Surgical landmarks during mastoidal and petrosal operations.

This study was made on twenty-one formalin fixed, adult skull left-half specimens. Each of the measurements was made using callipers accurate to 0.1 mm. The dissection of the temporal bone was begun with simple mastoidectomy and completed when the endosteum of the semicircular canals were opened. During the temporal bone dissection step by step, eleven different measurements have been made with small size callipers, and mean, median, range and standard deviations have been determined. The following set of correlations was found to be significant; I--The correlation between the orbitomeatal length and the distance from the most lateral point of the tympanomastoid suture to the facial canal (r = 0.69, p < 0.001). II--The correlation between the orbitomeatal length and the distance from the tympanic ring to the facial canal (r = 0.49, p = 0.011). III--The correlation between the distance from the most lateral point of the tympanomastoid suture to the facial canal and the distance from the tympanic ring to the facial canal (r = 0.71, p < 0.001).