Eardrum

Eardrum (tympanic membrane, myringa)
Right eardrum as seen through a speculum.
Details
Identifiers
Latin	membrana tympanica; myringa
MeSH	A09.246.272.702
Dorlands /Elsevier	Tympanic membrane
TA	A15.3.01.052
FMA	9595
Anatomical terminology []

In the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear from the middle ear. Its function is to transmit sound from the air to the ossicles inside the middle ear, and then to the oval window in the fluid-filled cochlea. Hence, it ultimately converts and amplifies vibration in air to vibration in fluid. The malleus bone bridges the gap between the eardrum and the other ossicles.

Rupture or perforation of the eardrum can lead to conductive hearing loss. Collapse or retraction of the eardrum can cause conductive hearing loss or cholesteatoma.

There are two general regions of the eardrum: the pars flaccida in the upper region and the pars tensa. The pars flaccida consists of two layers, is relatively fragile, and is associated with eustachian tube dysfunction and cholesteatomas. The larger pars tensa region consists of three layers: skin, fibrous tissue, and mucosa. It is comparatively robust and is the region most commonly associated with perforations.

The pars tensa forms most of the tympanic membrane. Its periphery is thick and forms a fibrocartilaginous ring called the anulus tympanicus. The central part of the pars tensa is tented inward at the level of the tip of malleus and is called the umbo. When the eardrum is illuminated during an examination, a cone of light radiates from the tip of the malleus to the periphery in the antero-inferior quadrant. The pars flaccida is above the lateral process of the malleus between the notch of Rivinus and the anterior and posterior malleal folds. It appears slightly pinkish.