用成年家兔１１只，在脊髓腰膨大部注射ＨＲＰ或麦芽凝集素结合的辣根过氧化物酶（ＷＧＡ－ＨＲＰ），逆行追踪长下行脊髓固有束神经元在颈髓和部分胸髓的分布。其中５例动物在腰膨大注射ＨＲＰ的同时进行大脑皮质脊髓束起始区的损毁，电镜观察皮质脊髓束在颈髓的溃变末梢与ＨＲＰ逆行标记神经元的关系。结果表明，长下行脊髓固有束神经元在脊髓灰质内可分为背腹两群，背侧群主要集中在Ｖ层，细胞较少；腹侧群位于ＶＩＩ、ＶＩＩＩ层，细胞数较多。电镜下可观察到与标记神经元相突触的终扣多为圆形含圆形和混合型小泡。演变末梢有些与标记神经元的胞体或树突形成突触，也有些通过未标记的终扣间接与标记神经元相联系。本研究表明，家兔皮质脊髓束可能通过多种下行通路控制腰部运动，其中，胞体位于颈髓的长下行脊髓固有束神经元肯定与这一下行运动控制机制有关。 Eleven adult rabbits were injected with horseradish peroxidase (WGA-HRP) with HRP or malto-lectin in the lumbar spondylolisthesis and retrogradely tracked the distribution of longitude descending spinal cord intrinsic bundle neurons in the cervical cord and part of the thoracic cavity . Among them, 5 cases of animals were injected with HRP into the lumbar region, meanwhile, the initiation region of corticospinal tract was destroyed. The relationship between cortical spinal cord bundles and the HRP retrogradely labeled neurons was observed by electron microscopy. The results showed that there were two groups of dorsal and ventral constrictors in the long descending spinal cord. The dorsal group was mainly concentrated in the V layer with fewer cells. The ventral group was located in the layers VII and VIII with more cells. Electron microscopy can be observed with the labeled neurons synaptic termination mostly circular round and mixed vesicles. Some of the evolutionary terminals are synaptically with the cell body or dendrites of labeled neurons, and some are indirectly linked to labeled neurons through unlabeled terminators. This study shows that the rabbit corticospinal tract may be through a variety of downstream pathways to control lumbar movement, which is located in the cervical spinal cord long spinal cord inherent bundle fascicular neurons certainly with this downstream motor control mechanism.