Fig. 12. Diagrammatic representation of the movement of the left extrastapes when the ascending process is intact. For clarity, surrounding middle ear structures are not shown. When the tympanic membrane is inflected inwards, the distal tip of the extrastapes moves ventromedially, sliding on its loose connection with the internal surface of the membrane. The thin ascending process, connected to the parotic crest dorsomedially, bends. As a result of the bending at the ascending process, the vibration velocity at the region of the extrastapes articulating with the pars media has a strong vertical component. This is necessary for the pars media and footplate to be set into motion. Movement is greatly exaggerated for clarity.

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