| Paranasal sinuses | |
|---|---|
 Paranasal sinuses seen in a frontal view | |
 Lateral projection of the paranasal sinuses | |
| Details | |
| Identifiers | |
| Latin | sinus paranasales |
| MeSH | D010256 |
| TA98 | A06.1.03.001 |
| TA2 | 3176 |
| FMA | 59679 |
| Anatomical terminology | |
Paranasal sinuses are a group of four pairedair-filled spaces that surround thenasal cavity.[1] Themaxillary sinuses are located under theeyes; thefrontal sinuses are above the eyes; theethmoidal sinuses are between the eyes, and thesphenoidal sinuses are behind the eyes. Thesinuses are named for thefacial bones and sphenoid bone in which they are located. The role of the sinuses is still debated.
Humans possess four pairs of paranasal sinuses, divided into subgroups that are named according to thebones within which the sinuses lie. They are all innervated by branches of thetrigeminal nerve (CN V).
The paranasal sinuses are lined withrespiratory epithelium (ciliated pseudostratified columnar epithelium).
![[icon]](/mt/?noimg=&dark=on&url=http%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aWiki_letter_w_cropped.svg) | This sectionneeds expansion. You can help byadding to it.(April 2024) |
One known function of the paranasal sinuses is the production ofnitric oxide, which also functions as a facilitator of oxygen uptake.[3]
Paranasal sinuses form developmentally through excavation of bone by air-filled sacs (pneumatic diverticula) from thenasal cavity. This process begins prenatally (intrauterine), and it continues through the course of an organism's lifetime.[citation needed]
The results of experimental studies suggest that the natural ventilation rate of a sinus with a singlesinus ostium (opening) is extremely slow. Such limited ventilation may be protective for the sinus, as it would help prevent drying of its mucosal surface and maintain a near-sterile environment with highcarbon dioxide concentrations and minimalpathogen access. Thus composition of gas content in the maxillary sinus is similar tovenous blood, with high carbon dioxide and loweroxygen levels compared to breathing air.[4]
At birth, only themaxillary sinus and theethmoid sinus are developed but not yet pneumatized; only by the age of seven are they fully aerated. Thesphenoid sinus appears at the age of three, and thefrontal sinuses first appear at the age of six, and fully develop during adulthood.[5]
The paranasal sinuses are joined to thenasal cavity via small orifices calledostia. These become blocked easily by allergic inflammation, or by swelling in the nasal lining that occurs with acold. If this happens, normal drainage ofmucus within the sinuses is disrupted, andsinusitis may occur. Because the maxillary posterior teeth are close to the maxillary sinus, this can also cause clinical problems if any disease processes are present, such as an infection in any of these teeth. These clinical problems can include secondary sinusitis, the inflammation of the sinuses from another source such as an infection of the adjacent teeth.[6]
These conditions may be treated with drugs such asdecongestants, which causevasoconstriction in the sinuses; reducing inflammation; by traditional techniques ofnasal irrigation; or bycorticosteroid.[medical citation needed]
Malignancies of the paranasal sinuses comprise approximately 0.2%[7] 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 thansarcomas. Metastases are rare.Tumours of the sphenoid and frontal sinuses are extremely rare.
Sinus is aLatin word meaning a fold, curve, or bay. Comparesine.
Paranasal sinuses occur in many animals, including mostmammals,birds, andcrocodilians. They have also been discovered in non-aviandinosaurs. The bones occupied by sinuses vary with species.
