The nasal septum is a thin structure separating the two sides of the nose. If it is not in the middle of the nose, it is considered deviated.

The nasal septum has two parts. Toward the back of the head the nasal septum is rigid bone, but further forward it is cartilage. By placing one finger in each nostril, this cartilage can easily be bent back and forth. If the nasal septum is sufficiently displaced to one side, it will impede the flow of air and mucus through the nose. This condition, called a deviated septum, can cause symptoms and disease.

A deviated septum can be a simple variation in normal structure or the result of a broken nose. Any narrowing of the nasal passageway caused by a deviated septum will threaten the drainage of secretions from the sinuses, which must pass through the nose. It...