Microanatomy of facial nerve segment related to acoustic neuromas

Objective To study the microanatomy of facial nerve related t o acoustic neuromas so as to provide the anatomic data and the techniques of int raoperative protection of facial nerve for surgery. Methods 15 corpse head s treated with formaldehyde solution were involved in the basic research, with t heir brain stem, cerebellopontine angle, internal auditory canal and adjacent st ructure relevant to facial nerve were measured and photographed. Results T here was a regular distance between the brain stem segment and the adjacent stru cture. The cerebellopontine angle segment was composed of motor root and interme diate nerve and showed a regular relation with vestibulocochlear nerve in their pathways. At the segment of internal acoustic meatus, the motor root of facial n erve had its root in the anterosuperior vestibulocochlear nerve and converged in to one with the intermediate nerve in the middle of internal acoustic meatus. Ne ar the floor of internal acoustic meatus, the facial nerve extended along upper transverse crest and anterior vertical crest. Conclusion The microanatomy o f facial nerve related to acoustic neuromas is helpful for the removal of acoust ic neuromas and intraoperative protection of facial nerve, which is the anatomic base to reserve facial nerve in the operation of acoustic nearomas.