.

2. DEVELOPMENT OF FACE, PARANASAL
SINUSES, ASSOCIATED STRUCTURES &
ANOMOLIES
DR.ASHWIN K HAREKAL
1ST MDS
DEPT OF ORAL AND MAXILLOFACIAL SURGERY

3. CONTENTS
• Introduction
• Phases Of Development
• Formation Of Germ Layers
• Formation Of The Pharyngeal Arches
• Development Of Face
• Development Of Lips
• Development Of Cheeks
• Development Of Nose
• Development Of Eye
• Development Of External Ears
• Development Of Paranasal Sinuses
• Development Of Mandible
• Development Of Maxilla
• Anomalies Associated With Each

4. INTRODUCTION
 Every individual spends the first nine months of its life within the womb or uterus of its
mother.
 During this period, it develops from a small one- celled structure to an organism having
billions of cells
 Numerous tissue are formed and come to function in a perfect harmony
 The most spectacular changes occur in the first 2 months of IUL; the unborn acquires its
main organs and just begins to be recognizable as HUMAN .
 During these 2 months ,we call the develo-
ping individual an embryo
o From the 3rd month until birth we call it a
fetus

5. INTRODUCTION
 Human development is a continuous process that does not stop at birth.
 Begins when an oocyte (ovum) from the female is fertilized by a sperm
(spermatozoon) from a male.
 Fertilization takes place when one spermatozoon enters an ovum. The fused ovum
and sperm form the zygote
 Development involves changes from a
single cell, the zygote into a
multicellular human being.

6. PHASES OF DEVELOPMENT
 Embryogenesis is divided into three distinct phases during the 280 days of
gestation.
 Pre-implantation period:
the first 7 days
 Embryonic period:
the next 7 weeks
 Fetal period:
the next 7 months

7. PRE-IMPLANTATION PERIOD
 Cleavage: within 24 hours after fertilization, the zygote initiates a rapid series of
mitotic cell divisions
 no increase in size of the embryo.
 The zygote is subdivided into many small daughter cells called as the
Blastomeres.

8. • After morula formation, compaction
occurs.
• Centrally placed blastomeres are called
as the inner cell mass.
• Blastomeres at the periphery are called
as the trophoblast.
• Inner cell mass forms the embryo proper
hence called as the embryoblasts.
• Trophoblast forms the fetal component
of the placenta.
• on the 7th day, the blastocyst which
develops from the morula, implants in
the decidual layer of the uterine wall.

9. CLEAVAGE, BLASTULATION, GASTRULATION, AND NEURULATION

11. THE EMBRYONIC PERIOD
 From the end of 1st week to the 8th week
PRESOMITE
• 8-21 days
postconception
• germ layers & the
fetal membranes
are formed
SOMITE
• 21-31 days
postconception
• Basic pattern of
the main body
systems & organs
are established
POSTSOMITE
• 32-56 days
postconception
• formation of
body’s external
features

12. THE FOETAL PERIOD
 Longest phase.
 8th week to term.
 Identified by 1st appearance of ossification centers and the earliest
movements by the fetus.
 Organogenesis occurs.
 Rapid expansion of the basic structures already formed.

13. FORMATION OF GERM LAYERS
 Blastocyst develops to form various structures that support the embryo &
helps it to acquire nutrition.
 Embryonic disc is formed.
 3 layers:
 Endoderm
 Ectoderm
 Mesoderm
 All the tissues of the body are derived from these layers.

14. Some cell of the inner cell mass differentiate into
flattened cell that comes to line its free sueface.this layer
is hypoblast.
The remaining cell of the inner cell mass become
columnar .these cell form the epiblast. The embryo is
now in the form of a disc having 2 layers.
A space appears between the epiblast and the
trophoblast.This is the amniotic cavity filled by amniotic
fluid. The roof of this cavity is formed by amniogenic cell
derived from the trophoblast,while its floor is formed by
the epiblast
Flattened cell arising from the hypoblast or according to
some from trophoblast spread and line the inside of the
blastocystic cavity .this lining of flattened cell is called
Heuser’s membrane.this cavity is called the primary yolk
sac

15.  The cell of the trophoblast give origin to a
mass of cells called the extra-embryonic
mesoderm(primary mesodem).
 These cell comes to lie in between the
trophoblast and the flattened endodermal
cells lining the yolk sac,thus seprating from
each other
 These cell also seprate the wall of the
amniotic cavity from the trophoblast.this
mesoderm is called the extra-embryonic
mesoderm

16.  Small cavity appear in the extra-embryonic
mesoderm.gradually, these join together to form
a larger space and ultimately one large cavity is
formed.this cavity is called extra embryonic
coelom.
 Its clearly seen that the extra embryonic coelom
does not extend into the part of the extra
embryonic mesoderm which attaches the wall
of the amniotoc cavity to the trophoblast. This is
called a structure called the connecting stalk.
 At this stage two very important structure are
formed chorion and amnion
 This both play a important role in child
birth(parturition).

17.  With the appearance of the extra-embryonic mesoderm and later the extra
embryonic coelom,the yolk sac becomes much smaller and is called the
secondary yolk sac.
 Embryo is a circular disc composed of 2 layers
upper layer (towards amniotic cavity)-epiblast
lower layer (towards yolk sac) -hypoblast

18.  We soon see that,at one circular area near the
margin of the disc,the cuboidal cell of the
endoderm becomes columnar.its called
prochordal plate.

19.  After the formation of prochordal
plate, some of the epiblasts cells
lying along the central axis near the
tail end, proliferate to form an
elevation, which becomes the
primitive streak.
 In starting primitive streak is an
oval swelling but as the elongation
take place it become linear
structure.

20.  Cells which proliferate in the region of
primitive streak pass sideways , between
epiblast and hypoblast
 These cells form intra embryonic
mesoderm(secondary mesoderm)
 Some cells from the primitive streak displace
hypoblast and form the endoderm.thus
endoderm and mesoderm are derived from
epiblast
 Remaining cells of epiblast form ectoderm
 Hence, a disc of 3 layers- ectoderm, endoderm
and mesoderm are seen
 Formation of primitive streak, endoderm
and intra embryonic mesoderm-
GASTRULATION

21.  We have seen that when the
embryonic disc is formed it s
suspended from the tropoblast by the
connecting stalk
 This connecting stalk is very broad as
compared to the size of embryo
 As the embryonic disc enlarges in size
the coonecting stalk becomes smaller
and its attachment becomes confined
to the region of the tail end of the
embryonic disc
 Some intraembryonic mesoderm
passes through this

22. FATE OF THE GERM LAYERS FORMED AT
GASTRULATION
ECTODERM
• Nervous system & sense
organs
• Outer layer of skin
(epidermis) & its
associated structures like
the hair, nail
• Pituitary gland
MESODERM
• Notocord
• Skeleton
• Muscles
• Circulatory system
• Respiratory system
• Urinary system
• Inner layer of skin
(dermis)
• Outer layers of
digestive tube
ENDODERM
• Inner linings of the
digestive tube

23. FORMATION OF THE PHARYNGEALARCHES
 The forgut is bounded ventrally by the
pericardium and dorsally by the
developing brain.
 At this stage,head is represented by
bulging caused by developing
brain,while the pericardium may be
considered as occupying the region of
the future thorax.
 This elongation is mainly due to
appearance of a series of mesodermal
thickening in the wall of the cranial
most part of the foregut

24. CONT…..
 The pharyngeal apparatus consists of:
 Pharyngeal arches
 Pharyngeal pouches
 Pharyngeal clefts
 Pharyngeal membranes
 Pharyngeal arches appear in the 4th and 5th week of
development and contribute to the characteristic
external appearance of the embryo.
 They are rod- like thickenings of mesoderm present in the wall of
foregut.
 They contribute extensively to the formation of the face, nasal cavity, mouth, larynx,
pharynx and neck.

26. STRUCTURE TO BE SEEN IN PHARYNGEAL ARCH
o SKELETAL ELEMENTS
o STRIATED MUSCLE
o ARTERIAL ARCH
VENTRAL AORTA
DORSAL AORTA

28. DERIVATIVES OF THE SKELETAL COMPONENT
 The derivative of the first arch is called
meckel’s cartilage.
 The incus and the malleus of the middle ear
are derived from itz dorsal end
 The vental part is surrounded by the
developing mandible and its resorbed.

29.  Cartilage of the second arch forms the
Stapes
Styloid process
Stylohyoid ligament
Smaller cornu of the hyoid bone
Superior part of the hyoid bone
 Cartilage of the third arch forms the
greater cornu of hyoid bone
lower part of the body of the hyoid bone
 The cartilage of the larynx are derived from the
fourth and sixth arch with the possible
contribution from the fifth arch,but their exact
derivation is controversial

30. FATE OF ECTODERMAL CLEFT
o Epithelial linning of the
external Acoustic meatus
o cervical sinus

31. FATE OF ENDODERMAL POUCHES
 First pouch
formation of the tongue
inner and the middle ear
o Second pouch
ventral part of this pouch
contributes to the formation of
tonsil
dorsal part in the formation of
tubotympanic recess
o Third pouch
inferior parathyroid gland and
thymus
o Fourth pouch
superior parathyroid gland and
thyroid gland

32. DEVELOPMENT OF THE FACE
 Formation of the fronto-nasal process
 After the formation of head fold, the developing
brain & pericardium form two prominent bulgings
on the ventral aspect of the embryo.
 Bulgings are separated by the stomatodeum
floor is formed by the buccopharyngeal
membrane separates it from the fore gut.
 Soon the mesoderm covering the developing
forebrain proliferates and form the downward
projection it overlap the upper part of the
stomadeum
 This downward projection is called the frontonasal
process.

33.  It will now be readily appreciated that the face is
derived from the following structure
frontonasal process
1st pharangeal arch (mandibular arch)
o Each mandibular arch form the lateral wall of
the stomadaeum
o This arch gives abud from its dorsal end that is
maxillary process
o The mandibular process grow ventro-medially

34. 1 Frontonasal prominence
2 Maxillary prominences
3 Mandibular prominences
Stomatodeum

35.  The ectoderm overlying the frontonasal
process soon show bilateral localised…
 They are called nasal placode
 The formation of this nasal placode is
induced by underlying forebrain
 The placodes sink below the surface to
form nasal pits
 The pits are continous with stomadaeum
below
 There are 2 process
medial nasal process
lateral nasal process

36. DEVELOPMENT OF LIPS
 Lower lip
 The mandibular processes of 2 sides grow towards each other
& fuse in midline.
 Form the lower margin of the stomatodeum.
 Fused mandibular process give rise to lower lip and lower jaw
 UPPER LIP
 Each maxillary process now grow medially and fuses first
with lateral nasal process then with medial nasal process.
 The 2 nasal process also fuse with each other, thus cutting off
the nasal pits from the stomatomedum.

37. • Maxillary process further grows, whereas the
frontonasal process becomes narrower from side to
side, causing the external nares to come closer.
• Upper lip is formed by the :
• Mesodermal basis of the lateral part of the lips is
formed by the maxillary process. The overlying skin
is derived from the ectoderm covering this process.
• The mesodermal basis of the median part of the lip,
philtrum, is formed by the frontonasal process. The
ectoderm of the maxillary process overgrows &
meet in the midline.
• Thus, entire upper lip is supplied by the maxillary
nerve.

38. DEVELOPMENT OF CHEEKS
 After formation of upper & lower lip, the
Stomatodeum is very broad.
 It is bounded above by Maxillary Process & below
by Mandibular Process. These processes undergo
progressive fusion with each other to form Cheeks.
 The fusion of Maxillary Process with Lateral Nasal
Process occurs not only in the region of lip but
extends from the stomatodeum to the median angle
of the developing eye.
 This line of fusion is marked by a groove called
Naso-optic furrow or Nasolacrimal sulcus.
 A strip of ectoderm becomes buried along
this furrow & gives rise to the Nasolacrimal
Duct.

39. DEVELOPMENT OF NOSE
 Nose is formed by the contribution of -
 Frontonasal & medial and lateral nasal processes.
 External nares are formed when the nasal pits are cut off
from the stomatodeum by the fusion of the maxillary
process with the medial nasal process.
 External nares approach each other.
 Frontonasal process becomes progressively narrower &
forms the nasal septum.
 Mesoderm becomes heaped up in the medial plane to form
the prominence of the nose….
 As the nose become prominent the external nares project
downwards instead of forwards

40. DEVELOPMENT OF EYE
• Region of eye is 1st seen as ectodermal
thickenings, lens placode, which appears
lateral & cranial to the nasal placode.
• Sinks below the surface & cut off from surface
ectoderm.
• Developing eyeball produces a bulging.
• Bulgings are at first seen laterally & lie in the
angles between the maxillary& lateral nasal
processes.
• After narrowing of the frontonasal process
they lie forward.

41. DEVELOPMENT OF EXTERNAL EARS
• It is formed around dorsal part of first
ectodermal cleft.
• A series of mesodermal thickenings
(tubercles or hillocks) appear on mandibular
and hyoid arches where they adjoin this
cleft.
• Pinna or auricles is formed by fusion of
these thickenings.
• The pinna lies caudal to the developing jaw
• It is pushes upward and backward to it
original position due to enlargement of the
mandibular process

42. DEVELOPMENT OF PALATE
 Maxillary process not only form the
upper lip but also extend backward on
either side of the stomadaeum
 From the maxillary process a plate like
shelf grow medially
 This is called palatal process
 3 components from which the palate will
be formed
-2 palatal process
-primitive palate formed from FNP

43.  Palate forms from 3 components fusing with each
other--
 1) 2 Palatal processes, fuse in midline. Thier fusion
begin anterior and proceeds backward.
 2) each palatal process fuses with posterior margin of
primitive palate.
 The medial edge of the palatal process fuse with free
lower edge of the nasal septum…
 At later stage mesoderm in palate undergoes
intramembranous ossification to form hard palate.
Ossification does not extend into posterior most
portion which remains as Soft palate.
 The part of palate derived from FNP is Premaxilla
which carries incisors.

44. DEVELOPMENTALANOMALIES OF THE FACE
 Hare lip
 upper lip of the hare normally has a cleft.
 Due to non- fusion of one or both of Maxillary Process
with Median nasal Process. Can be of various degrees
& can be unilateral or bilateral.
 Defective development of lowermost part of
Frontonasal Process may give rise to Midline defect of
upper lip.
 When 2 Mandibular Process do not fuse with each
other the lower lip shows midline defect , this cleft may
extend into the jaw.

45.  Oblique facial cleft
 Non fusion of Maxillary Process & Lateral Nasal Process gives rise to a cleft from
median angle of eye to mouth. The nasolacrimal duct is not formed.
 Macrostomia:
 Inadequate fusion of Maxillary & Mandibular Process- wide mouth
 Microstomia:
 Too much fusion –small mouth

46.  Nose : bifid. May be associated with median cleft lip.
 One half of the nose may be absent.
 Proboscis:
 Rarely nose forms a cylindrical projection on forehead. This anomaly is
associated with Cyclops. ( fusion of 2 eyes).
 One half of the face may be underdeveloped or overdeveloped.
 Congenital tumours : may attempt at duplication of some parts.
 Hypertelorism:
 Eyes widely separated.

47.  Mandibulo-facial dysostosis / Treacher Collins syndrome-
 First arch syndrome
 The entire arch is underdeveloped on one or both sides
 affecting lower eyelid, maxilla, mandible & external ear.
 cheek prominence is absent, ear may be displaced ventrally & caudally.
 Cleft palate
 Genetic condition ( autosomal dominant)

48. DEVELOPMENT OF NASAL CAVITY
 Formed by extension of nasal pits.
 Initially, nasal pits are in open communication with
the stomatodeum.
 Soon medial & lateral nasal processes fuse to form a
partition between them, the primitive plate.
 Nasal pits deepens to form nasal sacs, which
expands both dorsally & caudally.
 dorsal part is 1st separated from the stomatodeum by
a thin membrane, bucconasal membrane.

49. • This soon breaks down, leading to the
opening on the face, anterior or external
nares & on the stomatodeum, posterior
nasal aperture.
• The two nasal sacs are separated by the
frontonasal process, which eventually
forms the nasal septum.
• lateral nasal process forms the lateral
wall of nose.
• Nasal conchae appear as elevations on
the lateral wall

50. ANOMOLIES OF NASAL CAVITY
 There may be atresia of the cavity at external nares, at posterior nasal aperture, or in
cavity proper. May be unilateral or bilateral.
 Congenital defects in cribriform plate of ethmoid bone may lead to communication
between cranial cavity and nose.
 Septum may be deviated or absent.
 Nasal cavity may communicate with mouth.

51. DEVELOPMENT OF PARANASAL SINUSES
 PNS appear as diverticula from nasal cavity
 Maxillary and sphenoidal sinus begins to
develop before birth.
 Frontal and ethmoidal sinuses develop after
birth.
 Enlargement of paranasal sinuses is associated
with overall enlargement of the facial skeleton.

52.  The 4 sets of paranasal sinuses begin their development at the end of the 3rd month of IUL as
outpouchings of the mucous membrane of the middle & superior nasal meatus.
 Primary pneumatization: The early nasal sinuses expands into the cartilage walls & roof
of the nasal fossae by growth of mucous membrane sacs into the respective bones
 Secondary pneumatization: the sinuses enlarge into bone and always retain
communication with the nasal fossae through ostia.

53. MAXILLARY SINUS
 Largest sinus & radiographically identifiable
 1st to develop around 10th week of IUL
 Develops from the evagination from primitive ethmoid infundibulum in lateral walls of middle
meatus
 At birth, maxilla is filled with decidous tooth germs, which are very close to orbital floor.
 The maxillary sinus averages 7mm in AP length & 4mm in Height and width at this stage.
 It expands approx 3mm in AP dimension and 2mm vertically each year.

54.  Pneumatization of maxilla commences just below the orbital floor.
 Downward growth of maxillary sinus leaves the ostium in a position unfavourable for gravitational
drainage.
 The maxillary sinus expands not only downward but also forwards and backwards.
 sinus enlarges by the resorption of all walls of the maxilla, except medial wall.
 It undergoes lateral expansion & by the end of 1st year extends beneath the orbit as far as infra orbital
canal.
 By end of 2nd year sinus has reached half of adult size. During 3rd & 4th year there is very conspicuous
growth in width.
 At 7th year dimension is –
 AP- 27 mm
 height- 17mm
 width-18mm
 By 12th year maxillary sinus extends to same level as nasal floor and is surgically accessible by Inferior
Meatus.

55. SPHENOID SINUS
 Starts developing at 4 months IUL, by constricting the
posterosuperior portion of the spheno-ethmoid recess.
 The recess is between the sphenoidal conchae (bone of
bertin) & the sphenoid body.
 No primary pneumatization takes place.
 Secondary pneumatization occurs at 6-7 years into the
presphenoid & later the basisphenoid bones.
 It continues growing in early adulthood & may invade
wings, rarely the pterygoid plates of the sphenoid bone.

56. ETHMOIDAL SINUS
 Ethmoid air cells from the middle & superior meatus &
spheno-ethmoid recess invade the nasal capsule in the
4th month IUL.
 Secondary pneumatization occurs between birth & at 2
years, as group of 3-15 air cells grow irregularly to form
the ethmoid labyrinth.
 The most anterior ethmoidal cells grow upward into
frontal bone; they may form the frontal sinus.
 The air cells may also expand in the sphenoid, lacrimal
or the maxillary bones.

57. FRONTAL SINUS
 Starts as mucosal invaginations in the frontal
recess of the middle meatus of the nasal fossa at
3-4 months IUL.
 Do not invade the frontal bone (secondary
pneumatization) until between 6 months & 2
years post-nataly.
 They grow upward till puberty .
 All the para nasal sinus appear to continue
increasing their size into old age.

58. ANOMOLIES OF PARANASAL SINUSES
 Absence of development of frontal and sphenoidal sinus is characteristic of
down syndrome (TRISOMY21) and Apert’s syndrome.
 If an inter frontal (metopic) suture persists, frontal sinuses are small, or
even absent.

59. DEVELOPMENT OF MANDIBLE
 The mandible develops from the fibrous
membrane of the meckel’s cartilage
 The fibrous membrane of the ventral part
of meckel’s cartilage is ossified to form
the body of the mandible,which extends
from the mandibular foramen to the
mental foramen
 The cartilage cells disappear later
 The 1st structure to develop in the lower
jaw region is the mandibular branch of the
trigeminal nerve, which is considered to
be the initiator of osteogenesis.

60. • A single ossification center for each half of the mandible arises 6th week IUL
.
• In the region of the bifurcation of the inferior alveolar nerve & artery into mental and incisive branches.
• The ossifying membrane is lateral to the Meckels’ cartilage & its accompanying neuromascular bundles.
• Ossification spreads from the primary center below & around the inferior alveolar nerve & its incisive
branches, upwards to form a trough for developing teeth.
• The spread of the intramembraneous ossification dorsally & ventrally
forms the body & ramus of the mandible.
• Meckels cartilage becomes surrounded & invaded by the bone.
• Ossification stops dorsally at a site that forms the mandibular lingula.
• The neuromascular bundle ensures formation of the mandibular &
mental foramen.

61. SECONDARY GROWTH CARTILAGES
 Further growth of the mandible till birth is influenced by the formation
of three secondary cartilage.
CONDYLE CORONOID SYMPHYSEAL

62.  Condyle:
 At 5th week of IUL- area of mesenchymal condensation is seen above ventral
part of developing mandible .
 At 10th week- develops in a cone shaped cartilage.
 At 14th week- ossification starts
 At 4 months – migrates inferiorly and fuses with ramus.
 Most of cartilage forms bone but its upper end persists acting as growth &
articular cartilage.

63.  Coronoid:
 At 10-14 weeks of IUL- secondary accessory cartilages appear.
 This secondary cartilage grows as a result of developing Temporalis muscle.
 These accessory cartilage becomes incorporated into expanding intramembranous
bone of ramus & disappears before birth.
 Mental region:
 On either side of symphysis 1 or 2 small cartilages appear and ossify in 7 month
of IUL to form variable number of mental ossicles in the fibrous tissue of
symphysis.
 These ossicles becomes incorporated into the body of the mandible.
 Symphysis ossify after 1 year after birth.

64. DEVELOPMENTALANOMALIES OF MANDIBLE
 Agnathia:
 Mandible is grossly deficient or absent
 Deficiency of neural crest tissue in the lower face
 Can occur in combination with the absence of the hyoid bone ( i.e. 1st and 2nd arch
syndrome)
 Lethal combination
 Multiple defects of the eye and maxilla
 Well developed low-set ears and auditory ossicles suggest that ischaemic necrosis of
mandible and hyoid bone occurs after the formation of ear

65.  Micrognathia:
 Small mandible
 Defective neural crest production, migration, or destruction leads to hypoplastic mandible
 Pierre Robin Syndrome
 Cri-du-chat syndrome
 Progeria
 Downs syndrome
 Turners syndrome
 Bifid or double condyle:
 Results from the persistence of septa dividing the fetal cartilage
 Macrognathia:
 Large mandible
 Prognathism
 Acromeagly
 Congenital hemifacial hyperthrophy:
 Evident at birth but tends to increase at puberty

66. DEVELOPMENT OF MAXILLA
 Develops from the center of ossification in the mesenchyme
of the maxillary process.
o No primary cartilage exist
oCenter of ossification is closely associated with the cartilage of the nasal septum
oPrimary centre of ossification develop near the division of inferior orbital nerve into the
anterior superior nerve
o From the center of ossification the bone formation extends posteriorly towards the
developing zygoma and anteriorly towards the incissor region.
o ossification spreads superiorly to form the central process of maxilla
o A bony trough is formed further in infra orbital nerve
o From this trough lateral alveolar plate forms for the developing tooth germ

67.  Ossification spreads into the palatine process to form the hard palate
 Median alveolar plate develops from the palatal process
 Median and lateral alveolar plate form the trough for the tooth germ.

68. CONCLUSION

69. REFRENCES
 Human embryology: 8th edition : Inderbir Singh
 Larsen’s Human embryology: 4th edition
 Craniofacial embryology: 4th edition : G.H. Sperber
 Before we were born: Moore Persaud