The spaces in the bones around the nose and eyes are called “facial sinuses (paranasal sinuses)”. The paranasal sinuses are divided into 4 main groups: the frontal sinuses on the forehead, the maxillary sinuses on the cheeks, the ethmoid sinuses near the roof of the nose and between the two eyeballs, and the sphenoid sinuses in the head at the very back. Inflammation of the mucosa that fills these spaces is called “sinusitis”.
The most common cause of sinusitis is the spread of the infection from the nasal cavity to one or more sinuses. Even a simple cold causes an infection in the sinuses and mucous membranes, but this often does not cause symptoms. Although paranasal sinus infections develop as a result of a simple rhinitis (cold), they can occur for the following reasons that mainly concern the nasal cavity: