Tectorial membrane (cochlea)

Covering the sulcus spiralis internus and the spiral organ of Corti is the tectorial membrane, which is attached to the limbus laminae spiralis close to the inner edge of the vestibular membrane. The tectorial membrane partially covers the hair cells in Organ of Corti and vibrate when fluid sound waves hit it.

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 inconceivably delicate and flexible; far more sensitively flexible in the transverse than in the longitudinal direction and the readiness with which it bends when touched is beyond description.

It is ectodermal in origin.

It consists of fine colorless fibers embedded in a transparent matrix (the matrix may be a variety of soft keratin), of a soft collagenous, semisolid character with marked adhesiveness.

The general transverse direction of the fibers inclines from the radius of the cochlea toward the apex.