Sinus is the anatomical name, while paranasal sinus is the general term for the sinuses, which generally include maxillary sinus, sieve sinus, pterygoid sinus, and frontal sinus. The sinuses are usually divided into anterior group sinuses and posterior group sinuses. The anterior group sinuses include maxillary sinus, frontal sinus, and anterior group sieve sinus, and the posterior group sinuses include butterfly sinus and posterior group sieve sinus. The location of their purulent secretions is different, with the anterior group of sinuses generally located in the middle nasal tract and the posterior group of sinuses generally located in the upper nasal tract. The location of the sinuses is then determined according to the characteristics of their purulent secretions. Usually, a CT scan of the sinuses can also be performed to confirm the location of the inflamed sinuses.