Armand J
Rev Neurol (Paris). 1984;140(5):309-29.
The cortical origin of the pyramidal tract is first considered. Contributions of retrograde degeneration studies as well as fiber counting method following different cortical lesions are presented and discussed. The results of these classical neuro-anatomical methods are compared with those of the more recent retrograde transport tracing method. The number and the diameter spectrum of pyramidal tract fibers differ in various mammals. In more evolved species the number of pyramidal fibers increase and their diameter span becomes wider. The thickest fibers are found in man. Along their diencephalic, mesencephalic, pontine and medullary course, axonal collaterals of corticospinal axons may terminate onto cells of origin of other descending pathways, onto relay cells of ascending pathways, and onto neurons projecting to the cerebellum. At the spinal level, the rostrocaudal extent and the termination area of corticospinal fibers may differ in various mammals. In a first group of mammals, the corticospinal fibers extend only to cervical or mid-thoracic segments and terminate in the dorsal horn. In a second group of mammals, the corticospinal fibers extend throughout the spinal cord and terminate in the dorsal horn and the intermediate zone. In a third group of mammals, the corticospinal fibers extend throughout the spinal cord and terminate in the dorsal horn, the intermediate zone and the dorsolateral part of the lateral motoneuronal cell group. In a fourth group of mammals, the corticospinal fibers also extend throughout the spinal cord and terminate in the dorsal horn, the intermediate zone and the dorsolateral as well as the ventral parts of the lateral motoneuronal cell group. A comparison is made between these different types of spinal terminations and the motor capacities of these different species. The motor deficits observed after pyramidal lesions are summarized and a comparison is made between the corticospinal tract and the descending brain stem pathways. According to electrophysiological studies in conscious animals different pyramidal units can be activated during different types of movements and at different times during the preparation or execution of a movement. Recent neuro-anatomical data suggest that the pyramidal tract is composed of many structural subsystems. Recent physiological data suggest that the pyramidal tract can be involved in various aspects of the motor control.
首先考虑锥体束的皮质起源。本文展示并讨论了逆行性变性研究以及不同皮质损伤后的纤维计数方法的贡献。将这些经典神经解剖学方法的结果与更新的逆行运输示踪方法的结果进行了比较。锥体束纤维的数量和直径谱在各种哺乳动物中有所不同。在进化程度更高的物种中，锥体纤维的数量增加，其直径范围变宽。最粗的纤维见于人类。沿其在间脑、中脑、脑桥和延髓的行程，皮质脊髓轴突的轴突侧支可终止于其他下行通路的起始细胞、上行通路的中继细胞以及投射至小脑的神经元上。在脊髓水平，皮质脊髓纤维的 rostrocaudal 范围和终止区域在各种哺乳动物中可能有所不同。在第一组哺乳动物中，皮质脊髓纤维仅延伸至颈部或胸中段，并终止于背角。在第二组哺乳动物中，皮质脊髓纤维贯穿脊髓全长，并终止于背角和中间带。在第三组哺乳动物中，皮质脊髓纤维贯穿脊髓全长，并终止于背角、中间带以及外侧运动神经元细胞群的背外侧部分。在第四组哺乳动物中，皮质脊髓纤维也贯穿脊髓全长，并终止于背角、中间带以及外侧运动神经元细胞群的背外侧和腹侧部分。对这些不同类型的脊髓终末与这些不同物种的运动能力进行了比较。总结了锥体损伤后观察到的运动缺陷，并对皮质脊髓束和下行脑干通路进行了比较。根据对清醒动物的电生理研究，不同的锥体单元可在不同类型的运动期间以及运动准备或执行过程中的不同时间被激活。最近的神经解剖学数据表明，锥体束由许多结构子系统组成。最近的生理学数据表明，锥体束可参与运动控制的各个方面。
