1
|
Muro S, Akita K. Pelvic floor and perineal muscles: a dynamic coordination between skeletal and smooth muscles on pelvic floor stabilization. Anat Sci Int 2023:10.1007/s12565-023-00717-7. [PMID: 36961619 DOI: 10.1007/s12565-023-00717-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Accepted: 03/15/2023] [Indexed: 03/25/2023]
Abstract
The purpose of this review is to present our researches on the pelvic outlet muscles, including the pelvic floor and perineal muscles, which are responsible for urinary function, defecation, sexual function, and core stability, and to discuss the insights into the mechanism of pelvic floor stabilization based on the findings. Our studies are conducted using a combination of macroscopic examination, immunohistological analysis, 3D reconstruction, and imaging. Unlike most previous reports, this article describes not only on skeletal muscle but also on smooth muscle structures in the pelvic floor and perineum to encourage new understanding. The skeletal muscles of the pelvic outlet are continuous, which means that they share muscle bundles. They form three muscle slings that pass anterior and posterior to the anal canal, thus serving as the foundation of pelvic floor support. The smooth muscle of the pelvic outlet, in addition to forming the walls of the viscera, also extends in three dimensions. This continuous smooth muscle occupies the central region of the pelvic floor and perineum, thus revising the conventional understanding of the perineal body. At the interface between the levator ani and pelvic viscera, smooth muscle forms characteristic structures that transfer the lifting power of the levator ani to the pelvic viscera. The findings suggest new concepts of pelvic floor stabilization mechanisms, such as dynamic coordination between skeletal and smooth muscles. These two types of muscles possibly coordinate the direction and force of muscle contraction with each other.
Collapse
Affiliation(s)
- Satoru Muro
- Department of Clinical Anatomy, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-Ku, Tokyo, 113-8510, Japan.
| | - Keiichi Akita
- Department of Clinical Anatomy, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-Ku, Tokyo, 113-8510, Japan
| |
Collapse
|
2
|
Hernandez-Reynoso AG, Rahman FS, Hedden B, Castelán F, Martínez-Gómez M, Zimmern P, Romero-Ortega MI. Secondary urethral sphincter function of the rabbit pelvic and perineal muscles. Front Neurosci 2023; 17:1111884. [PMID: 36875671 PMCID: PMC9978527 DOI: 10.3389/fnins.2023.1111884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 02/01/2023] [Indexed: 02/18/2023] Open
Abstract
Perineal and pelvic floor muscles play an important role in continence by providing mechanical support to pelvic organs. It is also known that the pubococcygeus muscle (PcM) contracts in the storage phase and is inactive during voiding, while the bulbospongiosus muscle (BsM) is active during the voiding phase. Recent evidence suggested an additional role of these muscles in supporting urethral closure in rabbits. However, the individual role of perineal and pelvic muscles as urethral sphincters is not well-defined. Here we evaluated the individual, sequential and synergistic roles of the PcM and BsM in assisting urethral closure and defined the optimal electrical stimulation parameters that can effectively contract these muscles and increase the urethral pressure (P ura ) in young nulliparous animals (n = 11). Unilateral stimulation of either the BsM or PcM at 40 Hz induced modest increases in average P ura (0.23 ± 0.10 and 0.07 ± 0.04 mmHg, respectively). Investigation on the changes in P ura evoked by stimulation frequencies between 5 and 60 Hz show that sequential contralateral PcM-BsM activation at 40 Hz induced a 2-fold average P ura increase (0.23 ± 0.07 mmHg) compared to that evoked by PcM stimulation. Simultaneous activation of PcM and BsM at 40 Hz also showed an increased average P ura (0.26 ± 0.04 mmHg), with a 2-fold increase in average P ura observed during the unilateral sequential PcM-BsM stimulation at 40 Hz (0.69 ± 0.2 mmHg). Finally, stimulation at 40 Hz of the bulbospongiosus nerve (BsN) induced an approximate 4-fold increase in average P ura (0.87 ± 0.44 mmHg; p < 0.04) compared to that elicited by BsM stimulation, confirming that direct nerve stimulation is more effective. Together, this study shows that in the female rabbit, both perineal and pelvic muscles support of the urethral function during continence, and that unilateral stimulation of the BsN at 40-60 Hz is sufficient to achieve maximal secondary sphincter activity. The results also support the potential clinical value of neuromodulation of pelvic and perineal nerves as bioelectronic therapy for stress urinary incontinence.
Collapse
Affiliation(s)
- Ana G Hernandez-Reynoso
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Farial S Rahman
- Department of Biomedical Engineering and Biomedical Sciences, University of Houston, Houston, TX, United States
| | - Brian Hedden
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Francisco Castelán
- Departamento de Biología Celular y Fisiología, Unidad Foránea Tlaxcala, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlaxcala, Tlaxcala, Mexico.,Centro Tlaxcala de Biología de la Conducta, Universidad Autónoma de Tlaxcala, Tlaxcala City, Mexico
| | - Margarita Martínez-Gómez
- Departamento de Biología Celular y Fisiología, Unidad Foránea Tlaxcala, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlaxcala, Tlaxcala, Mexico.,Centro Tlaxcala de Biología de la Conducta, Universidad Autónoma de Tlaxcala, Tlaxcala City, Mexico
| | - Philippe Zimmern
- Department of Urology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Mario I Romero-Ortega
- Department of Biomedical Engineering and Biomedical Sciences, University of Houston, Houston, TX, United States
| |
Collapse
|
3
|
Henkenjohann C, Bramke S, May CA. Dermal smooth muscle in the labia majora-a female dartos muscle equivalent? Am J Obstet Gynecol 2022; 227:105-106. [PMID: 35278378 DOI: 10.1016/j.ajog.2022.03.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 02/04/2022] [Accepted: 03/06/2022] [Indexed: 11/26/2022]
|
4
|
Ishiyama G, Kim JH, Chai OH, Viebahn C, Wilting J, Murakami G, Abe H, Abe S. A missing distal complex of the external and internal anal sphincters: a macroscopic and histologic study using Japanese and German elderly cadavers. Surg Radiol Anat 2020; 43:775-784. [PMID: 33135107 DOI: 10.1007/s00276-020-02606-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 10/20/2020] [Indexed: 12/13/2022]
Abstract
The lower margin of the internal anal sphincter (IAS) is considered to lie on a J-shaped, subcutaneous part (SCP) of the external anal sphincter (EAS). The lower IAS is united with the J-shaped SCP to form a smooth-striated muscle complex. In the first part of this study, we ensured the presence of the J-shaped EAS in the lateral wall of the anal canal from 12 near-term fetuses. Second, in the lateral anal wall, the examination of the longitudinal section from 20 male and 24 female Japanese cadavers (72-95 years-old) demonstrated that the J-shaped EAS was lost in 15 (34%) due to the very small SCP. Third, we demonstrated that the J-shaped EAS was restricted in the latera anal wall using longitudinal histological sections of the anal canal from 11 male Japanese cadavers (75-89 years-old). Therefore, a site-dependent difference in the IAS-EAS configuration was evident. Finally, we compared a frequency of the lost J-shape between human populations using 10 mm-thick frontal slices from 36 Japanese and 28 German cadavers. The two groups of cadavers were compatible in age (a 0.2-years' difference in males). The macroscopic observations revealed that the J-shaped EAS was absent from 13 (36%) Japanese and six (20%) German specimens, suggesting that the SCP degeneration occurred more frequent in elderly Japanese than elderly German individuals (p < 0.05). The distal IAS-EAS complex seemed to push residual feces out of the anal canal at a transient phase from evacuation to closure. The absence might be the first sigh of anal dysfunction.
Collapse
Affiliation(s)
- Gentaro Ishiyama
- Division of Surgery, Ishiyama Proctology Hospital, Sapporo, Japan
| | - Ji Hyun Kim
- Department of Anatomy, Jeonbuk National University Medical School, 20 Geunji-ro, Deokjin-gu, Jeonju, 54907, Korea.
| | - Ok Hee Chai
- Department of Anatomy, Jeonbuk National University Medical School, 20 Geunji-ro, Deokjin-gu, Jeonju, 54907, Korea
| | - Christoph Viebahn
- Department of Anatomy, School of Medicine, Georg-August-Universität Gőttingen, Gőttingen, Germany
| | - Jőrg Wilting
- Department of Anatomy, School of Medicine, Georg-August-Universität Gőttingen, Gőttingen, Germany
| | - Gen Murakami
- Division of Internal Medicine, Jikou-Kai Clinic of Home Visit, Sapporo, Japan
| | - Hiroshi Abe
- Emeritus Professor of Akita University School of Medicine, Akita, Japan
| | - Shinichi Abe
- Department of Anatomy, Tokyo Dental College, Tokyo, Japan
| |
Collapse
|
5
|
Yamamoto M, Hashimoto K, Honkura Y, Murakami G, Abe H, Rodríguez-Vázquez JF, Abe SI. Morphology of the Upper Esophageal Sphincter or Cricopharyngeus Muscle Revisited: A Study Using Adult and Fetal Specimens. Clin Anat 2019; 33:782-794. [PMID: 31659797 DOI: 10.1002/ca.23506] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Revised: 09/17/2019] [Accepted: 10/15/2019] [Indexed: 12/15/2022]
Abstract
Histological examination of specimens from 22 donated elderly cadavers and 15 human fetuses revealed that the cricopharyngeus muscle (CPM) provided (1) posterior circular muscle fibers adjacent to the external aspect of the uppermost esophageal circular muscle and (2) a thin anterior sling connecting to that same muscle. Another thick lateral bundle of longitudinal muscle originated independently from a fascia covering the posterior cricoarytenoideus muscle, extended laterally and posteriorly, and occupied a space after the CPM had disappeared at the anterolateral angle of the esophagus below the cricoid. The thick fascia contained abundant elastic fibers along the internal surface of the pharyngeal constrictors (posteromedial elastic lamina), but was interrupted or discontinued near the cricoid origin of the CPM. As no submucosal smooth muscles or elastic fibers were connected to it, the CPM did not accompany a specific elastic structure at the interface between the pharyngeal and esophageal muscles. In fetuses, the medial half of the CPM was inserted into the cricoid while the lateral half continued to the sternothyroideus muscle or ended at a fascia covering the cricothyroideus. These anterolateral ends provided a mechanical load for longitudinal growth of the pharyngeal constrictors. Consequently, the CPM was unlikely to develop and grow to form the upper esophageal sphincter, and the muscle bundle crossing the lateral aspect of the pharyngo-esophageal junction appeared to have a secondary passive role as a sphincter. This situation contrasts with that of another sphincter in the human body formed from striated muscle. Clin. Anat., 33:782-794, 2020. © 2019 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Masahito Yamamoto
- Department of Anatomy, Tokyo Dental College, Chiyoda-ku, Tokyo, Japan.,Tokyo Dental College Research Branding Project, Tokyo Dental College, Chiyoda-ku, Tokyo, Japan
| | - Keishi Hashimoto
- Department of Anatomy, Tokyo Dental College, Chiyoda-ku, Tokyo, Japan.,Tokyo Dental College Research Branding Project, Tokyo Dental College, Chiyoda-ku, Tokyo, Japan
| | - Yohei Honkura
- Department of Otolaryngology-Head and Neck Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Gen Murakami
- Department of Anatomy, Tokyo Dental College, Chiyoda-ku, Tokyo, Japan.,Division of Internal Medicine, Sapporo Asuka Hospital, Sapporo, Japan
| | - Hiroshi Abe
- Department of Anatomy, Akita University School of Medicine, Akita, Japan
| | | | - Shin-Ichi Abe
- Department of Anatomy, Tokyo Dental College, Chiyoda-ku, Tokyo, Japan.,Tokyo Dental College Research Branding Project, Tokyo Dental College, Chiyoda-ku, Tokyo, Japan
| |
Collapse
|
6
|
Muro S, Tsukada Y, Harada M, Ito M, Akita K. Anatomy of the smooth muscle structure in the female anorectal anterior wall: convergence and anterior extension of the internal anal sphincter and longitudinal muscle. Colorectal Dis 2019; 21:472-480. [PMID: 30614646 PMCID: PMC6850065 DOI: 10.1111/codi.14549] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 10/08/2018] [Indexed: 12/18/2022]
Abstract
AIM The anatomy of the region between the vagina and anal canal plays an essential role when performing a proctectomy for low-lying tumours. However, the anatomical characteristics of this area remain unclear. The purpose of the present study was to clarify the configuration, and both lateral and inferior extensions, of the muscle bundles in the anorectal anterior wall in females. METHODS Using cadaveric specimens, macroscopic anatomical and histological evaluations were conducted at the anatomy department of our institute. Macroscopic anatomical specimens were obtained from six female cadavers. Histological specimens were obtained from eight female cadavers. RESULTS The smooth muscle fibres of the internal anal sphincter and longitudinal muscle extended anteriorly in the anorectal anterior wall of females and the muscle bundles showed a convergent structure. The anterior extending smooth muscle fibres merged into the vaginal smooth muscle layer, distributed subcutaneously in the vaginal vestibule and perineum and spread to cover the anterior surface of the external anal sphincter and the levator ani muscle. Relatively sparse space was observed in the region anterolateral to the rectum on histological analysis. CONCLUSION Smooth muscle fibres of the rectum and vagina are intermingled in the median plane, and there is relatively sparse space in the region anterolateral to the rectum. Therefore, when detaching the anorectal canal from the vagina during proctectomy, an approach from both the lateral sides should be used.
Collapse
Affiliation(s)
- S. Muro
- Department of Clinical AnatomyTokyo Medical and Dental UniversityTokyoJapan
| | - Y. Tsukada
- Department of Colorectal SurgeryNational Cancer Center Hospital EastChibaJapan
| | - M. Harada
- Department of Clinical AnatomyTokyo Medical and Dental UniversityTokyoJapan
| | - M. Ito
- Department of Colorectal SurgeryNational Cancer Center Hospital EastChibaJapan
| | - K. Akita
- Department of Clinical AnatomyTokyo Medical and Dental UniversityTokyoJapan
| |
Collapse
|
7
|
Nyangoh Timoh K, Moszkowicz D, Zaitouna M, Lebacle C, Martinovic J, Diallo D, Creze M, Lavoue V, Darai E, Benoit G, Bessede T. Detailed muscular structure and neural control anatomy of the levator ani muscle: a study based on female human fetuses. Am J Obstet Gynecol 2018; 218:121.e1-121.e12. [PMID: 28988909 DOI: 10.1016/j.ajog.2017.09.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 09/01/2017] [Accepted: 09/25/2017] [Indexed: 12/28/2022]
Abstract
BACKGROUND Injury to the levator ani muscle or pelvic nerves during pregnancy and vaginal delivery is responsible for pelvic floor dysfunction. OBJECTIVE We sought to demonstrate the presence of smooth muscular cell areas within the levator ani muscle and describe their localization and innervation. STUDY DESIGN Five female human fetuses were studied after approval from the French Biomedicine Agency. Specimens were serially sectioned and stained by Masson trichrome and immunostained for striated and smooth muscle, as well as for somatic, adrenergic, cholinergic, and nitriergic nerve fibers. Slides were digitized for 3-dimensional reconstruction. One fetus was reserved for electron microscopy. We explored the structure and innervation of the levator ani muscle. RESULTS Smooth muscular cell beams were connected externally to the anococcygeal raphe and the levator ani muscle and with the longitudinal anal muscle sphincter. The caudalmost part of the pubovaginal muscle was found to bulge between the rectum and the vagina. This bulging was a smooth muscular interface between the levator ani muscle and the longitudinal anal muscle sphincter. The medial (visceral) part of the levator ani muscle contained smooth muscle cells, in relation to the autonomic nerve fibers of the inferior hypogastric plexus. The lateral (parietal) part of the levator ani muscle contained striated muscle cells only and was innervated by the somatic nerve fibers of levator ani and pudendal nerves. The presence of smooth muscle cells within the medial part of the levator ani muscle was confirmed under electron microscopy in 1 fetus. CONCLUSION We characterized the muscular structure and neural control of the levator ani muscle. The muscle consists of a medial part containing smooth muscle cells under autonomic nerve influence and a lateral part containing striated muscle cells under somatic nerve control. These findings could result in new postpartum rehabilitation techniques.
Collapse
Affiliation(s)
- Krystel Nyangoh Timoh
- Unité Mixte de Recherche 1195, University Paris Sud, Institut National de la Santé et de la Recherche médicale, Université Paris-Saclay, Le Kremlin-Bicetre, France; Department of Obstetrics and Gynecology, Hopital Universitaire de Rennes, University Rennes 1, Rennes, France
| | - David Moszkowicz
- Unité Mixte de Recherche 1195, University Paris Sud, Institut National de la Santé et de la Recherche médicale, Université Paris-Saclay, Le Kremlin-Bicetre, France.
| | - Mazen Zaitouna
- Unité Mixte de Recherche 1195, University Paris Sud, Institut National de la Santé et de la Recherche médicale, Université Paris-Saclay, Le Kremlin-Bicetre, France
| | - Cedric Lebacle
- Unité Mixte de Recherche 1195, University Paris Sud, Institut National de la Santé et de la Recherche médicale, Université Paris-Saclay, Le Kremlin-Bicetre, France
| | - Jelena Martinovic
- Department of Fetal Pathology, Hopitaux Universitaires Paris-Sud, Assistance Publique-Hôpitaux de Paris, Clamart, France
| | - Djibril Diallo
- Unité Mixte de Recherche 1195, University Paris Sud, Institut National de la Santé et de la Recherche médicale, Université Paris-Saclay, Le Kremlin-Bicetre, France
| | - Maud Creze
- Unité Mixte de Recherche 1195, University Paris Sud, Institut National de la Santé et de la Recherche médicale, Université Paris-Saclay, Le Kremlin-Bicetre, France
| | - Vincent Lavoue
- Department of Obstetrics and Gynecology, Hopital Universitaire de Rennes, University Rennes 1, Rennes, France
| | - Emile Darai
- Department of Obstetrics and Gynecology, Tenon University Hospital, Assistance Publique des Hôpitaux de Paris, Unité Mixte de Recherche-S 938, Pierre and Marie Curie University, Paris, France
| | - Gérard Benoit
- Unité Mixte de Recherche 1195, University Paris Sud, Institut National de la Santé et de la Recherche médicale, Université Paris-Saclay, Le Kremlin-Bicetre, France
| | - Thomas Bessede
- Unité Mixte de Recherche 1195, University Paris Sud, Institut National de la Santé et de la Recherche médicale, Université Paris-Saclay, Le Kremlin-Bicetre, France; Urology Department, Hopitaux Universitaires Paris-Sud, Assistance Publique-Hôpitaux de Paris, Le Kremlin-Bicetre, France
| |
Collapse
|
8
|
Reorganization of mammalian body wall patterning with cloacal septation. Sci Rep 2017; 7:9182. [PMID: 28835612 PMCID: PMC5569103 DOI: 10.1038/s41598-017-09359-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 07/25/2017] [Indexed: 11/22/2022] Open
Abstract
Septation of the cloaca is a unique mammalian adaptation that required a novel reorganization of the perineum–the caudal portion of the trunk body wall not associated with the hindlimb. Fish, the basal vertebrates, separate ventrolateral body wall musculature of the trunk into two discrete layers, while most tetrapods expand this pattern in the thorax and abdomen into four. Mammals, the only vertebrate group to divide the cloaca into urogenital and anorectal portions, exhibit complex muscle morphology in the perineum. Here we describe how perineal morphology in a broad sample of mammals fits into patterning of trunk musculature as an extension of the four-layer ventrolateral muscular patterning of the thorax and abdomen. We show that each perineal muscle layer has a specific function related to structures formed by cloacal septation. From superficial to deep, there is the subcutaneous layer, which regulates orifice closure, the external layer, which supplements both erectile and micturition function, the internal layer, which provides primary micturition and defecation regulation, and the transversus layer, which provides structural support for pelvic organs. We elucidate how the four-layer body wall pattern, restricted to the non-mammal tetrapod thorax and abdomen, is observed in the mammalian perineum to regulate function of unique perineal structures derived from cloacal septation.
Collapse
|
9
|
|
10
|
Abstract
Although several studies have reported that the peritoneum does not contribute to the formation of a fascia between the urogenital organs and rectum, Denonvilliers' fascia (DF), a fascia between the mesorectum and prostate (or vagina) in adults, is believed to be a remnant of the peritoneum. Remnants of the peritoneum, however, were reportedly difficult to detect in other fusion fasciae of the abdominopelvic region in mid-term fetuses. To examine morphological changes of the pelvic cul-de-sac of the peritoneum, we examined 18 male and 6 female embryos and fetuses. A typical cul-de-sac was observed only at 7 weeks, whereas, at later stages, the peritoneal cavity did not extend inferiorly to the level of the prostatic colliculus or the corresponding structure in females. The cul-de-sac had completely disappeared in front of the rectum at 8 weeks and homogeneous and loose mesenchymal tissue was present in front of the rectum at the level of the colliculus at 12-16 weeks. We found no evidence that linearly arranged mesenchymal cells developed into a definite fascia. Therefore, the development of the DF in later stages of fetal development may result from the mechanical stress on the increased volumes of the mesorectum, seminal vesicle, prostate and vagina and/or enlarged rectum. Therefore, we considered the DF as a tension-induced structure rather than a fusion fascia. Fasciae around the viscera seemed to be classified into (1) a fusion fascia, (2) a migration fascia and (3) a tension-induced fascia although the second and third types are likely to be overlapped.
Collapse
|
11
|
The urethral rhabdosphincter, levator ani muscle, and perineal membrane: a review. BIOMED RESEARCH INTERNATIONAL 2014; 2014:906921. [PMID: 24877147 PMCID: PMC4022307 DOI: 10.1155/2014/906921] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Revised: 03/04/2014] [Accepted: 03/05/2014] [Indexed: 01/31/2023]
Abstract
Detailed knowledge of the anatomy of the rhabdosphincter and adjacent tissues is mandatory during urologic surgery to ensure reliable oncologic and functional outcomes. To characterize the levator ani (LA) function for the urethral sphincter, we described connective tissue morphology between the LA and urethral rhabdosphincter. The interface tissue between the LA and rhabdosphincter area in males contained abundant irregularly arrayed elastic fibers and smooth muscles. The male rhabdosphincter was positioned alongside the LA to divide the elevation force and not in-series along the axis of LA contraction. The male perineal membrane was thin but solid and extends along the inferior margin or bottom of the rhabdosphincter area. In contrast, the female rhabdosphincter, including the compressor urethrae and urethrovaginal sphincter muscles, was embedded in the elastic fiber mesh that is continuous with the thick, multilaminar perineal membrane. The inferomedial edge of the female LA was attached to the upper surface of the perineal membrane and not directly attached to the rhabdosphincter. We presented new diagrams showing the gender differences in topographical anatomy of the LA and rhabdosphincter.
Collapse
|
12
|
Sasaki H, Hinata N, Kurokawa T, Murakami G. Supportive tissues of the vagina with special reference to a fibrous skeleton in the perineum: A review. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/ojog.2014.43025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|