Docstoc

DEVELOPMENT OF FACE AND PALATE_ CONGENITAL - Ksums

Document Sample
DEVELOPMENT OF FACE AND PALATE_ CONGENITAL - Ksums Powered By Docstoc
					DEVELOPMENT
OF
FACE , NOSE
AND
PALATE


By
Prof.
Saeed Abuel Makarem

                      Prof. Makarem   1
       Development The of Face
   The facial
    primordia appear
                                   FN
    early in the fourth
    week around the       MX         MX
                           md        md
    primordial
    stomodeum                  S




                          Prof. Makarem   2
    Five facial primordia
    appear as prominences
    around the stomodeum

                                     FNP
   The single frontonasal
    prominence

   The paired maxillary
    prominences

   The paired mandibular
    prominences

                             Prof. Makarem   3
   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.
                                       1st
    These cells migrate
    from the
    Mesencephalon and &
    Rhombencephalon
    regions of the neural
    folds into the arches
    during the fourth week

                                  Prof. Makarem   4
   The Nasal placodes:
   Two bilateral oval thickenings
    in the surface ectoderm, of
    the frontonasal prominence,
    appear, by the end of the
    fourth week.

     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.
                                     Prof. Makarem   5
Prof. Makarem   6
   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 Makarem
           Prof.                 7
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
(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

                                            Prof. Makarem   9
   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.




                                          Prof. Makarem   10
   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




                                Prof. Makarem     11
   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
                                  M
    a very rare condition
                                      Prof. Makarem   12
    Each lateral nasal
    prominence is
    separated from
    the maxillary
    prominence by a
    cleft called
    nasolacrimal
    groove




                          Prof. Makarem   13
   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

                                            Prof. Makarem   14
   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 External 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
        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.




                             Prof. Makarem        18
          Development 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 end of the sixth week until the beginning of ninth
 week (6 ------ 9)
                                   Prof. Makarem        19
                  Primary Palate
   Early 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).
                                    Prof. Makarem          20
21
Secondary Palate
   The 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


                                    Prof. Makarem   22
          the lateral
 Initially
 palatine processes or
 palatal shelves project
 inferomedially on each
 side of the developing
 tongue




                           Prof. Makarem   23
Prof. Makarem   24
   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

                                     Prof. Makarem   25
   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                          Prof. Makarem   26
Prof. Makarem   27
        shelves move medially and
 Palatal
 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.



                                        Prof. Makarem   29
 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

                                   Prof. Makarem   30
Prof. Makarem   31
            Cleft Lip and Palate
   The 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
                                Prof. Makarem       32
Prof. Makarem   33
Prof. Makarem   34
Prof. Makarem   35
Prof. Makarem   36
Prof. Makarem   37

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:7
posted:1/11/2013
language:English
pages:37