目的　研究三叉神经中枢髓鞘部、周围髓鞘部与移行区的结构特点。 方法　在15例尸头标本上进行解剖学研究。通过不同的颅底入路，在手术显微镜下观察三叉神经的走行。然后将三叉神经脑池段（三叉神经从脑干端至美克氏腔开口的部分）完整取下，制作成组织学切片并用Luxol fast blue髓鞘染色，观察三叉神经移行区的结构特点，并测量各项数据。  结果　三叉神经的中枢髓鞘伴随三叉神经出脑干，前行在脑桥小脑角池内；中枢髓鞘出脑干后（2.34±0.81）mm开始向周围髓鞘部移行，在距脑干（3.78±0.69）mm左右截止。中枢髓鞘占脑池段全长的(30.5±5.6)%，周围髓鞘占脑池段全长的(81.1±8.1)%，移行区出现在脑池段(18.8±6.5)%～(30.5±5.6)%的位置。  结论　三叉神经的移行区与神经根进出脑干端处于两个不同的位置。三叉神经的中枢髓鞘部和移行区位于脑桥小脑角池内，该区域受到的血管压迫可能是导致三叉神经痛的病因之一。

Objective    To examine anatomic features of the central myelin, the peripheral myelin and the transitional zone of trigeminal nerve.    Methods    Anatomical and histological techniques were used to investigate 15 adult cadaveric head specimens. The different skull base approaches were performed on those specimens under surgical microscope. The cistern segment of the nerves were embedded in paraffin and sectioned，for Luxol fast blue staining. The photomicrographs were used to measure the length of central myelin and transition zone.    Results    The central myelin extended into the cistern. About  (2.34±0.81)mm from the pons, the central myelin gradually transferred to peripheral myelin. The transition zone terminated at (3.78±0.69)mm from the pons. (30.5±5.6)% of the cistern segment of the trigeminal nerve composed of cental myelin, whereas the peripheral myelin formed aboudt (81.1±8.1)% of the cistern part. The TZ located at the site from (18.8±6.5)% to (30.5±5.6)% of the cisternal segment.    Conclusions    The extension of the central myelin and transition zone into the cistern gives the conception that REZ and TZ are distinct areas. The vascular compression in this region might be contributive to the trigeminal neuralgia.