Development of palate Flashcards
The palate develops from two primordia and they are
Primary palate
Secondary palate
Palatogenesis begins and ends when
end of 5th week and ends in 12th week
The palate develops in two stages, and they are
Primary
Secondary
When does the primary palate starts developing
early in the 6th week
The primary palate is formed by
fusion of two medial
nasal prominences as median palatine process
The fusion of the medial nasal prominences forms a wedge-shaped mass of mesenchyme opposite upper jaw carrying four incisor teeth called
Primary palate
The primary palate ossifies to forms the anterior and midline aspect of the maxilla called the
premaxilla
The premaxilla represents what
only a small part of the hard palate anterior to the incisive fossa
The secondary palate is the primordium of
the hard and soft parts of the palate located posterior to incisive fossa
Secondary palate starts developing when
early in 6th week
Secondary palate is formed by
fusion of two mesenchymal projections called palatine
shelves from inner aspects of the maxillary prominences
Another name of palatine shelves
lateral palatine processes
At what week does the palatine shelves assume horizontal position above the tongue and form secondary palate
during 7th and 8th week
Once the palatine shelves are fused, what happens
The ossification of the maxilla and palatine bones extend into the lateral palatine process forming the hard palate
How is the soft palate formed
The posterior parts of the palatine shelves do not ossify. They extend posteriorly beyond the nasal septum and fuse to
form the soft palate, including its soft conical projection,
the uvula.
What indicates the line of fusion of the lateral palatine processes
palatine raphe
Anteriorly the secondary palate fuses with the primary
palate by
an irregular suture
Junction between the primary and secondary palates is represented in adults by
incisive fossa
incisive fossa opens into
left and right incisive canals
The nasal septum develops as a down growth from
the merged medial nasal prominences
The nasal septum grows down and joins the
superior aspect of anterior three-fourth of the hard palate in the midline
The fusion between nasal septum and secondary palate begins anteriorly during
9th week
The fusion between nasal septum and secondary palate is completed posteriorly
by the 12th week
Most common cleft lip
Unilateral cleft of upper lip
Commonest congenital anomaly of face
Unilateral cleft of upper lip
Clinical correlates
Oblique facial cleft: It
is a rare congenital anomaly of the face, which occurs when
maxillary process fails to fuse with the lateral nasal process.
The fissure extends from medial angle of the eye to the upper lip.
Clinical correlates
Complete cleft palate
– Unilateral complete cleft palate occurs if maxillary process on one side does not fuse with the premaxilla. It is
always associated with the cleft lip on the same side.
– Bilateral complete cleft palate occurs if both the maxillary
processes fail to fuse with the premaxilla. In this type,
secondary palate is divided into two equal halves by a
median cleft.
Clinical correlates
Cleft lip: Usually occurs in the upper lip. It is of different types, and they include:
Unilateral cleft lip: It occurs due to failure of fusion of maxillary process with the medial nasal process of the same side.
Bilateral cleft lip: It occurs due to failure of fusion of maxillary processes with the frontonasal process.
Central cleft lip/hair lip: It occurs due to failure of development of philtrum of the upper lip from the frontonasal
process.
