Mediterr J Otol 2006:2(2):52-57

Anatomic Observations on Variations of the Round Window Niche and Its Relationship to the Tympanic Membrane

Asım Aslan, İbrahim Tekdemir, Kıvanc Günhan, Görkem Eskiizmir, Alaittin Elhan

Department of Otolaryngology, Celal Bayar University School of Medicine, Manisa, Turkey asimas98@yahoo.com

OBJECTIVE: To study the anatomic variations of the round window niche and its relationship to the tympanic membrane.

MATERIALS AND METHODS: Eleven dry temporal bones and 9 temporal bone specimens were studied. Visualization of the round window niche through external auditory canal, position of the round window niche opening, and relationship of the position of the round window niche to the posterior quadrant of the tympanic membrane were recorded.

RESULTS: If the round window niche was visible (75% of the bones) through the external auditory canal in otologic surgery position, it was located 2.2 mm posterior to the umbo, and the round window niche was located just at the level of midportion of the posterior tympanic annulus. Anteroinferior quadrant dimension (3.4 × 3.9 mm) of the tympanic membrane was found to be narrower than the posteroinferior dimension (4.8 × 3.9 mm).

CONCLUSION:  From the surgical standpoint, these findings about the anatomic features of the round window niche might be important for several otologic interventions, such as ventilation tube insertions, intratympanic drug applications, and cochlear implantation.