What is a sinus?

A sinus is a hollow space within the bones of the face. The sinuses are lined by delicate membrane. The membrane is called mucosa. As shown in the normal anatomy picture, there are four pairs of sinuses. The function of the sinuses is to humidify and warm the air, add to the sense of smell and to play a significant role in the quality of human sound. It is well known that during acute sinusitis, rhinitis and common cold, the quality of our voice changes and the senses of smell and taste are reduced.