The Distribution of Nerve Endings in the sheath of Human Cervical Nerve Roots, with a Focus on Free Nerve Endings

用18例死后12小时内的39例颈神经根-背根神经节标本，对颈神经根硬膜鞘内神经末梢的存在和分布进行了组织病理学研究。年龄4个月~88岁，平均58岁。用Suzuki银染法或Kluver-Barrera法对硬脑膜根鞘不同部位的20微米连续切片进行光镜观察。在前根、后根和背根神经节(包括隔部)的每个硬膜根鞘中均有游离神经末梢，在背根节和隔部的每个硬膜根鞘中均有两种感觉小体。游离神经末梢的纤维直径与A、C纤维的直径相当。游离神经末梢在背根鞘的近端和远端的分布大于硬膜根鞘的其他部分。在体积为0.01 mm^3(0.16 mm^2*0.06 mm)的组织圆柱体中，含有C-纤维的游离神经末梢最多，为12个，平均3.7个。这些神经末梢被发现沿着两条向心路线中的任何一条，一条通过窦神经，另一条通过从神经末梢直接进入DRG的小神经。硬膜根鞘内的游离神经末梢数随年龄增加而增加(Gamma=0.75)。60岁以下组游离神经末梢数低于60岁以上组，差异有统计学意义(p=0.019)。这些位于硬膜根鞘中的神经末梢，特别是在背根节鞘中的神经末梢，被认为在颈神经根痛的调节中起着重要作用。

The presence and distribution of nerve endings in the dural sheath of cervical nerve roots (dural root-sheaths) was investigated histopathologically using 39 cervical root-dorsal root ganglion specimens obtained from 18 postmortem examinations within 12 hours after death. Ages ranged from 4 months to 88 years, with a mean of 58 years. Microscopic investigation was conducted using 20 mum serial sections of various parts of the dural root-sheath, stained by the Suzuki silver impregnation method or Kluver-Barrera method. Free nerve endings were identified in each of the dural root-sheaths of the anterior root, posterior root and dorsal root ganglia (DRG), including the septum, and two types of sensory corpuscles were identified in each of the dural root-sheaths of the dorsal root ganglia and the septum. The fiber diameters of free nerve endings corresponded to those of either Adelta-fibers or C-fibers. The distribution of free nerve endings was greater in the proximal and distal portions of the DRG sheath than in other parts of the dural root-sheath. The largest population of free nerve endings with C-fibers in the DRG sheath was 12 in a tissue cylinder with a volume of 0.01 mm^3 (0.16mm^2*0.06mm), with an average of 3.7. These nerve endings were found to follow either of two centripetal routes, one through a sinuvertebral nerve and the other through small nerves which penetrated directly into the DRG from nerve endings. The number of free nerve endings in the dural root-sheath increased with ages (gamma=0.75). In addition, the number of free nerve endings in subjects below the age of sixty was lower than that of subjects above sixty with a statistical significance (p=0.019). These free nerve endings in the dural root-sheath, especially those in the DRG sheath, are thought to play an important role in the mediation of cervical radicular pain.