Dictionary of Human Evolution and Biology

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Paranasal Sinuses

Four pairs of air-filled cavities that occur within the maxillary, frontal, ethmoid, and sphenoid bones. In life these sinuses are lined by mucous membranes that are continuous with the lining of the nasal cavity. As these sinuses develop during growth, along with the mastoid air cells, they reduce the density of the head and serve as resonation chambers for the human voice. Energetics physiologists also attribute energy conservation to the sinuses because muscle size can be smaller with a less dense head. These sinuses are expanded in Neandertals.

See sinus.

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