DEVELOPMENTDEVELOPMENT OF OF FACE , NOSE FACE , NOSE AND AND PALATEPALATE
By
Prof.
Saeed Abuel Makarem
1Prof. Makarem
Development The of Development The of FaceFace
The facial primordia appear early in the fourth week around the primordial stomodeum
mdmd
FN
S
2Prof. Makarem
MXMX
Five facial primordia appear as prominences around the stomodeum
The single frontonasal prominence
The paired maxillary prominences
The paired mandibular prominences
FNP
3Prof. Makarem
The paired facial prominences are derivatives of the first pair of pharyngeal arches
The prominences are produced mainly by the proliferation of neural crest cells.
These cells migrate from the MesencephalonMesencephalon and & RhombencephaloRhombencephalonn regions of the neural folds neural folds into the arches during the fourth week 4Prof. Makarem
1st
The The Nasal placodesNasal placodes:: Two bilateral oval
thickenings in the surface ectoderm, of the frontonasal prominence, appear, by the end of the fourth week.
Nasal placodes Nasal placodes are the
primordia of the nose and nasal cavities.
Initially these placodes are
convex. Later, they are stretched
to produce a flat depression in each placode.
5Prof. Makarem
6Prof. Makarem
Mesenchyme in the margins of the placodes proliferate, producing horse shoe shaped elevations called medial and lateral nasal prominences
Now the nasal placodes lie in depression called nasal pits
These pits are the primordia of the anterior nares (nostrils) and nasal cavities
7Prof. Makarem
Mesenchymal cells are the major source of the connective tissue components, including muscles, cartilage, bone, and ligaments in the facial and in the oral regions.
Prof. Makarem 8
The frontonasal prominence The frontonasal prominence (FNP) is formed of 2 parts:(FNP) is formed of 2 parts:
1- Frontal part: forms the forehead
2- Nasal part: forms the rostral boundary of the stomodeum.
The paired maxillary prominences form the lateral boundaries of the stomodeum
The paired mandibular prominences constitute the caudal boundary of the primitive mouth
9Prof. Makarem
Facial development occurs mainly between the fourth and eighth weeks.
By the end of the embryonic period, (8th week) the face has an unquestionabl human appearance.
10Prof. Makarem
Between the 7th and 8th weeks, the two medial nasal prominences merge with each other and with the maxillary and lateral nasal prominences
Merging of the medial nasal and maxillary prominences results in continuity of the upper jaw and upper lip and separation of the nasal pits from the stomodeum
11Prof. Makarem
The lower jaw and lower lips are the first parts of the face to form
They result from merging of the medial ends of the mandibular prominences in the median plane
Median cleft lower lip is a very rare condition
M
12Prof. Makarem
Each Each lateral lateral nasal nasal prominence is prominence is separated from separated from the the maxillarymaxillary prominence by prominence by a cleft called a cleft called nasolacrimal nasolacrimal groovegroove
13Prof. Makarem
The nasolacrimal duct develops from a rodlike thickening of ectoderm in the floor of the nasolacrimal groove
This thickening gives rise to a solid epithelial cord that separates from the ectoderm and sinks into the mesenchyme
As a result of cell degeneration, this epithelial cord canalizes to form the nasolacrimal duct
14Prof. Makarem
The cranial end of this duct expands to form the lacrimal sac
By the late fetal period, the nasolacrimal duct drains into the inferior meatus in the lateral wall of the nasal cavity
The duct usually becomes completely patent only after birth
Occasionally, part of the duct fails to canalize causing atresia of the nasolacrimal duct.
Prof. Makarem 15
Prof. Makarem 16
Development of the Development of the External EarExternal Ear By the end of the fifth week, the
primordia of the auricles of the ears have begun to develop
Six auricular hillocks form
around the first pharyngeal groove (cleft).
Three on each side of the 1st pharyngeal groove (cleft).
These are the primordia of the auricle and external acoustic meatus.
Initially the ear located in the neck. As the mandible develops the ears
ascend to the level of the eye.
Prof. Makarem 17
Prof. Makarem 18
Development of The Palate As the medial nasal prominences merge, they form an intermaxillary segment
The intermaxillary segment gives rise to: 1- The Philtrum (median part of the upper lip). 2- The Premaxillary part of the maxilla and associated gingiva (gum). 3- The primary palate.
Development of PalateDevelopment of Palate
The palate develops from two stages:
Primary palate Secondary palate
Palatogenesis begins at the end of the fifth week and is completed at twelfth week (5------12 )
The critical period of the palate development is from the endend of the sixth week until the beginningbeginning of ninth week (6 ------ 9) 19Prof. Makarem
Primary PalatePrimary PalateEarly in the sixth week the primary palate
or median palatine process begins to develop from the intermaxillary segment of the maxilla
Initially this segment is formed by merging of the medial nasal prominences
The primary palate forms the premaxillary part of the maxilla
It represents only a small part of the adult hard palate
(2 Medial nasal prominences >>>>intermaxillary segment .>>>>>>>>>-primary palate).20Prof. Makarem
21
Secondary Secondary PalatePalateThe secondary palate is
the primordium of the hard and soft palate
It begins to develop early in the sixth week from two mesenchymal projections that extend from the internal aspects of the maxillary prominences
22Prof. Makarem
Initially the lateral palatine processes or palatal shelves project inferomedially on each side of the developing tongue
Prof. Makarem 23
24Prof. Makarem
As the jaws develop, the tongue becomes relatively smaller and moves inferiorly
During the 7th & 8th weeks, the lateral palatine processes elongate and ascend to a horizontal position superior to the tongue
Gradually these processes approach each other and
fuse in the median plane 25Prof. Makarem
Palatine processes also fuse with the nasal septum and the posterior part of the primary palate
The nasal septum develops as a downgrowth from internal parts of the merged medial nasal prominences
The fusion between the nasal septum and the palatine processes begins anteriorly during the ninth week and is completed posteriorly by the twelfth week 26Prof. Makarem
27Prof. Makarem
Palatal shelves move medially and fuse with the nasal septum.
Prof. Makarem 28
Bone gradually develops in the primary palate, forming the premaxillary part of the maxilla, which lodges the incisor teeth
Concurrently bone extends from the maxillae and palatine bones into the lateral palatine processes to form the hard palate
The posterior part of these processes do not ossified.
29Prof. Makarem
They extend posteriorly beyond the nasal septum and fuse to form the soft palate.
Its soft conical projection is called uvula
The median palatine raphe indicates the line of fusion of the lateral palatine processes
30Prof. Makarem
31Prof. Makarem
Cleft Lip and PalateCleft Lip and PalateThe defect is usually classified
according to developmental criteria
There are two major groups of cleft lip and palate:
Clefts involving the upper lip and anterior part of the maxilla
Clefts involving the hard and soft regions of the palate
32Prof. Makarem
33Prof. Makarem
34Prof. Makarem
35Prof. Makarem
Prof. Makarem 36
Prof. Makarem 37