The clinical anatomy of the facial nerve correlated with the temporal bone surgery

Objective To study the anatomy features and the location of the facial nerve during the temporal approaches.Methods The mastoidotympanectomy,the facial recess approaches,the facial nerve decompression,the middle cranial fossa approach and the infrelabyrine approach were simulated on 15 adult cadaveric specimens(30 sides).The topographical features and the relationship of facial nerve with the surrounding structures were explored.30 dry temporal bones were cut along the facial canal,for exploring the relationship of the facial canal and the surrounding structures.Results(1) The distance from the vertical part of the facial nerve to the glomus was about(3.58±1.33)mm,and to the sigmoid sinus(6.42±2.65)mm.(2) The air cells of lateral facial recess was found in 26 cases(86.67%),which is helpful for locating the facial recess and the facial nerve.(3) The lateral lap of the facial nerve was under the point between the posterior and middle 1/3 of the lateral semicircular canal about(1.70±0.33)mm.The vertical line connected this point to the anterior extremity of the conker's crista represented the vertical part of the facial nerve.(4) Geniculate ganglion located anteriorly to the cochleariform process about(2.48±0.23)mm.(5) The fundus of internal acoustic meatus was in the anterior aspect of the lateral point of the eminence of superior semicircular.The ramus lacrimales nervi petrosi superficialis majoris was the convenient signal for locating the labyrinthine segment of the facial nerve.Conclusions It is valuable for locating the facial nerve through its relationship with the surrounding structures,the topography and the features of substantia ossea surrounding the facial nerve,during the temporal approach.