Sinus

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Sinuses (human). Frontal sinus: purple, sphenoid sinus: yellow

The paranasal sinuses ( Latin sinus paranasales ) are air-filled sacs of the mucous membrane of the nasal cavity that push themselves between the two cover plates ( tabula externa and interna ) of some skull bones . Since the paranasal sinuses are connected to the nasal cavity, they are assigned to the respiratory system.

construction

Schematic representation of the paranasal sinuses
Nasal cavity and paranasal sinuses of humans in the X-ray image of humans with a colored background on one side.
orange: cavum nasi
green: sinus maxillary
yellow: cellulae ethmoidales
purple: sinus frontalis
blue: sinus sphenoidalis
cyan: processus mastoideus

In mammals, a distinction is made between various paranasal sinuses , depending on the respective pneumatized skull bone, although not all of them have to be developed in every species:

The lacrimal sinus and palatal cavity do not occur in humans.

function

Sinus paranasales:
1. Frontal sinus (green)
2. Ethmoidal cell (purple)
3. Sphenoid sinus (red)
4. Maxillary sinus (blue)

These bones are pneumatized through penetration points of the sinuses to the inner nose . H. filled with air. The evolutionary advantage of these formations is believed to be an increase in the size of the skull without unduly increasing the weight of the head. The paranasal sinuses are located in bone parts that are hardly or not at all tensile stressed, which is why the bone recedes in these areas. Contrary to previous assumptions, the paranasal sinuses have no function as resonance cavities for voice formation.

According to another thesis, the paranasal sinuses function as “ crumple zones ” in the cranial skeleton, in that they partially absorb the impact energy when the face is exposed to violence. This will reduce damage to delicate soft tissues, especially the eyes and brain .

development

In humans, only the ethmoid cells are formed at birth. Small children cannot develop sinusitis ; if the ethmoid cells are involved, one speaks of children's rhinosinusitis . The development of the frontal sinuses begins after the first year of life, in the 6th year of life they are about the size of a pea, they only reach their final size when the skull has finished growing (20-25 years of age). The sphenoid sinus begins after the 3rd – 6th Year of life to develop. The maxillary sinuses only develop gradually with the eruption of the permanent teeth, i.e. from around the age of 7, as the upper jaw first contains the tooth anus of the second teeth.

Diseases

Since the sinuses with the middle meatus of the nose (which is therefore also referred to as sinus passageway is signified) are in open communication, diseases can of the nasal mucosa ( "runny nose", see rhinitis ) also spill over to the paranasal sinuses (sinusitis, sinusitis ).

Since the mucous membrane of the paranasal sinuses has relatively little blood supply and they only have narrow entrances ( ostia ), secretions can quickly accumulate in these cavities. The narrow accesses, especially if they are swollen in the context of rhinitis, may lead to pain when there are strong changes in pressure ( diving , mountain hiking , flying). A collection of pus in a preformed cavity is called empyema . In addition, the antibiotic levels are not as high here , so that infectious agents find a special refuge here. Unhealed inflammations of the paranasal sinuses can lead to recurrent ( recurrent ) reinfections of the nasal cavity.

The formation of nasal polyps in chronic polypoid sinusitis also usually starts from the sinuses and not from the nasal cavity itself.

Finally, it should be mentioned that in animals certain parasites (e.g.  nasal dassel and nose worm , Linguatula serrata ) prefer to settle in the paranasal sinuses.

Extensive pneumatization of the skull bones also occurs in birds . Of greater practical importance is the infraorbital sinus , the wall of which consists only of soft tissues and which, if there is accumulation of pus, leads to significant swellings below the eye.

literature

  • Franz-Viktor Salomon: Bony skeleton. In: Franz-Viktor Salomon, Hans Geyer, Uwe Gille (Ed.): Anatomy for veterinary medicine. Enke, Stuttgart 2004, ISBN 3-8304-1007-7 , pp. 37-110.

Web links

Commons : Sinuses  - Collection of pictures, videos and audio files

Individual evidence

  1. https://onlinelibrary.wiley.com/doi/abs/10.1002/lary.20583 ; accessed on August 14, 2018
  2. https://www.researchgate.net/publication/260154531_Crumple_Zone_Effect_of_Nasal_Cavity_and_Paranasal_Sinuses_on_Posterior_Cranial_Fossa ; August 14, 2018