后颅窝远外侧手术入路的显微外科解剖研究

THE STUDY ON THE MICROSURGICAL ANATOMY OF FAR LATERAL APPROACH OF POSTERIOR CRANIAL FOSSA

目的:探讨后颅窝远外侧手术入路的显微外科解剖。方法:在30个(60侧)干颅骨上对枕大孔区的重要骨性结构(枕骨大孔、枕髁、舌下神经管等)的形状、大小及毗邻结构进行测量。在10个(20侧)10%福尔马林固定的成人连颈尸体头颅标本上进行模拟远外侧手术入路进行解剖,显露枕下区的椎动脉,测量相关参数。在手术显微镜下(×4～10)对15个(30侧)10%福尔马林固定的成人尸头标本进行解剖,显露枕髁关节面,自后外向前内方向磨除枕髁,记录显露舌下神经管内口所磨除的枕髁量。结果:①枕髁位于枕骨大孔两侧,舌下神经管位于枕髁中后1/3处,磨除枕髁至舌下神经管内口处,可较好地显露枕大孔区腹侧结构。②第二颈神经根的前支均从椎动脉寰枢椎段的背侧越过,椎动脉颅外段长度及弯曲变异较大,外周有静脉丛或静脉窦包裹。③从椎动脉前方切开硬膜,可避开在后组颅神经根丝间的操作,减少对脑干的牵拉。结论:研究后颅窝远外侧入路的显微解剖,有助于在切除枕大孔腹侧及下斜坡区的肿瘤中重要结构的保护。

Objective：The purpose of this study is to observe microsurgical anatomy of far lateral approach of posterior cranial fossa.Methods：Thirty （60 sides）aduh dried skulls ,10 （20 sides）adult cadaveric heads with connected neck fixed with 10% formalin,and another 15（30 sides） adult cadaveric heads were involved in this study . The important structures such as the foramen magnum,occipital condyle,and hypoglossal canal were investigated on the dried skulls. The suboccipital segment of vertebral artery was dissected and measured on the cadaveric heads with connected neck according to the procedures of far lateral approach. The occipital condyle was drilled to the intracranial end of the hypoglossal canal from posterior lateral margin according to the procedures of far lateral approach under the surgical microscope （x4-10 magnification）.Then the drilled length was measured . Resuits： （1）The occipital condyle was located at lateral side of the foramen magnum, the intracranial end of the hypoglossal canal was located above the junction of the posterior and middle one-third of the occipital condyle.The structures of ventroforamen magnum region were exposed preferably when the occipital condyle was drilled to the intracranial end of the hypoglossal canal. （2）The former branch of C2 nerve all crossed from the back of the suboecipital segment of vertebral artery which was enclosed by either venous plexus or venous sinus and its length and curve were various significantly. （3）Dura opened from front of the vertebral artery may avoid operation among the low cranial nerves and reduce the pull of brain stem.Conclusion ：Study of microanatomy in the far lateral approach is helpful in resecting turnouts of the ventro- foramen magnum and the lower clival region and preserving important tissues.