Transcript 04-face, nasal cavity and palate2008-03

FACE
It is the anterior aspect 
of the head that extends
from the forehead to the
chin and from one ear to
the other.
BONES
Forehead. 
Maxillae (upper jaw). 
Mandible (lower jaw). 
Nasal bones. 
THE FACE
Development of the 
face started in the 4th
week and is
completed in the 8th
week.
The lower jaw and 
lower lip are the first
parts of the face to
form.
Facial proportions 
develop during the
fetal period.
THE FACE IN EARLY FETAL
LIFE
1. The nose is flat. 
2. The mandible is 
under developed.
3. The brain is 
enlarged with
prominent forehead.
4. The ears are in the 
neck.
SMALL SIZED FACE
1. Rudimentary 
upper and lower
jaws.
2. Unerupted teeth. 
3. The small sized 
nasal cavities and
maxillary sinus.
FACE DEVELOPMENT
It begins around the 
stomodeum.
It is initiated by the 
influence of the
organizing centers in
the prosencephalon
(Forebrain) and
rombencephalon
(Hind brain).
FACIAL PROMINENCES
The face is developed from 
(5) facial primordia:
1. A single Fronto Nasal 
prominence (FNP).
2. Paired Maxillary 
prominences.
3. Paired Mandibular 
prominences.
The paired prominences are 
derivatives of the 1st
pharyngeal arch.
FACIAL PROMINENCES
The mesenchyme of 
these prominences is
derived from Neural
Crest cells that migrate
into the arches in the 4th
week.
These neural crest cells 
are the source of the
cartilage, bone and
ligaments of the facial
and oral regions.
FRONTONASAL
PROMINENCE
It surrounds the ventro lateral 
part of the forebrain (that
forms the optic vesicles).
The FRONTAL prominence 
forms :
The forehead. 
The NASAL prominence 
forms:
The rostral boundary of the 
stomodeum,dorsum and tip of
the nose.
MAXILLARY PROMINENCE
It constitutes the lateral 
boundary of the
stomodeum.
It Forms : 
1.The upper cheek 
region (most of the
maxilla).
2. Upper Lip ( lateral 
parts) and
3.The Secondary Palate. 
MANDIBULAR PROMINENCE
It constitutes the 
caudal boundary of
the stomodeum.
It Forms : 
1. The lower cheek 
regions.
2. Chin and lower lip. 
THE NASAL
PROMINENCES
They begin at the end of 
the 4th week as bilateral
thickening of the surface
Ectoderm (NasalPlacodes) on the infero
lateral parts of the fronto
nasal prominence.
NASAL PLACODES
(1) Convex in shape. 
(2) Stretched : A flat 
depression is formed in
the center of each
placode.
(3) Horse shoe : 
proliferation of
mesenchyme in the
margins produces
Medial and Lateral
Nasal Prominences.
NASAL PROMINENCES
4) Nasal pits : are 
depressions in which
the placodes now lie.
These pits represent
the primordia of the
anterior nasal
openings (Nares).
DERIVATIVES OF NASAL
PROMINENCE
Medial nasal 
prominence:
(1) Nasal septum. 
(2) Inter maxillary 
segment.
Lateral Nasal 
Prominence:
Lateral sides of the 
nose.
INTER MAXILLARY SEGMENT
7th -10th weeks :
Proliferation of the mesenchyme
in the maxillary prominences
cause their enlargement and
their medial migration towards
each other and to the nasal
prominences.
As a result The Medial Nasal
prominences move towards
each other and to the median
and form the Inter Maxillary
Segment.
INTER MAXILLARY
SEGMENT
It gives: 
A. Middle part of the 
upper lip (Philtrum).
B. Pre maxillary part 
of the maxilla and
gingiva.
C. Primary palate. 
NASO LACRIMAL GROOVE
It separates the maxillary and 
lateral nasal prominences.
In the 6th week, the maxillary 
prominence merges with the
lateral nasal prominence along
this groove. This establishes
continuity between the lateral
part of the nose from the
(lateral nasal prominence) and
the cheek from the (maxillary
prominence).
FORMATION OF NASO
LACRIMAL DUCT
(1) Ectoderm in the 
floor of the
nasolacrimal groove
forms a solid
epithelial cord.
(2) This cord is 
detached from the
overlying ectoderm.
(3) Canalisation of 
this cord forms the
duct.
NASO LACRIMAL DUCT
The duct is 
completely patent
after birth.
It drains into the 
lateral nasal wall.
LACRIMAL SAC 
It is the expanded 
upper end of the
duct.
NOSE
It is formed from (5) 
primordia :
(1) Dorsum and Apex : Nasal 
part of Fronto Nasal
prominence.
(2) The Septum: merged 
Medial Nasal prominences.
(3) The lateral sides (Alae): 
Lateral Nasal prominences
NASAL CAVITY
NASAL SACS 
Deepening of the nasal pits 
by the proliferating nasal
prominences.
.NASAL PLUG : 
A temporary plug that is 
formed in the nasal cavities
from proliferation of the
lining epithelium.
It degenerates between 
(13th-14th) weeks.
NASAL CAVITY
The nasal sacs are separated 
from the oral cavity by the
Oropharyngeal membrane.
Rupture of this membrane in 
the 6th week, leads to
communication of these two
cavities.
The CHOANAE (posterior 
nasal openings) are the sites
of this communication
NASAL CAVITY
CONCHAE : 
Elevations of the lateral 
walls of the nasal cavities
will form superior,
middle and 
inferior conchae. 
NASAL CAVITY
The ectodermal epithelium 
in the roof of the nasal
cavities will be specialized
to form the Olfactory
Epithelium.
Some of the epithelial cells 
differentiate into olfactory
receptors (neurons) whose
their axons will form the
olfactory nerve.
PARA NASAL SINUSES
They are formed as 
diverticula of the walls of
the nasal cavities that
become pneumatic and
extend into the adjacent
bones.
The Maxillary sinus 
begins to develop in late
fetal life.
The remainder of the 
sinuses form after birth.
EARS
Appear in the 5th week as 
six small mesenchymal
swellings (auricular
hillocks) around the 1st
pharyngeal groove.
They are three on each 
side.
These are the primordia 
of the of the auricles and
the external auditory
meatus.
EARS
Initially the external 
ears are in the neck
and they ascend to
be besides the eyes
as the mandible is
developed.
LIPS & GINGIVA
A linear thickening of 
ectoderm (Labiogingival
lamina) grows into the
underlying mesenchyme.
Degeneration of this lamina, 
forms the labiogingival
groove between the lips
and gingiva.
A small part of this lamina 
persists in the median plane
as (frenulum of the upper
lip).
BLOOD SUPPLY
In the 7th week, blood is shifted from the 
internal carotid artery to the external carotid
artery.
This is because the primitive aortic arch is 
transformed into the posnatal arterial
arrangement.
THE MUSCLES OF THE
FACE
The mesenchyme in the 1st 
pharyngeal arch gives
muscles of mastication
which are innervated by the
mandibular nerve.
The mesenchyme in the 2nd 
pharyngeal arch gives the
muscles of facial expression
which are innervated by the
facial nerve.
PALATOGENESIS
It started from the 5th 
and completed by
the 12th week.
The Critical period 
of palatogenesis is
(6th –9th ) weeks.
THE BONY PALATE
The palate is 
developed from Two
primordia :
1. Primary Palate 
(Median Palatine
process).
2. Secondary Palate 
(Lateral Palatine
processes).
THE PRIMARY PALATE
It is formed in the 6th 
week from the deep
part of the Inter
Maxillary segment
It is represented in the 
adult by the part
anterior to the Incisive
Fossa.
It gives rise to the pre 
maxillary part of the
maxilla.
THE SECONDARY PALATE
It is the primordium 
of the hard and soft
palates.
It extends posterior 
to the Incisive Fossa
DEVELOPMENT
(1) Lateral palatine 
processes (palatal
shelves) appear as two
mesenchymal projections
from the internal aspects
of the maxillary
prominences in the (6th
week).
They project infero- 
medially on each side of
the tongue.
STEPS OF ITS
DEVELOPMENT
2) During (7th- 8th) 
weeks :
A. Elongation of the 
palatal shelves.
DEVELOPMENT
B. Ascend to a 
horizontal position
superior to the
tongue.
DEVELOPMENT
C. Approach each 
other and fuse in the
median plane.
Their line of fusion is 
marked by the
Median Palatine
Raphe.
DEVELOPMENT
3). Fusion with the nasal 
septum. The fusion
begins in the 9th week
(anterior) and completed
in the 12th week
(posterior).
(4). Fusion with the 
posterior end of the
primary palate.
NASO PALATINE CANAL
It is in the median 
plane between the
premaxillary part of
the maxilla and the
lateral palatine
processes .It is
represented as the
INCISIVE FOSSA in
the adult hard palate.
HARD PALATE
Bone gradually develops 
in the primary palate to
form the premaxillary part
of the maxilla (that lodges
the incisor teeth).
This ossification process 
extends from the maxilla
and palatine bones to the
lateral palatine processes.
SOFT PALATE
The posterior parts of 
the palatal processes
do not ossify and
extend posteriorly
beyond the nasal
septum and fuse to
form the soft palate
and uvula.
CONGENITAL ANOMALIES
(1) Congenital anomalies 
of the face and palate are
common.
(2) They cause abnormal 
facial appearance and
difficult speech.
(3) They are due to arrest 
of development and or
failure of fusion of the
facial and palatal
prominences.
CAUSES
inductive combination of 
genetic and environmental
factors ( teratogenic
agents, chromosomal
syndromes).
They interfere with the 
development of the neural
crest tissue as regards :
number, incomplete
migration into the
prominences of the 1st
pharyngeal arch or failure
of their capacity.
TYPES
Two major groups of cleft 
lip and palate :
1. Anterior anomalies 
Clefts involving the upper
lip and anterior part of
maxilla.
2. Posterior anomalies 
Clefts involving the hard 
and soft palates.
ANTERIOR CLEFT
ANOMALIES
It is cleft lip with or 
without cleft of the
alveolar part of the
maxilla.
A complete anterior cleft 
extends through the lip
and alveolar part of the
maxilla to the incisive
fossa.It separates the
anterior and posterior
parts of the palate.
CLEFT LIP
It is due to failure of 
mesenchymal
masses in the Medial
nasal and Maxillary
prominences to
merge. It is sex
linked and is more
common in Male
infants.
CLEFT PALATE
It is due to failure of 
mesenchymal masses
in the palatine
processes to meet and
fuse. It is more
common in Females.
The incisive fossa is 
used as a land mark to
distinguish between
anterior and posterior
cleft palate anomalies.
CLEFTS OF ANTERIOR
PALATE
It is anterior to the 
incisive fossa.
It is due to failure of 
the mesenchymal
masses in the lateral
palatal shelves to
meet and fuse with
the mesenchyme in
the primary palate.
CLEFTS OF THE
POSTERIOR PALATE
It is failure of fusion of 
mesenchyme in the
lateral palatal shelves to
fuse with each other and
with the nasal septum.
The cleft extends through 
the soft and hard palates
to the incisive fossa.
It separates the anterior 
and posterior parts of the
palate.
COMPLETE CLEFT
PALATE
Both anterior and 
posterior :
Failure of fusion of 
mesenchyme of palatal
shelves to fuse with
each other, with the
primary palate and with
the nasal septum.