4. Bony part & cartilaginous part covered by muscle & skin
Cartilaginous part – upper & lower lateral cartilages, lesser alar
cartilages & septal cartilage
Nasal skin
Internal nose divided into the
Right and left by the nasal
septum
5. NASAL CAVITY PROPER
Roof – Nasal bone,
sphenoid & ethmoid bone
Floor - Palatine process of
the maxilla & Palatine bone
Medial wall
Lateral wall
7. Mainly by both Internal &
external carotid, both on the
septum & lateral walls
Anterior & posterior ethmoidal
artery
Sphenopalatine artery
Septal branch of greater
palatine
Septal branch of superior labial
artery
8. Formed by bony, soft tissue &
cartilage
Bony –
Ethmoid infundibulum & uncinate
Perpendicular plate of palatine
bone
Medial plate of pterygoid process
of sphenoid bone
Medial surfaces of lacrimal bones
and maxillae
Inferior conchae
9. Cartilage – In external nose,
the lateral wall of cavity is
supported by cartilage
(lateral process of septal
cartilage & major, minor
alar cartilage)
10. Marked by three bony projections, they extend medially across the
nasal cavity separating the nasal cavity into for air channels – the
turbinates or conchae
Superior ,middle & inferior tubinates or conchae. The conchae do not
extend forwards into the external nose
The air space below and lateral to each turbinate is called as meatus
Superior, middle & inferior meatus & sphenoethmoidal
recess
Middle Meatus – much significant
12. Superior Meatus – Limited only to posterior one third of lateral
wall. Posterior ethmoidal sinus opens into it.
Middle Meatus
Inferior Meatus – Runs along the whole length of lateral wall.
Nasolacrimal duct opens in its anterior part. Largest of all meatus
Sphenoethmoidal recess – Above the superior turbinate. It
receives the opening of sphenoid sinus
15. Infundibulum – Air passage
connecting the maxillary sinus
ostium to middle meatus
Hiatus Semilunaris – Gap
between the uncinate process
and bulla ethmoidalis.
Medially it communicates with
middle meatus. Laterally & inf
it communicates with
infundibulum
16. Frontal sinus – Opens into the
anterior part of hiatus
semilunaris
Maxillary sinus – Opens into the
posterior part of hiatus
semilunaris
Anterior and middle ethmoidal
cells – Opens into the upper
margin bulla ethmoidalis
20. Air containing cavity in certain skull bones
Develop as a diverticula/outpouching from the lat wall of nose
& extend into Maxilla, Ethmoid, sphenoid and frontal bones
Four sinuses – Maxillary, Frontal, Ethmoid (Ant & Post) &
Sphenoid
Some sinuses are well developed & asymmetrical
21. Each sinuses have
orifices that open into
the meatus, covered by
turbinates
24. Clinically -
two groups
Anterior –
Frontal,
Maxillary,
Ant.Ethmoidal
Posterior – Post
Ethmoidal,
Sphenoid
25. Significance
Lighten the skull & facial bones
Contributes to vocal resonance
Collapsible framework that helps the brain to protect from blunt
trauma
EPITHELIUM
They are lined by mucosa similar to that of the nasal cavity – pseudo
stratified ciliated columnar epithelium
Epithelium contains – Mucinous & serous glands
Mucoperiosteum
27. Sinuses Status at
Birth
First
Radiological
evidence
Reaches
Adult size
by
Maxillary sinus Present at birth 4-5 months after
birth
15 years
Ethmoid sinus Present at birth 1 year 12 years
Sphenoid sinus Not Present 4 years 15 years –
adult age
Frontal Sinus Not Present 6 years Size increases
until teens
29. Largest paranasal sinus
Pyramidal in shape
Base - towards lateral wall of nose
Apex – towards zygomatic process of maxilla
30. Present at birth as a rudimentary sinus
First radiological evidence is at 4-5 months after birth
Reaches adult size by 15 years
On average,
it has capacity
of 14.75 ml (14-15)
31. • Facial surface of maxilla and cheek Ant wall
• Infra temporal & pterygopalatine
fossa Post wall
• Middle & inferior meatuses (this
wall is thin & membranous) Med wall
• Floor of orbits Roof
• Alveolar part of maxilla Floor
33. DRAINAGE – OSTIUM
Seen high up in the medial wall
Does not open directly into the nasal cavity, but opens into post.
part of ethmoidal infundibulum, via hiatus semilunaris into middle
meatus.
The infundibulum is the air passage that connects the maxillary
sinus ostium to the middle meatus.
Unfavourable for natural sinus drinage
Accessory ostium – 30 % cases
36. Situated between the outer & inner table of frontal bone
Funnel shaped
Two sinuses on either side
Asymmetrical
Intervening bony septum which may be thin or deficiency
37. Not present at birth
First radiological evidence is at 6 years
Reaches adult size after puberty
The natural frontal sinus ostium is usually located in the
posteromedial floor of the sinus (most dependent part).
It opens into the middle meatus
The ethmoidal infundibulum can act as a channel for carrying the
secretions (and infection) from the frontal sinus to anterior ethmoid
cells and the maxillary sinus or vice versa.
39. They develop from a variable site, their drainage will be either
via an ostium into the frontal recess or via a nasofrontal duct
into the anterior infundibulum. The opening or duct can be
distorted by expansion of adjacent ethmoid cells
Boundaries
Ant wall – Skin over the forehead
Post wall - Meninges & the frontal lobe of brain
Inferior wall - orbit & its contents
40. FRONTAL RECESS
The frontal recess is an hourglass
like narrowing between the
frontal sinus and the anterior
middle meatus through which
the frontal sinus drains. It is not a
tubular structure, as the term
nasofrontal duct might imply,
and therefore the term recess is
preferred.
41. The frontal recesses are the
narrowest anterior air
channels and are common
sites of inflammation. Their
obstruction subsequently
results in loss of ventilation
and mucociliary clearance of
the frontal sinus
42. AGGER NASI CELL
Anterior, lateral, and inferior to the frontal recess is the
agger nasi cell. It is aerated and represents the most anterior
ethmoid air cell, usually lying deep to the lacrimal bone.
It usually borders the primary ostium or floor of the frontal
sinus, and thus its size may directly influence the patency of
the frontal recess and the anterior middle meatus.
44. The frontal sinus can pneumatize both the vertical and the
horizontal (orbital) plates of the frontal bone. The deepest area
of the vertical portion of the sinus is near the midline at the
level of the supraorbital ridge, and the medial sinus floor and
the caudal anterior sinus wall are thinnest in this area. As a
result, the sinus is best approached for a trephination at this
level
45. There is a rich sinus venous plexus (Breschet’s canals) that
communicates with both the diploic veins and the dural
spaces.
Arterial supply – supra orbital & supra trochlear
Venous supply – superior opthalmic vein
Lymph – Submandibular lymph node
Sensory innervation – supra orbital & supra trochlear
46. Occupies the body of sphenoid
Right & left, seperated by a thin strip
of bony septum (like frontal sinus)
Ostium opens into spheno ethmoidal
recess
Relations of the sinus are very
important, esp during the surgical
approach of pituitary gland
48. Relations –
Anterior part –
Roof – olfactory tract, optic chiasma &
frontal lobe
Lateral – optic nerve, internal carotid
artery & maxillary nerve
Posterior part
Roof – Pituitary gland in sella turcica
Lateral – Cavernous sinus,ICA & Cranial
nerves III, IV, VI & all divisions of V
49. Thin strips of bone separate the
sphenoidal sinuses from the nasal cavities
below and hypophyseal fossa above
The pituitary gland can be surgically
approached through the roof of the nasal
cavities by passing first through the
anteroinferior aspect of the sphenoid
bone and into the sphenoidal sinuses and
then through the top of the sphenoid
bone into the hypophyseal fossa
50. Thin walled air cavities in the lateral masses of the ethmoid
bone
Varies from 3 – 18
Occupy the space between the upper third of the lateral nasal
wall and the medial wall of orbit
Clinically divided into anterior ethmoidal air cells & posterior
ethmoidal air cells, by basal lamella (lateral attachment of
middle turbinate to lamina papyracea)
52. DRAINAGE:
Anterior - a recess of hiatus
semilunaris & middle meatus via
ehmoid bulla
Post- sup.meatus & spenethmoidal
recess.
Present at birth
Reaches adult size by 12 years
First radiological evidence seen at 1
year
53. Relations
Roof – formed by the anterior cranial fossa
Lateral wall - orbit
Medial wall – nasal cavity
Thin paper like bony part of the ethmoid separating the air cells
from the orbit, called lamina papyracea, can be easily destroyed
leading to spread of ethmoidal infections into the orbit
Optic nerve forms a close relationship with the posterior ethmoidal
cells & is at risk during ethmoidal surgery
55. The osteomeatal complex is the key anatomic area addressed
by endoscopic sinus surgeons. Blockage of the osteomeatal
complex prevents effective mucociliary clearance, thus leading
to a stagnation of secretions and therefore leading to recurrent
or chronic sinusitis.
56. The OMC is bounded
medially by the middle
turbinate,
posteriorly and superiorly by
the basal lamella, and
laterally by the lamina
papyracea.
Inferiorly and anteriorly the
OMC is open.
57. This anatomic region therefore
includes
Maxillary sinus ostium
ethmoid bulla
frontal recess
uncinate process
infundibulum
hiatus semilunaris
middle meatus.
60. Paradoxic Curvature
Normally, the convexity of the middle
turbinate bone is directed medially, toward
the nasal septum.
When paradoxically curved, the convexity
of the bone is directed laterally toward the
lateral sinus wall.
The inferior edge of the middle turbinate
may assume various shapes, which may
narrow and/or obstruct the nasal cavity,
infundibulum, and middle meatus.
61. Concha Bullosa
It is an aerated turbinate, most often the middle
turbinate.
Less frequently, superior & inferior turbinate
aeration can occur.
When the pneumatization involves the bulbous
segment of the middle turbinate, the term
concha bullosa applies.
If only the attachment portion of the middle
turbinate is pneumatized, and the
pneumatization does not extend into the
bulbous segment, it is known as a lamellar
concha.
62. Other Variations
Additional variations of the middle turbinate can occur, including
medial & lateral displacement, lateral bending, L shape, and sagittal
transverse clefts
Medial displacement – due to other middle meatal structures (i.e.,
polypoid disease, pneumatized uncinate process) encroaching upon
the middle turbinate.
Lateral displacement - due to the compression of the turbinate
toward the lateral nasal wall by a septal spur or septal deviation.
63. The nasal septum deviation may
compress the middle turbinate
laterally, narrowing the middle
meatus and the presence of
associated bony spurs may
further compromise the OMU.
Obstruction, secondary
inflammation, swollen
membranes, and infection can
occur
64. DEVIATION
The course of the free edge of the uncinate process may either
extend slightly obliquely toward the nasal septum, with the
free edge surrounding the inferoanterior surface of the ethmoid
bulla, or it extends more medially to the medial surface of the
ethmoid bulla. If the free edge of the uncinate is deviated in a
more lateral direction, it may cause narrowing or obstruction of
the hiatus semilunaris and infundibulum.
65. Attachment
Attachment to the lamina papyracea, the lateral surface of the
middle turbinate, or the fovea ethmoidalis in the floor of the
anterior cranial fossa may occur.
If the uncinate process attaches to the ethmoidal roof or middle
turbinate, during uncinatectomy, traction could inadvertently
damage the ethmoid roof and result in CSF rhinorrhea or other
intracranial complications.
67. Sometimes the free edge of
the uncinate process
adheres to the orbital floor,
or inferior aspect of the
lamina papyracea. This is
referred to as an atelectatic
uncinate process
68. Pneumatization
The pneumatization of the uncinate
process is believed to be due to
extension of the agger nasi cell within
the anterosuperior portion of the
uncinate process.
Functionally, the pneumatized
uncinate process resembles a concha
bullosa or an enlarged ethmoid bulla.
69. Infraorbital ethmoid cells are
pneumatized ethmoid air cells
that project along the medial
roof of the maxillary sinus and
the most inferior portion of the
lamina papyracea, below the
ethmoid bulla and lateral to
the uncinate process
71. Two definitions of Onodi cells.
The first defines them as the most
posterior ethmoid cells, being
superolateral to the sphenoid sinus and
closely associated with the optic nerve.
Another, more general description
defines Onodi cells as posterior ethmoid
cells extending into the sphenoid bone,
situated either adjacent to or impinging
upon the optic nerve
73. Its appearance varies considerably, based on the extent of
pneumatization.
Extensive pneumatization may obstruct the ostiomeatal
complex.
Elongated ethmoid bullae are usually in a superior to inferior
direction rather than in an anterior to posterior direction.
So, Relatively unlikely to obstruct the ostiomeatal complex.
74. Encountered rarely
extends into the lesser wing
and the anterior and
posterior clinoid processes
Can lead to distortion of
optic cannal configuration
75. May be either congenital or the
result of prior facial trauma.
It occur most often at the site of
the insertion of the basal
lamella into the lamina
papyracea, thus rendering this
portion of the lamina papyracea
most delicate
Orbit at risk
77. When aeration of the normally bony crista galli occurs the
aerated cells may communicate with the frontal recess, and
obstruction of this ostium.
To avoid unnecessary surgical extension into the anterior
cranial vault, it is important to recognize an aerated crista galli
and differentiate it from an ethmoid air cell.
78. Air cells are commonly found within the posterosuperior
portion of the nasal septum and, when present, communicate
with the sphenoid sinus.
As a result, any inflammatory disease that occurs within the
paranasal sinuses may also affect these cells
79. It is important to note any asymmetry in the height of the
ethmoid roof.
Intracranial penetration during surgery is more likely to
occur on the side where the position of the roof is lower
82. X ray – Water’s view & caldwell view
Ct – gold standard. Coronal & axial sections
MRI is predominantly used for pre and post operative
management of naso sinus malignancy
The chief disadvantage of MRI is its inability to show the bony
details of the sinuses, as both air and bone give no signal
84. CT is currently the modality of choice in the evaluation of the
paranasal sinuses and adjacent structures.
Its ability to optimally display bone, soft tissue, and air
provides an accurate depiction of both the anatomy and the
extent of disease in and around the paranasal sinuses.
In contrast to standard radiographs, CT clearly shows the fine
bony anatomy of the osteomeatal channels.
85. There are few pre requisites in few situations
a course of adequate medical therapy to eliminate or
diminish reversible mucosal inflammation.
pretreatment with a sympathomimetic nasal spray 15
minutes prior to scanning in order to reduce nasal congestion
(mucosal edema) and thus improve the display of the fine
bony architecture and any irreversible mucosal disease
86. Coronal & axial views
The coronal plane best shows the ostiomeatal unit (OMU),
shows the relationship of the brain to the ethmoid roof.
Coronal plane should be the primary imaging orientation for
evaluation of the sinonasal tract in all patients with
inflammatory sinus disease who are endoscopic surgical
candidates
89. Prone with chin hyperextended
Gantry anglutaion- perpendicular
to hard palate
Section thickness-3mm
contigous
Table increment- 3-4 mmeach
step
Kvp-125
Mas-80
Hanging head technique
92. HEAD HANGING METHOD
Performed in the prone position, so
that any remaining sinus secretions
do not obscure the OMU
In patients who cannot tolerate
prone positioning (children,
patients of advanced age, etc.), the
hanging head technique can
sometimes be utilized.
93. In this technique, the patient is
placed in the supine position and the
neck is maximally extended.
A pillow placed under the patient’s
shoulders facilitates positioning.
The CT gantry is then angled to be
perpendicular to the hard palate.
It is not always possible to obtain
true direct coronal images with this
technique
94. Axial images complement the coronal study, particularly when
there is severe disease (opacification) of any of the paranasal
sinuses and surgical treatment is contemplated.
The axial studies provide the best CT evaluation of the anterior
and posterior sinus walls
Axial images are particularly important in visualizing the
frontoethmoid junction and the sphenoethmoid recess.
96. Whenever there is total opacification of the frontal, maxillary, or
sphenoid sinuses, a complete axial and coronal CT examination
should be performed.
And also, if the patient has a suspected neoplasm, a complete
axial and coronal examination need to be performed to provide
the most detailed analysis of the sinonasal cavities and the
adjacent skull base
97. IMAGING PLANE :
REIDS’S LINE – runs b/w infraorbital margin (IOM line)
& EAM. (parallel - axial)
ALEXANDER’S LINE – perpendicular to reids line.
(perpendicular - coronal)
98. Contrast is not required for all cases of CT paranasal sinus
Used in cases such as vascular lesion, malignancy, mass
extending intra cranially, acute infections