Open Journal of Obstetrics and Gynecology, 2014, 4, 144-157 OJOG http://dx.doi.org/10.4236/ojog.2014.43025 Published Online February 2014 (http://www.scirp.org/journal/ojog/ ) Supportive tissues of the vagina with special reference to a fibrous skeleton in the perineum: A review Hiromasa Sasaki 1 , Nobuyuki Hinata 2* , Tetsuji Kurokawa 3 , Gen Murakami 4,5 1 Division of Gynecology and Obsterics, Ishikawa Prefectural Central Hospital, Kanazawa, Japan 2 Department of Urology, Kobe University Graduate School of Medicine, Kobe, Japan 3 Department of Obstetrics and Gynecology, Fukui University School of Medicine, Fukui, Japan 4 Division of Internal Medicine, Iwamizawa Kojin-kai Hospital, Iwamizawa, Japan 5 Department of Anatomy, Tokyo Dental College, Chiba, Japan Email: * hinata@med.kobe-u.ac.jp Received 15 December 2013; revised 12 January 2014; accepted 20 January 2014 Copyright © 2014 Hiromasa Sasaki et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In accor- dance of the Creative Commons Attribution License all Copyrights © 2014 are reserved for SCIRP and the owner of the intellectual property Hiromasa Sasaki et al. All Copyright © 2014 are guarded by law and by SCIRP as a guardian. ABSTRACT With the aid of immunohistochemistry, the present review attempts to demonstrate the composite fibers and nerve topographical anatomy in the vaginal sup- portive tissues. Along the tendinous arch of the pelvic fasciae, distal parts of the pelvic plexus extend ante- ro-inferiorly and issue nerves to the internal anal sphincter as well as the cavernous tissues. At the at- tachment of the levator ani muscle to the rectum, smooth muscles in the endopelvic fascia lining the levator ani merge with the longitudinal smooth mus- cle layer of the rectum to provide the conjoint longi- tudinal muscle coat or the longitudinal anal muscle (LAM: smooth muscle). However, at the rectovaginal interface, the longitudinal smooth muscle layer of the rectum continues to the LAM without any contribu- tion of the endopelvic fascia. The bilateral masses of the perineal smooth muscles (PSMs) are connected by the perineal body, and the PSMs receive 1) the longi- tudinal anal muscle, 2) the internal and external anal sphincters and, 3) the perineal membrane lining the vestibular wall. Tensile stress from the levator ani seems to be transferred to the PSMs via the LAM. Because of their irregularly arrayed muscle fibers, instead of a synchronized contraction in response to nerve impulses, the PSMs are likely to act as a barrier, septum or protector against mechanical stress be- cause, even without innervation, such smooth muscle fibers resist (not absorb) pressure, in accordance with Bayliss’ rule. The external anal sphincter, a strong striated muscle, inserts into the PSMs and seems to play a dynamic role in supporting the rectovaginal interface to maintain the antero-posterior length of the urogenital hiatus. However, we do not think that smooth muscles play an active traction role without cooperation from striated muscle. The fibrous skele- ton composed of smooth muscle in the female peri- neum is explained in terms of a “catamaran” model. KEYWORDS Vagina; Levator Ani Muscle; Perineal Membrane; Smooth Muscles; Elastic Fibers; Nerves; Pelvic Floor Anatomy 1. INTRODUCTION The vaginal support structures comprise a series of con- nective tissues that are well known to gynecologists, i.e., levels I, II and II described by DeLancey [1-3]. However, few studies have attempted to demonstrate the configura- tion of composite fibers in these tissues. In order to con- sider the transfer of tensile stress from the vagina to the pelvic floor and wall, we believe that a detailed know- ledge of the morphology of the composite fibers is ne- cessary. In particular, since the initial report by Oelrich [4], there have been very few histological demonstrations of level III support. Soga et al. [5] demonstrated a dis- tinct connective tissue mass in the lateral side of the dis- tal vagina, which they termed a difficult name, the lateral extension of the perineal body. They considered that the connective tissue, comprising mainly smooth muscles alongside the vestibule, is located adjacent to and con- nects with both the external and internal anal sphincters, thus suggesting functional cooperation between the va- * Corresponding author. OPEN ACCESS