6. Appearance of NASAL PLACODES at the end of 4th
week of IUL
Appears lateral to the FRONTONASAL prominence
as a LOCAL THICKENING of SURFACE ECTODERM.
NASAL PITS are formed on 5th week of IUL, by
invagination of NASAL PLACODES.
NASAL PROMINENCE are formed following the
formation of NASAL PITS
NASAL PROMINENCE divided into 2 subdivisions:
1. LATERAL nasal prominence
2. MEDIAL nasal prominence
7. Following 2 weeks after 5th week of IUL, maxillary
prominence continue to INCREASE IN SIZE.
Simultaneously, they grow medially, compressing
the medial nasal prominence towards the midline.
In the formation of upper lip LATERAL NASAL
PROMINENCE is not involved
The deep furrow which separates maxillary
prominence and later nasal prominence is called as
NASOLACRIMAL GROOVE.
Nasolacrimal groove forms NASOLACRIMAL DUCT
and its upper wider end forms the LACRIMAL SAC.
8. Development of lateral wall
of nose
During 8th week of IUL 6 to 7 ridges appear
on the lateral nasal wall, those ridges are
called as ETHAMO TURBINALS.
9. 1st ETHAMO TURBINAL
1. ASCENDING portion forms AGGER NASI
2. DESCENDING portion forms UNCINATE
PROCESS
2nd ETHAMO TURBINAL forms MIDDLE
TURBINATE.
3rd ETHAMO TURBINAL forms SUPERIOR
TURBINATE
4th and 5th ETHAMO TURBINAL forms
SUPREME TURBINATE
MAXILLO TURBINAL forms INFERIOR
TURBINATE
10. FURROWS between each ETHAMO TURBINALS
forms respective NASAL MEATUSES
1st FURROW :- MIDDLE MEATUS (b/w 1st &
2nd ET)
2nd FURROW :- SUPERIOR MEATUS
3rd FURROW :- SUPREME MEATUS
4th FURROW :- INFERIOR MEATUS
26. Paranasal sinuses develop as OUTPOUCHING from
mucous membrane of lateral wall of nose.
Maxillary sinus and Ethmoidal sinuses are present
at birth
Growth of sinuses continues during childhood and
early adult life
Radiologically various sinuses can be identified at
various milestones of growth. They are:
I. Maxillary sinus – 4th to 5th month
II. Ethmoidal sinus – 1 year
III. Sphenoidal sinus – 4 years
IV. Frontal sinus – 6 years.