tympanon

Tympanon is a term used in anatomy to refer to a thin, membranous structure that plays a key role in hearing. In humans and other mammals, the tympanon is the tympanic membrane, or eardrum, which forms the boundary between the external auditory canal and the middle ear. The name derives from the Greek tympanon, meaning drum. The membrane converts airborne sound waves into mechanical vibrations that are transmitted to the auditory ossicles of the middle ear.

Structurally, the tympanic membrane is a trilaminar, cone-shaped membrane anchored around its circular rim to a bony ring called the tympanic annulus. It consists of an outer cutaneous layer, a fibrous middle layer, and an inner mucous layer. The handle of the malleus attaches to the inner surface at the umbo, giving the membrane its characteristic cone shape. The outer surface is exposed to the external acoustic environment, while the inner surface interfaces with the middle ear cavity.

Functionally, the tympanic membrane vibrates in response to air pressure changes caused by sound, initiating movement of the auditory ossicles (malleus, incus, stapes). This mechanical amplification helps convey sound energy into the fluid of the inner ear. The membrane also participates in middle-ear pressure regulation via the Eustachian tube.

Clinical notes: Perforation or scarring of the tympanic membrane from infection or trauma can impair hearing and increase infection risk. Treatments include medical management of underlying conditions, myringoplasty or tympanoplasty to repair, and drainage or placement of tympanostomy tubes in cases of persistent effusion.

In zoology, tympanon or tympanum can also denote a tympanal membrane or organ in various insects and other animals, serving as a hearing or vibration-sensing structure.