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The Paranasal Sinuses

The paranasal sinuses are four air-filled spaces within the bones of skull that surround and connect to the nasal cavity. The four structures that makeup the paranasal sinuses are the maxillary, frontal, sphenoid, and ethmoid sinuses. The maxillary sinuses are the largest of the four and are located just under the eyes. The frontal sinuses are located within the frontal bone just above the eyes, while the ethmoid sinuses are located between the nose and eyes, and the sphenoid sinuses are located under the pituitary gland.


While the complete functions of the paranasal sinuses are still not known and are being debated, there are some biological functions of the paranasal sinuses that scientists do seem to have been able to reach an agreement upon. Some of the agreed upon functions of the paranasal sinuses include:

  • reducing the weight of the head (specifically the front of the head)
  • warming and moistening inhaled air
  • increasing the resonance of speech
  • the protection of vital structures in the event of facial trauma
  • insulating sensitive structures (such as dental roots and eyelids) against rapid temperature changes