Diamant N E
University of Toronto, Ontario.
Gastroenterol Clin North Am. 1989 Jun;18(2):179-94.
The esophagus is a region with three functional zones: (1) the upper esophageal sphincter; (2) the esophageal body; and (3) the lower esophageal sphincter. Control mechanisms within the central nervous system and peripherally serve to integrate these functional zones in a region where voluntary and involuntary control mechanisms and the activity of two different types of muscle are intimately coordinated. The distal 50 to 60 per cent of the esophagus in humans is entirely smooth muscle. Extrinsic control for esophageal motor function resides in a brainstem swallowing center with an afferent reception system, an efferent system of motor neurones, and a complex organizing or internuncial system of neurones. Sensory information from the esophagus is carried in the vagus nerves, but sensory pathways are also present in sympathetics entering the spinal cord. The vagus nerve receiving fibers both from the nucleus ambiguus and the dorsal motor nucleus innervates the striated and smooth muscle esophagus, respectively, including the sphincters. There is a myenteric nerve plexus in both the striated and smooth muscle segments. In the smooth muscle esophagus, there are two important effector neurones, an excitatory cholinergic neurone, and a nonadrenergic, noncholinergic (NANC) inhibitory neurone. The striated muscle contraction is directed and coordinated by sequential excitation through vagal fibers programmed by the central control mechanism. There are at least four potential control mechanisms for peristalsis in the smooth muscle esophagus: efferent motor fibers programmed by the swallowing center fire sequentially during peristalsis; the intramural neural mechanism can be excited to produce peristalsis near the onset of stimulation or with a delay after termination of stimulation; there is evidence for myogenic propagation of a peristaltic contraction. In humans, swallow-induced peristalsis is cholinergic and appears to result primarily from sequencing and activation of the intramural excitatory cholinergic neurones. Both central and peripheral levels of control are highly integrated to focus on the excitatory cholinergic neurones. It is likely that under normal circumstances, the central control mechanism exerts the dominant influence on these neurones for initiation and coordination of peristalsis in the smooth muscle esophagus. In humans, resting tone in the lower esophageal sphincter is predominantly cholinergic, but this tone is regulated by a balance between many excitatory and inhibitory influences. The relaxation on swallowing is caused by active inhibition of the muscle through NANC inhibitory neurones and cessation of tonic neural excitation to the
（1）食管上括约肌；（2）食管体；（3）食管下括约肌。中枢神经系统内及外周的控制机制，将这些功能区整合于一个区域，在此区域中，自主和非自主控制机制以及两种不同类型肌肉的活动密切协调。人类食管远端的50%至60%完全由平滑肌组成。食管运动功能的外在控制位于脑干吞咽中枢，该中枢具有传入接收系统、运动神经元传出系统以及复杂的神经元组织或联络系统。来自食管的感觉信息通过迷走神经传导，但感觉通路也存在于进入脊髓的交感神经中。迷走神经分别接收来自疑核和迷走神经背核的纤维，支配食管的横纹肌和平滑肌，包括括约肌。横纹肌段和平滑肌段均有肌间神经丛。在平滑肌食管中，有两种重要的效应神经元，一种是兴奋性胆碱能神经元，另一种是去甲肾上腺素能、非胆碱能（NANC）抑制性神经元。横纹肌的收缩是由中枢控制机制编排程序的迷走神经纤维顺序兴奋来指导和协调的。平滑肌食管蠕动至少有四种潜在的控制机制：吞咽中枢编排程序的传出运动纤维在蠕动过程中顺序发放冲动；壁内神经机制可在刺激开始时或刺激终止后延迟激发以产生蠕动；有证据表明蠕动收缩可进行肌源性传播。在人类，吞咽诱发的蠕动是胆碱能的，似乎主要源于壁内兴奋性胆碱能神经元的顺序激活和兴奋。中枢和外周控制水平高度整合，聚焦于兴奋性胆碱能神经元。在正常情况下，中枢控制机制可能对这些神经元在平滑肌食管蠕动的起始和协调中发挥主导作用。在人类，食管下括约肌的静息张力主要是胆碱能的，但这种张力受多种兴奋性和抑制性影响之间平衡的调节。吞咽时的松弛是通过NANC抑制性神经元对肌肉的主动抑制以及对……的紧张性神经兴奋停止所引起的
