Internal acoustic opening is a space that opens to facies posterior of the petrous piece of temporal bone that goes inside facial nerve, vestibulocochlear nerve, intermedial nevre and labyrinthine artery. The purpose of this study is the assessment of internal acoustic opening from a morphometric perspective, determination of the shape of the hole and determination of the distance to some important anatomic formations. This study is conducted on 166 temporal bones with unknown sex formation which are part of the skull collection in NEU and KTO Karatay University, Anatomy Department. In this study, the vertical and diameter of internal acoustic meatus, its distance to the bottom and top sides of posterior surface of the petrous part, its distance to groove for superior sagittal sinus and its distance to apex were measured. Moreover, in this study internal acoustic opening spaces are categorized into six groups as round, oval, U-shaped, fissure, irregular and V shape. Digital caliper was used for internal acoustic meatus measurements. While the vertical horizontal diameters and distance to groove for superior sagittal sinus of internal acoustic opening on the right side are 4.12 mm, 6.83 mm and 19.64mm respectively, they are 4.56 mm, 7.10 mm and 21.06 mm on the left side respectively. We have observed in this study, 37.3 % of the internal acoustic opening as round, 34.3 % as oval, 6.6 % as U-shaped, 6.6 % as fissure, 12.7 % as irregular and 2.4 % as V-shaped. We believe that these measurements can provide guidance and help in surgical procedures

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