The ear cavity (which is affected in infectious otitis) is connected by a duct (the Eustachian tube) to the nasopharynx located behind the nasal fossae.
Otitis is related to a bacterial or viral infection, which most often contaminating the middle ear as a result of rhino-sinusitis or rhino-pharyngitis by borrowing the Eustachian tube or vice versa (otitis media evolving towards a pharyngitis).