Structure
The tympanic membrane is a thin, semi-transparent membrane with an oval shape. Most of the circumference of the membrane is a thickened rim of fibrocartilage known as the anulus. The anulus contains some smooth muscle cells.
The tympanic membrane can be divided into two parts, the pars flaccida, superiorly, and the pars tensa, inferiorly. These parts are separated by the anterior and posterior mallear folds, which pass from the tympanic membrane to the malleus.
The inner surface of the tympanic membrane is convex and projects into the tympanic cavity. The handle of the malleus is firmly attached to the inner surface of the membrane. The primary innervation of the tympanic membrane is the auriculotemporal nerve, which conveys pain sensation.
Related parts of the anatomy
Anatomical Relations
The tympanic membrane forms the division between the external acoustic meatus and the tympanic cavity. The handle of the malleus is attached to its internal surface.
Function
The tympanic membrane vibrates with the force of sound waves entering the cavity through the external acoustic meatus. This vibration is transferred from the tympanic membrane to the auditory ossicles. The anulus around the circumference of the tympanic membrane potentially plays a role in maintaining tension of the membrane and controlling blood flow.
List of Clinical Correlates
—Otitis media
—Perforation
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Eardrum
A deep tympanogram can be produced either by a healed perforation of the eardrum or by a break in the ossicles (called an ossicular disruption), which is often caused by head trauma.
