Veins of the lumbar spinal ganglia in human adults and fetuses.

To obtain a fundamental knowledge of the morphological relationship between nerve root symptoms and circulatory disorders, the distribution pattern of the veins in the lumbar spinal ganglia from the first to fifth vertebrae was investigated in 5 adult human cadavers (mean age 69.6 years) and 5 human fetuses (mean age 6.6 months). The following results were obtained: 1) In the adults the veins perforating from the outer surface of the fifth lumbar spinal ganglion were smaller in number than those perforating from the first to fourth ganglia. In contrast, in the fetuses the number of such veins was increased in the lower lumbar spinal ganglia. In each of the ganglia, the number of veins emerging through the dorsal side was much higher than the number perforating from the outer surface of the ventral sides. The veins perforating through the outer surface of the ganglion formed weak venous networks (periganglionic venous plexus) surrounding the dorsal ramus of the spinal nerve. 2) The veins communicating with the tributaries from the periganglionic venous plexus were classified into three types. Type 1 veins flowed into the intervertebral veins (the frequency ranged from 9.2 to 18.2 in the adults and from 22.4 to 37.0 in the fetuses). Type 2 veins coursed in the spinal cord along the dorsal root fibers and penetrated the dura mater on the way (the frequency ranged from 0.4 to 4.8 in the adults and from 1.2 to 2.2 in the fetuses). Type 3 veins opened directly into the internal vertebral plexus (the frequency ranged from 0.4 to 1.8 in the adults and from 0 to 0.4 in the fetuses). Type 1 veins were the most frequent among the three types of veins in both adults and fetuses. Few type 3 veins were observed in either group. 3) In the first and second lumbar vertebrae in the adults, three-quarters of each spinal ganglion was situated in the vertebral canal. In the lower lumbar region (L3-L5), three quarters of each spinal ganglion lay on the outside of the vertebral canal. In the fetuses, approximately one half to three-quarters of each lumbar spinal ganglion was located in the vertebral canal.