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