Wondering why respiratory infection spread easily to the sinus and ears?

Mucosa: Hello. The reason your sinuses, ears and respiratory airways get infected at the same time is because the lining or mucosa is continuous. They are comprised of the exact same cells, mucus and pathogens. It is very hard to look at magnified areas of the ears, nose, throat and airways and differentiate one from the other. Since they are continuous, inflammation or infection can easily travel.