Holographic vibration analysis of the ossicular chain.

The mechanics of movement of the ossicular chain has been investigated on human temporal bone preparations by means of time average holography. The malleus and incus moved like a lever around an axis, which position was somewhat dependent upon frequency. Simulation of contraction of the muscles of the middle ear gave as result a change in the pattern of movement of the ossicular chain. The position of the rotatory axis was changed, and the amplitudes of vibration were reduced. This should be a protecting mechanism.