The ethmoid sinus (one of six sets of sinuses) is part of the paranasal sinus system and is located between the nose and eyes. It is very small at birth and becomes walnut-sized during puberty. The primary function of the ethmoid sinus, like all the sinus cavities in the skull, is to provide lubrication (mucus) to the inner nose. In addition to creating mucus, the sinuses — including the ethmoid sinus — reduce the skull's overall weight and make one's voice more resonant as they grow in size during puberty.
The ethmoid sinus, like all sinuses, can become infected occasionally during one's life for various reasons; such sinus infections are usually treated with decongestants and antibiotics. In severe cases of chronic sinus infection, the affected sinuses may need to be surgically cleaned and/or expanded.
The ethmoid sinus is susceptible to a form of cancer called "cancer of the ethmoid sinuses." This may be caused by exposure to substances like chromium, mustard gas, and nickel. Exposure to chromium and nickel is a hazard of working in certain industries, like carpentry, nickel mining, and tanning. Studies have also shown that chronic sinusitis (inflammation of the sinus) can be a risk factor in developing ethmoid sinus cancer.