Paranasal sinusesare a group of four pairedair-filled spacesthat surround thenasal cavity.[1]Themaxillary sinusesare located under theeyes;thefrontal sinusesare above the eyes; theethmoidal sinusesare between the eyes and thesphenoidal sinusesare behind the eyes. Thesinusesare named for thefacial bones and sphenoid bonein which they are located. Their role is disputed.
| 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 | |
Structure
editHumans possess four pairs of paranasal sinuses, divided into subgroups that are named according to theboneswithin which the sinuses lie. They are all innervated by branches of thetrigeminal nerve(CN V).
- Themaxillary sinuses,the largest of the paranasal sinuses, are under theeyes,in the maxillary bones (open in the back of thesemilunar hiatusof the nose). They are innervated by themaxillary nerve(CN V2).[2]
- Thefrontal sinuses,superior to the eyes, in thefrontal bone,which forms the hard part of theforehead.They are innervated by theophthalmic nerve(CN V1).[2]
- Theethmoidal sinuses,which are formed from several discrete air cells within theethmoid bonebetween thenoseand the eyes. They are innervated by theethmoidal nerves,which branch from thenasociliary nerveof the ophthalmic nerve (CN V1).
- Thesphenoidal sinuses,in thesphenoid bone.They are innervated by the ophthalmic and maxillary nerve (CN V1 and V2).[2]
The paranasal sinuses are lined withrespiratory epithelium(ciliated pseudostratified columnar epithelium).
Functions
editThis 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]
Development
editParanasal sinuses form developmentally through excavation of bone by air-filled sacs (pneumatic diverticula) from thenasal cavity.This process begins prenatally (intrauterine life), and it continues through the course of an organism's lifetime.
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 dioxideconcentrations and minimalpathogenaccess. Thus composition of gas content in the maxillary sinus is similar tovenous blood,with high carbon dioxide and loweroxygenlevels compared to breathing air.[4]
At birth, only themaxillary sinusand theethmoid sinusare developed but not yet pneumatized; only by the age of seven are they fully aerated. Thesphenoid sinusappears at the age of three, and thefrontal sinusesfirst appear at the age of six, and fully develop during adulthood.[5]
CT scans, radiographs (x-ray) and other illustrations
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Coronal CT scan of the paranasal sinuses (bone)
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Paranasal sinuses radiograph (occipitofrontal) -
Paranasal sinuses radiograph (occipitomental) -
Paranasal sinuses radiograph (lateral) -
3D cast of maxillary, frontal, ethmoid and sphenoid sinuses, nasal cavity and hypopharynx
Clinical significance
editInflammation
editThe paranasal sinuses are joined to thenasal cavityvia 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 ofmucuswithin the sinuses is disrupted, andsinusitismay 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 causevasoconstrictionin the sinuses; reducing inflammation; by traditional techniques ofnasal irrigation;or bycorticosteroid.[medical citation needed]
Cancer
editMalignancies 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.Carcinomasare more frequent thansarcomas.Metastases are rare.Tumoursof the sphenoid and frontal sinuses are extremely rare.
Etymology
editSinusis aLatinword meaning a fold, curve, or bay. Comparesine.
Other animals
editParanasal sinuses occur in many other animals, including mostmammals,birds,andcrocodilians.They have also been discovered in non-aviandinosaurs.The bones occupied by sinuses vary with species.
Illustrations
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Paranasal sinuses -
Illustration depicting sinusitis
See also
editReferences
edit- ^"Paranasal sinuses".23 December 2021.
- ^abc"Paranasal Sinus Anatomy: Overview, Gross Anatomy, Microscopic Anatomy".2016-08-24.
- ^Lundberg, Jon O (November 2008)."Nitric oxide and the paranasal sinuses".The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology.291(11):1479–1484.doi:10.1002/ar.20782.PMID18951492.
- ^"ARTICLES | Journal of Applied Physiology".jap.physiology.org.Retrieved2017-09-07.
- ^Towbin, Richard; Dunbar, J. Scott (1982)."The paranasal sinuses in childhood".RadioGraphics.2(2):253–279.doi:10.1148/radiographics.2.2.253.
- ^Illustrated Anatomy of the Head and Neck, Fehrenbach and Herring, Elsevier, 2012, p. 68