Oral

1. OROFACIAL DEVELOPMENT

3. Results of folding
1- the cranial end of the embryo folds
Before the caudal end(growth of the brain is
very fast).
2- formation of stomatodeum (primitive oral
cavity
3- part of the yolk sac is taken in the embryo
forming the future gut. Foregut, midgut, and
hindgut

4. Primitive stomatodeum
Shallow depression surrounded by
neural plate cranially and cardiac
plate caudally.

5. Early orofacial development

6. 1- Time:- Early somaite period 21 to 31 days.
2- Number& Nature :- Formation of five
mesodermal elevations, augmented by
neural crest cells , and lined with ectoderm.
3- Name one central large elevation
(frontonasal process) , two maxillary
processes , and two mandibular processes.

7. Differentiation of facial processes
1- The wide frontonasal present between
the developing eyes, forming forehead and
nose.
2- Two maxillary process------- lateral part
of the upper lip, and cheek .
3- Two mandibular process merge in the
midline to form the lower lip and Jew.

8. Nasal placodes
Specialized epithelial thickening at
the inferolateral corners of
the frontonasal process.

9. Globular process
Origin 5th intrauterine two horseshoe shaped nasal
processes demarcate and enclose the nasal placode
forming anterior nares
Two medial processes fuse to form one large
globular processe

10. Derivatives of globular process:-
1- tip of the nose
2- columella.
3- philtrum.
4-labial tuberculum & frenum of upper lip.
5-primary palate.

14. Branchial arches

15. Branchial arches
Number and nature:- five to six mesenchymal
swellings augmented by neural crest cells.
site:- they are developed between the
stomatodeum and future heart.( future
Mandibulocervical region) .
Size:- they decrease in size from first to sixth
Time:- fourth week of I.U.

16. Each arch is formed of:
1- central cartilage Derived from neural crest cells)
2- vascular core Derived from lateral mesoderm)
3-nervous element
4- muscular component From lateral mesoderm)

18. Arch Skeleton Muscle Artery nerve
Mandibular Maxilla Muscles of External Mandib
mandible mastication carotid ular .
Hyoid Hyoid bone Muscles of facial Facial facial
expression
Third Lower of Pharyngeal muscle Internal glossop
hyoid Common haryng
carotid eal
Fourth Thyroid Pharyngeal muscle Aorta vagus
cartilage subclavian
Sixth Laryngeal Laryngeal muscle pulmonary vagus
cartilage

19. Fate Branchial grooves
Persists
1st Forming External aoustic meatus
Obliterated
2nd ,3rd & 4th By caudal overgrowth of
2nd arch.
Obliteration Failure
BRANCHIAL FISTULA BRANCHIAL SAC

20. Derivatives Branchial grooves
cleft derivatives
1st external auditory
meatus, ectodermal
aspect of tympanic
membrane
2nd – 4th cervical sinus?

21. Derivatives Branchial pouches
POUCH VENTRAL DORSAL
PART
First Obliterated Auditory tube.
by tongue Tympanic
membrane.
Second Obliterated Palatine tonsil
by tongue
Third Thymus parathyroid
Fourth uncertain uncertain
Fifth calcitonin Calcitonin cells

22. Formation of the tongue
1- It begins to develop at the 4th week of intra
uterine life, in relation to the first 4 branchial
branches
2- The anterior two thirds of the tongue is
derived from the first (mandibular) arch.
Posterior one-third is derived from 3rd branchial
arch.
3- The posterior most part of the tongue is
derived from the 4th arch , the same as the
epiglottis

26. Sensory nerve of the tongue
First arch Mandibular nerve
1- Anterior two thirds Chorda tympani nerve
Third arch
2- Posterior one third Glossopharyngeal nerve
fourth arch Superior laryngeal branch of
3- Posterior most part
vagus
Motor nerve of the tongue
12th cranial nerve (Hypoglossal nerve )
supplies all muscles of the tongue

27. Dorsal and ventral aspects
of the tongue
Epithelium covering of the tongue

28. Epithelium covering of the tongue
1- only one layer of epithelial cells
2- stratified multilayered epithelial cells
3- appearance of circumvallate papillae on
(v) shaped sulcus. 8-12 ( from2nd to 5th
month)
4- development of taste buds .
5- development of the crypts of palatine
tonsil at birth.

31. Formation of the palate
The palate is formed from three components:-
1- the primitive palate.
2 – two palatal process from maxillary process which
fuse to form the palate proper at the 7th week.
at late stage the palate undergoes intramemberanous
Ossification to form hard palate . Ossification does not
extend to the most posterior portion, which forms soft
palate.

34. Development of the jaw
1- About the six week of intrauterine life bone of
the jaw is started to appear.
2- Both of the maxilla and the mandible are
developed from the first branchial arch.
3- The maxilla formed within the maxillary
process and the mandible within the mandibular
process.

35. Development of the madible

36. Development of the mandible
1- the major part of the mandible mandible is
intramembranous ossification, only the tip of
condlye process, cronoid process and the
symphyseal region are of endochondoral
ossification.
2- Meckel,s cartilage , the cartilage of the first
branchial arch, act as a guideline for mandible
formation, dense fibro-cellular tissue outside and
lateral to the cartilage forming the mandible
through intramembranous ossification.

37. 3- the symphyseal cartilages ,two in number
,appear in the connective tissue between the
two ends of Meckel,s cartilage but completely
separated from it , they are obliterated within
the first year of life.

39. Intra-membranous ossification

40. Development of the maxilla
1- the maxilla is formed of maxilla proper and
premaxilla.
2- maxilla proper is formed as an extension of
mandibular arch.(1st branchial arch)
3- around the 6 week intra membranous
ossification center appears near the part which
forms the enamel organ of the canine tooth.

41. 4- from this center of ossification bone spread
below the orbit towards pre-maxilla.
5-maxillary air sinus appears at 16th week
featal life as a projection from nasal cavity
6- sinus increase gradually and separates the
orbital surface from the dental surface, the final
height Reached after eruption of all permanent
teeth.

42. Development of (TMJ)
tempero-mandibular joint
1- It is an articular surface between two
bones; mandible and temporal bone in the
base of the skull
2- at the 7th week of intra-uterine life
Meckel,es cartilage extends from the chin to
the base of the skull
3- the formation of tempro-mandibula joint
is established at the end of fetal life.

43. Development of salivary gland
1-There are three pairs of major and
innumerable minor salivary glands in the
oral cavity.
2- the parotid and sub-mandibular buds
appear during six week.
3- bud of the sublingual gland appear
during seventh week of intrauterine life
4- the majority of glands are ectodermal
in origin, some glands about the base of
the tongue are endodermal.

44. Clinical consideration
1- Nonuion.
2- cleft lip and cleft palate
4- lateral facial cleft and macrostromia.
5- Bifid tongue.
6- lingual thyroid.

45. 1- Folding of the emberyo begins by the end of
a) Third week b) 7th week c) 15th week
2- Folding of the emberyo is caused by
a) Overgrowth of the nervous system b) overgrowth of the uterine wall c) overgrowth
of the placenta
3- anterior two thirds of the tongue developes from
a) First branchial arch b) first and third branchial archs c) fourth
branchial arch.
4- the ossification center of the maxilla is near to
a) enamel organ of the canine tooth b) enamel organ of the first molar tooth c)
enamel organ of the premolar tooth.
5- maxillary air sinus get their final length only after
a) eruption of All the permanent teeth b) eruption of all the deciduous teeth c)
development of the tongue.
6- The number of major salivary glands is
a) Two pairs b) three pairs c) only one pair
7- ------------------------------ is aguide for development of the mandible.
a) Meckel cartilage b) alveolar bone c) prochord.
8) Meckel cartilage participate in the formation of the mandible.
a) True b) false.