The Maxillary Sinus
- Sinus ostium located in the middle meatus
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The Ethmoid Sinuses
- Anterior ethmoids: drain into the middle meatus
- Posterior ethmoids: drain into superior meatus
The Frontal Sinus
- Rarely present at birth; usually not visible until age 2
- Great variability in size; congenitally absent in 5%
The Sphenoid Sinus
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Lining of the Sinuses
- Pseudostratified, columnar epithelium (respiratory epithelium) which is continuous with the nasal epithelium
Blood Supply
- Branches from the internal and external carotids
Nerve Supply
- Branches from the trigeminal