Department of Anatomy and Neuroscience, University of Melbourne, Parkville, VIC, 3010, Australia,
Adv Exp Med Biol. 2014;817:39-71. doi: 10.1007/978-1-4939-0897-4_3.
The digestive system is innervated through its connections with the central nervous system (CNS) and by the enteric nervous system (ENS) within the wall of the gastrointestinal tract. The ENS works in concert with CNS reflex and command centers and with neural pathways that pass through sympathetic ganglia to control digestive function. There is bidirectional information flow between the ENS and CNS and between the ENS and sympathetic prevertebral ganglia.The ENS in human contains 200-600 million neurons, distributed in many thousands of small ganglia, the great majority of which are found in two plexuses, the myenteric and submucosal plexuses. The myenteric plexus forms a continuous network that extends from the upper esophagus to the internal anal sphincter. Submucosal ganglia and connecting fiber bundles form plexuses in the small and large intestines, but not in the stomach and esophagus. The connections between the ENS and CNS are carried by the vagus and pelvic nerves and sympathetic pathways. Neurons also project from the ENS to prevertebral ganglia, the gallbladder, pancreas and trachea.The relative roles of the ENS and CNS differ considerably along the digestive tract. Movements of the striated muscle esophagus are determined by neural pattern generators in the CNS. Likewise the CNS has a major role in monitoring the state of the stomach and, in turn, controlling its contractile activity and acid secretion, through vago-vagal reflexes. In contrast, the ENS in the small intestine and colon contains full reflex circuits, including sensory neurons, interneurons and several classes of motor neuron, through which muscle activity, transmucosal fluid fluxes, local blood flow and other functions are controlled. The CNS has control of defecation, via the defecation centers in the lumbosacral spinal cord. The importance of the ENS is emphasized by the life-threatening effects of some ENS neuropathies. By contrast, removal of vagal or sympathetic connections with the gastrointestinal tract has minor effects on GI function. Voluntary control of defecation is exerted through pelvic connections, but cutting these connections is not life-threatening and other functions are little affected.
消化系统通过与中枢神经系统 (CNS) 的连接以及胃肠道壁内的肠神经系统 (ENS) 来进行神经支配。ENS 与 CNS 反射和命令中心以及穿过交感神经节的神经通路协同工作，以控制消化功能。ENS 与 CNS 之间以及 ENS 与交感前脊椎神经节之间存在双向信息流。人类的 ENS 包含 2 亿至 6 亿个神经元，分布在数千个小神经节中，其中绝大多数存在于两个神经丛中，即肌间神经丛和黏膜下神经丛。肌间神经丛形成一个从食管上段延伸至肛门内括约肌的连续网络。黏膜下神经节和连接纤维束在小肠和大肠中形成神经丛，但在胃和食管中没有。ENS 与 CNS 的连接通过迷走神经和盆神经以及交感神经通路传递。神经元也从 ENS 投射到前脊椎神经节、胆囊、胰腺和气管。ENS 和 CNS 在沿着消化道的相对作用有很大的不同。横纹肌食管的运动由 CNS 中的神经模式发生器决定。同样，CNS 在监测胃的状态方面起着主要作用，并通过迷走神经反射来控制其收缩活动和胃酸分泌。相比之下，小肠和结肠中的 ENS 包含完整的反射回路，包括感觉神经元、中间神经元和几类运动神经元，通过这些神经元可以控制肌肉活动、黏膜间液通量、局部血流和其他功能。CNS 通过腰骶脊髓中的排便中枢控制排便。一些 ENS 神经病变会产生危及生命的影响，这突出了 ENS 的重要性。相比之下，切断迷走神经或交感神经与胃肠道的连接对胃肠道功能的影响较小。排便的自主控制是通过骨盆连接来实现的，但切断这些连接不会危及生命，其他功能也几乎不受影响。
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