Tectorial membrane (cochlea)

Covering the sulcus spiralis internus and the spiral organ of Corti in the cochlea is the tectorial membrane, which is attached to the limbus laminae spiralis (spiral limbus) close to the inner edge of the vestibular membrane. The tectorial membrane covers the hair cells in Organ of Corti, with the longer hairs of the outer hair cells touching, but not penetrating, it. The membrane itself is a gel-like structure containing at three different glycoproteins; α-tectorin, β-tectorin and otogelin. It also contains collagen fibers (type XI), which help make the membrane anisotropic with respect to its mechanical properties.

The mechanical role of the tectorial membrane in hearing is not yet completely understood, and indeed has been neglected or downplayed in many models of the cochlea. However, recent results indicate that the tectorial membrane might play a more important role than previously appreciated.

Its inner part is thin and overlies the auditory teeth of Huschke; its outer part is thick, and along its lower surface, opposite the inner hair cells, is a clear band, named Hensen's stripe, due to the intercrossing of its fibers.

The lateral margin of the membrane is much thinner.

American anatomist Irving Hardesty (1866–1944) considered the tectorial membrane as the vibrating mechanism in the cochlea. A structure known as Hardesty's membrane divides the subtectorial space into two compartments, one facing the surfaces of inner hair cells and one facing the surfaces of outer hair cells.

It is ectodermal in origin.