Development of Face, oral cavity and pharyngeal arches

1. Development of the Face, Oral
Cavity & Pharyngeal arches
Dr.Mangesh Andhare
Post graduate student
Dept. of periodontology

2. Development of the Face

3. • The development of the face occurs mainly between 4
– 8 weeks
• The lower jaw (mandible) is the first to form (4th week)
• The facial proportions develop during the fetal period
(9th week to birth)
• During infancy & childhood, following the
development of teeth and paranasal sinuses, the facial
skeleton increases in size and contribute to the
definitive shape of the face

4. Embryo at 4 - 5 weeks (Lateral view)

5. Early in the 4th week, five primordial swellings consisting
primarily of neural crest-derived mesenchyme appear
around the stomodeum and play an important role in the
development of face
Stomodeum
1 Frontonasal prominence
2 Maxillary prominences
2 Mandibular prominences

6. • The single frontonasal
prominence ventral to the
forebrain
• The paired maxillary
prominences develop from
the cranial part of first
pharyngeal arch
• The paired mandibular
prominences develop from
the caudal part of first
pharyngeal arch
Lateral view

7. • The mesoderm of the
five prominences is
continuous with each
other
• There is no internal
division corresponding
to the grooves
demarcating the
prominences externally

8. Stomodeum
• An ectoderm lined depression
• Separated from the primitive pharynx by the
buccopharyngeal (oropharyngeal) membrane
• The membrane later breaks down and stomodeum opens
into the pharynx
Forms the vestibule
of the oral cavity

9. • By the end of 4th week,
bilateral oval-shaped
ectodermal thickenings
called ‘nasal placodes’
appear on each side of the
lower part of the
frontonasal prominence
• Nasal placodes are
primordia of the nose and
nasal cavities.
Frontonasal
prominence

10. • Mesenchymal cells proliferate
at the margin of the placodes
and produce horse-shoe
shaped swellings around these.
• The sides of these swellings
are called ‘medial’ and
‘lateral’ nasal prominences
• The placodes now lie in the
floor of a depression called
‘nasal pits’
Each lateral nasal prominence is separated from the
maxillary swelling by nasolacrimal groove

11. • The maxillary prominences
continue to increase in size
and:
• Laterally, merge with the
mandibular prominences to
form the cheek
• Medially, compress the medial
nasal prominences toward the
midline and finally fuses with
these to form the upper lip.
The upper lip is formed by the two medial nasal
prominences & the two maxillary prominences

12. The medial nasal swellings
enlarge, grow medially and
merge with each other in the
midline to form the
intermaxillary segment
Human embryo: 7 weeks

13. Intermaxillary Segment
Gives rise to the:
• Philtrum of lip
• Premaxillary part of the
maxilla, that bears the
upper 4 incisors and the
associated gums
• Primary palate (region
of hard palate just
posterior to the upper
incisors)

14. Besides the fleshy derivatives, the facial
prominences also give rise to bones of the facial
skeleton
The mesenchyme from the
1st & 2nd pairs of
pharyngeal arches invade
the facial prominences and
give rise to the muscles of
mastication and muscles of
facial expression
respectively

15. The frontonasal
prominence forms the:
 Forehead and the bridge of
the nose
 Frontal and nasal bones
The maxillary prominences form the:
 Upper cheek regions and most of the upper lip
 Maxilla, zygomatic bone, secondary palate
Derivatives of Facial Components

16. The mandibular
prominences fuse and form
the:
 Chin, lower lip, and
lower cheek regions
 Mandible
The lateral nasal prominences form the alae of the
nose
The medial nasal prominences fuse and form the
intermaxillary segment

17. Development of the Nasal Cavity

18. • With the formation of the
medial and lateral nasal
prominences, the nasal
placodes lie in the floor of
depressions called the
nasal pits
• By the end of 6th week,
nasal pits deepen and form
nasal sacs
• Each nasal sac grows
dorsocaudally, ventral to
the developing brain

19. • Initially the nasal sacs
are separated from the
oral cavity by oronasal
membrane.
• The oronasal
membrane ruptures by
the 7th week,
communicating the
primitive nasal
cavities with the oral
cavity

20. • These communications
are called the primitive
choanae and are located
posterior to the primary
palate
• After the development of
the secondary palate, the
choanae change their
position and become
located at the junction of
nasal cavity and the
pharynx

21. • The nasal septum
develops as a
downgrowth from the
internal parts of merged
medial nasal
prominences
• Fuses with the palatine
process in 9-12 weeks,
superior to the hard
palate primordium

22. • The superior, middle
and inferior conchae
develop on the lateral
wall of each nasal cavity
• The ectodermal
epithelium in the roof of
each nasal cavity
becomes specialized as
the olfactory epithelium

23. • The olfactory cells of
the olfactory
epithelium give
origin to olfactory
nerve fibers that grow
into the olfactory
bulb

24. Nasolacrimal duct
• Develops from a rod-like thickening of the ectoderm in the floor
of the nasolacrimal groove
• This solid cord of cells separates from the surface ectoderm and
lies in the underlying mesenchyme
• The cord gets canalized to form the nasolacrimal duct
• The cranial end of the duct expands to form the lacrimal sac
• The caudal end opens into the inferior meatus of the nasal cavity
• The duct is usually becomes completely patent only after birth
• Failure of complete canalization of the duct leads to atresia of the
duct (seen in about 6% of newborn infants)

25. Development of Palate
(Palatogenesis)

26. The palate develops from two primordia:
• The Primary palate
• The Secondary palate
• Begins at the end of the 5th week
• Gets completed by the end of the 12th week
• The most critical period for the development
of palate is from the end of 6th week to the
beginning of 9th week
Palatogenesis

27. The Primary Palate
• Begins to develop:
 Early in the 6th week
 From the deep part of
the intermaxillary
segment, as median
palatine process
• Lies behind the
premaxillary part of the
maxilla
• Fuses with the developing
secondary palate

28. The primary palate represents only a small
part lying anterior to the incisive fossa, of the
adult hard palate
Hard palate
Primary
palate
Soft palate
Secondary
palate

29. The Secondary Palate
• Is the primordia of hard
and soft palate posterior
to the incisive fossa
• Begins to develop:
 Early in the 6th week
 From the internal
aspect of the
maxillary processes,
as lateral palatine
process

30. • In the beginning, the
lateral palatine
processes project
inferomedially on each
side of the tongue
• With the development
of the jaws, the tongue
moves inferiorly.
• During 7th & 8th weeks,
the lateral palatine
processes elongate and
ascend to a horizontal
position above the
tongue
Tongue

31. • Gradually the lateral
palatine processes:
 Grow medially and
fuse in the median
plane
 Also fuse with the:
• Posterior part of
the primary palate
& nasal septum

32. • Fusion with the nasal
septum begins
anteriorly during 9th
week, extends
posteriorly and is
completed by 12th week
Bone develops in the
anterior part to form the
hard palate. The posterior
part develops as muscular
soft palate

33. Changes in Face during Fetal period
• Mainly result from changes in the
proportion & relative positioning of
facial structures
• In early fetal period the nose is flat and
mandible underdeveloped. They attain
their characteristic form during fetal
period
• The enlargement of brain results in the
formation of a prominent forehead
• Eyes initially appear on each side of
frontonasal prominence move medially
• Ears first appear on lower portion of
lower jaw, grow in upper direction to
the level of the eyes

34. DEVELOPMENT OF TONGUE
The tongue begins to develop at about 4 weeks. The oral part (anterior
two-thirds) develops from two distal tongue buds (lateral lingual
swellings) and a median tongue bud (tuberculum impar) [1st branchial
arch].
Innervation: V nerve
The pharyngeal part develops from the copula and the hypobranchial
eminence [2nd, 3rd and 4th branchial arches].
Innervation: IX cranial nerve
The line of fusion of the oral and pharyngeal parts of the tongue is
roughly indicated in the adult by a V-shaped line called the terminal
sulcus.
At the apex of the terminal sulcus is the foramen cecum.
Muscles of the tongue develop form the occipital somites and
innervated by hypoglossal nerve

35. Lingual swelling
Tuberculum impar

36. Pharyngeal Arch Nerve Muscles Skeleton
1. Mandibular
(maxillary ,mandibular
processes)
Trigeminal:
maxillay &
mandibular
divisions
Mastication;
mylohyoid; anterior
belly of digastric,
tensor palatine,
tensor tympani
Premaxilla, maxilla,
zygomatic bone,part
of temporal bone,
Meckel’s cartilage,
mandible malleus,
incus,anterior
ligament of malleus,
sphenomadibular
lig.
2. Hyoid Facial n Facial expression,
posterior belly of
digastric,
stylohyoid,
stapedius
Stapes, styloid
process, stylohyoid
ligament, lesser horn
& upper portion of
body of hyoid
3. Glossopharyngea
l
Stylopharyngeus Greater horn &
lower portion of
body of hyoid bone
4-6 Vagus
Superior
laryngeal (n to 4th
Cricothyroid, levator
palatine, constrictors
of pharynx
Laryngeal cartilages

38. Fate of the Pharyngeal Grooves and Pouches
First groove and pouch: external auditory meatus
tympanic membrane
tympanic antrum
mastoid antrum
pharyngotympanic or eustachian tube
2nd, 3rd and 4th grooves are obliterated by overgrowth of the second
arch forming a cervical sinus – if persists forms the branchial fistula
that opens into the side of the neck extending form the tonsillar sinus
2nd pouch is obliterated by development of palatine tonsil
3rd pouch: dorsally forms inferior parathyroid gland
ventrally forms the thymus gland by fusing with the
counterpart from opposite side

39. 4th pouch: dorsal gives rise to the superior parathyroid gland
ventral gives rise to the ultimobranchial body (which
gives rise to the parafollicular cells of the thyroid gland)
5th pouch in humans is incorporated with the 4th pouch

40. Anomalies related to Face,
Nose & Palate

41. Facial clefts
Failure of the embryonic facial
prominences to fuse properly
• May be unilateral or bilateral
• May involve:
 Lips only: Cleft lip
 Palate only: Cleft palate
 Lip & palate: Cleft lip & palate
 Region of nasolacrimal groove:
Facial clefts
Lead to
difficulty in
breathing
feeding
sucking
swallowing
&
speech

42. • Median cleft lip: results from
failure of the medial nasal
prominences to merge and form
the intermaxillary segments
• Unilateral cleft lip: result from
failure of the maxillary
prominence to merge with the
medial nasal prominence on the
affected side
• Bilateral cleft lip: results due to
failure of maxillary prominences
to meet and unite with the medial
nasal prominences on both sides
Median Cleft lip
Unilateral cleft lip
Bilateral cleft lip

43. 2. Oblique facial cleft: results
from failure of the maxillary
prominence to fuse with the
lateral nasal prominence
3. Cleft palate leaves the nasal
and oral cavities connected &
results in nursing problem for
the new born
May be:
 Anterior/posterior to incisive
foramen
 Unilateral/bilateral
 Isolated/associated with cleft
lips
Cleft lip, cleft jaw &
cleft palate
Oblique facial cleft

44. Cleft lip coupled with clefts of the anterior
palate or entire palate.

46. • Gnathochisis- failure of central fusion of
mandibular prominences
• Micrognathia-underdevelopment of lower jaw,
incorrect positioning of ear.
• Agnathia- total lack of development of lower
jaw & incorrect positioning of ear.
• Failure of maxillary prominence to fuse with
median nasal prominence results in unilateral
or bilateral cleft palate

47. SUMMARY OF STRUCTURES
CONTRIBUTING TO
FORMATION OF THE FACE
PROMINENCE STRUCTURES FORMED
Frontonasal* Forehead, bridge of nose, medial and
lateral nasal prominences
Maxillary Cheeks, lateral portion of upper lip
Medial nasal Philtrum of upper lip, crest & tip of nose
Lateral nasal Alae of nose
Mandibular Lower lip

48. What matters most is how you see yourself …
Thank U
&
Good luck