Illustration of Upper Respiratory System. In anatomy, a nasal concha (or turbinate) is a long, narrow and curled bone shelf (shaped like an elongated sea-shell) that protrudes into the breathing passage of the nose. Turbinate bone refers to any of the scrolled spongy bones of the nasal passages in vertebrates.rade 1 is 0-25% of the airway, grade 2 is 26-50% of the airway, grade 3 is 51-75% of the airway and grade 4 is 76-100% of the airway. There is sometimes a pair of supreme turbinates superior to the superior turbinates.