Sinus Anatomy, Sinus Problems & Sinusitis Basics
Understanding Sinus Pain, Sinus Headache & Sinus Pressure Relief
Nov 10, 2009
Paranasal sinuses are air-filled cavities in the skull bones, in and around the nose. Knowledge of the anatomy of the sinuses and their functioning helps in understanding sinus problems like chronic sinusitis, sinus headache and sinus congestion and also gives an insight into the measures for sinus pressure relief like endoscopic sinus surgery.
Paranasal Sinus Anatomy
Some of the paranasal sinuses are present at birth and enlarge with the development of the facial skeleton, while others develop later.
There are four pairs of paranasal sinuses. They are:
- Maxillary sinuses – located in the cheek bones, on either side of the nose
- Frontal sinuses – present in the frontal bones or forehead, above the eyebrows
- Ethmoid sinuses – situated deep, in between the eyes and the nose
- Sphenoid sinuses – located even deeper, above and behind the nose and nasopharynx
Each sinus is a hollow in the skull bone in which it is located and communicates with the nasal cavity through a narrow opening or passageway called the sinus ostium. The sinus cavity is lined all around by the same mucosa that drapes the nasal cavity, continuous with that of the sinuses through the ostium. This facilitates the spread of infection from the nose into the sinuses.
Glands present in the mucosal lining of the sinuses secrete mucus, just like in the nose. Normally, these secretions are propelled towards the sinus ostia by cells with arm-like appendages called cilia, just like oars pushing water. The secretions therefore get driven into the nose from where they are washed into the pharynx and swallowed, similar to nasal mucus.
Paranasal Sinus Functions
The functions performed by the paranasal sinuses are:
- Adding resonance to voice
- Lightening the skull bones
- Humidifying inhaled air
- Acting as thermal insulators to protect the delicate structures in the orbit and the skull
Sinus Headache, Sinus Blockage and Chronic Sinusitis
Sometimes, infection or allergy can cause swelling in the tissue around the sinus openings, leading them to become narrower or sometimes even completely blocked. This sinus blockage leads to retention of secretions within the sinus cavity, making the once air-filled cavity a fluid-filled one. This gives rise to sinus congestion and sinus headache. Further, the retained secretions may become infected leading to chronic sinusitis.
Other Sinus Problems
The sinuses are adjacent to important structures like the orbits and the brain. Untreated and severe sinusitis (like invasive fungal sinusitis) can spread to these vital organs resulting in dangerous complications like meningitis and blindness.
Benign growths called polyps may arise from the mucosal lining of the sinuses and cause nasal block, discharge and headache. Malignant growths of the sinuses, paranasal sinus cancers, may present with bleeding or blood stained discharge from the nose.
Sinus Pressure Relief and Endoscopic Sinus Surgery
Measures for sinus pressure relief like endoscopic sinus surgery and balloon sinuplasty are based on a sound knowledge of paranasal sinus anatomy. These procedures are used to widen the blocked sinus ostia in order to drain the retained secretions and provide adequate ventilation to the sinuses.
A knowledge of paranasal sinus anatomy and function lays the foundation for understanding chronic sinusitis, sinus headache and other sinus problems and devising measures to relieve them.
Sources:
Gleeson, Michael J. "Scott-Brown's Otorhinolaryngology: Head and Neck Surgery" (Oxford University Press; 7 edition, 2008)
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