The suboccipital segment of vertebral artery was enclosed by either venous plexus or venous sinus . its length and curve were various significantly 寰枢段椎动脉由静脉丛或静脉窦包裹，长度及弯曲变异很大。
The occipital sinus has connections with intracranial veins and vertebral vein plexus , thus play a role in accessory venous drainage from the intracranial and in metastatic spread of diseases to intracranium 枕下海绵窦与颅内静脉、椎静脉丛存在交通，在颅内辅助引流静脉及疾病脑转移中起着重要作用。
We describe a modification of surgical technique in which the puboprostatic ligaments are left intact and dissection of neurovascular bundle is performed immediately after the ligationo of dorsal vein complex 我们采用的手术方式与传统不同之处为保留耻骨摄护腺韧带，同时神经血管束的分离是在背静脉丛结扎后再进行。
