The document summarizes the development of the oral cavity and face from the 4th week of embryonic development. It discusses how the frontonasal process, nasal placodes, maxillary processes, and mandibular processes give rise to different structures of the face. It also describes the development of the palate from palatal shelves growing from the maxillary processes that later fuse together.

1. DEVELOPMENT OF
ORAL CAVITY AND FACE
Submitted to:
Dr. Sarabjeet Kaur
Assistant Professor
Submitted by:
Samidha Arora
First year MDS student

2. • Introduction
• General embryology
• Pharyngeal arches
• Development of head
• Development of face
• Derivation of different parts of face
• Development of mouth
• Development of palate
• Development of mandible
• Development of maxilla
• Development of tongue
• Development of salivary glands
• Conclusion

3. An indiviual spends 9 months or 266 days nearly of life in his mother's
womb. Human development is a continuous process and does not stop
even after birth.
Anatomical structures are more diverse in tha mouth than in any other
region of our body.
The human face is a fascinating study of physiology and psychology. The
amount of information a human face can relay is unending. Face is the
mirror of one’s personality.

4. • It is our most useful and most underestimated tool for
communication. Face is the most beautiful and attractive part of body
which is most likely to develop malformations.
• So, the knowledge of normal development of face will aid in
understanding the potential reasons for preventing or treating of
anamolies.
• Human face begins to form during the 4th week of embryonic
development.
• By the 6th week,the external face is completed.
• Between 6th & 8th week ,development of palate subdivides nasal and
oral cavity.

5. Differentiation is the change from a generalized cell or
tissue to one that is more specialized. It is change in
quality or kind.
Development is progress towards maturity - Todd

6. • Increase in size, change in proportion and progressive complexity-
Krogman
• An increase in size -Todd
• Change in any morphological parameter which is measurable - Moss
• Increase in size, change in proportion and
progressive complexity - Krogman
• An increase in size - Todd
• Change in any morphological parameter which is
measurable - Moss

7.  Process by which one cell divides to give 2 daughter cells that are
genetically identical to the parent cell.
 Parent cell → each chromosome replicates its DNA
 DNA spread diffusely through the nucleus, they can not be
recognized by light microscopy.
 Onset of mitosis →chromosome begin to coil, contract and condense
(beginning of Prophase)

8.  At prometaphase, chromatids become distinguishable.
 During metaphase chromosome line up in equatorial plane, doubled
structure is clearly visible.
 Centromere of each chromosome divides( beginning of Anaphase)
migration of chromatids to opposite poles
 During Telophase - Chromosome uncoil & lengthens, Nuclear
envelop reforms, Cytoplasm divides.

10.  Cell division that takes place germ cells to generate gametes.
 Meiosis I: Germ cells (spermatocyte or primary oocyte) →replicate
their DNA so that each of 46 chromosomes is duplicated into sister
chromatides→ homologous chromosomes then align themselves i in
pairs, a process known as SYNAPSIS → Homologous pair then
separate into 2 daughter cells
 Meiosis II: These cells are haploid—have just one chromosome from
each homologue pair—but their chromosomes still consist of two
sister chromatids. In meiosis II, the sister chromatids separate,
making haploid cells with non-duplicated chromosomes.

14.  Occur in ampullary region of uterine tube
(Widest tube).
 From cervix to oviduct sperm move by their
own propulsion (assisted by uterine cilia) it
takes 2-7 hours.
 At isthmus, sperm become less motile.
 At ovulation, chemoattractants produced by
oophorus cells causes sperm to move
 Sperm reach ampulla where fertilization
occurs.

15. The phases of fertilization include
 Phase 1, penetration of the
corona radiata
 Phase 2, penetration of the zona
pellucida
 Phase 3, fusion of the oocyte
and sperm cell membranes

17. • The 2 cells formed (ZYGOTE) undergoes a series of divisions.
• One cell divides first so that we can have a 3 cell stage of the
embryo followed by the 4 cell stage , a 5 cell stage.
• This process of subdivision of the ovum into smaller cells is
called cleavage.
• Cleavage proceeds the ovum comes to have 16 cells . Its looks
like a mulberry and is called Morula.

18. When morula enters uterine cavity,fluid
begins to penetrate through zona
pellucida into intercellular spaces of
inner cell mass.
It results in a cavity, blastocele. Now
embryo is called blastocyst.
Inner cell mass called as embryoblast
and outer cell mass as trophoblast.

19.  Trophoblast cells over the
embryoblast pole begin to penetrate
between epithelial cells uterine
mucosa about 6th day.
 Hence by the end of 1st week of
development the human zygote has
passed through the morula and
blastocyst and has begun
implantation.

21.  Blastocyst is partially embedded in endometrial stroma.
 Trophoblasts present over embryoblast differentiate into
cytotrophoblast
syncytiotrophoblast
 Embryoblasts also differentiate into ,
Layer of small cuboidal cells adjacent to blastocyst cavity hypoblast layer.
A layer of high columnar cells adjacent to amniotic cavity,epiblast layer.

22.  Together they form flat bilaminar disc.
 At same time, small cavity appears with in epiblast, it enlarges to become
amniotic cavity.

23.  Flattened cells originating from hypoblast form a
thin membrane, the exocoelonic (heuser’s)
membrane that lines the inner surface of
cytotrophoblast
 Now cavity lined by hypoblast and heuser’s
membrane is called as exocoelomic cavity or
primitive yolk sac.
 The cells of the trophoblast give origin to a mass
of cells called extra embryonic mesoderm
 Small cavities appear in the extra embryonic
mesoderm which become large and called extra
embryonic coelom or chorionic cavity

24.  The space surrounds the primitive yolk sac
and amniotic cavity, except where the
germ disc is connected to the trophoblast
by the connecting stalk.
 The extraembryonic mesoderm lining the
cytotrophoblast and amnion is called the
extraembryonic somatic mesoderm;
 The lining covering the yolk sac is known
as the extraembryonic splanchnic
mesoderm.

25.  Cell of cytotrophoblast proliferate locally and
penetrate into syncytotrophoblast forming primary
villi.
 Hypoblast produces additional cells that migrate
along the inside of exocoelomic membrane. They
form a new cavity within exocoelomic cavity known
as secondary yolk sac or definitive yolk sac.
 During its formation large portions of exocoelomic
cavity are pinched off, represented by exocoelomic
cysts usually found in extraembryonic coelom.
 Mean while, extraembryonic coelom expands and
form chorionic cavity.

26.  The most characteristic event occurring during 3rd
week of gestation is “gastrulation”.
 Gastrulation begins with formation of primitive
streak on the surface of epiblast.
 Primitive streak is a narrow groove with slightly
bulging region on either side.
 Cephalic end of streak, the primitive node consists
of a slightly elevated area surrounding a Primitive
knot/ Hensons node.

29. Prenotochordal cells migrate through the
primitive streak, become intercalated in the
endoderm to form the notochordal plate
and finally detach from the endoderm to
form the definitive notochord and serves as
the basis for the axial skeleton.
The cloacal membrane is formed at the
caudal end of the embryonic disc. When
the cloacal membrane appears, the
posterior wall of the yolk sac forms a small
diverticulum.

30. NEURAL TUBE
►formed by ectoderm overlying the notochord.
►extends from prechordal plate to primitive knot.
►divisible into 2 parts:
Cranium (forms the brain)
Caudal(forms the spinal chord)
Some of the neuroectodermal cells lying along the crest of each neural fold lose
their epithelial affinities and are called Neural crest cells.

32. 8th day – bilaminar disc
14th day- prochordal plate and primitive streak
16th day- intraembryonic mesoderm
17th day- notochord
23th day- neural tube

33. • Rod-like thickenings of mesoderm in the foregut.
• At first 6 arches. 5 th arch disappear, only 5 remains.
• The ventral ends of the arches of the right and left sides meet at the middle
line in the floor of the pharynx.
• They bring about elongation of the region between the stomatodeum and the
pericardium forming neck.
• In the interval between any two adjoining arches, endoderm extends
outwards to form a series of pouches.They are called endodermal or
pharyngeal pouches.

35. Consists of two portions:
Dorsal:-also known as the maxillary process , giving rise to
premaxilla ,maxilla, zygomatic bone and part of the temporal
bone.
Ventral:- also known as the mandibular process , which
contains the MECKEL’S CARTILAGE. During further
development , Meckel’s cartilage disappears except for two
small portions at it’s dorsal end that persist and form the
Incus and Malleus.

36.  Musculature of the 1st pharyngeal arch includes the muscle of
mastication (temporalis,masseter,lateral pterygoid and medial
pterygoid),anterior belly of the digastric,mylohyoid,tensor tympani
and tensor palatini.
 Nerve supply to the muscles of the 1st arch is provided by Mandibular
branch of trigeminal nerve.

37. The cartilage of the second arch (hyoid arch)is called as REICHERT’S
CARTILAGE which gives rise to the stapes ,styloid process of the
temporal bone , stylohyoid ligament, upper half & lesser cornue of
hyoid bone
Muscles of the hyoid arch are the stapedius , stylohyoid,posterior belly
of digastric ,auricular and muscles of facial expressions.
 Facial nerve-the nerve of the 2nd arch supplies all these muscles.

38. The cartilage of this arch produces the lower part of the body and the
greater horn of the hyoid bone.
Muscle of this arch is the Stylopharyngeus muscle which is innervated
by the Glossopharyngeal nerve.

39. Cartilages of the 4th and 6th branchial arch fuse to form thyroid
cartilage and cricoid ,arytenoid ,corniculate & cuniform cartilages
Muscles of the larynx and the pharynx supplies the 4th and 6th
branchial arch
4th and 6th branchial arches nerve supply is by superior and recurrent
laryngeal nerve

41. • 1st pouch: ventral part obliterated by formation of tongue.
Dorsal part – tubotympanic recess
Proximal – auditory tube, middle ear cavity, tympanic antrum.
• 2nd pouch: tonsil, tubotympanic recess
• 3rd pouch: inferior parathyroid glands, thymus.
• 4th pouch: superior parathyroid glands, thyroid glands
• 5th pouch: ultimobranchial body.

42.  During the 4th week of development, after the
formation of the head fold, two prominent bulgings
appear on the ventral aspect of the developing
embryo, separated by the stomatodeum. They are:
– Developing brain cranially
– Pericardium caudally
The floor of the stomatodeum is formed by the
buccopharyngeal membrane, which separates it from
the foregut. On each side, the stomatodeum is bounded
by first arch.
 Soon, mesoderm covering the developing forebrain
proliferates and forms a downward projection that
overlaps the upper part of the stomatodeum. downward
projection is called the frontonasal process.

43. The face is derived from the structures that lie
around the stomatodeum
– Unpaired: Frontonasal process from above.
– Paired: First pharyngeal (or mandibular) arch
of each side
Each mandibular arch forms the lateral wall of
the stomatodeum . This arch gives off a bud
from its dorsal end called the maxillary
process. It grows ventromedially cranial to the
main part of the arch which is now called the
mandibular process.

44.  The ectoderm overlying the frontonasal process
soon shows bilateral localized thickenings that are
situated a little above the stomatodeum on either
side of midline. These are called the nasal placodes.
 This placodes soon sink below the surface to form
nasal pits.
 The edges of each pit are raised above the surface:
the medial raised edge is called the medial nasal
process and the lateral edge is called the lateral
nasal process. Lateral and cranial to the nasal
placodes pair of thickenings appear and are called
lens placodes.

45. Upper Lip
 Each maxillary process now grows medially below the developing eye
and fuses, first with the lateral nasal process , and then with the medial
nasal process . The medial and lateral nasal processes also fuse with each
other. In this way, nasal pits (now called external nares) are cut off from
the stomatodeum.
 The maxillary processes undergo considerable growth. At the same time,
the frontonasal process becomes much narrower from side to side, with
the result that the two external nares come closer together.
Lower lip
 The mandibular processes of the two sides grow toward each other
and fuse in the midline and give rise to the lower lip, and to the lower
jaw

47. • CHEEKS: After formation of upper and lower lips, the stomatodaeum is very broad.
On the lateral side it is bounded above by maxillary process and below by
mandibular process. The maxillary and mandibular processes fuse to form the
cheeks.
• EYES: The eyes develop from the lens placode which are ectodermal thickenings
present lateral and cranial to the nasal placode.
• EYELID: Eyelids are derived from folds of ectoderm that are formed above and
below the eyes, and by mesoderm enclosed within the folds.

48. • PINNA: The pinna (auricle) is formed by the fusion of the mesodermal thickenings
on the mandibular and hyoid arches.
• NASOLACRIMAL DUCT: Nasolacrimal duct is formed by fusion between the lateral
nasal & maxillary processes, separated by a deep groove. The epithelium in the
floor of the groove between them forms a solid core that separates from the
surface and eventually canalizes to form nasolacrimal duct.

49. •The mouth is derived partly from the stomatodeum (ectodermal) and partly from
the foregut (endodermal).
• After the disappearance of the buccopharyngeal membrane the stomatodeum
communicates with the foregut.
• Epithelium lining the lips, cheek, palate; teeth and gums are ectodermal in origin.
Epithelium of the tongue is endodermal.
• In the region of the floor of the mouth; the mandibular process forms the lower
lip, lower parts of cheek, lower jaw and tongue.

50.  Formation of primary and secondary palate
 Elevation of palatal shelves
 Fusion of palatal shelves

51.  From each maxillary process 2 plate-
like shelf grow medially called palatal
process.
 3 components contribute to the palate
formation
• 2 palatal process
• primitive palate from the frontonasal
process

52. The definitive palate is formed by the fusion of
these three parts as follow:
 Each palatal process fuses with the posterior
margin of the primitive palate.
 The two palatal processes fuse with each other
in the midline. Their fusion begins anteriorly
and proceeds backward.
 The medial edges of the palate processes fuse
with the free lower edge of nasal septum, thus
separating the two nasal cavities from each
other, and from the mouth.

53.  At a later stage, the mesoderm in the palate
undergo intramembranous ossification to form
hard palate.
 However, ossification doesnot extend into the
most posterior portion, which remains as soft
palate.
 The part of the palate derived from the
frontalnasal process forms premaxilla which
carries the incisor teeth.

54. Meckel's cartilage (cartilage of the 1st branchial arch)
 Their proximal ends are connected with the ear capsules and their distal
extremities are joined to one another at the symphysis by mesodermal tissue.
 It has a close relation to the mandibular nerve.
Meckel's cartilage Fate and Derivatives
 The proximal portion gives the Malleus and Incus.
 The middle portion is replaced by fibrous tissue, which persists to form the
sphenomandibular ligament & the perichondrium of the cartilage persist as
sphenomallular ligament.
 The distal portion gives rise to the cartilaginous remnants in the midline of the
mandible.

55. Ossification spreads as follow
 Medially: below the incisive nerve.
 Ventrally: around the mental nerve to form the
mental foramen.
 Upwards: between this nerve and Meckel’s
cartilage.
 Forwards: towards the middle line where it comes
into close relationship with the similar bone of
the opposite side, but from which it is separated
by connective tissue.
 Backward: produces at first a trough of bone in
which lies the inferior dental nerve and much
later the mandibular canal is formed. The
ossification stops at the site of future lingula.

56.  The ramus of the mandible develops by a rapid spread of ossification backwards
into the mesenchyme of the first branchial arch diverging away from Meckel’s
cartilage.
 This point of divergence is marked by the mandibular foramen.

57. The condylar cartilage -
• It is rapidly converted to bone by endochondral
ossification.
• It acts as an active center of growth till the age of 20
years. It gives rise to:
1. Condyle head and neck of the mandible.
2. The posterior half of the ramus to the level of inferior
dental foramen
II. The coronoid cartilage
• It is relatively transient growth cartilage center ( 4th - 6th
MIU). It gives rise to:
1. Coronoid process.
2. The anterior half of the ramus to the level of inferior
dental foramen

58.  After the meckel’s cartilage disappears, the main
growth centre of the mandible is the condyle.
 At the time of birth,mandible is fibro-cartilaginous in
nature. Later on it is converted into bony structure.
 Condyle grows in upward & backward direction ,As a
result mandible grows in downward & forward
direction

59.  It starts when the deciduous tooth germs reach the early bell stage.
 The bone of the mandible begins to grow on each side of the tooth germ.
 By this growth the tooth germs come to be in a bony trough, which also
includes the alveolar nerves and vessels.
 Later on, septa of bone between the adjacent tooth germs develop, keeping
each tooth separate in its bony crept.
 The alveolar processes grow rapidly during the periods of tooth eruption.

60. • Bony trough forms for the infraorbital nerve and from this trough downward
extension forms lateral alveolar plate.
• Ossification spreads to the palatine process and forms hard palate.
• Median alveolar plate forms from the junction of the palatal process & the
main body of the forming maxilla.
• A secondary cartilage; zygomatic or malar cartilage appears in the developing
zygomatic process.

61. • Forms around 3rd month of intra-uterine life.
• Develops by expansion of nasal mucous membrane into maxillary bone.
• Later enlarges by resorption of internal wall of maxilla.

62.  The tongue develops in relation to the pharyngeal
arches (1st to 4th) in the floor of the developing mouth.
 It develops during 4th to 8th weeks.
 The medial most parts of the mandibular arches
proliferate to form two lingual swellings.
 The lingual swellings are partially separated from
each other by another swelling that appears in the
midline. This median swelling is called the tuberculum
impar.

63.  Immediately behind the tuberculum impar, the
epithelium proliferates to form a downgrowth
(thyroglossal duct) from which the thyroid gland
develops.
 Another, midline swelling is seen in relation to the
medial ends of the second, third and fourth arches.
This swelling is called the hypobranchial eminence or
copula of His.
 The eminence soon shows a subdivision into a cranial part
related to the second and third arches (called the copula)
and a caudal part related to the fourth arch. The caudal
part forms the epiglottis.

65. • The salivary glands develop as outgrowths of the buccal epithelium.
• The outgrowths are at first solid and are later canalized.
• They branch repeatedly to form the duct system.
• The terminal part of the duct system develop into secretory acini.

66. •The outgrowths of the parotid gland arise in relation to the line along which the
maxillary and mandibular processes fuse to form the cheek. It is ectodermal.
• The outgrowths for the submandibular and sublingual glands arise in relation to
the linguogingival sulcus. They are endodermal in origin.
• One or more salivary glands may sometimes be absent.

67. DEVELOPMENTAL
ANOMALIES OF FACE

68. ANOMALIES OF FACIAL SKELETAL DEVELOPMENT
Development of face involves fusion of various components.this fusion is
occasionally incomplete and gives rise to facial anomalies as a result of
some genetic and environmental factors
Genetic factors- these includes chromosomal aberrations and disorders
arising from abnormal genes or gene combinations
Environmental factors –Infections, drugs, chemical agents and metabolic
factors.

69.  It is the commonest congenital deformity occurs in face,
 It may be unilateral or bilateral
 It may involve:
1. lip only : CLEFT LIP
2. palate only: CLEFT PALATE
3. lip& palate: CLEFT LIP & PALATE

70. Median cleft lip
Occurs due to failure of the medial nasal process(fronto-nasal
process) to merges to each other & unable to form intermaxillary
segment.
Unilateral & Bilateral cleft lip
Occurs due to failure of the maxillary process to merge with the
medial nasal process(MNP) on the affected side (in unilateral type
defect) or both side.
Oblique facial cleft
Occurs due to failure of maxillary process to fuse with the lateral nasal
process(LNP) on affected side.

71.  occurs when the palatal processes( from maxillary
process) fails to fuse with each others or with
premaxilla.
 leaves the nasal cavity & oral cavity connected and
results in feeding problems in newborns.
 It can be associated with cleft lip

72. CLASS 1:Cleft of the soft palate only
CLASS 2:Cleft of the soft and hard palate
CLASS 3:complete cleft extending from uvula
to incisive foramen & deviate to one side
through alveolusI(unilateral)
CLASS 4: bilateral complete cleft of the lip and
palate.

73. • Natal or neonatal teeth
• Congenitally missing teeth
• Supernumerary teeth
• Anomalies of tooth morphology
• Crossbite (unilateral /bilateral)
• Teeth erupt adjacent to cleft have insufficient bone support leading to
premature loss
• Concave facial profile(pseudo mandibular prognathism)
• Teeth erupt adjacent to cleft are rotated & with axial root inclination

74. Macrostomia
Inadequate fusion of the mandibular and maxillary
processes with each other may lead to an
abnormally wide mouth.
Microstomia
Too much fusion may result in a small mouth.
The mandible may be small compared to the rest of the face resulting
in a receding chin.
Agnathia
In extreme cases, it may fail to develop.
Retrognathia

75.  This condition is called mandibulofacial
dysostosis, Treacher Collins syndrome or first
arch syndrome
 The entire first arch may remain
underdeveloped on one or both sides
 affecting the lower eyelid (coloboma type
defect), the maxilla, the mandible, and the
external ear.
 The prominence of the cheek is absent and
the ear may be displaced.
 There may be presence of cleft palate and of
faulty dentition.
Mandibulofacial dysostosis

76. • Macroglossia, microglossia, aglossia
• Bifid tongue
• Ankyloglossia
• Persistence of tuberculum impar
• Thyroid tissue within the muscles
• Remnants of thyroglossal duct
• Fissured tongue

77. ANKYLOGLOSSIA
The apical part of the tongue may be anchored to the floor of
the mouth by an overdeveloped frenulum. It interferes with
speech.
A red, rhomboid-shaped smooth zone may be present on the
tongue in front of the foramen cecum. It is considered to be
the result of persistence of the tuberculum impar.
MEDIAN RHOMBOID GLOSSITIS

80. The human face is a fascinating study of physiology and psychology. The
amount of information a human face can relay is unending. Face is the
mirror of one’s personality. It is our most useful and most underestimated
tool for communication. Face is the most beautiful and attractive part of
body which is most likely to develop malformations.
So, the knowledge of normal development of face will aid in understanding
the potential reasons for preventing or treating of anamolies.

81. Langman’s medical embryology by T.W..Sadler 12th edition
Human enbryology, InderBir Singh ..10th edition
Textbook of ORAL MEDICINE by Anil Govind Ghom
Shaffer a textbook of oral pathology
Tencates oral histology , 5th edition
Textbook of OMFS by Neelima Anil Malik
Orban’s Oral Histology and Embryology
Woelfel’s Dental Anatomy by Rickne C. Scheid
Contemporary Orthodontics, William R Profitt
REFERENCES