Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands.
Department of Informatics, University of Bergen, Norway.
Clin Anat. 2020 May;33(4):567-577. doi: 10.1002/ca.23444. Epub 2019 Aug 30.
Intersphincteric resection (ISR) enables radical sphincter-preserving surgery in a subset of low rectal tumors impinging on the anal sphincter complex (ASC). Excellent anatomical knowledge is essential for optimal ISR. This study describes the role of the longitudinal muscle (LM) in the ASC and implications for ISR and other low rectal and anal pathologies. Six human adult en bloc cadaveric specimens (three males, three females) were obtained from the University of Leeds GIFT Research Tissue Programme. Paraffin-embedded mega blocks containing the ASC were produced and serially sectioned at 250 μm intervals. Whole mount microscopic sections were histologically stained and digitally scanned. The intersphincteric plane was shown to be potentially very variable. In some places adipose tissue is located between the external anal sphincter (EAS) and internal anal sphincter (IAS), whereas in others the LM interdigitates to obliterate the plane. Elsewhere the LM is (partly) absent with the intersphincteric plane lying on the IAS. The LM gave rise to the formation of the submucosae and corrugator ani muscles by penetrating the IAS and EAS. In four of six specimens, striated muscle fibers from the EAS curled around the distal IAS reaching the anal submucosa. The ASC formed a complex structure, varying between individuals with an inconstant LM affecting the potential location of the intersphincteric plane as well as a high degree of intermingling striated and smooth muscle fibers potentially further disrupting the plane. The complexity of identifying the correct pathological staging of low rectal cancer is also demonstrated. Clin. Anat. 33:567-577, 2020. © 2019 Wiley Periodicals, Inc.
肛门括约肌间切除术（ISR）可使一部分累及肛门括约肌复合体（ASC）的低位直肠肿瘤进行保肛根治性手术。对于最佳的 ISR，出色的解剖学知识是必不可少的。本研究描述了 ASC 中纵向肌（LM）的作用及其对 ISR 和其他低位直肠和肛门病变的影响。本研究从利兹大学 GIFT 研究组织计划中获得了六个成人尸体标本（三个男性，三个女性）。制作了包含 ASC 的石蜡 mega 块，并以 250μm 的间隔进行连续切片。对整个组织切片进行了组织学染色和数字扫描。结果显示，肛门括约肌间平面具有潜在的高度变异性。在某些部位，脂肪组织位于外括约肌（EAS）和内括约肌（IAS）之间，而在其他部位，LM 相互交错以闭塞平面。在其他部位，LM 部分缺失，肛门括约肌间平面位于 IAS 上。LM 通过穿透 IAS 和 EAS 形成黏膜下层和肛提肌。在六个标本中的四个标本中，来自 EAS 的横纹肌纤维卷曲围绕远端 IAS 到达肛门黏膜下层。ASC 形成了一个复杂的结构，个体之间存在差异，LM 不恒定会影响肛门括约肌间平面的潜在位置，并且存在高度混杂的横纹肌和平滑肌纤维，可能进一步破坏平面。还展示了识别低位直肠癌正确病理分期的复杂性。临床解剖学 33：567-577，2020。©2019 Wiley Periodicals，Inc.
