Anatomy of Internal Nose & PNS in relation to Endoscopic
Surgery
Dr Vishav Yadav
ENT
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Introduction
One of the most complex anatomy.
The complications – non-familiarity with the
anatomical landmarks
Besides clinical judgment and technical skills,
a competent surgeon must also be a good
anatomist.
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Clinically two groups :
Anterior : Maxillary, frontal and anterior ethmoidal.
Posterior : Post. Ethmoidal and sphenoid sinuses.
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 Developmental Anatomy
 Macroscopic Anatomy
 Endoscopic Anatomy
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Developmental anatomy
Nose : 4- 8 wks
4 – 5 wks
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Developmental anatomy
4-5 wks
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Developmental anatomy
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Developmental anatomy
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Developmental anatomy
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Developmental anatomy
Secondary Palate Development
- develop from vertical projection from maxillary
process(palatal shelves)
- palatal closure progresses from anterior to posterior
- the area between the junction of the pre-maxilla and the
palate remains incomplete during the prenatal life and
thereafter : the incisive canal
- The posterior choana is repositioned more posteriorly
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Developmental anatomy
 The nasal capsule (skull base): cartilaginous envelope that
encases the developing nasal structures
 boundary to the nasal and paranasal sinus development.
 limited to the bounds of the perichondrium of the nasal capsule
or extends beyond the borders of the perichondrium with
reabsorption.
 Chondrification start in head mesenchyme at ant aspect of
sphenoid bone , later involves lateral ethmoid
 Then undergo ossification
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Developmental anatomy
 Paranasal Sinus Development :
-The growth pattern is totally unpredictable
-The paranasal sinuses, with the exception of the
sphenoid sinus, arise as evaginations from the lateral
nasal wall.
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Paranasal Sinus Development
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Paranasal Sinus Development
 During the 7th week the lateral nasal wall starts to
develop.
 A projection into the nasal capsule just superior to
the palatal shelves appears first and is called the
maxilloturbinal.
 followed by five other ethmoturbinals and the
nasoturbinal.
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Paranasal Sinus Development
 The maxilloturbinal - inferior turbinate,
 The first ethmoturbinal originates at either the superior
aspect of the septum or the superior junction of the septum
and the lateral nasal wall- middle turbinate.
 The furrow between the maxilloturbinal and the first
ethmoturbinal - middle nasal meatus. (an evagination of the
lateral nasal wall produces a blind diverticulum) the
embryonic infundibulum.
 The second ethmoturbinal develops shortly after - the
superior
turbinate.
 The furrow between the superior turbinate and the middle
turbinate is the superior meatus.
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Paranasal Sinus Development
 The third ethmoturbinal is the precursor of the supreme
turbinate (26% of adults)
 The supreme meatus is the furrow between the superior and
the supreme turbinates.
 The nasoturbinal is an additional prominence anterior and
superior to the ethmoid furrow or middle meatus and will
develop into the agger nasi
 Another mesenchymal ridge , uncinate process, develops on
the superior and posterior border of the agger nasi.
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Paranasal Sinus Development
 The uncinate process may extend superiorly to the roof of the
anterior ethmoid bone and posteriorly along the superior
surface of the inferior turbinate.
 the ethmoturbinals form bony structures that traverse the
ethmoid complex to attach to the lamina papyracea of the
orbit and skull base. The furrows continue to grow, developing
evaginations that contribute to the extensive and complex
pneumatization of the ethmoid bone.
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Paranasal Sinus Development
 Pneumatization:
- Primary pneumatization -The maxillary bone, frontal bone,
ethmoid bone, and nasoturbinate bone (agger nasi) are invaded
and filled with air from the ethmoid cells.
-Secondary pneumatization - epithelial-lined pockets expand into
the adjacent bony structures for which the sinuses eventually will
be named.
 Primary pneumatization occurs during the chondrocranial stage.
Much of the secondary pneumatization takes place postnatally.
 The overall development of the paranasal sinuses is slow for the
first 6 years
 By age 12 to 14, most of the sinuses reach the adult size
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• Maxllary sinus : Secretion transport occur in a stellete
pattern. Ostium opens into the floor of the post third
of ethmoidal infundibulam which opens into middle
meatus through hiatus semilunaris.
• Frontal sinus : Only sinus in which there is an active
inwardly directed transportation of mucous. all the
mucous leaves the sinus
after one ‘round trip’ ,
which is the result of a WHORL like formation in the
cilliary
pattern. after passing through the ostium
secretion is transported through a narrow cleft
called frontal recess.
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Ethmoidal and Sphenoidal sinus :
Secretions are usually transported in Spiral
pattern.. Anterior ethmoid cells drain into the
middle meatus.
Posterior ethmoid cells and Sphenoid
sinus drain via the superior meatus into
the spheno ethmoidal recess.
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Maxillary Sinus Development
- first to develop (10th week)
- outpouching of the lateral wall of the
ethmoid area within the infundibulum and
immediately posterior to the developing
uncinate process
- enlarges slowly during fetal life
-appears as a slit b/w the developing ethmoid
cells, the inferior turbinate, and the bone of
the maxilla.
- nasal capsule is resorbed during its
ossification,
maxillary sinus enters the developing
maxillary process. As the maxillary sinus
expands
into the maxilla, it is restricted by dental
development.
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Maxillary Sinus Development
 In the neonate, is represented by a small cavity whose
lower border lies above that of the nasal floor and is
encroached upon by the upper dentition.
 However, as the development the face progresses and
eruption of the permanent dentition occurs, the floor of
the sinus migrates to a lower level than that of the nasal
cavity (0.5–10 mm).
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Ethmoid Sinus Development
 earliest -fourth fetal month
 multicentric origin.
 majority :middle meatus as anterior ethmoid cells
(evaginations in the lateral nasal wall)
 minority develop from the superior and supreme meatus as
posterior ethmoid cells
 Other primitive structures called ethmoturbinals , the
uncinate process , the agger nasi , and the ethmoid bulla are
medial extensions of the lateral wall of the nasal capsule.
 The attachments of these structures to the lateral nasal wall
of the nasal capsule are the lamellae.
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Ethmoid Sinus Development
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Ethmoid Sinus Development
 The ethmoid sinus is well developed at birth.
 2nd yr the air cells may grow beyond the confines of the
ethmoid bone into the surrounding bones: maxilla, frontal,
lacrimal, and sphenoid.
 The growth pattern of the ethmoid sinus is completely
unpredictable, and development will continue until 12years
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Ethmoid Sinus Development
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Ethmoid Sinus Development
 Ethmoid cells
A. that belong to the ethmoid bone ( conchal, bullar, infundibular,
and frontal recess cells)
B. that extend beyond the ethmoid bone :
- agger nasi cells (anterior ethmoid cells that pneumatize
the agger nasi on the medial surface of the frontal process of
the maxilla and lacrimal bone)
- frontal sinus cells (anterior ethmoid cells that pneumatize
the frontal bone)
- orbital cells (anterior ethmoid cells that pneumatize the orbital
roof), and palatine bone
-sphenoid bone cells (posterior ethmoid cells that pneumatize
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these bones).
Ethmoid Sinus Development
-The
superior meatus is the
origin of most of the posterior
ethmoid air cells.
-some cells may also grow
laterally into the junction of the
nasal capsule and orbit
posterior to the maxillary sinus
cleft. Expansion of these cells
into the posterior, lateral, and
superior aspect of the maxilla is
the usual origin of the
ethmomaxillary
cells (Haller’s cells)
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Frontal Sinus Development
-4th fetal month, after the
development of the frontal recess.
-Initially, this recess is a pocket
found medial to the very cephalic
or superior aspect of the uncinate
process and expands into the thick
nasal capsule mesenchyme.
-The fetal frontal recess is found
between the uncinate process and
the anterior attachment of the
middle turbinate.
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frontal Sinus Development
 The frontal sinus is described as developing in several ways:
1. by direct extension of the whole frontal recess
2. from the laterally placed anterior ethmoid cells within
frontal recess
3. from the ethmoid infundibular cells
4. from one or more of the anterior group of ethmoid cells
arising in the frontal furrows
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Frontal sinus development
 A frontal sinus that develops from the ethmoid
infundibulum or the first or second frontal furrows may
have its drainage pathway restricted into a nasofrontal
duct. The growth of the surrounding anterior ethmoid
cells may also encroach on the proximal part of the
frontal sinus, compressing it into a nasofrontal duct. The
diameter of this duct depends largely on the degree of
encroachment by the surrounding ethmoid cells.
 does not affect the frontal sinus, which develops directly
from the wall of the frontal recess and has a distinct
ostium named the primary frontal sinus ostium (the
point of origin of the frontal sinus)
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Frontal recess
Tract that leads from the frontal sinus into
the nasal cavity
Ethmoid bulla is the posterior border of
the frontal sinus outflow tract
Medial border is formed by lat surface of
most ant portion of middle turbinate
Anteriorly tract is bordered by the
uncinate process or the agger nasi cells
(frontal anterior ethmoid air cells)
Frontal ostium is usually found in the
most anterosuperior part of frontal recess.
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Frontal sinus development
 Secondary pneumatization -6 months and 2 yrs
 Initially, the secondary pneumatization occurs laterally toward the orbital side of
the frontal bone
 second year - pneumatization has a more vertical direction. However, by
definition, a
frontal sinus is not present until the cell enters the vertical (ascending) portion of
the frontal bone.
 the superior extremity
- midvertical height of the orbit – 4 years
- superior orbital rim at 8 years
- frontal squama at 10 years
-continues its growth at a slow rate into adolescence
 The expansion into the vertical frontal bone occurs closer to the cranial cavity, and
consequently the external table of the frontal bone is thicker than the inner table.
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Frontal sinus development
 The development may be affected by the expansion of
the surrounding anterior ethmoid cells.
 one or more of these cells begin pneumatizing the
frontal bone and may even exceed the primary frontal
sinus outgrowth.
 The “true” sinus may encroach on the lumen of the
second sinus by forming a bulbous projection (bulla
frontalis) in the wall of the latter larger sinus.
 The left and the right frontal sinuses develop
independently,
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Modified kuhn classification of frontal
sinus & frontal recess cells
 Agger nasi cells - usually a single cell anterior to middle turbinate
 Supraorbital cells – region of anterior ethmoidal artery
 Frontoethmoidal cells :
Type I : Single frontal cell above agger nasi cell
Type II : Tier of cells in frontal recess above agger nasi cell
Type III : Single massive cell pneumatizing cephalad into frontal sinus
Type IV : A cell pneumatising through into frontal sinus & extending > 50%
of vertical height of frontal sinus
 Suprabullar cells : a cell / cells above bulla ethmoidalis
 Frontal bulla cells : a suprabulla cell that pneumatises along skull base into
frontal sinus which appears on coronal CT as isolated
frontal sinus cell
 Interfrontal sinus septal cell : a cell a/w frontal sinus septum pushing the sinus
drainage pathway laterally & narrowing the frontal ostium
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Sphenoid Sinus Development
The development of the sphenoid sinus is
unique because of two factors:
(1) It is the only sinus that does not arise
as an outpouching from the lateral nasal
wall
(2) there is no primary pneumatization, but
rather a constriction of the developing
presphenoid recess followed by secondary
pneumatization.
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Sphenoid Sinus Development
 During the third month of fetal development the nasal mucosa
invaginates into the posterior portion of the cartilaginous nasal
capsule.
 This primordium is only a small presphenoid recess,separated
incompletely from the nasal cavity by the development of a nasal
mucosal fold, inferiorly based, curving upward and anterior to the
body of the presphenoid.
 As the nasal capsule undergoes chondrification, a cartilaginous
concha forms within this fold, developing cartilaginous concavities,
which, by the fifth fetal month, enclose the presphenoid recess.
 Site of initial sinus rudiment and of initial constriction is preserved
in adulthood as the location of the sinus ostium
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Sphenoid Sinus Development
 After birth, the sphenoid sinus primordium grows inferiorly and
posteriorly.
 2 – 3 yrs:the intervening cartilage is resorbed, and part of the
sphenoid concha fuses to the presphenoid body;
 The presphenoid recess becomes the sphenoethmoid recess.
Following this fusion, pneumatization of the sphenoid occurs
 8 to 10 years - real sinus cavity may be observed,
 The origin - always identified by the sinus ostium, located high
on the anterior sinus wall, just a few millimeters below the
sphenoethmoid recess.
 The shape of the sinus is determined by the varying degrees
of pneumatization that take place in the secondary
pneumatization.
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Sphenoid Sinus Development
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Macroscopic Anatomy
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 The vestibule is limited above and behind by a curved
ridge, the limen nasi
 The union of the vestibule with the mucosa of the
nasal cavity has the shape of a triangular aperture nasal valve
- superior and lateral limits - upper lateral cartilage
- medial wall - the nasal septum
- base -by the floor of the nose.
 The nasal valve area marks the junction between the
lower limit of the upper lateral cartilage and the upper
portion of medial and lateral crura of the lower lateral
cartilages.
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boundaries
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Middle turbinate
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Osteomeatal complex
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Uncinate process
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There is frequently a small sulcus on the lateral wall of nose at
the insertion of the uncinate process. Posterior to this pt.,the
uncinate process can be readily incised.
The safest method however is to identify the uncinate process
at its free post. margine.
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SUPRABULLAR RECESS
It is a cleft between roof of ethmoid, ground lamella,and
bulla. It has only a surface communication with the middle
meatus through hiatus semilunaris and anteriorly with the
frontal recess.
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Inferior turbinate
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Ethmoid labyrinth
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Sphenoid sinus
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Frontal sinus
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Sphenoid sinus
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Blood supply
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Nervr supply
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Maxilla bone
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orbit
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Ethmoid bone
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Kero classification?
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Anterior ethmoid artery
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Endoscopic anatomy
 The opening of the nasolacrimal duct :
-anterosuperior part of the inferior meatus~1 cm behind
the anterior end of the inferior turbinate.
-slitlike opening, often recognized by a surrounding
crescent of mucosal fold.
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Endoscopic anatomy
First narrow point : Nasal valve area
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Endoscopic anatomy
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First pass: floor of nose
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Second pass : medial to middle
turbinate
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Third pass : middle meatus
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Endoscopic anatomy
 The attachment of the posterior insertion of the middle
turbinate (situated in the upper third of the posterior choana
just in front of its anterior edge) forms a landmark for the
front wall of the sphenoid sinus
 can also be palpated 1 cm above the dome of the choana
paramedially.
 The location of the sphenoethmoid recess and the sphenoid
ostium is higher somewhat more medially and
posterosuperiorly to the superior turbinate.
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Endoscopic anatomy
 The middle turbinate is the most important landmark of the nasal cavity.
 The anterior attachment extends superiorly to articulate with the cribriform
plate of the ethmoid bone.
 The middle meatus is the most important region for endoscopic nasal surgery
because it is the normal pathway to the maxillary, ethmoid, and frontal
sinuses and also provides surgical exposure to those sinuses.
 The endoscopic view shows the uncinate process, part of the ethmoid bulla,
and the hiatus semilunaris
 The ethmoid infundibulum is usually not visible, and therefore the maxillary
ostium cannot be inspected.
 The infundibulum may be quite shallow when the uncinate process is in close
proximity to the lamina papyracea. Also, in the presence of a concha bullosa
and/or paradoxical turbinate, the ethmoid infundibulum may be completely
obliterated, resulting in recurrent sinus infections.
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Endoscopic anatomy
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Endoscopic anatomy
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Endoscopic anatomy
 1-2 mm infront of agger nasi area lies the nasolacrimal canal.
It runs lateral to the lateral nasal wall and parallel to the agger
nasi after descending medially under some ethmoid cells.
 The agger nasi, the frontal recess, and the nasolacrimal canal
lie in roughly the same frontal plane.
 This proximity explains why the nasolacrimal canal is in
danger in this area during endoscopic dissection, particularly
in massive polyposis with bony erosion of the ethmoid cells.
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thanks
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