Download Rounded Rectangles - Otolaryngology online

Radiological anatomy of
Frontal sinus
Balasubramanian Thiagarajan
drtbalu's otolaryngology online
1
Introduction

Highly complex and variable anatomy

Variations – impact on drainage

Efficiency of muco-ciliary clearance –
relationship to morphology of frontal sinus
drtbalu's otolaryngology online
2
Embryology
drtbalu's otolaryngology online
3
Embryology - contd



Continuation of embryonic infundibulum,
frontal recess superiorly
Upward migration of anterior ethmoid air
cells
Penetration via inferior aspect of frontal
bone between the two tables

Pneumatization 2-9 years

Complete – 9 years
drtbalu's otolaryngology online
4
Frontal sinus drainage




Expands into the diploic space of frontal
bone from frontal sinus ostium
Each sinus grows independently of the
other
Growth is dependent on ventilation,
drainage, growth of surrounding sinuses
and skull base
Drainage is hence highly variable
drtbalu's otolaryngology online
5
Frontal sinus drainage - contd



Inferomedially into
funnel shaped area
(frontal sinus ostium)
Anterior wall of
drainage channel is
bounded by nasal
beak
Ostium is oriented
perpendicular to the
posterior wall of the
sinus at the skull base
level
drtbalu's otolaryngology online
6
Frontal beak
drtbalu's otolaryngology online
7
Frontal sinus drainage
pathway compartments




Drainage pathway is divided into superior
and inferior compartments
Superior compartment is formed by union
of adjacent air cells at the antero inferior
portion of ethmoid bone
Size and shape of this component varies
with the varying anatomy for fronto
ethmoidal air cells
Superior compartment communicates with
the inferior compartment
drtbalu's otolaryngology online
8
Inferior component



This passage is really narrow
This compartment is formed by ethmoidal
infundibulum / middle meatus
This is dependent on the attachment of
uncinate process
drtbalu's otolaryngology online
9
Inferior compartment
Inferior portion - infundibulum
Inferior portion infundibulum
drtbalu's otolaryngology online
10
Attachment to lamina papyracea – inferior component formed by
middle meatus
drtbalu's otolaryngology online
11
Inferior compartment formed by infundibulum
drtbalu's otolaryngology online
12
drtbalu's otolaryngology online
13
Frontal beak
Frontal beak forms the floor of frontal sinus
drtbalu's otolaryngology online
14
Frontal recess





Antero superior portion of ethmoidal air
cell system
This is where the frontal bone
pneumatization begins
Lateral wall is formed by lamina papyracea
Medial wall is formed by vertical
attachment of middle turbinate
Posterior wall is variable ? Bulla if it
manages to reach up to skull base
drtbalu's otolaryngology online
15
Frontal recess
drtbalu's otolaryngology online
16
Agger nasi
drtbalu's otolaryngology online
17
Large bulla



Can obstruct frontal sinus outflow
This area should be critically studied
during imaging
Causes obstruction from behind
drtbalu's otolaryngology online
18
Bulla
drtbalu's otolaryngology online
19
Uncinate vs frontal sinus
drainage



Uncinate – skull base attachment causes
frontal sinus to drain into superior portion
of ethmoidal infundibulum
Uncinate – attached to middle turbinate
causes frontal sinus to drain into ethmoidal
infundibulum
Uncinate – attached to lamina papyracea
causes frontal to drain into superior aspect
of middle meatus. Ethmoidal infundibulum
ends in terminal recess
drtbalu's otolaryngology online
20
Ethmoidal infundibulum

3 – d space

Lateral – LP


Anteromedial –
Uncinate
Posterior - Bulla
drtbalu's otolaryngology online
21
Frontal recess block
Large agger cell causing
narrowingonline
of frontal recess
drtbalu's otolaryngology
22
drtbalu's otolaryngology online
23
uncinate process attached to skull base. The frontal
recess is seen between the agger nasi and uncinate
process
drtbalu's otolaryngology online
24
Scan showing uncinate process being attached to lamina
papyracea. This causes terminal recess to form. Frontal
sinus drains directly into middle meatus
drtbalu's otolaryngology online
25
scan shows the uncinate process being attached to the
middle turbinate. Note the presence of infundibulum
between the bulla and the uncinate process. Frontal sinus is
seen opening into the infundibulum
drtbalu's otolaryngology online
26
Bent's classification of frontal
cell variants




Type I: Single frontal recess cell above the
agger
Type II: Tier of air cells above agger
projecting into the frontal recess
Type III: Single massive air cell above
agger expanding in superior direction
Type IV: Single isolated cell within frontal
sinus. Difficult to visualize due to thin
walls
drtbalu's otolaryngology online
27
Type I & II frontal cell
drtbalu's otolaryngology online
28
Type III
drtbalu's otolaryngology online
29
Type IV
drtbalu's otolaryngology online
30
Supraorbital air cells



Pneumatization of
orbital plate of
frontal bone
Posterior to frontal
recess & lateral
to frontal sinus
Sometimes can
reach high up
mimicking frontal
sinus
drtbalu's otolaryngology online
31
Thank you
drtbalu's otolaryngology online
32