Tympanic annulus

Last revised by Dr Daniel J Bell on 27 Jun 2021

The tympanic annulus is the thickened edge of the pars tensa of the tympanic membrane, anchoring it in the tympanic sulcus 3.

Gross anatomy

The tympanic annulus is formed by a fibrocartilaginous thickening of the edge of the pars tensa and has a horseshoe-shaped configuration. It is deficient superiorly at the notch of Rivinus, where the pars flaccida is found 1. The tympanic annulus inserts into the tympanic sulcus, a shallow groove of the external acoustic canal (EAC), attaching the tympanic membrane to the EAC. The annulus has a triangular cross-section with the base inserted into the sulcus and the apex pointing towards the tympanic membrane 3.

History and etymology

The notch of Rivinus was first described by Augustus Quirinus Rivinus (1652–1723), a German anatomist 2.

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