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The tympanic membrane, commonly known as the eardrum, is a thin, cone-shaped membrane that forms the boundary between the external auditory canal and the middle ear. It vibrates in response to sound waves and transmits these vibrations to the auditory ossicles.

Anatomy and structure: The membrane is about 8–10 mm in diameter and roughly 0.05 mm thick. It has three layers: an outer squamous epithelium continuous with the ear canal skin, a middle fibrous layer that provides rigidity, and an inner mucous membrane continuous with the middle ear. The handle of the malleus attaches to the center of the membrane (the umbo), and a characteristic cone of light may be seen on otoscopic examination.

Blood supply and innervation: The outer surface is supplied by the deep auricular branch of the maxillary artery, while the inner surface receives tympanic branches from the glossopharyngeal and facial nerves. Sensory innervation of the outer surface comes mainly from the auriculotemporal nerve.

Function: The eardrum converts airborne sound waves into mechanical vibrations that are transmitted to the auditory ossicles (malleus, incus, and stapes). This mechanical energy is then conveyed to the inner ear, where it is translated into neural signals. The membrane also acts as a barrier protecting the middle ear and participates in pressure regulation through its interactions with the tympanic cavity.

Clinical significance: Perforation or scarring can result from trauma, infection, or chronic otitis media and may cause conductive hearing loss. Treatment ranges from observation for small perforations to surgical repair (myringoplasty or tympanoplasty) for persistent defects. Tympanometry and otoscopy are commonly used to assess its function and integrity.

Development and variation: The tympanic membrane develops from both external canal and middle ear tissues and may vary in appearance with retraction, fluid presence, or chronic disease.