Craniofacial growth is a complex and a beautiful phenomenon. It all begins when a sperm cell fuses with an egg cell, a process called fertilization. Human fertilization is the union of a human egg and sperm, usually occurring in the ampulla of the fallopian tube. The result of this union is the production of a ’Zygote’ cell, or fertilized egg, initiating prenatal development Prenatal growth can be divided into 3 main stages: Germinal stage: From ovulation to implantation(0-2 weeks). Embryonic stage : 3rd week to 8th week. Fetal stage: 9th week till birth.

1. Growth and Development of
Facial Structures
Guided by-Dr. Jeevan M. Khatri sir
(Professor & HOD)
Dept. of Orthodontics and Dentofacial Orthopaedics
Presented by-Dr. Krutika A. Patankar (1st YR MDS)

2. Contents:
• Introduction
• Embryology
• Pre-natal development of facial structures
• Post-natal development of facial structures
• Conclusion
• References

3. Introduction:
• Craniofacial growth is a complex and a beautiful phenomenon.
• It all begins when a sperm cell fuses with an egg cell, a process called
fertilization.
• Human fertilization is the union of a human egg and sperm, usually
occurring in the ampulla of the fallopian tube. The result of this union
is the production of a ’Zygote’ cell, or fertilized egg, initiating prenatal
development
• Prenatal growth can be divided into 3 main stages:
1) Germinal stage: From ovulation to implantation(0-2 weeks).
2) Embryonic stage : 3rd week to 8th week.
3) Fetal stage: 9th week till birth.

5. Let’s start from the very beginning….
• A zygote is the single cell formed when an egg and a sperm cell
fuse; the fusion is known as fertilization
• The first 12-to 24-hours after a zygote is formed are spent
in cleavage – very rapid cell division.

6. Blastulation and cell differentiation:
• During blastulation, the mass of cells forms a hollow ball
• Cells begin to differentiate, and form cavities

7. The outermost layer of the sphere is the trophoblast. Inside the sphere are two
spaces that are each lined by either the hypoblast or the epiblast. The point where
the epiblast and hypoblast press up against each other is known as the bilaminar
disc, and this disk is what splits the sphere to make the two cavities.

8. Gastrulation:
• During gastrulation the three germ layers form; the cell mass is now known as a
gastrula.
• Week 3 of development is the week of gastrulation. A germ layer is a layer of cells
that will go on to form one of our organizational tubes.
• The three germ layers that will translate into these tubes are the ectoderm,
the mesoderm, and the endoderm.

9. Primitive streak:
• Gastrulation begins with the formation of the primitive streak.
• The primitive streak is a linear band of thickened epiblast that first appears at
the caudal end of the embryo and grows cranially. At the cranial end its cells
proliferate to form the primitive knot (primitive node). With the appearance of
the primitive streak it is possible to distinguish cranial (primitive knot) and caudal
(primitive streak) ends of the embryo.

10. Notochord:
• Directly beneath the primitive streak the mesoderm (the middle germ layer)
forms a thin rod of cells known as the notochord. The notochord helps define the
major axis of our bodies, and is important in inducing the next step of
embryogenesis.The notochord is a defining feature of the Chordate phylum, and
will eventually become our intervertebral discs.

11. Neurulation:
• The notochord induces the formation of the neural plate
• The neural plate folds in on itself to make the neural tube and neural
crest

12. Neural crest cells:
• The neural crest is sometimes called the fourth germ layer, because the cells that
become the sympathetic and parasympathetic nervous systems, melanocytes,
Schwann cells, even some of the bones and connective tissue of the face.

13. • The tissue of the face,both hard and soft tissues,are of
neural crest cell in origin.
• They have great migrating capacity and though they are of
ectodermal origin,they exibit mesenchymal properties and
thus they are also called ectomesenchyme.
• They give rise to diverse structure both near the site of their
origin and at remote places.
• In the head and neck region,the neural crest cells give rise to
facial processes,the branchial arches and their
catilages,osteobleast,ganglia of autonomic nervous
system,leptomeninges,melanocytes etc.

14. Development of facial structures:
• The most typical feature in the development of the head and neck is formed by
the pharyngeal or branchial arches.
• These arches appear in the 4th and 5th weeks of development and contribute to
the characteristic external appearance of the embryo.
• Initially there are bars of mesenchymal tissue separated by deep clefts known as
pharyngeal or branchial clefts .

15. • With the development of the arches and clefts ,a number of
outpocketings arise ,the pharyngeal pouches .
• Although the development of pharyngeal arches ,clefts ,and pouches
resembles formation of gills in fish and amphibia,in the human embryo;
real gills (branchia)are never formed.
• Therefore the term pharyngeal has been adapted.

16. Prenatal growth of maxilla

17. Frontonasal process
• At around 21 days after conception, the head begins to take shape. The
migrating neural crest cells form two streams when they encounter the
lens placode. The anterior stream of cells forms the mesenchyme of the
frontonasal process and the posterior stream migrates to form the
structures of the branchial arches.
• Between 3rd and 8th week of intrauterine life (IUL), most of the
development of the face takes place. At around 4th week of IUL, the
branchial arches begin to develop.
• The developing forebrain, the prosencephalon, forms downward projection
called the frontonasal process which overhangs the primitive oral cavity or
the stomodeum.
• The stomodeum at this stage is not opened to the environment but closed
by a bilaminar membrane called the buccopharyngeal or oropharyngeal
membrane. This is a temporary structure which is formed by the mucosa of
the pharynx on the inside (endoderm) and mucosa of the mouth on the
outside (ectoderm). This is one of the two sites where there is no
intervening mesoderm; the other site being the cloacal membrane.
• The buccopharyngeal membrane ruptures at about 28th day of IUL. This
establishes the continuity of passage between the mouth and pharynx.

19. Branchial arches:
• The branchial arches, developing during the late somite period, are formed
from the mesoderm of the ventral foregut. The mesoderm segments to
form five bilateral mesenchymal swellings.
• There are five pairs of branchial arches, the fifth being transitory. The
branchial arches are separated by four branchial grooves on the external
aspect and corresponding five pharyngeal pouches on the internal aspect
of the gut.
• The first arch is the mandibular arch and the second arch is the hyoid arch.
The jaws of the face, e.g. maxilla and mandible, are derived from the first
arch.
• In the meanwhile, the frontonasal process of the forebrain just above the
stomodeum develops bilateral thickenings called nasal placode. In the
middle, there is invagination of the placode to form nasal pits.
• On both sides of the nasal pits, there are elevations, which are medial and
lateral nasal processes.

21. Maxillary process:
• By about 4th week of IUL, facial process arises from the first arch which corresponds to
the mandibular processes. Later, the mandibular processes give two more swellings,
which grow ventromedially. These are the maxillary processes.
• By about 6th week, the processes of the face are easily discernible. The stomodeum is
bound by the frontonasal process above, the mandibular process below and the sides
being occupied by the maxillary processes. The stomodeum is very wide at this stage but
as the development of the various processes proceeds, it narrows and forms the mouth.
• The maxillary process grows ventromedially towards the nasal processes. The maxillary
process fuses with the lateral nasal process and migrates medially to contact the
inferolateral side of the medial nasal process.
• The maxillary and the medial nasal processes are initially separated by the epithelial
nasal fin, which soon degenerates so that the mesenchyme of the two processes can
fuse. The maxillary and mandibular processes fuse at the sides to form the cheek tissue.
• The lateral nasal process forms the alae of the nose. The medial nasal process of both
sides fuses to form the globular process in the middle which gives rise to the tip of the
nose, columella, the philtrum, the labial tuberculum of the upper lip, the frenulum and
the entire primary palate.
• The maxillary process forms the alveolus, which bears teeth distal to the canines and the
secondary palate.
• The area of fusion of the maxillary and mandibular processes forms the
commissures/corners of the mouth. As the two processes grow towards the fellow of the
opposite side, the stomodeum is narrowed.

23. Prenatal growth of palate
The palate develops from two primordia:
• The Primary palate
• The Secondary palate

24. • The development of 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 .
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

25. • The primary palate represents only a small part lying anterior to the
incisive fossa, of the adult hard palate .

27. 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

28. • 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

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

30. • Fusion with the nasal septum begins anteriorly during 9 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

31. Prenatal growth of mandible:
• Mandible is the only movable bone of all the bones of the face. Mandible is a
horseshoe-shaped bone with the following parts:
• a. Body of the mandible b. Ramus
• c. Condylar process consisting of the head and neck; the head articulates with the
glenoid fossa for the formation of the temporomandibular joint (TMJ)
• d. Coronoid process e. Alveolar process
• Mandible is derived from the first branchial arch, which is called the mandibular
arch. The branchial arches start developing at about 4th week in utero.

32. Branchial arches and their components
• Branchial arches are bilateral mesodermal swellings that develop at around 4th
week in utero. The mesodermal core of each arch is surrounded by invasion of
the ectomesenchymal tissue that augments it.
• There are five branchial arches in total; the fifth being transitory. The first arch is
the mandibular arch and the second arch is the hyoid arch.
• The branchial arches are separated by the four branchial grooves on the external
aspect and five pharyngeal pouches in the inner aspect of the foregut.
• Each branchial arch has the following components:
• A central cartilage rod that forms the skeleton of the arch.
• A muscular component called the branchiomere.
• A vascular component, consisting of an aortic arch artery running around the
pharynx from the ventrally located heart to the dorsal aorta.
• A nervous element, consisting of sensory and special visceral motor fibres of
one or more cranial nerves supplying the mucosa and the branchial muscle arising
from that arch.
• The cartilage of the first arch is called Meckel’s cartilage developing at about 41st
to 45th day in utero. The Meckel’s cartilage provides a template for the
development of mandible.

34. • The mandible starts its development as a swelling, which grows ventromedially to
approach the fellow of the opposite side.
• In the mean time, it gives off a bud for the maxillary arch. By the time the
mandibular swelling is developing, the downward growth of the forebrain can be
visualized as the frontonasal process, which overhangs the stomodeum or the
primitive oral cavity. The floor of the stomodeum is covered by the
buccopharyngeal membrane.
• By the 5th week of IUL, the mandibular processes of both sides approach each
other and are fused. The Meckel’s cartilage extends from the area of future ear to
the midlines of the fused mandibular processes.
• At about the 6th week, the cartilaginous rods begin to chondrify which is
continuous from the malleolus region to the future symphysis. The rods are
separated in the midline. The rods support the forming skeletal framework of the
mandible.
• The part of mandible mesial to the mental foramen undergoes endochondral
ossification, whereas lateral to the mental foramen undergoes intramembranous
ossification.
• The process of ossification proceeds anteriorly and posteriorly. Posterior
intramembranous ossification forms the rest of the body and the ramus of the
mandible.

35. Development of condyle and coronoid process:
• The formation of condylar process starts only at the 10th week;
hence, till such time malleus and incus function as a temporary joint
with the glenoid fossa of the temporal bone to permit mandibular
movements.
• The Meckel’s cartilage is replaced largely by bone, and the remnant of
it is left as the bones malleus and incus and the soft tissue part
sphenomandibular ligament. Ossification centre is present at the site
of future mental foramen.
• The condylar cartilage is a secondary cartilage and its origin is
unrelated to the Meckel’s cartilage, which is a primary cartilage. The
condyle arises as a separate mesenchymal condensation that is cone-
shaped at about 10th week of IUL.
• The process of ossification does not start till 14th week. The cartilage
is replaced by bone except the region of the tip of the head of the
condyle superiorly which is maintained till teens for future growth.

36. • Now that condyle is established, the TMJ is shifted anteriorly.
• The growth of the mandible at about 7th week to permit elevation of the palatal
shelves is largely contributed by the growth of the Meckel’s cartilage.
• The ossification of the ramus proceeds and the condyle is soon fused to the
mandible at about 16 weeks.
• Coronoid process develops from secondary cartilage that arises at about 10th–14th
week in utero. Soon the growing intramembranous ossification fuses the coronoid
process to the ramus.
• One or two cartilaginous fragments in the region of the mental foramen ossify and
become fused with bone at 7th month of IUL.
• The ossification centre is at the site of future Meckel’s cartilage, one on either side.
Ossification proceeds anteriorly and posteriorly from here and stops at the site of
future lingula.

37. Development of ear:
• The three parts of the ear -External
-Middle and Internal ,arise from separate ,diverse embryonic origins .

38. • The external ear forms around the first branchial groove which
deepens to become the external acoustic meatus .
• Malleus and Incus are derived from the dorsal end of the first
branchial arch cartilage –MECKEL’S CARTILAGE.
• Stapes arise from the dorsal end of the second branchial arch
cartilage- REICHERT’SCARTILAGE .
• This is the first sensory organ to begin development .

39. Development of eye:
• The light sensitive portion of the eye retina ,is the outgrowth from the forebrain
,projecting bilaterally as the optic vesicles which are connected to the brain by
the optic stalks, this results in a thickening called as lens placodes.
• These placodes invaginates in it’s centre by the development of peripheral folds .
• The optic vesicles invaginate partly to form the double layered optic cusps and
the optic stalk becomes the optic nerve .
• The outer layer of the optic cup acquires pigmentation to become the pigmented
layer of the retina.

40. Development of upper and lower lips:
• Lower lip :The mandibular processes of the two sides grow towards
each other and fuse in the midline ,they form the lower margin of the
stomatodeum .
• Upper lip :Each maxillary process now grows medially and fuses, first
with the lateral nasal process and the with the medial nasal process.

41. • The mesodermal basis of the lateral part of the lip is formed from the
maxillary process.
• The overlying skin is derived from the ectoderm covering this process
• The mesodermal basis of the medial part of the lip(PHILTRUM)is
formed from the frontonasal process .
• The muscles of the face (including those of the lips)are derived from
the 2nd branchial arch and are supplied by the facial nerve.

42. Development of tongue:
• The tongue appears in the embryo of approximately 4 weeks in the form of two
lateral lingual swelling and one medial swelling –TUBERCULUM IMPAR .
• The three swellings orginate from the 1st pharyngeal arch.
• As the 3 swellings increase in size ,they overgrow the tuberculum impar and
merge with each other thus forming the anterior two thirds or the body of the
tongue.

44. Post natal growth of maxilla:
• Maxilla is a membranous bone and the development/growth of maxilla is
completed early when compared to the mandible.
• According to the cephalocaudal gradient of growth, growth does not
proceed proportionately in the human.
• The best example of this phenomenon is the growth of head which being
cranial part of the body occupies about 50% of the body length in utero but
during birth it is reduced due to the growth of the other caudal structures
and in adult life head occupies only 8% of the body length.
• The rationale is that head completes its growth early while all other
structures, like trunk and limbs, catch up later.
• So is the case of maxilla, it completes its growth early in life in certain
aspects, relative to the mandible.
• The maxilla (especially width) also follows closely the neural growth curve
more than the general growth curve in the Scammon’s curve.

45. Anatomy of Maxilla Sutures of Maxilla

48. Mechanism of growth of different parts of Maxilla:

49. Post natal development of Palate:
• Postnatal growth of the palate follows the concept of expanding ‘V’ by Enlow.
Many of the cranial bones have a V-shaped configuration. The process of growth
by this concept does not follow the arbitrary rule of apposition on one surface
and resorption on the other. It is more complex.
• Growth at the midpalatal suture
• Growth at the suture by bone fill-in contributes more to the increase in width of
the palate than remodelling. The growth of width of the palate also increases by
the growth of the alveolar process which diverges out.

50. Palate as ‘V’
• In the young child, the maxillary arch and the nasal floor are very close to
the inferior orbital rim. By deposition on the palatal periosteal surface and
resorption on the nasal floor, the palate comes to occupy a lower position.
• When viewed in the cross-section, the deposition of the bone occurs along
the whole of the periosteal surface of the palate in such a way that the
bone expands in a lateral direction and also downwards.
• The nasal floor due to resorption increases in volume and descends down
from the level of infraorbital rim.
• In conjunction with the V principle, half of the external surface involved in
this growth is depository and half resorptive; thus, half of the bone tissue
of the palate is endosteal and half is periosteal.
• Even in the anteroposterior growth of the palate/midsagittal section of the
palate, the same concept is seen. There is deposition on the palatal surface
and resorption along the anterior surface/incisor area and superior
surface, expanding the palate like a V.

52. Postnatal growth of mandible :
Mandible at birth
• Mandible at birth is much smaller in size and there is slight variation in
shape from the adult form. The infant mandible has a short more or less
horizontal ramus with obtuse gonial angle. The condyles are low and at the
position of the occlusal plane. The symphyseal suture has not ossified.
Growth in the first year
• The growth of mandible in the first year of life involves growth at the
symphyseal suture and lateral expansion in the anterior region to
accommodate the erupting anterior teeth. The mental foramen is directed
at right angle to the surface of the corpus.
• There is increased deposition in the posterior surface of the ramus of the
mandible.
• The infant mandible is suited for the suckling activity since the condyle and
the glenoid fossa is flat, which helps in the anteroposterior movement of
the mandible.

53. Mandible in the adult is different from the mandible of an infant. The
ramus is longer and the gonial angle is less obtuse. The bone is larger
on the whole and the condyle is well developed.

54. V principle of growth: Mandible
• All these changes take place with the growth of the mandible in the
form of an expanding V (Fig. 5.8). It is easier to visualize mandible as
the V-shaped bone than the maxilla because of its horseshoe shape.

55. • The growth of the mandible in length anteroposteriorly is by the
deposition of bone at the posterior surface of the ramus and
resorption of the leading edge of the anterior surface (Fig. 5.9). This
helps to lengthen mandible so that the anterior part of the ramus is
occupied by the posterior part of the body in the future and to
accommodate the developing permanent molars.
• As the mandible grows posteriorly, it is displaced anteriorly because
the articulation of the condyle to the glenoid fossa is constant and the
change in length can take place only by the anterior displacement. As
the mandible grows anteriorly, the opening of the mental foramen
faces backwards so that the neurovascular bundle leaves the foramen
directed backwards.
• There is corresponding surface remodelling at the anterior border
with deposition in the posterior surface of the symphysis and
resorption in the superior part of the anterior surface and deposition
in the inferior aspect.

56. The growth of mandible is largely influenced by the functional matrices and
condylar cartilage has little influence in its overall growth.

57. Mechanism of growth of different parts of mandible:

58. Post natal growth of condyle:
• Condylar cartilage covers the surface of the mandibular condyle at the TMJ.
• The individual condyle remodels according to the expanding V principle.
• Condylar cartilage can be visualized as being positioned on the inner aspect of
the expanding V.
• Neck of the condyle is lengthened by the reduction of the bone situated on the
side of the V, away from the direction of the growth

59. Conclusion:
• Growth and development of craniofacial structures is a complex and a beautiful
phenomenon.

60. References:
• William R Proffit, Henry Fields, David M Server; Contemporary
Orthodontics, 5th edition
• Graber, Vanarsdall, Vig; Orthodontics - Current principles and Techniques
• Enlow & Hans- Essential of facial growth, 1st edition.
• ORTHODONTICS-Sridhar Premkumar,3rd edition.
• Color atlas of embryology –Ulrich drews.
• Langman’s medical embryology-Sadler.
• Netter’s atlas of human embryology.
• Cochard -Human embryology –Inderbeer singh.
• Craniofacial embryology –Sperber.
• Cleft lip and craniofacial anomalies –Ann kummer.

61. THANK YOU