Acoustic role of the buttress and posterior incudal ligament in human temporal bones.

Abstract

In middle ear surgery using intact ear canal wall techniques, the buttress, which is the bony bridge at the medial end of the posterior-superior bony ear canal, is commonly retained during posterior tympanotomy. In some cases, the surgical exposure may be improved by resectioning the buttress, and this requires sectioning the posterior incudal ligament. To date, the acoustic effects of removing the buttress with sectioning of the attached ligament have not been studied. Using a laser Doppler vibrometer system, 15 human cadaver temporal bones were measured with 80 dB sound pressure level at the tympanic membrane over the 0.1 to 10 kHz frequency range. The resection of the buttress and sectioning the posterior incudal ligament had no effect on stapes footplate velocity. These results suggest that the posterior incudal ligament does not play a significant role in the acoustic function of the ossicles.