Stefanski Leszek, Lampe Paweł, Aleksandrowicz Ryszard
Department of Gastrointestinal Tract Surgery, Medical University of Silesia, Central Teaching Hospital, ul. Medyków 14, 40-752, Katowice, Poland.
Surg Radiol Anat. 2008 Nov;30(8):675-8. doi: 10.1007/s00276-008-0379-5. Epub 2008 Jul 31.
Normal defecation is a combination of several elements of reflex and voluntary functions. The issue of external anal sphincter innervation is of theoretical and clinical significance; however, literature on the subject is still scarce. Most study reports discuss the course of the pudendal nerve with no close insight into inferior rectal nerves supply to the external anal sphincter. We have not found any statistical "mapping" of the site of the nerve branches insertion into the external anal sphincter. Thus, the purpose of the present study was to determine the least and most typical location of nerve branches to the external anal sphincter. One hundred and ten pudendal nerve preparations were analysed. Following the dissection of the pudendal nerve and its branches, a beam compass was used to take linear measurements from the apex of the coccygeal bone to the point of nerve branch insertion to the external anal sphincter. The distance between coccygeal bone apex and the central tendon of the perineum was also measured. For the purpose of comparison, results are presented as relative Bi/A values. Computer programmes devised by the author of this paper within Turbo Pascal were then used to determine the probability of finding nerve branches to the external anal sphincter.
Based on the analysis of 110 preparations of the pudendal nerve and its branches, one might conclude that the former was the main although not necessarily the only source of external anal sphincter innervation. While analysing the most and the least probable location of nerve branches to the external anal sphincter, the muscle length was expressed as percentage, i.e., 0% of sphincter length = the apex of the coccygeal bone; 100% of sphincter length = the central tendon of the perineum. The length was then divided into 5% intervals with the probability of finding nerve branches determined by programmes written in Pascal. Within 30-85% of external anal sphincter length, the probability of finding nerve branches to the external anal sphincter is greater than 0.3 with peak probability of 0.68 in the interval between 55 and 65%.
Sphincter innervation and clinicoanatomical function of anal canal closure apparatus has been discussed with reference to external anal sphincter injury. Transcutaneous electrostimulation of the pudendal nerve and the use of anal canal electrodes have also been mentioned.
The most probable location of nerve branches to the external anal sphincter is half way of its length, i.e., at hour 3 or 9 of the knee-elbow position or lithotomy position. The external anal sphincter can also be directly supplied by nerve branches originating from the sacral nerve root S4; the branches then go towards the posterior part of the sphincter.
正常排便由多种反射和自主功能要素共同构成。肛门外括约肌的神经支配问题具有理论和临床意义；然而，关于该主题的文献仍然稀少。大多数研究报告讨论了阴部神经的走行，而没有深入探究直肠下神经对外肛门括约肌的供应情况。我们尚未发现任何关于神经分支插入肛门外括约肌部位的统计学“图谱”。因此，本研究的目的是确定肛门外括约肌神经分支的最不常见和最典型位置。分析了110个阴部神经标本。在解剖阴部神经及其分支后，使用梁式圆规从尾骨尖到神经分支插入肛门外括约肌的点进行线性测量。还测量了尾骨尖与会阴中心腱之间的距离。为了进行比较，结果以相对Bi/A值表示。然后使用本文作者在Turbo Pascal中设计的计算机程序来确定找到肛门外括约肌神经分支的概率。
基于对110个阴部神经及其分支标本的分析，可以得出结论，阴部神经是肛门外括约肌神经支配的主要来源，尽管不一定是唯一来源。在分析肛门外括约肌神经分支最可能和最不可能的位置时，肌肉长度以百分比表示，即括约肌长度的0% = 尾骨尖；括约肌长度的100% = 会阴中心腱。然后将长度分成5%的间隔，并使用用Pascal编写的程序确定找到神经分支的概率。在肛门外括约肌长度的30%至85%范围内，找到肛门外括约肌神经分支的概率大于0.3，在55%至65%的间隔内概率峰值为0.68。
已参照肛门外括约肌损伤讨论了括约肌神经支配以及肛管闭合装置的临床解剖功能。还提到了阴部神经的经皮电刺激和肛管电极的使用。
肛门外括约肌神经分支最可能的位置在其长度的一半处，即在膝胸位或截石位的3点或9点处。肛门外括约肌也可由骶神经根S4发出的神经分支直接供应；这些分支然后走向括约肌的后部。
