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Drtbalu's otolaryngology online1 Radiological anatomy of Frontal sinus Balasubramanian Thiagarajan.

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Presentation on theme: "Drtbalu's otolaryngology online1 Radiological anatomy of Frontal sinus Balasubramanian Thiagarajan."— Presentation transcript:

1 drtbalu's otolaryngology online1 Radiological anatomy of Frontal sinus Balasubramanian Thiagarajan

2 drtbalu's otolaryngology online2 Introduction Highly complex and variable anatomy Variations – impact on drainage Efficiency of muco-ciliary clearance – relationship to morphology of frontal sinus

3 drtbalu's otolaryngology online3 Embryology

4 drtbalu's otolaryngology online4 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

5 drtbalu's otolaryngology online5 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

6 drtbalu's otolaryngology online6 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

7 drtbalu's otolaryngology online7 Frontal beak

8 drtbalu's otolaryngology online8 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

9 drtbalu's otolaryngology online9 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

10 drtbalu's otolaryngology online10 Inferior compartment Inferior portion - infundibulum

11 drtbalu's otolaryngology online11 Attachment to lamina papyracea – inferior component formed by middle meatus

12 drtbalu's otolaryngology online12 Inferior compartment formed by infundibulum

13 drtbalu's otolaryngology online13

14 drtbalu's otolaryngology online14 Frontal beak Frontal beak forms the floor of frontal sinus

15 drtbalu's otolaryngology online15 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

16 drtbalu's otolaryngology online16 Frontal recess

17 drtbalu's otolaryngology online17 Agger nasi

18 drtbalu's otolaryngology online18 Large bulla Can obstruct frontal sinus outflow This area should be critically studied during imaging Causes obstruction from behind

19 drtbalu's otolaryngology online19 Bulla

20 drtbalu's otolaryngology online20 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

21 drtbalu's otolaryngology online21 Ethmoidal infundibulum 3 – d space Lateral – LP Anteromedial – Uncinate Posterior - Bulla

22 drtbalu's otolaryngology online22 Large agger cell causing narrowing of frontal recess Frontal recess block

23 drtbalu's otolaryngology online23

24 drtbalu's otolaryngology online24 uncinate process attached to skull base. The frontal recess is seen between the agger nasi and uncinate process

25 drtbalu's otolaryngology online25 Scan showing uncinate process being attached to lamina papyracea. This causes terminal recess to form. Frontal sinus drains directly into middle meatus

26 drtbalu's otolaryngology online26 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

27 drtbalu's otolaryngology online27 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

28 drtbalu's otolaryngology online28 Type I & II frontal cell

29 drtbalu's otolaryngology online29 Type III

30 drtbalu's otolaryngology online30 Type IV

31 drtbalu's otolaryngology online31 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

32 drtbalu's otolaryngology online32 Thank you

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