the growth and development of skull and jaws part 1..along with clincial correlates

1. GROWTH
AND
DEVELOPMENT
OF
SKULL AND
JAWS
Dr.AUREUS DESOUZA
P.G Resident
Oral medicine and radiology
MCODS, Mangalore

2. CONTENTS of PART 1
•
Introduction.
•
Pre natal development of cranium.
•
Post natal development of cranium.
•
Clinical correlates.
•
Development of face.
•
Clinical correlates.

3. CONTENTS of PART 1
• Special note: neural crest cells
• Clinical correlates
• Conclusion
• References

4. CONTENTS of PART 2
• Pre Natal development of the
maxilla.
• Post Natal development of maxilla.
• Development of paranasal
sinuses.
• Clinical correlates.

5. CONTENTS of PART 2
• Pre Natal development of the
mandible
• Post natal development of
mandible
• Clinical correlates
• Timeline of development

6. CONTENTS of PART 2
• Conclusion
• References

8. GROWTH
• Quantitative aspect of biologic
development per unit of time.
– Moyers
•
Growth refers to increase in size.
– Todd

9. DEVELOPMENT

10. DEVELOPMENT
Development refers to all naturally
occurring progressive, unidirectional,
sequential changes in the life of an
individual from it’s existence as a single
cell to its elaboration as a multifunctional
unit terminating in death.
– Moyers

12. DEVELOPMENT OF CRANIUM

13. CRANIUM
NEUROCRANIUM
(protective case
around brain)
VISCEROCRANIUM
(skeleton of face)
NASOMAXILLARY
COMPLEX
(DESMOCRANIUM)
CRANIAL VAULT
MANDIBLE
(CHONDROCRANIUM) CRANIAL
BASE

14. NEUROCRANIUM
MEMBRANOUS
NEURAL CREST
CELLS
&
PARAXIAL
MESODERM
CARTILAGINOUS
Prechordal chondrocranium
NEURAL CREST CELLS
Chordal chondrocranium
OCCIPITAL SCLEROTOMES
PARAXIAL MESODERM

15. Courtesy :langman medical embryology 11th ed

16. MEMBRANOUS
NEUROCRANIUM
Mesenchyme from these sources
invests the brain and undergoes
membranous ossification
Needle like bony spicules radiate from
primary ossification centre towards
periphery

17. Courtesy:langman’s medical
embroyology 11th ed

18. With growth during fetal and
postnatal life ,membranous bones
enlarge
Apposition on outer surface
Osteoclastic resorption from inside

19. CARTILAGINOUS
NEUROCRANIUM
Cartilages that lie in front of rostral
limit of notochord arise from
• neural crest cells forming
prechordal chondrocranium
Cartilages posterior to this limit arise
from
Occipital sclerotomes forming
Chordal chondrocranium

20. Base of the skull
All cartilages fuse
Ossify by Endochondral ossification

21. • kjjkkjhihihk
VISCEROCRANIUM
MEMBRANOUS
Intramembranous ossification
in maxillary and mandibular
prominence of first pharyngeal
arch
squamous temporal,
maxillary, zygomatic
bone,mandible
CARTILAGINOUS
Neural crest cells
Bones and connective tissue of
craniofacial structures

22. SKULL of the NEWBORN
Flat bones are connected through
seams of connective tissue
SUTURES.
Sagittal suture- neural crest cells
Coronal suture- paraxial mesoderm
FONTANELLES-more than two bones
meet, sutures are widened.

23. Courtesy: “The developing human”,
8th ed by Keith Moore

24. Courtesy: “The developing human”,
8th ed by Keith Moore

25. ANTERIOR FONTANELLE - where two parietal
and two frontal bones meet
POSTERIOR FONTANELLE -where two parietal
and occipital bones meet
TIMINGS OF CLOSURE:
ANTERIOR FONTANELLE= 18 months of age
POSTERIOR FONTANELLE = 1 to 2 months of age
Reference :Langman’s medical Embryology ,11th ed

26. Post Natal Development of skull

27. POST NATAL GROWTH OF
CRANIAL BASE
• Maxilla is attached to the cranial base
by a number of sutures.
• Mandible too is attached to the cranial
base at the temporomandibular joint.
• This growth processes occuring at the
cranial base can affect the placement of
maxilla and mandible.

28. • The bones forming the calvarium include
the frontal, parietal, occipital, sphenoid
and temporal bones.
• The suture systems associated with these
are the coronal, sagittal and lambdoidal
sutures and a temporary metopic suture
(permitting rapid transverse expansion
pre nataly and post nataly).

29. • As the brain expands, the separate bones
of the calvaria are displaced in an
outward direction passive movement.
• This primary displacement causes a
tension in the sutural membranes, which
respond by depositing new bone on the
sutural edges.
• Each separate bone thus enlarges in
circumference.

30. • At the same time, there is apposition on
the flat surfaces of both the ectocranial
and endocranial sides increasing thickness
of bone.
• The arc of curvature of the whole bone
decreases, and the bone becomes flatter.
• Reversal of growth may occur in areas
adjacent to the sutures outside/inside
surface resorption can take place
reduces the curvature.

31. Growth of cranial base
Cranial base grows post-natally by complex
interaction between the following three
growth processes.
• Extensive cortical drift and remodelling
• Elongation at synchondrosis
• Sutural growth

32. Cortical drift and
remodelling
• Remodelling : Process where bone
deposition and resorption occur so as to
bring about change in size, shape and
relationship of bone
• Cranium is divided into a no. of
compartments by bony elevations and
ridges present in the cranial base.

33. • These elevated ridges and bony
partitions show bone deposition, while
floor shows resorption
• This helps in increasing the intracranial
space to accommodate the growing
brain

34. • Cranial base is perforated by the
passage of a number of blood vessels
and nerves communicating with the
brain
• The foramina that allow the passage of
these nerves and blood vessels undergo
drifting by bone deposition and
resorption so as to constantly maintain
their proper relationship with the
growing brain

35. Synchondral growth
• The midline part of the basicranium is
characterized by the presence of
synchondroses.
• A number of synchondroses are
operative during the fetal and early
postnatal periods.

36. •
Inter-sphenoidal synchondrosis
fusion.
•
Spheno-ethmoidal synchondrosis- Juvenile/
adolescence
•
Spheno-occipital synchondrosis – Active: 12-15
years
Fuses: 20yrs
•
Intra-occipital synchondrosis
- Perinatal
- Fuses: 3-5 years
Structure of synchondrosis is like 2 epiphysial plates
positioned back to back and separated by a common
zone of reserve cartilage

37. • The spheno-occipital ,principal growth
cartilage of the basicranium.
• As with all growth cartilages associated
directly with bone development, the
sphenooccipital synchondrosis provides a
pressure adapted bone growth
mechanism.
• This is because the cranial base supports
the weight of the brain and face that bears
down on the synchondrosis in the midline
of cranial base.

38. • As endochondral bone growth occurs at the
spheno-occipital synchondrosis, the sphenoid
and occipital bones are moved apart.
• At the same time new endochondral bone is
laid down in the medullary region, and
cortical bone is formed in the endosteal and
periosteal regions.
• Thus the sphenoid and occipital bones
increase in length and width

39. • This is in contrast to the tension
adapted sutural growth process of the
calvaria, lateral neurocranial walls, and
the endocranial fossae.
• Endochondral bone growth by the
spheno-occipital synchondrosis relates
to primary displacement of the bones
involved

40. • The sphenoid and the occipital bones
become sieved apart by the primary
displacement process and at the same
time, new endochondral bone, is laid
down by the endosteum within each
bone.
• The direction of spheno-occipital
synchondrosis is upwards, it therefore
carries the midface forward and
downward

41. Sutural growth
• Cranial base has a number of bones that
are joined to one another by means of
sutures
1. Spheno - frontal suture
2. Fronto - temporal suture
3. Spheno - ethmoid suture
4. Fronto - ethmoid suture
5. Fronto - zygomatic suture
• As the brain enlarges during growth, bone
formation occurs at the ends of the bone
(that is at either ends of the suture)

42. • The temporal and
frontal bones have
fibrous attachments
to the middle and
anterior cranial
fossae, respectively.
As both bones expand,
the two fossae are thus
pulled away from each
other, but both also
being moved together in
a protrusive direction.

43. • This sets up tension fields in the various
frontal, temporal, sphenoidal, and
ethmoidal sutures, and this presumably
triggers sutural bone responses (in
addition to direct basicranial
remodeling ).
• Both fossae are thus enlarged, and the
nasomaxillary complex is carried along
anteriorly with the floor of the anterior
cranial fossa from which it is suspended.

44. CLINICAL CORRELATES
CRANIOSYNOSTOSIS:
Caused by premature closure of 1 or more sutures.
Premature fusion of the synchondroses of the skull base
•
•
•
•
causes
underdevelopment of the middle third of the face
reduced cranial base
excessive vaulting of the calvaria
(in some cases) anomalies such as exophthalmia,
midfacial hypoplasia, and dental malocclusion.

45. CRANIOSYNOSTOSIS

46. Syndromes associated with
craniosynostosis
•
•
•
•
•
Crouzon syndrome
Apert syndrome
Pfeiffer syndrome
Muenke syndrome
Saethre chotzen syndrome

47. Types of craniosynostosis
•
•
•
•
•
•
Brachycephaly
Plagiocephaly
Oxycephaly
Trigonocephaly
Scaphocephaly
Pansynostosis

48. Brachycephaly

49. Plagiocephaly

51. scaphocephaly

52. Trigonocephaly

53. Kleeblattschädel /clover leaf
shaped skull

54. Oxycephaly

56. CRANIOSCHISIS
• Greek: "kranion" skull, and "schisis” split)
is a developmental birth defect in which
cranial vault fails to form.
• Hence brain tissue exposed to amnion
degenerates resulting in ANENCEPHALY

57. ACHONDROPLASIA
• Primarily affecting long bones
• Other defects include a large
skull(megalocephaly),
• short fingers,
• accentuated spinal curvature

58. THANATOPHORIC
DYPLASIA
• Most common lethal neonatal form
• Autosomal dominant
• Occurs when all of the sutures close
prematurely,resulting in bone growing through
anterior and sphenoid fontanelles.
• Short curved femurs
• Cloverleaf skull(kleeblattschadel)
• relative macrocephaly
• frontal bossing

59. HYPOCHONDROPLASIA
•
•
•
•
•
•
Autosomal dominant form of dwarfism
Short stature
Broad, short hands and feet;
Mild joint laxity
Macrocephaly
Skeletal features are very similar to those seen in
achondroplasia but tend to be milder.

60. CROUZON SYNDROME
• Results from an early closing (fusion) of several
of the skull’s sutures – always including the side
(coronal) sutures.
• Wide head across the front
• Short head from front to back
• Flat-looking face due to underdeveloped
cheekbones, eye sockets and lower jaw
• Shallowly placed, protruding eyes that may be
crossed or wide-set
• Small nose with an upwardly tilted beak shape
• No foot or hand defects

61. APERT SYNDROME
• Apert syndrome is caused by an early closing
(fusion) of the skull's side (coronal) sutures
• Taller-than-usual head shape
• Recessed mid-face
shallowly placed, protruding eyes
• Short, beak-shaped nose
and feet
• Symmetric syndactyly of hands
• Cleft palate (may be present)

63. Pfeiffer syndrome
Results from an early closing (fusion) of up to three
of the skull’s sutures (coronal, lambdoid, and
sometimes, sagittal).
• Wide head across the front
• Short head from front to back
• Flat-looking face due to underdeveloped
cheekbones, eye sockets, and lower jaw
• Shallowly placed, protruding eyes that may be
crossed or wide-set
• Small nose with an upwardly tilted beak shape
• Cleft palate(may be present)

64. MICROCEPHALY
• Abnormality in which brain fails to grow and skull
fails to expand.
• Skull growth is determined by brain growth
• Conditions that can cause microcephaly
• Include infections, genetic disorders, and severe
malnutrition.
• Mental retardation

65. Microcephaly

66. Genetic conditions that cause microcephaly
include:
•
•
•
•
•
•
•
Cornelia de Lange syndrome
Cri du chat syndrome
Down syndrome
Rubinstein-Taybi syndrome
Seckel syndrome
Smith-Lemli-Opitz syndrome
Trisomy 18
Reference: 1.A.D.A.M. Medical Encyclopedia.
2.http://www.ncbi.nlm.nih.gov/pubmedhealth
/PMH0003756

67. These additional conditions may indirectly cause
microcephaly:
• Uncontrolled phenylketonuria (PKU) in the
mother
• Methylmercury poisoning
• Congenital rubella
• Congenital toxoplasmosis
• Congenital cytomegalovirus (CMV)
• Use of certain drugs during pregnancy, especially
alcohol and phenytoin.

68. HOLOPROSENCEPHALY
• Most common developmental defect of forebrain
• Often accompanied by the failure of fetal facial
midline structures to form properly.
• Hence, here are usually midline facial defects
(cleft lip, cleft palate, cyclopia, etc)
accompanying this condition.
Reference:
http://medgen.genetics.utah.edu/phot
ographs/pages/holoprosencephaly.htm

69. CONGENITAL
HYDROCEPHALOUS
• Hydrocephalus is due to a problem with the flow
of the fluid that surrounds the brain.

71. • By 4th week of development ,bars
of mesenchymal tissue (P.arches)
separated by deep clefts(P.clefts).
• A number of outpocketings
(P.pouches) appear along the
lateral wall of pharyngeal gut.
• At the end of 4th week,centre of
face is formed by stomodeum
surrounded by first pair of
P.arches

72. • At 42 days embryo
•
Differentiation of structers depends on
epithelial and mesenchymal interactions

73. • Fourth week: development of a frontal
prominence forms the stomatodeum
• Below this is the formation of the first
branchial arch
• The first pair appears as surface
elevations lateral to the developing
pharynx
• Soon other arches develop as obliquely
disposed, rounded ridges on each side
of the future head and neck region.

74. PHARYNGEAL APPRATUS
•
•
•
•
consists of:
Pharyngeal arches
Pharyngeal pouches
Pharyngeal grooves/clefts
Pharyngeal membrane

75. PHARYNGEAL ARCHES
• Also called as branchial arches.
• Begin to develop in the fourth week just as
neural crest cells migrate into the head and
neck region.
• Form in craniocaudal succession
• Five pairs which are numbered 1,2,3,4 and
6.
• Arch 5 either never forms in humans or
forms as a short lived rudiment that
regresses.

76. PHARYNGEAL ARCH
COMPONENTS
• Core – mesenchyme(3rd week)
• -mostly replaced by neural crest
cells (4th week)
• Covered externally by –ectoderm
• Internally by -endoderm

77. Fate of the pharyngeal arch
components
A typical pharyngeal arch contains:
•
An aortic arch, an artery that arises from the
truncus arteriosus of the primordial heart
•
A cartilaginous rod that forms the skeleton of
the arch
•
A muscular component that differentiates into
muscles in the head and neck
•
A nerve that supplies the mucosa and muscles
derived from the arch

80. PHARYNGEAL ARCHES
The first pharyngeal arch
Consists of dorsal portion- maxillary process
Ventral portion- mandibular process
Mesenchyme of maxillary process gives rise to
• Premaxilla
• Maxilla
• Zygomatic bone
• Part of temporal bone
(through membranous ossification)
Mandible is formed by membranous ossification of
mesenchyme surrounding Meckel’s cartilage.
The first pair of pharyngeal arches plays a major role in
facial development

81. Fate of pharyngeal arches
• The pharyngeal arches contribute exclusively to
the formation of the face, nasal cavities,
mouth, larynx, pharynx and neck
• During the fifth week, the second pharyngeal
arch enlarges and overgrows the third and
fourth arches, forming the ectodermal
depression called cervical sinus
• By the end of seventh week the second to
fourth pharyngeal grooves and the cervical
sinus have disappeared, giving the neck a
smooth contour

82. Derivatives of Pharyngeal
arch cartilages
• The dorsal end of first arch cartilage (Meckel
cartilage) ossifies to form malleus and incus
• The middle part of cartilage forms anterior
ligament of malleus and sphenomandibular
ligament
• Ventral part of the first arch cartilages form
primordium of the mandible
• The cartilage disappears as mandible
develops around it

83. Derivatives of pharyngeal
arch cartilages
• The dorsal end of second arch cartilage
(Reichert cartilage) ossifies to form the stapes
and styloid process of the temporal bone
• The ventral end of second arch cartilage
ossifies to form the lesser cornu and superior
part of the body of the hyoid bone
• Its perichondrium forms the stylohyoid
ligament

84. Derivatives of pharyngeal
arch cartilages
• The third arch cartilage ossifies to form the
greater cornu and the inferior part of the
body of the hyoid bone
• The fourth and sixth arch cartilages fuse to
form the laryngeal cartilages except epiglottis
which develops from hypopharyngeal
eminence
• The fifth pharyngeal arch is rudimentary and
has no derivatives

86. Derivatives of Pharyngeal
Arch Muscles
• The musculature of the first pharyngeal arch
forms the muscles of mastication
• The second pharyngeal arch forms the
stapedius, stylohyoid, posterior belly of
digastric, auricular and muscles of facial
expression
• The third arch forms the stylopharyngeus
• The fourth arch forms cricothyroid, levator veli
palatini and constrictors of pharynx
• Sixth pharyngeal arch forms the intrinsic
muscles of the larynx

88. Derivatives of Pharyngeal
Arch Nerves
• Caudal two branches of Trigeminal nerve
(maxillary and mandibular) supply
derivatives of the first pharyngeal arch
• The facial, glossopharyngeal and vagus
nerves supply the second, third and caudal
(fourth to sixth) arches respectively
• The fourth arch is supplied by superior
laryngeal branch of vagus nerve
• The sixth arch is supplied by its recurrent
laryngeal branch

91. Pharyngeal Pouches
• The primordial pharynx, derived from the
foregut, widens cranially where it joins the
primordial mouth or stomodeum
• It narrows caudally where it joins the
esophagus
• The endoderm of the pharynx lines the
internal aspects of pharyngeal arches and
passes into balloonlike diverticula called
pharyngeal pouches

92. • The endoderm of the pouches contacts
the ectoderm of the pharyngeal grooves
and together they form the double
layered pharyngeal membranes that
separate the pharyngeal pouches from
the pharyngeal grooves

93. Derivatives of First
Pharyngeal Pouch
• The first pharyngeal pouch expands into an
elongate tubotympanic recess
• The expanded distal part of this recess
contacts the first pharyngeal groove, where it
contributes to the formation of the tympanic
membrane (eardrum)
• The cavity of the tubotympanic recess gives
rise to the tympanic cavity and mastoid
antrum

94. Derivatives of Second
Pharyngeal Pouch
• The second pharyngeal pouch is largely
obliterated as the palatine tonsils develop
• Part of the cavity of this pouch remains as the
tonsillar sinus or fossa
• The endoderm of the pouch proliferates and
grows into the underlying mesenchyme

95. Continued:
• The pouch endoderm forms the surface
epithelium and the lining of the tonsillar
crypts
• At about 20 weeks the mesenchyme around
the crypts differentiates into lymphoid tissue
• These tissues soon organize into the
lymphatic nodules of the palatine tonsil

96. Derivatives of Third
Pharyngeal Pouch
• The primordia of thymus and parathyroid
glands lose their connections with the
pharynx and migrate into the neck
• Later the parathyroid glands separate from
the thymus and lie on the dorsal surface of
the thyroid gland

97. Derivatives of Fourth Pharyngeal
Pouch
• The fourth pharyngeal pouch also
expands into dorsal bulbar and elongate
ventral parts
• Its connection with the pharynx is reduced
to a narrow duct that soon degenerates
• By the sixth week, each dorsal part
develops into a superior parathyroid gland
• It lies on the dorsal surface of the thyroid
gland

98. Continued:
• The parathyroid glands derived from the third
pouches descend with the thymus and are
carried to a more inferior position than the
parathyroid derived from the fourth pouches
• This explains why the parathyroid glands
derived from the third pair of pouches are
located inferior to those from the fourth
pouches

99. The Fifth Pharyngeal
Pouch
• When this develops, this
rudimentary pouch becomes part of
the fourth pharyngeal pouch and
helps to form the ultimopharyngeal
body

100. Pharyngeal Grooves
• During the fourth and fifth weeks, head and
neck region of the human embryo exhibit
four pharyngeal grooves or clefts on each side
• These grooves separate the pharyngeal
arches externally
• Only first pair persists as the external acoustic
meatus
• The other grooves normally obliterated with
the cervical sinus as the neck develops

101. Pharyngeal Membranes
• Pharyngeal membranes appear in the floor of
the pharyngeal grooves
• These membranes form where the epithelia
of the grooves and pouches approach each
other
• The endoderm of the pouches and ectoderm
of the grooves are soon separated by
mesenchyme
• Only first pharyngeal membrane becomes the
tympanic membrane, others obliterate

102. The First Pharyngeal Arch
Arch derivatives
Muscle
Mastication muscles (temporal, masseter, medial and lateral pterygoids),
mylohyoid, anterior belly of the digastric, tensor velli palatini, tensor tympanI
Bone and cartilage
Mandible, maxilla, premaxilla, zygomatic bone, squamous part of the
temporal bone, pinna of the ear (anterior), Meckel's cartilage (malleus, incus)
Other connective
tissue
Anterior ligament of the malleus, sphenomandibular ligament
Pouch derivatives
Middle ear cavity, auditory (Eustachian) tube, tympanic membrane
Cleft derivatives
External auditory meatus
Nerve supply
V (trigeminal nerve)

103. The Second Pharyngeal Arch
Arch derivatives
Muscle
Facial expresion muscles, stapedius, stylohyoid, posterior belly of the digastric
Bone and
cartilage
Reichert's cartilage (stapes, styloid process), hyoid bone (leser horn and upper body), pinna of the ear
(posterior)
Other
connective
tissue
Stylohyoid ligament
Pouch derivatives
Palatine tonsils
Cleft derivatives
None
Nerve supply
VII (facial nerve)

104. The Third Pharyngeal Arch
Arch derivatives
Muscle
Stylopharyngeus
Bone and cartilage Hyoid bone (greater horn and lower part of the body)
Other connective
tissue
None
Pouch derivatives
Inferior parathyroid, thymus
Cleft derivatives
None
Nerve supply
IX (glossopharyngeal nerve)

105. IV - VI Pharyngeal Arch
Arch derivatives
Muscle
Cricothyroid, levator velum palatini, constrictors of pharynx, intrinsic muscles of
the larynx
Bone and
cartilage
Laryngeal cartilages (cricoid, thyroid, arytenoid, corniculate, cuneiforme)
Other
connective
tissue
None
Pouch derivatives
Superior parathyroid, ultimobranchial bodies of the thyroid
Cleft derivatives
None
Nerve supply
X (superior and recurrent laryngeal branch of the vagus nerve)

106. Branchial fistula, sinus, cyst
An abnormal canal that opens internally into tonsillar
sinus and externally in the side of the neck is branchial
fistula.
Due to persistence of parts of second pharyngeal groove
and pouch.
The birth defect may appear as open spaces called cleft
sinuses, which may develop on one or both sides of the
neck.
A branchial cleft cyst may form from fluid drained from
a sinus. The cyst or sinus can become infected.
Reference: 1.Clin Otolaryngol Allied Sci. 1978
Feb;3(1):77-92.
Branchial cysts, sinuses and fistulae.
Maran AG, Buchanan DR.
2.”The developing Human “, 8th ed, Keith Moore

107. Branchial Sinus
Branchial Fistula

108. • Lie free in the neck
just inferior to the
angle of mandible.
• Develop anywhere
along anterior
border of
sternocleidomastoid
• Become apparent in
late childhood or
early adulthood
Branchial cyst

109. Piriform Sinus Fistula
• It is thought to result from the
persistence of remnants of the
ultimopharyngeal body.
• The fistula traces the path of this
embryonic body to the thyroid
gland.

110. Branchial Vestiges
• Remnants of pharyngeal arch
cartilages under the skin in the side
of the neck.
• Found anteriorly to the inferior third
of sternocleidomastoid muscle

111. First Arch Syndrome
• Abnormal development of the components of
first pharyngeal arch results in various
congenital anomalies of the
eyes, ears, mandible and palate that together
constitute the first arch syndrome.
• Believed to result from the insufficient
migration of neural crest cells into the first
arch during the fourth week.

112. First Arch Syndrome
Two main manifestations:
• Treacher collins syndrome
• Pierre robin Syndrome

113. Treacher Collins Syndrome
Also called as mandibulofacial dysostosis.
autosomal dominant congenital
disorders.
Features:
• Malar hypoplasia
• Down-slanting palpebral fissures
• Micrognathia
• conductive hearing loss
• malformed or absent ears.

115. Pierre Robin Syndrome
Autosomal recessive disorder
Features:
• Hypoplasia of mandible
• Cleft palate
• Defects of eye and ear are present

116. Robin morphogenetic complex
Initiating defect is a small mandible
Results
posterior displacement of tongue
Obstruction to full closure palatal
processes
Resulting in bilateral cleft palate

117. DiGeorge syndrome
Occurs because the third and fourth
pharyngeal pouches fail to differentiate
Into thymus and parathyroid glands
As a result of breakdown in signalling
between pharyngeal endoderm and
adjacent neural crest cells

118. Features:
• Shortened philtrum of lip(fish mouth
deformity)
• Low set ears
• Nasal clefts
• Thyroid hypolplasia
• cardiac abnormalities

119. NEURAL CREST CELLS
Neural crest cells originating in the
neuroectoderm form the facial skeleton
and most of skull.
Often a target of teratogens.
Crest cells are easily killed by compounds
such as retinoic acid and alcohol This is
because these cells are deficient in
superoxide dismutase and catalase
enzyme which are basically free radical
scavengers.

120. Example of craniofacial defects involving
neural crest cells include :
• Treacher collins syndrome
• Robins sequence
• Goldenhar syndrome

121. Goldenhar syndrome
• Also known as oculo-auriculovertebral (OAV) syndrome
• Anomalous development of the first
branchial arch and second branchial
arch.
• Rare congenital defect.
Features:
• Incomplete development of the ear,
nose, soft palate, lip, and mandible
on usually one side of the body.

122. CONCLUSION
Growth and development of the
craniofacial structures is a complex
interplay of a variety of factors. A thorough
understanding of the intricate interactions
of related structures is necessary to
understand and differentiate between the
normal and the abnormal, to aid in the
diagnosis, management and treatment
planning of different anomalies.

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