Contribution à l’étude anatomo-morphologique du muscle levator ani. Utilisation de l'IRM

Student thesis: Master's Thesis


A new look at the M. levator ani in asymptomatic womenSnoeck Th1,2, Provyn S.1, Balestra C2, Clarys J.P.11.Experimental Anatomy – Vrije Universiteit Brussel2.Physiologie enviorementale et occupationelle – Haute école P.H. SpaakPurpose :The aim of this study is to demonstrate that the descriptions in the anatomy atlases and texbooks, based on dissections, do not correspond with the reality observed in healthy in-vivowomen. In fact this study is validating or referring Cadaveric evidence under in-vivocircumstances. Methodology :Eleven nulliparous women aged between 22 and 26 years (23,64 ±1.12) and nine multiparouswomen, both with no clinical symptoms (urology, gynaecology, proctology) participated inthe study. Magnetic Resonance Images were produced in frontal planes, posterior of the anus and in saggital paramedian planes allowing to study of the ilio-coccygeal parts of the M. levator ani. In the frontal plane the centre of the Dome arch was calculated and differences between theDomes were verified.In the saggital plane the anterior - posterior ratio was compared between Domes in order to precisely locate the arches.The data were treated with a Fisher correlation test and a Student t-test for unpaired groups.Results:All (100%) nullipareous women show ilio-coccygeal bundles in a double Dome topographywith a inferior and posterior concavity. The left dome Arches are the highest (p=0.0166) andthe most anterior (p=0.0216) in the nullipareous women while the opposite is shown in themultipareous group, characterised by significantly less concave (p=0.0360) and moreposterior oriented Dome Arches (p=0.0038).Discussion and Conclusion:Against the atlases' evidence supported by dissections the M. levator ani does not take theshape of a hammock with its concavity oriented anterior and superior. In asymptomaticwomen the Magnetic Resonance Images and the ad hoc calculations we do observe anopposite topography. One can assume that the principle of a vault with its pillars and with aninferior and posterior concavity allows for a better absorption of loads (forces) generated bydaily abdominal pressure and a more efficient protection of pudendal plexus.Bibliography1-Aukee and al. - An evaluation of pelvic floor anatomy and function by MRI. - European journal of obstetrics and gynecology and reproductive biology ; n°112:pp.84-88 ; 20042-Constantinou and al. - Determining the displacement of the pelvic floor pelvic organs during voluntary contractions using MRI in younger and older women. - British journal of urology international ; n°90:pp.408-414 ; 20023-DeLancey and al. - The appearance of levator ani muscle abnormalities in MR images after vaginal delivery.-Obstetrics and gynecology ; n°101:pp.46-48 ; 20034-Fletcher and al. - MRI of anatomic and dynamic defects of the pelvic floor in defecatory disorders - American journal of gastroenterology ; vol. 98, n°2 ; 20037-Kruger and al. - Alterations in levator ani morphology in elite nulliparous athletes : a pilot study. - Australian and New Zealand journal of obstetrics and gynaecology ; n°45:pp.42-47 ; 2005
Date of Award2005
Original languageEnglish
SupervisorThyl Snoeck (Promotor) & Steven Provyn (Co-promotor)

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