (disintegrate) -posterior nares www.indiandentalacademy.com
  • 78. VOMERONASAL ORGAN Ectoderm invasion into median nasal septum from nasal fossae Vomeronasal organ (Jacobson,s organ) Vestigial blind pouches- chemosensory - pheromone receptor in adulthood www.indiandentalacademy.com
  • 79. EAR - 6TH WEEK 1.Internal ear Hind brain induction of surface ectodermal cells Elongates into thick otic placode Invaginates into pit Internal ear www.indiandentalacademy.com
  • 80. 2.External ear 1ST Brachial groove -- External acoustic meatus Develops in neck region as 6 auricular hillocks i.e; the mesoderm of the 1st and 2nd Branchial arches www.indiandentalacademy.com
  • 81. 3.Middle ear 1st pharyngeal pouch (endoderm lined) -tympanic cavity &auditory tube Ossicles – 1st arch- malleus & incus 2nd arch- stapes www.indiandentalacademy.com
  • 82. EYE Localised thickenings of epithelium on sides of head (between FNP & MP) lens placodes (future eyes) Lateral growth of fore head lateral expansion of face Eyes thus positioned more anteriorly 5th WEEK 6TH WEEK www.indiandentalacademy.com
  • 83. TONGUE End of 4th week I,II,III arches &muscles from occipital myotomes Anterior 2/3rd : Median triangular elevation in the floor of the primitive pharynx anterior to foramen caecum Median tongue bed (Tuberculum Impar) Mesenchyme of the 1st arch on either side of median tongue bed. 2 distal tongue beds (lateral lingual swellings) . www.indiandentalacademy.com
  • 84. Posterior 2/3rd :  II branchial arch – venteromedial part fuses COPULA  III & IV arches – venteromedial parts- caudal to copula HYPOBRANCHIAL EMINENCE  Cranial part of hypobranchial eminence overgrows copula posterior 2/3rd of tongue www.indiandentalacademy.com
  • 86. • The first arch contributes to the surface of the anterior two-thirds of the tongue, while the third arch contributes the posterior one-third • The fourth arch contributes to the epiglottis. www.indiandentalacademy.com
  • 87. • Line of fusion Anterior and posterior parts Terminal sulcus • Lymphatics ,blood vessels & musculature – occipital myotomes • Connective tissue – branchial arch mesoderm Papillae: • Circumvallate papillae- 2-5 mon IU • Fungiform & filiform papillae – 2-5 weeks IUwww.indiandentalacademy.com
  • 88. MAXILLA 4TH WEEK IU – mesenchyme of 1st branchial arch Centre of ossification Angle where anterosuperior dental nerve to given off from infraorbital nerve Bone spreads form a trough: Posteriorly: - Below the orbit toward the developing zygoma Anteriorly: - Towards the future incisor region Superiorly: - To form the frontal process www.indiandentalacademy.com
  • 89. • Lateral alveolar plate: downward extension from the trough • Medial alveolar plate:junction of maxillary process & main body of maxilla around tooth germs • Secondary cartilage- zygomatic or malar www.indiandentalacademy.com
  • 90. PALATE: The palate develops in 2 parts . viz; 1.The primary palate 2.The secondary palate Formed by maxillary processes and frontonasal process. Primary palate medial nasal process small triangular, median part of the palate primary palate. www.indiandentalacademy.com
  • 91. • The medial nasal prominences contrib ute the tissues that will form the anterior part of the palate, the primary palate (circled). www.indiandentalacademy.com
  • 92. • Secondary palate: parts of the maxillary processes extend laterally on either side of the tongue MP’s grow medially Palatal shelves Union is prevented by - presence of the tongue. shelves grow vertically down Tongue developing from the occipital myotomes initially occupies the entire oronasal cavity 7th WEEK www.indiandentalacademy.com
  • 94. Descends of the tongue in to the oral cavity elevation of the palatal processes from a vertical to a horizontal plane fuse in the midline around the 9th week of I.U.L. www.indiandentalacademy.com
  • 97. • Complete tongue obstruction over a time specific period • Intrinsic shelf- elevating force – accumulation & hydration of hyaluronic acid • Rapid differential mititic growth • Biochemical transformations in physical consistenc of connective tissue matrix if shelves • Alteration in the cranial flexure CAUSES for rapid elevation of palatal shelves www.indiandentalacademy.com
  • 98. Fusion of palate: Entire palate does not contact and fuse at the same time Initial contact  In the region of the secondary palate  Just posterior to the anterior or primary palatine processes  Continues both anteriorly and posteriorly to this point. www.indiandentalacademy.com
  • 99. A process of “merging” which result in the medial space Anterior palatal suture and the foramen remain in the post natal period evidence of the early existence of primary and secondary palate. www.indiandentalacademy.com
  • 100. CLEFT LIP & PALATEwww.indiandentalacademy.com
  • 101. • At about 6th week of I.U. life – from 1st arch – meckel’s cartilage. • Makes little contribution towards the development of the mandible • Provides a template for subsequent development of the mandible. MANDIBLE www.indiandentalacademy.com
  • 102. • 7th week of I.U. life, • a centre of ossification appears lateral to the meckel’s cartilage. • From this centre, bone formation spreads rapidly backwards, forwards & upwards around inferior alveolar nerve & its terminal branches. www.indiandentalacademy.com
  • 103. • Trough of bone extends to the midline, where it comes into close approximation with a similar trough formed in the adjoining mandibular processes. • The two separate centers of ossification remain separated at the mandibular symphysis until shortly after birth www.indiandentalacademy.com
  • 104. Ramus of the mandible Rapid spread of ossification posteriorly into the mesenchyme of the first arch Turning away from meckels cartilage Point of divergence (lingula) By 10 weeks the rudimentary mandible is formed almost entirely by membranous ossification www.indiandentalacademy.com
  • 105. SECONDARY CARTILAGES - 3 10th & 14th week of I.U. life. condylar , coronoid and symphysial cartilage Condylar cartilage 12 weeks IU Cone like mass occupies developing ramus Endochondral ossification Condyle almost formed (20 weeks) Thin cartilage remains on the condylar headswww.indiandentalacademy.com
  • 107. coronoid cartilage 4 month anterior border and the top of the condylar process between the two ends of meckels cartilage obliterated within the first year of birth The neural, alveolar and muscular elements and growth are assisted by the development of these secondary cartilages www.indiandentalacademy.com
  • 108. DEVELOPMENT OF FACIAL FEATURES • Due to differential growth by increase in breadth of MNP,LNP AND MP’s • 7th week –face acquires more of human appearance -medial part increases in anterior direction -mouth merges at an angle & limit to size (large at 5th week) • As vertical height increases – nose increases in length so eyes & nose- not in same horizontal plane • Eyes move from lateral aspects to front as orbits grow-protrusion as in 7th & 8th weeks decreases www.indiandentalacademy.com
  • 109. • Orbital cavities attain adult size by 7 years Mandible • Initially small-compared to upper face • 7-12th week-normal /more rapid face • Later-smaller than maxilla Changes in facial features critically seen from 5th to 7th weeks www.indiandentalacademy.com