颞骨内面神经水平段的显微解剖

Microanatomical study of the horizontal segment of facial nerve in temporal bone

目的研究颞骨内面神经水平段及其毗邻结构的显微解剖，为临床应用提供解剖学资料。方法通过模拟临床经乳突入路的手术方法，分层解剖加个成人湿头颅标本（40侧颞骨），显露并观测颞骨内面神经水平段及其毗邻结构。结果面神经水平段的长度为[（8．85±1．01）（7．10—11．25）]mm、直径为[（1．88±0．65）（1.55～1．90）]mm；FN水平段与垂直段的夹角（向前）为[（115．5±6．89）（109．5～128．6）]°；面神经水平段与鼓室天盖的夹角（向后）为[（28．5±3．66）（25．8—31．5）]°；匙突至面神经水平段的垂直距离为[（1．89±0．58）（0．90—3．05）]mm；镫骨头至面神经水平段（垂直距离）为[（2．30±0．85）（1．97—3．11）]mm；锥曲段顶点到砧骨短脚尖的距离为[（2．55±0．21）（2．10—2．90）]mm；锥曲段顶点至外半规管隆突距离为[（2．86±0．31）（2．23—3．56）]mm；未发现面神经水平段有分支的或者移位的情况。面神经水平段的远段位于水平半归管隆突的前内侧。有2侧（2／40）水平段的远段位于外半规管隆突外侧0．89mm和1．02mm．占5％。结论膝状神经节、匙突、镫骨、鼓室天盖、水平半规管、砧骨是手术中确定FN水平段的重要标志。颞骨内面神经水平段与其毗邻结构的空间位置关系复杂，手术操作必须熟悉面神经水平段上述定位标志，以免损伤面神经。

Objective To explore the microanatomy of the horizontal segment of the facial nerve （FN） in temporal bone and its adjacent structures, in order to provide microanatomical datas for the clinical works. Methods In 20 adult wet skull specimens （40 temporal bones）, horizontal segment of FN and their adjacent structures in temporal bones were observed according to operational layers by simulating transmastoid approach. Results The length of the horizontal segment was [ （8.85 ± 1.01 ） （7.10-11.25 ） ] mm; The diameter of the horizontal segment was [ （1.88 ± 0.65 （1.55-1.90）] mm;The angle opening towards anterior direction between horizontal segment and vertical segment was [（115.5 ± 6.89）（109.5-128.6）]°. The angle towards posterior direction between horizontal segment of FN and tympanic tegmen was [ （28.5 ± 3.66） （25.8- 31.5）]° ;The vertical distance from the cochlear form process to the horizontal segment of the FN was [ （1.89 ± 0.58）（0.90-3.05）] mm; The vertical distance from the head of the stapes to the horizontal segment of the FN was [ （2.30 ± 0.85）（1.97 - 3.11）]mm;The distance between the summit of pyramidal segment of FN and the apex of shor limb of incus was 2.55 ± 0.21 （2.10-2.90）mm;The distance between the summit of pyramidal segment of FN and the eminence of the lateral semicircular canal was [（2.86 ± 0.31）（2.23 - 3.56）]mm; No branching or dislocated nerve of the horizontal segment of the FN was found in all 40 cases. Five pereent（2/40）distal part of the horizontal segment of FN tracks forward lateral to the eminence of the lateral semicircular canal. Conclusion Geniculate ganglion, cochlearform process, stapes, tympanic tegmen, lateral semicircular canal, incus are important landmarks by which horizontal segment of FN might be located in manipulation of mastoid; The relations of horizontal segment of FN and its adjacent structures are complicated , compact. It will be good that the manipulater absorb a great deal of anatomical knowledge about landmarks that can be used in locating horizontal segment of FN.