The levator ani is a complex funnel-shaped structure mainly composed of striated muscle with some smooth muscle components (see Image. Female Perineum). Located on either side of the lower pelvis, it supports and raises the pelvic floor and allows various pelvic structures to pass through it. The levator ani muscle and the coccygeus muscle are part of the pelvic floor. It forms from the confluence of 3 muscles: puborectalis, pubococcygeus, and iliococcygeus muscles. These mostly receive innervation by the somatic nerves from the sacral plexus, namely the pudendal nerve and nerve of the levator ani muscle, and autonomic nerves from the inferior hypogastric plexus.

The renal pelvis (RP) is a funnel-shaped, smooth muscle structure that facilitates normal urine transport from the kidney to the ureter by regular, propulsive contractions. Regular RP contractions rely on pacemaker activity, which originates from the most proximal region of the RP at the pelvis-kidney junction (PKJ). Due to the difficulty in accessing and preserving intact preparations of the PKJ, most investigations on RP pacemaking have focused on single-cell electrophysiology and Ca2+ imaging experiments. Although important revelations on RP pacemaking have emerged from such work, these experiments have several intrinsic limitations, including the inability to accurately determine cellular identity in mixed suspensions and the lack of in situ imaging of RP pacemaker activity. These factors have resulted in a limited understanding of the mechanisms that underlie normal rhythmic RP contractions. In this paper, a protocol is described to prepare intact segments of mouse PKJ using a vibratome sectioning technique. By combining this approach with mice expressing cell-specific reporters and genetically encoded Ca2+ indicators, investigators may be able to more accurately study the specific cell types and mechanisms responsible for peristaltic RP contractions that are vital for normal urine transport.

BACKGROUND We evaluated the utility of three-dimensional transperineal ultrasonography in detecting occult stress urinary incontinence in women undergoing anterior pelvic floor reconstruction surgery for severe cystocele. MATERIAL AND METHODS We enrolled 207 women with stage III-IV cystocele without urinary stress incontinence. One week before the operation, the patients underwent pelvic floor ultrasonography. We measured the vertical distance between the bladder neck and posterior margin of the pubic symphysis, the posterior vesicourethral angle, the urethral rotation angle, the formation of funnel shape, the hiatus area, and the length of the urethra and the funnel shape. Postoperatively, the patients were evaluated for symptoms of stress urinary incontinence and with the 20-minute pad test. RESULTS The posterior vesicourethral angle with Valsalva maneuver, the difference in the posterior vesicourethral angle between the resting state and with the Valsalva state, and the angle of the proximal urethra were larger in the incontinence-positive group than in the incontinence-negative group (P<0.05). Funnel shape urethra was longer in the incontinence-positive group than in the incontinence-negative group (P<0.05). The cutoff value was 137.5° for the posterior vesicourethral angle with Valsalva maneuver, 39.5° for the difference in the posterior vesicourethral angle, 44.5° for the angle of the proximal urethra, and 0.35 cm for the length of the funnel shape. Multivariate analysis revealed that the difference between the posterior vesicourethral angle in the resting state and with Valsalva, the angle of the proximal urethra, and the length of funnel shape were strongly correlated with occult stress urinary incontinence. CONCLUSIONS Ultrasonography is an effective method for identifying occult stress urinary incontinence.

The peristaltic pressure waves in the renal pelvis that propel urine expressed by the kidney into the ureter towards the bladder have long been considered to be 'myogenic', being little affected by blockers of nerve conduction or autonomic neurotransmission, but sustained by the intrinsic release of prostaglandins and sensory neurotransmitters. In uni-papilla mammals, the funnel-shaped renal pelvis consists of a lumen-forming urothelium and a stromal layer enveloped by a plexus of 'typical' smooth muscle cells (TSMCs), in multi-papillae kidneys a number of minor and major calyces fuse into a large renal pelvis. Electron microscopic, electrophysiological and Ca2+ imaging studies have established that the pacemaker cells driving pyeloureteric peristalsis are likely to be morphologically distinct 'atypical' smooth muscle cells (ASMCs) that fire Ca2+ transients and spontaneous transient depolarizations (STDs) which trigger propagating nifedipine-sensitive action potentials and Ca2+ waves in the TSMC layer. In uni-calyceal kidneys, ASMCs predominately locate on the serosal surface of the proximal renal pelvis while in multi-papillae kidneys they locate within the sub-urothelial space. 'Fibroblast-like' interstitial cells (ICs) located in the sub-urothelial space or adventitia are a mixed population of cells, having regional and species-dependent expression of various Cl-, K+, Ca2+ and cationic channels. ICs display asynchronous Ca2+ transients that periodically synchronize into bursts that accelerate ASMC Ca2+ transient firing. This review presents current knowledge of the architecture of the proximal renal pelvis, the role Ca2+ plays in renal pelvis peristalsis and the mechanisms by which ICs may sustain/accelerate ASMC pacemaking.

The fibro-muscular architecture of the urogenital triangle remains contentious. Reasons are small size of the constituting structures and poor visibility with most imaging methods. We reinvestigated the area in serial sections of three males (21-38 years old) of the American and Chinese Visible Human Projects and two 26-week-old male fetuses, and compared the findings with earlier observations in females. The mass of the levator ani muscle was approximately twofold smaller and its funnel shape steeper in males than females. In the levator hiatus, a strand of the smooth longitudinal muscle layer of the rectum, the 'rectourethral (RU) muscle', extended anteriorly from the anorectal bend to the penile bulb. Fibrous tissue that formed in the inferior reach of the fetal RU muscle identified the location of the developing perineal body (PB) and divided the muscle into posterior 'rectoperineal' and anterior 'deep perineal' portions. In males, the PB remained small and bipartite, so that the RU muscle presented as an undivided midline structure. The well-developed female PB, instead, intertwined with the deep perineal muscle and both structures passed the vagina bilaterally to form the perineal membrane in the posterior portion of the urogenital triangle. The urethral rhabdosphincter extended in the anterior portion of the urogenital triangle between the penile bulb inferiorly and the bladder neck superiorly, and consisted of a well-developed circular 'membranous' portion with bilateral posteroinferior 'wings' and a thinner 'prostatic' portion on the prostate anterior side. In men, muscles occupy the urogenital triangle, but additional tightening of the locally fibrous adipose tissue by the superficial transverse perineal muscle appears necessary to generate functional support in women. An interactive 3D pdf file with these anatomical details (available online) should allow more accurate interpretation of ultrasound, computed tomography and magnetic resonance images.

The anatomy of the levator ani muscle was studied in relation to the urinary bladder. The study was performed on 23 cadavers by dissection and microscopic examination. The levator ani is funnel-shaped and consists of a transverse portion called the levator plate and a vertical portion called the suspensory sling. The levator plate is a cone and consists of two "lateral masses" and two "crura," with the levator hiatus occupying its anterior part. Three crural patterns could be identified: classic, crural overlap, and crural scissors. The levator crura are connected to the intrahiatal organs by the hiatal ligament; the pubovesical ligament constitutes the anterior part of this ligament. The suspensory sling forms a vertical cuff around the intrahiatal organs, from which it is separated by a "tunnel septum." Its urethral portion ends in multiple fibrous septa, which penetrate the striated urethral sphincter. The levator ani plays an important role in bladder-neck fixation provided by the suspensory sling and hiatal ligament. Levator ani and hiatal ligament subluxation leads to ptosis of the urinary bladder. Furthermore, the present study demonstrates that the urethra is located in the infralevator compartment and is thus protected from the effect of intraabdominal pressure. A chronic increase in intraabdominal pressure leads to levator subluxation and sagging and to urethral exposure to intraabdominal pressure, which seems to interfere with the micturition mechanism. The infralevator location of the urethra might have a bearing on the pathogenesis and treatment of stress urinary incontinence.