Deep Transverse Perineal Muscle Research Articles

Anatomical and histological investigation of the area anterior to the anorectum passing through the levator hiatus

Objective: To document the anatomical structure of the area anterior to the anorectum passing through the levator hiatus between the levator ani slings bilaterally. Methods: Three male hemipelvises were examined at the Laboratory of Clinical Applied Anatomy, Fujian Medical University. (1) The anatomical assessment was performed in three ways; namely, by abdominal followed by perineal dissection, by examining serial cross-sections, and by examining median sagittal sections. (2) The series was stained with hematoxylin and eosin to enable identification of nerves, vessels, and smooth and striated muscles. Results: (1) It was found that the rectourethralis muscle is closest to the deep transverse perineal muscle where the longitudinal muscle of the rectum extends into the posteroinferior area of the membranous urethra. The communicating branches of the neurovascular bundle (NVB) were identified at the posterior edge of the rectourethralis muscle on both sides. The rectum was found to be fixed to the membranous urethra through the rectourethral muscle, contributing to the anorectal angle of the anterior rectal wall. (2) Serial cross-sections from the anal to the oral side were examined. At the level of the external anal sphincter, the longitudinal muscle of the rectum was found to extend caudally and divide into two muscle bundles on the oral side of the external anal sphincter. One of these muscle bundles angled dorsally and caudally, forming the conjoined longitudinal muscle, which was found to insert into the intersphincteric space (between the internal and external anal sphincters). The other muscle bundle angled ventrally and caudally, filling the gap between the external anal sphincter and the bulbocavernosus muscle, forming the perineal body. At the level of the superficial transverse perineal muscle, this small muscle bundle headed laterally and intertwined with the longitudinal muscle in the region of the perineal body. At the level of the rectourethralis and deep transverse perineal muscle, the external urethral sphincter was found to occupy an almost completely circular space along the membranous part of the urethra. The dorsal part of the external urethral sphincter was found to be thin at the point of attachment of the rectourethralis muscle, the ventral part of the longitudinal muscle of the rectum. We identified a venous plexus from the NVB located close to the oral and ventral side of the deep transverse perineal muscle. Many vascular branches from the NVB were found to be penetrating the longitudinal muscle and the ventral part of rectourethralis muscle at the level of the apex of the prostate. The rectourethral muscle was wrapped ventrally around the membranous urethra and apex of the prostate. The boundary between the longitudinal muscle and prostate gradually became more distinct, being located at the anterior end of the transabdominal dissection plane. (3) Histological examination showed that the dorsal part of the external urethral sphincter (striated muscle) is thin adjacent to the striated muscle fibers from the deep transverse perineal muscle and the NVB dorsally and close by. The rectourethral muscle was found to fill the space created by the internal anal sphincter, deep transverse perineal muscle, and both levator ani muscles. Many tortuous vessels and tiny nerve fibers from the NVB were identified penetrating the muscle fibers of the deep transverse perineal and rectourethral muscles. The structure of the superficial transverse perineal muscle was typical of striated muscle. These findings were reconstructed three-dimensionally. Conclusions: In intersphincteric resection or abdominoperineal resection for very low rectal cancer, the anterior dissection plane behind Denonvilliers' fascia disappears at the level of the apex of the prostate. The prostate and both NVBs should be used as landmarks during transanal dissection of the non-surgical plane. The rectourethralis muscle should be divided near the rectum side unless tumor involvement is suspected. The superficial and deep transverse perineal muscles, as well as their supplied vessels and nerve fibers from the NVB. In addition, the cutting direction should be adjusted according to the anorectal angle to minimize urethral injury.

Surgery for female dyspareunia after perineal trauma

Perineal trauma during labor and vulvo-vaginal surgery is common and entails pain, dyspareunia, and other quality of life issues. Herein we describe common pitfalls, reconstruction problems and considerations illustrated by two cases. Diagnosis: A thorough conversation with the woman about her history concerning trauma and present symptoms including sex life before the trauma. Examination: Visual traces of the trauma and palpation for persisting trigger points in accordance with the history. CASE 1: Had previously had two operations for Bartholinitis and two operations for vulvo-vaginal fistulas. She had severe external dyspareunia and not been able to engage in intercourse for 1 ½ year when referred. CASE 2: Suffered a total obstetric anal sphincter rupture during first delivery. Primary suturing was performed in the delivery room. The patient suffered from severe dysparunia and soiling during intercourse three months after the delivery. A low perineum and a low rectocele were seen. By 3D ultrasound a very short external anal sphincter was seen. The transverse perineal and bulbocavernose muscle were still torn. Surgery: Removal of scar tissue. Identifying affected anatomical structures. Usually, the superficial and deep transverse perineal muscle, the bulbocavernosus muscle and the rectovaginal fascia are traumatized. Examples of anatomical correct reconstruction are presented. Postoperative: Weekly Low Level Laser therapy (LLLT) for three weeks was applied, and pain killers were used. Scar tissue massage after four weeks. Recommendation of no intercourse for six weeks. After a longer period with dyspareunia, sex is usually connected with an expectation of pain even when the trigger is removed. This is partially caused by strong pelvic muscle contractions. Supportive consultations about sexual issues are usually necessary to obtain a complete recovery with a healed body and mind. Anatomical correct reconstructive surgery after long term dyspareunia is best treated in a bio-psycho-social frame. No conflict of interest

Anatomy of Cowper\u2019s gland in humans suggesting a secretion and emission mechanism facilitated by cooperation of striated and smooth muscles

This study presents the detailed anatomy of the Cowper’s gland in humans. Elucidating the mechanism of secretion and emission of the Cowper’s gland requires analysis of the muscles around the Cowper’s gland. We hypothesized that the Cowper’s gland involves not only smooth muscle but also the striated muscles of the pelvic floor. Here, we provide comprehensive and three-dimensional anatomy of the Cowper’s gland and its surrounding structures, which overcomes the current local and planar understanding. In this study, seven male corpses of body donors were used to conduct macroscopic anatomy, histology, and three-dimensional reconstruction. The Cowper’s gland was surrounded laterally and posterosuperiorly by striated and smooth muscles, respectively. The striated muscle bundle was connected from the superficial transverse perineal muscle, levator ani, and external anal sphincter to the external urethral sphincter (rhabdosphincter). The smooth muscle was part of the deep transverse perineal muscle and entered between the bilateral Cowper’s glands and lobules. Our findings indicate that the secretion and emission of the Cowper’s gland in humans are carried out through the cooperation of striated and smooth muscles.

‘Sequence graphics’ for gross anatomy diagrams and their objective evaluation

Background and Objectives: Drawing diagrams is an integral part of learning anatomy. The objective of the study was to evaluate sequence graphics to impart drawing skills among medical undergraduates. The other objective of the study was to design and evaluate an objective method of assessment of clinically relevant moderately complex gross anatomy diagrams. Methodology: In an experimental study, participated by 92 students, were asked to draw coronal section of male pelvis (moderately complex diagram) projected on the board. The same diagram was redone with PowerPoint in such a way that each component appears sequentially on command from the teacher, technique called sequence graphics. Sequence labelling followed appearance of each component. The perineal membrane was the key component. Prostate gland (with urethra), deep transverse perineal muscle (with bulbourethral glands) and Colle’s fascia were accessory components. Both diagrams were analyzed for the centeredness, appropriate color usage, bilateral symmetry, and representation of key and accessory components and labelling. Deviation of three accessory components of student images of more than one grid was considered as grossly disproportional diagram. Results: Sequence graphics image scores were significantly more than the scores from projected image tracing (6.04+2.03 vs. 4.72+2.18). The improvement was particularly in terms of symmetry, representation of key and accessory components, labelling and use of appropriate colors. Conclusions: Sequence graphics resulted in drawings with predefined components with labelling. Defining key component and accessory components for moderately difficult diagrams shall result in objective evaluation. Sequence graphics principles aids better drawing skills. Keywords: Artistic anatomy, Medical illustrations, Drawings, Sectional anatomy, Graphics.

The Perineal Membrane: Its Composite Fibers and Nerve Content, and Relationship to the Levator Ani and Deep Transverse Perineal Muscles

The perineal membrane (PM) is a thick, elastic fiber-rich, smooth muscle-poor membrane extending along the vestibule and lower vaginal wall and embedding the urethrovaginal sphincter and compressor urethrae muscles. To provide a better understanding of the topographical relationship between the PM and the levator ani muscle, we examined histological sections from 15 female cadavers. The composite fibers of the PM were usually continuous with that of a fascia covering the inferior or lateral surface of the levator ani (fascia diaphragmatis pelvis inferior) rather than the endopelvic fascia covering the superior or medial surface of the latter muscle. However, this fascial connection was sometimes interrupted by a venous plexus. The deep transverse perineal muscle was consistently adjacent to the posterolateral aspect of the PM, but whether it extended superficially or deeply to the PM depended on size of the muscle. In contrast to the endopelvic fascia embedding abundant middle-sized nerves (cavernous and sphincter nerves; 0.05 - 0.1 mm in thickness), the PM contained very thin nerves: many in 10 cadavers but few in 5 cadavers. Most of the nerves seemed to be sensory on the basis of immunohistochemistry. The levator ani muscle was considered likely to provide traction force to the PM, but active elevation appeared to be difficult because of the highly elastic nature of the PM and the interrupting venous plexus. Loss of nerves in the PM might be one of a number of factors that can accelerate pelvic organ prolapse.

The Male Rectourethralis and Deep Transverse Perineal Muscles and Their Relationship to Adjacent Structures Examined with Successive Slices of Celloidin-Embedded Pelvic Viscera

BackgroundThe precise relationship of the structures dorsal to the membranous urethra, including the rectourethralis muscle, the rhabdosphincter, the deep transverse perineal muscle (DTPM), the perineal body, and Denonvillier’s fascia, remains controversial. ObjectiveOur aim was to reexamine the detailed anatomy of the rectourethralis muscle and the deep transverse perineal muscle and their relationship with adjacent structures. Design, setting, and participantsThe pelvic viscera, including bladder, prostate, and rectum, were obtained from 20 formalin-fixed adult male cadavers. MeasurementsThe pelvic viscera were embedded in celloidin and then cut into successive slices with an immersing-alcohol microtome. All slices were explored with anatomic microscopy. Results and limitationsThe longitudinal muscle of the anterior rectal wall was divided into anterior and posterior bundles at the junction of the rectum and anal canal. The intermediate fibers of the anterior bundle ended at the perineal body. The lateral fibers of the anterior bundle terminated at the posterior connective tissue of the bulbus penis. The DTPM occupied the space between the rhabdosphincter, rectum, and the bilateral levator ani muscle. Denonvillier’s fascia terminated at the junction of the prostate and rhabdosphincter. Numerous slender nerves coming from the neurovascular bundle perforated the DTPM. ConclusionsThe anterior bundle of the longitudinal muscle of the rectum inserts into the bulbus penis forming the rectourethralis muscle and ends at the perineal body forming the rectoperinealis muscle. The anterior bundle and DTPM together may contribute to the rectal angle of the anterior rectal wall, and they support the posterior border of the rhabdosphincter.

Pelvic Floor Images: Anatomy of the Levator Ani Muscle

The levator ani has been divided into many functional portions based on necropic observation. Our objective was to use a combination of CT and magnetic resonance images to show a complete levator ani. Normal magnetic resonance images of the pelvis were obtained at rest in 22 volunteers while in the lying position (10 males, aged 21-23 yr). The pelvic floor images of ten cadavers (5 males) were obtained while in the supine position by CT. Source magnetic resonance images were used to measure the heights of the transverse portion of the levator ani and the area of the genital hiatus. Source magnetic resonance images and CT reconstructed images were used to study the anatomy of the levator ani. The levator ani had a transverse portion and a vertical portion. The anterior transverse portion was found to be basin-shaped, the middle transverse portion was funnel-shaped, and the posterior transverse portion was dome-shaped. The transverse portion sloped sharply downward to form the vertical portion at the puborectalis plane. The vertical portion was a muscular tube outside the intrahiatal structures. The puborectalis was a u-shaped muscle outside the vertical portion. One case of the deep transverse perineal muscle was found in 22 volunteers. The volume of the ischioanal fossa influenced the anatomic appearance of the pelvic floor in cadavers. The transverse portion of the levator ani has five kinds of shapes in the different-coronal sections of the pelvis, which changes from basin to dome in a lying position. The puborectalis is outside the vertical portion and not part of the levator ani.

Surgical anatomy of the perineal muscles and their role in perineal disorders

The anterior perineum contains the perineal body and muscles. It is the site of functional and pathological disorders, many of which have not yet been related to a precise cause. In the present study, we investigated the anatomy of the perineal muscles with the aim of elucidating their function in light of their anatomic structure. Knowledge of their functional-structural relationship is deemed necessary for the understanding of the disorders that affect this part of the perineum. The perineal muscles of 28 cadaveric specimens were studied by direct dissection, as well as histologically. Fifteen male and 13 female specimens were collected from 18 adult (mean (+/- SD) age 31.6 +/- 9.8 years) and 10 neonate cadavers. Histological sections were stained with hematoxylin and eosin and Masson's trichrome stain. The fibers of the superficial transverse perineal muscle proceeded medially to decussate in a criss-cross pattern with the muscle fibers of the contralateral muscle; a few muscle fibers passed directly without decussation. Similarly, the fibers of the deep transverse perineal muscle decussated with their fellows on the opposite side. The two decussation raphes constituted the main bulk of the perineal body. A 'digastric' pattern could be identified for each of the superficial transverse perineal muscle and deep transverse perineal muscle. This pattern allows simultaneous contraction of the muscles on both sides as a single unit. The perineal muscles, forming the floor of the anterior perineum, are apparently subjected to variations in intra-abdominal pressure, which, if exceeding normal physiological limits, may lead to weakening, subluxation and sagging of the perineal muscles and, eventually, to perineocele. Further studies to investigate the role of the perineal muscles in the functional disorders of the perineum are needed.

Clinical anatomy of the pelvic floor.

The study presented here comparing cross-sectional anatomy of the fetal and the adult pelvic connective tissue with the results of modern imaging techniques and actual surgical techniques shows that the classical concepts concerning the subdivision of the pelvic connective tissue and muscles need to be revised. According to clinical requirements, the subdivision of the pelvic cavity into anterior, posterior, and middle compartments is feasible. Predominating connecting tissue structures within the different compartments are: Paravisceral fat pad within the anterior compartment (Fig. 17, I), rectal adventitia or perirectal tissue within the posterior compartment (Fig. 17, II), and uterosacral ligaments within the middle compartment. The nerve-vessel guiding plate can be found in all of these compartments; it starts within the posterior compartment and it ends within the anterior one. It constitutes the morphological border between the anterior and posterior compartments in the male. This border is supplied by the uterosacral ligaments in the female. Whereas in gross anatomy no further border is discernable between anterior and posterior or middle compartment, the rectal fascia (hardly visible in embalmed cadavers) demarcates the rectal adventitia and is one of the most important pelvic structures for the surgeon. In principle, the outlined subdivision of the pelvic connective tissue is identical in the male and in the female; facts that become clear from early human life and that are already established during this period (Fig. 18). The uterus is interposed between the bladder and rectum and subdivides the pelvic peritoneum into two pouches thus establishing the only real difference between male and female pelvic cavity. The preferential direction of the pelvic connective tissue fibers is not changed by the interposition of the uterovaginal complex. The pelvic floor muscles are composed of the portions of the levator ani muscle, the muscles of the cavernous organs and the deep transverse perineal muscle in the male. The latter does not exist in the female. We have clearly shown that the different muscles can already be found in early human life and that they are never intermingled with the muscular walls of the pelvic organs. The levator ani muscle of the female, however, is intermingled with connective tissue long before the female sexual hormones exert influence. We have also shown that the distinct sexual differences within the pelvic floor muscles as well as within the sphincter muscles can already be found in early human life. Both the external urethral and the external anal sphincter muscles are not completely circular. The external anal sphincter is intimately connected with the internal sphincter as well as with the longitudinal muscle. Whereas the innervation and function of the urethral sphincter muscles are mostly clear, cloacal development, innervation, and function of all parts of anal sphincter complex are not completely clarified. As to the support of the pelvic viscera, we believe that intact pelvic floor muscles, an undisturbed topography of the pelvic organs, and an undisturbed perineum are of more importance than the so-called pelvic ligaments. Our hypothesis points to the fact that the support of pelvic viscera is multistructural. Thus in pelvic surgery, a lot of techniques have to be revised with the aim to preserve or to reconstruct all the structures mentioned. This is a multidisciplinary task that can only be solved by cooperation of morphologists, urologists, gynecologists, and coloproctologic surgeons or by creating a multidisciplinary pelvic floor specialist.

Individual variations in aging of the male urethral rhabdosphincter in Japanese.

Although the degenerative changes with aging of the male urethral rhabdosphincter (URS) have been investigated, its individual morphological variations are still unclear. To provide an anatomical basis for clinical evaluation of the individual URS function in the aged, we investigated the structural differences in the URS of 25 elderly Japanese men using semiserial sections stained immunohistochemically and by hematoxylin-eosin. Before removal of the histological specimens, we dissected the ischioanal fossa and labeled several structures by carbon particles to allow proper orientation during the histological observations. In addition, macroscopic slices (10 mm thickness) made from five other male pelves were examined and, when necessary, followed by routine histological procedure to confirm the gross observations. An extended circular URS (over (1/2) circumferential configuration) was found in 15/25 cadavers, but showed very limited height (proximal-distal length) and thickness. A more restricted URS, including even a thin, arc-like pattern, was observed in the remaining cadavers. The attachment of the URS to the smooth muscle layer was loose and usually clearly separated. Continuation between the URS and deep transverse perineal muscle was sometimes observed. The thick fascia of the levetor ani, with high content of smooth muscles, usually provided the lateral or dorsal insertions of the URS. Our results in elderly Japanese subjects suggest that the sphincteric action is weak or incomplete. We suggest that the elderly URS maintains continence by retracting the urethra backward and upward with the aid of the levator sling, rather than the real sphincteric action expected in younger men.

Anatomic principles of urinary incontinence

The morphological fundamentals of urinary continence are still subject to controversy. This was the reason for a renewed examination of the sphincter musculature of the lower urinary tract. This study included 50 male and 15 female autopsy specimens. The organs of the lower urinary tract including the neighboring organs had been removed in their entirety and histologically reprocessed en bloc as a complete series of sections. We were able to demonstrate that the internal sphincter or m. sphincter vesicae is represented as a circular, distinct structure which elliptically embraces the internal urethral orifice. Lamellas of the detrusor are not involved in the formation of the internal sphincter. In females and males, the external sphincter consists of a striated and a smooth muscular part (m. sphincter urethrae transversostriatus et glaber). In transverse sections, the muscle has a horseshoe shape. It is completely separated by connective tissue from the musculature of the pelvic floor. A deep transverse perineal muscle does not exist. The histological findings were used for the construction of a digital three-dimensional model of the anatomy of the lower urinary tract. Computer animations of the model with integrated original histologies were generated and stored as a computer video on a CD-ROM attached to this journal.

THE DISPUTE ABOUT THE EXTERNAL SPHINCTER AND THE UROGENITAL DIAPHRAGM

Basic scientific facts, such as anatomical structures, are rarely subjected to critical reappraisal. Nevertheless, several clinical phenomena exist which are inconsistent with the description of the anatomy of the so-called external sphincter muscle and urogenital diaphragm. We performed a global examination of the anatomy of the entire lower urinary tract in 50 male autopsy specimens. For comparison magnetic resonance imaging of the same regions was performed on 12 healthy patients. Direct comparison of the results of both methods revealed the exact same topography of the bladder neck. The external sphincter or musculus sphincter urethrae is an independent morphological unit separated from the surrounding pelvic floor muscles by connective tissue. The musculus transversus perinei profundus or deep transverse perineal muscle, which is believed to constitute the major element of the urogenital diaphragm, does not exist. There is histomorphological evidence that the external sphincter consists of a striated (musculus sphincter urethrae transversostriatus) and smooth muscle (musculus sphincter urethrae glaber) component.