Sinuses

The paranasal sinuses are air-filled, rigid cavities in the bony substance of the human skull, which are lined with a protective epithelial layer (mucosa).

Basic knowledge for Open Water Diver* (OWD*)

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Sinuses of the human skull: Frontal sinuses (1), ethmoid sinuses (2), sphenoidal sinuses (3) and maxillary sinuses(4).

The human boddy has four pairs of paranasal sinuses:

• frontal sinuses
• ethmoid sinuses
• sphenoidal sinuses
• maxillary sinuses

The paranasal sinuses are connected to the nasopharynx and, in some cases, to one each other by means of a canal system. In the case of an inflammatory change caused by e. g. a cold or an infection the connection routes can be changed or even blocked. Since pressure must be equalized in the paranasal sinuses, just like in the middle ear, diving under this circumstances can lead to a barotrauma in the sinuses. Therefore, you should never go diving if you have a cold or infection.