Time-saving and fail-safe dissection method for vestibulocochlear organs in gross anatomy classes.

Because the vestibulocochlear organs are tiny and complex, and are covered by the petrous part of the temporal bone, they are very difficult for medical students to dissect and visualize during gross anatomy classes. Here, we report a time-saving and fail-safe procedure we have devised, using a hand-held hobby router. Nine en bloc temporal bone samples from donated human cadavers were used as trial materials for devising an appropriate procedure for dissecting the vestibulocochlear organs. A hand-held hobby router was used to cut through the temporal bone. After trials, the most time-saving and fail-safe method was selected. The performance of the selected method was assessed by a survey of 242 sides of 121 cadavers during gross anatomy classes for vestibulocochlear dissection. The assessment was based on the observation ratio. The best procedure appeared to be removal of the external acoustic meatus roof and tympanic cavity roof together with removal of the internal acoustic meatus roof. The whole procedure was completed within two dissection classes, each lasting 4.5 hr. The ratio of surveillance for the chorda tympani and three semicircular canals by students was significantly improved during 2013 through 2016. In our dissection class, "removal of the external acoustic meatus roof and tympanic cavity roof together with removal of the internal acoustic meatus roof" was the best procedure for students in the limited time available. Clin. Anat. 30:703-710, 2017. © 2017Wiley Periodicals, Inc.