The middle ear is the air-containing irregular cavity located within the tympanic section of the temporal bone, between the external and internal auditory canals, and includes four parts: the tympanic chamber, the eustachian tube, the tympanic sinus, and the mastoid process. The temporal bones are located on both sides of the skull and are involved in making up the base and side walls of the skull. The ossicles of the external auditory canal, the middle ear, the inner ear, and the internal auditory canal are located in the temporal bones, and the middle ear communicates outwardly through the tympanic membrane with the external auditory canal, inwardly with the internal auditory canal, and forwardly with the Eustachian tube into the nasopharynx. The tympanic cavity is located between the tympanic membrane and the lateral wall of the inner ear, and there are 6 walls in total: anterior, posterior, superior, inferior, internal, and external. The contents of the tympanic cavity include the auditory ossicles, auditory ossicular ligament, and the auditory ossicular muscles, among which the auditory ossicles have 3 pieces, i.e., the hammer bone, the anvil bone, and the stapes bone, which together constitute the auditory ossicular chain and mediate the transmission of sound waves into the inner ear, and the ligament of the auditory ossicle makes the auditory ossicles fixed inside the tympanic cavity, and the auditory ossicular muscles include the tympanic membrane tensor and stapedial muscles. The Eustachian tube is the passageway between the tympanic cavity and the nasopharynx, and is located at the junction of the tympanic part of the temporal bone and the nasopharynx. The tympanic sinus is located behind and above the tympanic chamber and is an air-containing cavity that serves as a major transportation channel between the tympanic chamber and the mastoid airspace. The mastoid process is the flared portion of the tympanic cavity and sinus.