[Mechanics of the ear ossicles in static pressures. II. Impaired joint function and surgical reconstruction of the ossicle chain].

Following the presentation of ossicle chain mechanics in the normal ear, the air pressure-induced movements of the ossicles with artificially ankylosed incudomalleal joints were studied in the same static temporal bone-experiments. In this case, exaggerated inward-outward excursions also prevail at the incus and stapes. This isodirectional motion, first described by Helmholtz, and on which is based our concept of middle-ear function until now, can also be seen in insufficiently moistened temporal bone preparations. It is not inconceivable that former studies were conducted with insufficiently moistened preparations. Several quantitative comparisons also point to this possibility. Further measurements analysed the displacements in the reconstructed ossicle chain (interposition). In both these rigid transmissions between drum membrane and stapes there can be excessive air pressure-induced movements of the stapes. This might play a role in the pathomechanics of perilymph fistulas, which is frequently caused by variations of static air pressure.