Lacrimal Bone Anatomy
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Paranasal Sinuses
Introduction to the Paranasal Sinuses:
- The
paranasal sinuses are cavities in the bones of the face and cranium.
- These air – filled spaces vary in size and are lined by mucous membrane.
- The mucous secretions drain into the nasal cavity and help, warm, humidify, and clean the air.
- The paranasal sinuses also help lighten the skull and resonate the voice.
Anterior View:
Frontal sinuses – two cavities located just above the orbits and behind the superciliary arches. [
Anterior view]
- Mucous secretions are drained from each sinus by a frontonasal duct, which empties into the nasal cavity at the middle meatus.
Coronal View:
Ethmoid sinuses – a collection of small cavities located between the orbits in the lateral masses (or labyrinths) of the ethmoid bone. [
Coronal view]
- Each lateral mass contains approximately 6 to 12 cavities, which are referred to as ethmoid air cells.
- The mucous secretions produced by the air cells drain into the nasal cavity at the superior and middle meatuses.
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Maxillary sinuses – two large, cavities located in the body of the maxillary bone, on either side of the nasal cavity. [
Coronal view]
- Mucous produced by each sinus drains into the mid-lateral wall of the nasal cavity.
Sagittal View:
Sphenoid sinuses – two cavities (right & left) in the centre (or body) of the sphenoid bone. [
Sagittal view]
- A thin bony septum separates the two sinuses.
- Mucous from the sinuses drains into the spheno-ethmoidal recess located at the top of the nasal cavity.
Frontal sinuses – two cavities located just above the orbits and behind the superciliary arches. [
Sagittal view]
- Mucous secretions are drained from each sinus by a frontonasal duct, which empties into the nasal cavity at the middle meatus.
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