GENERAL GYNECOLOGY Functional interactions between the fossa ischioanalis, levator ani and gluteus maximus muscles of the female pelvic floor: a prospective study in nulliparous women Irina Soljanik • Udo Janssen • Florian May • Helga Fritsch • Christian G. Stief • Ernst R. Weissenbacher • Klaus Friese • Andreas Lienemann Received: 11 September 2011 / Accepted: 8 May 2012 / Published online: 13 June 2012 Ó Springer-Verlag 2012 Abstract Purpose We evaluated the role of the fossa ischioanalis (FI) in functional relations between the levator ani (LA) and glu- teus maximus muscles (GM) in healthy female volunteers. Methods Twenty-three nulliparae were examined. Elec- tromyogramms of LA and GM were simultaneously recorded during voluntary contraction of the pelvic floor muscles (PFM) and at rest in six body positions. The sur- face areas of LA (LAA), FI (FIA) and GM (GMA) were evaluated using MRI. Results Simultaneous LA and GM contractions were electromyographically observed irrespectively of body position in 97.2 %. MRI revealed synchronous movement of all structures: while LAA (-7.4 %) reduced, GMA increased (?6.8 %), FIA changed significantly (?3.4 %). Conclusions The LA, FI and GM are morphologically and functionally connected. We recommend considering these structures as the ‘LFG-Complex’, emphasising the importance of this unit for functional integration of the pelvic floor. The findings of this study may contribute to understanding of urinary continence mechanism and dis- orders after pelvic floor surgery and obstetrical trauma. Keywords Functional MRI of the female pelvic floor Á The female pelvic floor Á Urinary continence mechanism Á Pelvic floor muscles Abbreviations FISP Fast Imaging with Steady State Precession Fig. Figure FI Fossa ischioanalis FIA Fossa ischioanalis area GM Gluteus maximus muscle GMA Gluteus maximus area LA Levator ani muscle LAA Levator ani area LFG Levator ani—Fossa ischioanalis—Gluteus maximus MCT Maximal contraction tonus MRI Magnetic resonance imaging MVC Maximum voluntary contraction PF Pelvic floor PFM Pelvic floor muscles PFME Pelvic floor muscle exercises RT Tonus at rest I. Soljanik Á F. May Á C. G. Stief Department of Urology, Klinikum Grosshadern, Ludwig-Maximilians-University of Munich, Marchionini str. 15, 81377 Munich, Germany Present Address: I. Soljanik (&) Department of Neurourology, Spinal Cord Injury Centre, The Ruprecht Karl University, Schlierbacher Landstrasse 200a, 69118 Heidelberg, Germany e-mail: irasol@hotmail.com; irina.soljanik@med.uni-heidelbeg.de Present Address: U. Janssen Institute of German Hospitals, Duesseldorf, Germany U. Janssen Á E. R. Weissenbacher Á K. Friese Department of Obstetrics and Gynecology, Klinikum Grosshadern, Ludwig-Maximilians-University of Munich, Munich, Germany H. Fritsch Section of Clinical and Functional Anatomy, Medical University of Innsbruck, Innsbruck, Austria A. Lienemann Department of Clinical Radiology, Klinikum Grosshadern, Ludwig-Maximilians-University of Munich, Munich, Germany 123 Arch Gynecol Obstet (2012) 286:931–938 DOI 10.1007/s00404-012-2377-4