If the nasal septum, or the wall between the nostrils, is very crooked, it makes the air passage on one side narrow. This obstruction can make breathing somewhat difficult, because the flow of air through the narrower passage may become blocked. Substantial deviation of the septum is not common. It usually happens because of an injury, and the nose can look straight. There are no significant symptoms other than the mild breathing problem and, rarely, an increased tendency to sinusitis . The septum can be straightened by surgery if the deviation is troublesome. Most people who have a deviated septum simply live with it.