A Morphometric Study of the Internal Acoustic Meatus in Dry Skulls

CONTEXT: The internal auditory canal extends from the porous acusticus medially to the fundus laterally. At the fundus, a vertical bony plate formed by the falciform crest separates the canal from the inner ear and divides it into compartments. Owing to its role as a conduit for vital neurovascular structures, the internal acoustic meatus (IAM) is clinically important in otologic and neurosurgical procedures. AIM AND OBJECTIVES: To evaluate the morphometry of the IAM and provide reference data for neurosurgeons and otologists. SETTINGS AND DESIGN: This descriptive cross-sectional study was conducted on 72 temporal bones (36 right and 36 left) obtained from the department of anatomy of a tertiary care teaching hospital. SUBJECTS AND METHODS: Seventy-two dried adult human temporal bones were studied. A silicone material was injected into the internal acoustic meatus to obtain the impressions for morphometric assessment. STATISTICAL ANALYSIS USED: Mean values were calculated. Side comparisons were performed using the independent samples t-test, and Pearson's correlation coefficient assessed right-left relationships. RESULTS: The mean width of the porus acusticus was 3.60 ± 0.54 mm on the right and 3.74 ± 0.42 mm on the left. The mean height measured 4.27 ± 0.69 mm on the right and 4.53 ± 0.60 mm on the left. No statistically significant difference was found between the sides. Pearson's correlation showed a weak, negative, and statistically nonsignificant correlation. CONCLUSIONS: The findings indicate a relative bilateral symmetry of the porus acusticus, providing baseline morphometric data useful for surgical planning and minimizing neurovascular injury during procedures involving the IAM.