Abstract: Objective To explore the related structures of retrosigmoid approach by microanatomy and virtual anatomy and provide a reliable approach with more morphologic data. Methods Twenty sides of 10 adult cadaveric heads were dissected to simulate retrosigmoid approach under the microscope. The neurovascular structures of pontocerebellar trigone were observed, and the related structures were simultaneously measured based on the junction of superior petrosal sinus and sigmoid sinus and internal acoustic pore. The internal auditory canal was opened by drilling the margin of the internal auditory meatus and its structures were watched. With the help of Dexotroscope system, the data of five patients’ CT and MRI were applied to reconstruct and anatomize the structure of retrosigmoid approach. Results It was found that the distance from the junction of superior petrosal sinus and sigmoid sinus to the trigeminal nerve was (38.50±2.64)mm, to the acoustic-facial bundle (27.80±2.25)mm, to the glossopharyngeal nerve (32.70±2.11)mm, to the hypoglossal nerve (44.30±2.05)mm, and the distance from internal acoustic pore to the trigeminal nerve was (5.68±1.55)mm, to the abducent nerve (13.80±1.81)mm, to the tentorium of cerebellum (5.00±0.66)mm, to the glossopharyngeal nerve (6.34±1.24)mm. The pontocerebellar trigone was divided into the anterior compartment, the middle compartment, the posterior compartment built on the acoustic-facial bundle and the glossopharyngeal nerve. Their structures were displayed after drilling the margin of the internal auditory meatus. Dexotroscope system clearly displayed asterion, the angle of transverse and sigmoid sinus, jugular foramen, internal acoustic pore, basilar artery and its branches, and theirs spatial relationship.Conclusion. The three compartments of the pontocerebellar trigone are helpful to understand the feature of the neurovascular layer, the measurement is favorable to quantize the relation of the related structures and to judge the space of each compartment. Recognizing the anatomical marker of internal acoustic pore can support preservation of the inner structures. Virtual anatomy of Dexotroscope system can display local anatomical structure respectively. Both microanatomy and virtual anatomy have their advantages and disadvantag

Key words: Retrosigmoid approach, Pontocerebellar trigone, Microanatomy, Virtual anatomy, Human