THE MECHANICS OF THE ANAL-SPHINCTER COMPLEX
THE MECHANICS OF THE ANAL-SPHINCTER COMPLEX
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DOI：
10.1016/0021-9290(88)90223-0
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发表时间：
1988-01-01
影响因子：
2.4
通讯作者：
READ, NW
中科院分区：
文献类型：
--
作者：
GIBBONS, CP;BANNISTER, JJ;READ, NW
肛门括约肌复合体由周围排列的肌纤维组成，围绕着相对较厚的肛门衬里。该装置的力学模型为两个同心均匀各向同性线弹性圆柱体。内筒（肛门内衬）被认为是厚壁的，而外筒（圆形肌肉）被认为是薄壁的。该模型预测肛门括约肌张力随管腔直径呈线性变化。这一预测在正常情况下以及在外括约肌收缩和内括约肌松弛时得到了实验证实。在肛门衬里环向应力可忽略的情况下，该模型还预测，在管径达到零之前，腔内压力降至零。因此，提出了一种肛门垫增厚的自动调节机制，当腔压降至零时，产生肛门闭合。这种自我调节机制的缺陷可以解释痔疮患者经常出现的肛门失禁和排便障碍。
The anal sphincter complex consists of circumferentially arranged muscle fibres, which surround a relatively thick anal lining. This apparatus was modelled mechanistically as two concentric homogeneous isotropic linear elastic cylinders. The inner cylinder (anal lining) was considered to be thick walled, while the outer (the circular muscle) was assumed to be thin walled. The model predicts that the anal sphincter tension varies linearly with luminal diameter. This prediction was confirmed experimentally under normal conditions as well as during external sphincter contraction and internal sphincter relaxation. Under conditions of negligible hoop stress in the anal lining the model also predicts that the intra-luminal pressure falls to zero before the luminal diameter reaches zero. Hence, an autoregulatory mechanism of anal cushion thickening, as the luminal pressure falls to zero, to produce anal closure was proposed. Deficiencies in this autoregulation mechanism may explain anal incontinence and the obstructed defaecation often found in subjects with haemorrhoids.