Morphologies of the interfaces between the levator ani muscle and pelvic viscera, with special reference to muscle insertion into the anorectum in elderly Japanese

Takashi Arakawa, Gen Murakami, Futoshi Nakajima, Akio Matsubara, Aiji Ohtsuka, Tomohiko Goto, Tatsuo Teramoto

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)

Abstract

A specific, smooth muscle-mediated interface between the levator ani muscle (LA) and the pelvic viscera has been reported. Using 110 sagittally trimmed anorectal tissue strips (80 lateral, 15 anterior and 15 dorsal specimens) obtained from the donated cadavers of 46 elderly subjects, we examined variations in the interface between the LA and the rectal muscularis propria, including the so-called conjoined longitudinal muscles. In type A (9/46), little or no tissue connected the LA to the external rectal muscularis propria, but the LA and external sphincteric mass formed a definite complex. In type B (26/46), the covering fascia of the LA changed abruptly into smooth muscles, which merged into the external rectal muscularis propria. In type C (11/46), most of the LA-associated connective tissues, composed of smooth muscles, were tightly connected to the internal and external rectal muscularis propria. These variations seemed to depend on the morphology of the recto-urethralis, the lateral extension of which reinforced the LA-associated smooth muscles sufficiently to form type B and C insertions. We also demonstrated differences in the interfacial tissues between the LA and other pelvic viscera. We hypothesize that, to avoid injury of the LA and its interfaces during strong movement of the pelvic viscera, for example during childbirth, coitus or squeezed evacuation, the pelvic connective tissue-like smooth muscles play an important role as an autonomic buffer and/or modulator of pelvic floor function. Digital examination and transrectal or transvaginal sonography may be useful for evaluating interindividual variation in these interfacial tissues in elderly patients.

Original languageEnglish
Pages (from-to)72-81
Number of pages10
JournalAnatomical Science International
Volume79
Issue number2
DOIs
Publication statusPublished - Jun 2004

Keywords

  • Anal sphincter
  • Elastic fibers
  • Levator ani
  • Recto-urethralis
  • Rectum
  • Smooth muscle

ASJC Scopus subject areas

  • Anatomy

Fingerprint Dive into the research topics of 'Morphologies of the interfaces between the levator ani muscle and pelvic viscera, with special reference to muscle insertion into the anorectum in elderly Japanese'. Together they form a unique fingerprint.

Cite this