The eardrum is an air-filled cavity within the petrous pyramid of the temporal bone. It contains ossicles and connects, at the front, to the eustachian tube, and at the back, to the nasopharynx, and via the aditus, with the mastoid cavity (ear canal).
It is comprised of two levels and 6 membrane walls.
The upper level or atticus primarily contains the ossicles and connects to the mastoid cavity.
The lower level or atrium contains the opening to the eustachian tube and connects to the eardrum.
The outer wall primarily consists of the tympanum and the hammer « grip ».
The inner wall separates the middle ear from the inner ear.
The upper part, the semi-circular canal juts out – while the lower part is marked by the promontory, a projection formed by the first turn of the snail shell – with two openings, the oval window and the round window.
And anterior wall contains the opening to the eustachian tube, where the role of airing the eardrum is essential.
The posterior wall connects, via an opening, the aditus with the mastoid air cells.
The segmental wall corresponds to the temporal lobe.
The jugular wall contains the gulf of the jugular vein.