Sinuses are the spaces within the bones of the skull and face, which are filled with air. These open spaces serve the purpose of high temperatures and humidity in the air we breathe, as well as giving an echo of the voice. It also reduced the weight of the skull, which will be much heavier without these open spaces. Cells lining the sinuses also produce mucus that traps inhaled bacteria and keeps the inside of the nose from drying out. Sinus humans have several, located in different places around the eyes and nose. Usually, we refer to the sinuses and sinus simply we have, for convenience. In fact, though, there are other types of pockets in the skull as well. Small enclaves located in the middle ear, for example, and hence the term "sinus" to distinguish them from others. Because it is only partially developed before birth, and sinuses have to continue to develop throughout our lives. This applies to virtually every living creature with pockets of any kind. Sinus is set in four pairs that are more or less symmetrical from left to right. Maxillary sinuses are the largest of them, located under the eyes in the inner part of bones. The next is the largest front pockets, located in the forehead above each eye. This is the last to develop and time to occur, in some people, they do not develop at all.
