Synonyms
Paranasal sinus, nose, sinuses Medical: Sinus paranasalis
Definition
The nasal sinuses lie, as the name already expresses, beside the nose in the bony face-skull. The paranasal sinuses usually come into consciousness when they become inflamed and sinusitis (= inflammation of the paranasal sinuses) occurs. The paranasal sinuses fulfill important functions that also have to do with heating and moistening the air we breathe.
Anatomical composition
If our facial skulls were completely filled with bones and not with such cavities as the sinuses, our head would be very heavy and we would not be able to keep it upright for long. Therefore, one can attribute to them the task of relieving weight. The cavities of the paranasal sinuses, together with the main nasal cavity as a kind of resonance chamber, ensure improved voice and speech formation.
Singers in particular suffer severe limitations in their profession due to sinusitis. The sinuses include the paired maxillary sinus, the frontal sinus, the paired ethmoid sinus and the sphenoidal sinus. Like the nasal mucosa, all paranasal sinuses are lined with a thin seam of hairs (ciliated epithelium).
Since all paranasal sinuses are connected to the main nasal cavity, the hairs (kinocilia) also beat in the direction of the excretory ducts (ostia). The maxillary sinus is located on both sides of the main nasal cavity in the upper jaw bone (maxilla) and fills it almost completely. It is one of the largest paranasal sinuses.
The maxillary sinus is connected to the main nasal cavity by a crescent-shaped opening (Hiatus semilunaris). This is located just below the middle nasal concha (Concha nasi media). Seen from the maxillary sinuses, the discharge point is located quite high up, which makes the transport of secretions (e.g. in case of a cold) more difficult. Furthermore, the zygomatic bone limits the paranasal sinuses. If the maxillary sinuses are inflamed (maxillary sinusitis), they are particularly severely affected.
The paranasal sinuses
The frontal sinus lies above the main nasal cavity and delimits the orbits from above. A connection to the main nasal cavity also exists via the crescent-shaped structure (Hiatus semilunaris) in the middle nasal passage (Meatus nasi medius), slightly above the opening of the maxillary sinus. In the case of inflammation of the frontal sinus cavity (Sinusitis frontlis = inflammation of the frontal sinus), the orbit is particularly at risk.
If too much mucus and pus is formed, the orbita breaks through and the inflammation can spread to the eye (orbitaphlegmon, orbititis). The ethmoid sinuses (Sinus ethmoidales, Cellulae ethmoidales) consist of eight to ten pea-sized, pneumatized capsules. The front capsules open into the middle and the rear capsules into the upper nasal passage (Infundibulum ethmoidale).
The ethmoid cells are less likely to become inflamed than the maxillary or frontal sinuses, but one of the front ethmoid cells can still enter the middle nasal passage (Bulla ethmoidales), pushing the middle nasal concha (Concha nasi medius) towards the nasal septum. A bulge in the middle nasal passage makes breathing more difficult and can close the other openings of the paranasal sinuses. The sphenoid sinus (Sinus sphenoidales) has access to the upper nasal passage via a small opening (Recessus sphenoidales; Apertura sinus sphenoidales) above the main nasal cavity.
In the case of inflammatory processes in the sphenoid sinus cavity, it is particularly important to prevent the sphenoidal sinus from spreading to its vicinity. One of the most important neighbors is the pituitary gland, which produces important hormones. If an inflammation spreads to it, it can lead to life-threatening diseases.
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