Der longitudinale Muskel des Analkanals The anal longitudinal muscle

Gerdes, Berthold; Köhler, Heinz-H.; Stinner, B.; Barth, Peter; Çelik, I.; Rothmund, M.

doi:10.1007/s001040050360

Cited by 7 publications

(5 citation statements)

References 16 publications

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“…Our study confirms the intersphincteric location of the LAM, interposed between IAS and EAS, with mean thicknesses of 1.63 mm (LAM), 2.69 mm (IAS), and 2.95 mm (EAS). These data partially fit those of Gerdes et al, 22 who reported a mean thickness of the LAM of 2.85 mm and of the EAS of 3.62 at the level of the dentate line. These differences may be ascribed to different fixation and level of section.…”

Section: Discussionsupporting

confidence: 88%

Histo‐Topographic study of the longitudinal anal muscle

et al. 2008

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The longitudinal anal muscle (LAM) has been described as a vertical layer of muscular tissue interposed between the circular layers of the internal (IAS) and external (EAS) anal sphincters. There is, however, no general agreement in the literature on its composition and attachments. The aim of this study was to investigate the histological structure, attachments, and topography of the LAM in order to evaluate its role in continence and defecation, thus enhancing knowledge of the surgical anatomy of this region. After in situ formalin fixation, the pelvic viscera were removed from eight male and eight female cadavers (age range: 52–72 years). Serial macrosections of the bladder base, lower rectum and anal canal, cervix and pelvic floor complex, cut in the transverse (six specimens) and coronal (six specimens) planes, underwent histological and immunohistochemical studies. Four specimens were studied using the E12 sheet plastination technique. The LAM was identified in 10/12 specimens (83%). Transverse and coronal sections made clear that it is a longitudinal layer of muscular tissue, marking the boundary between the internal and external anal sphincters. From the anorectal junction it extends along the anal canal, receives fibers from the innermost part of the puborectalis and the puboanalis muscles, and terminates with seven to nine fibro‐elastic septa, which traverse the subcutaneous part of the external anal sphincter, reaching the perianal dermis. In the transverse plane, the mean thickness of the LAM was 1.68 ± 0.27 mm. Immunohistochemical staining showed that the LAM consists of predominantly outer striated muscle fibers and smaller numbers of inner smooth muscle fibers, respectively coming from the levator ani muscle and from the longitudinal muscular layer of the rectum. The oblique fibers suggest that the LAM may represent the intermediate longitudinal course of small bridging muscle bundles going reciprocally from the striated EAS to the smooth IAS and vice versa. The spatial result is the helical course of striated and smooth muscle fibers between the EAS and IAS, which contribute not only to the narrowing but also to some shortening of the anal canal during sphincter contraction. Thus, rather than being a boundary, the LAM gives anatomical evidence of a functional connection between two muscle systems with different structures and topography. Clin. Anat. 21:447–452, 2008. © 2008 Wiley‐Liss, Inc.

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Section: Discussionsupporting

confidence: 88%

Histo‐Topographic study of the longitudinal anal muscle

et al. 2008

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“…In contrast to other authors (Swash et al, 1988;Lowry, 1992;Lunniss and Phillips, 1992;McMinn, 1992;Fleshman, 1993;Gerdes et al 1997), we found that the internal anal sphincter muscle rings do not share the same fascia as the longitudinal fibromuscular band and that they could be easily dissected from each other. Because this fascial separation has heretofore been unappreciated, the ring-like structures of the internal anal sphincter have not been described in classic textbooks and in more recent studies.…”

Section: Discussioncontrasting

confidence: 82%

“…Mechanical insult to the internal anal sphincter may result in bowel incontinence. These insults may be surgical (e.g., fissurectomy, fistulotomy, and sphincterotomy), obstetrical (e.g., third-or fourth-degree tears of the perineum during delivery), or traumatic (e.g., blunt trauma, impalement, gunshot wounds, or foreign-body insertion) (Cherry and Greenwald, 1992;Lowry, 1992;Schrock, 1996;Gerdes et al, 1997;Corman, 1998). Because of its clinical significance in ensuring bowel continence, the structure and function of the internal anal sphincter should be thoroughly investigated and understood.…”

Section: Introductionmentioning

confidence: 98%

Internal anal sphincter: An anatomic study

Elhan

Ersoy

et al. 2003

Clinical Anatomy

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The anatomy of the internal anal sphincter and surrounding structures was investigated in 24 cadavers using a surgical microscope (6-25 x magnification). An understanding of the anatomy of the internal anal sphincter is helpful in avoiding complications during surgical procedures in the anorectal region. The external anal sphincter was composed of three ellipsoid rings of skeletal muscle (subcutaneous, superficial, and deep) that encircle the anal canal; in contrast, we found that the internal anal sphincter was composed of flat rings of smooth muscle bundles stacked one on top of the other, like the slats of a Venetian blind. In each anal canal, the average number of ring-like slats observed was 26.33 +/- 2.93 (range = 20-30) and each was covered by its own fascia. The smooth muscle fibers and fascia coalesced at three equidistant points around the anal canal to form three columns that extended distally into the lumen and differed in form from the other anal columns. When viewed from an anterior position, the columns were located anteriorly at the observer's right (5 o'clock position), posteriorly at the right (1 o'clock position), and laterally at the left (9 o'clock position). This heretofore unreported anatomy of the internal anal sphincter may play an important role in closing off the lumen of the anal canal and maintaining bowel continence.

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“…Lunniss and Phillips 23 and Gerdes et al 24 have independently investigated the anal longitudinal muscle and discussed its intersphincteric position in the rectal wall, demonstrating it both anatomically and by endoanal ultrasonography. Our group has also previously confirmed its presence in over two-thirds of patients assessed, using endoanal magnetic resonance imaging, where, on T1-weighted and T2-weighted images, it appears as a thin layer of beaded intermediate to low signal intensity running parallel to the anal canal.…”

Section: Discussion and Clinical Relevancementioning

confidence: 99%