Dalley A F
Am Surg. 1987 May;53(5):298-306.
Although easily taken for granted when functioning properly, malfunction of the anorectal mechanism presents profound inconvenience and embarrassment. The anal sphincters, internal and external, have been the subjects of extensive study yet much appears to remain unsettled. Each sphincter has been proposed, at one time or another, to be the sine qua non of fecal continence, and both clinical and nonclinical studies have often yielded contradictory results. For example, it has been established that the internal sphincter is actually relaxed during the moments of greatest need! On the other hand, the external sphincter can be fully contracted only for a matter of seconds before becoming fatigued. Anatomic studies of the external sphincter date from 1715, yet it has defied consistent and consensual description. A rather persistent theme has been the claimed existence of anatomic subdivisions (e.g., deep, superficial, and subcutaneous). Some form of this traditional description is found in all modern anatomic texts; however, when dissecting, the student is invariably disappointed in his or her efforts to discern the subdivisions. Further, the roles of other important, nonsphincteric mechanisms are often overlooked. This presentation will briefly review the controversial history of the anorectal mechanism and correlate the results of both clinical and anatomic/physiologic studies. By so doing, a functional concept of the structure of the anorectal mechanism emerges.
尽管肛门直肠机制正常运作时很容易被视为理所当然，但该机制出现故障会带来极大的不便和尴尬。肛门内外括约肌一直是广泛研究的对象，但似乎仍有许多问题尚未解决。每种括约肌都曾在不同时期被认为是粪便节制的关键所在，而临床和非临床研究常常得出相互矛盾的结果。例如，已经证实内括约肌在最需要的时候实际上是松弛的！另一方面，外括约肌完全收缩只能持续几秒钟就会疲劳。对外括约肌的解剖学研究可以追溯到1715年，但它一直没有得到一致认可的描述。一个相当持久的观点是声称存在解剖学细分（例如，深部、浅部和皮下）。所有现代解剖学教材中都能找到某种形式的传统描述；然而，在解剖时，学生总是对自己辨别这些细分的努力感到失望。此外，其他重要的非括约肌机制的作用常常被忽视。本报告将简要回顾肛门直肠机制的争议历史，并将临床研究结果与解剖学/生理学研究结果进行关联。通过这样做，肛门直肠机制结构的功能概念就会浮现出来。
