| Paranasal sinuses | |
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| Paranasal sinuses. | |
| Lateral projection of the paranasal sinuses | |
| Latin | sinus paranasales |
| Gray's | subject #223 998 |
| Dorlands/Elsevier | Paranasal sinuses |
Paranasal sinuses are a group of four paired air-filled spaces that surround the nasal cavity (maxillary sinuses), above and between the eyes (ethmoid sinuses and frontal sinuses), and behind the ethmoids (sphenoid sinuses). The sinuses are named for the facial bones behind which they are located.
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Humans possess a number of paranasal sinuses, divided into subgroups that are named according to the bones within which the sinuses lie:
The paranasal air sinuses are lined with respiratory epithelium (ciliated pseudostratified columnar epithelium).
Paranasal sinuses form developmentally through excavation of bone by air-filled sacs (pneumatic diverticula) from the nasal cavity. This process begins prenatally, and it continues through the course of an organism's lifetime.
Paranasal sinuses occur in a variety of animals (including most mammals, birds, non-avian dinosaurs, and crocodilians). In non-humans, the bones occupied by sinuses are quite variable.
The biological role of the sinuses is debated, but a number of possible functions have been proposed:
The paranasal sinuses are joined to the nasal cavity via small orifices called ostia. These become blocked easily by allergic inflammation, or by swelling in the nasal lining which occurs with a cold. If this happens, normal drainage of mucus within the sinuses is disrupted, and sinusitis may occur.
These conditions may be treated with drugs such as decongestants, which causes vasoconstriction in the sinuses, reducing inflammation, by traditional techniques of nasal irrigation, or by corticosteroid.
Malignancies of the paranasal sinuses comprise approximately 0.2% of all malignancies. About 80% of these malignancies arise in the maxillary sinus. Men are much more often affected than women. They most often occur in the age group between 40 and 70 years. Carcinomas are more frequent than sarcomas. Metastases are rare. Tumours of the sphenoid and frontal sinuses are extremely rare.
Sinus is a Latin word meaning a fold or pocket; in particular the front pocket in a toga.
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