男性盆腔神经丛及神经血管束的应用解剖

目的认识盆丛、神经血管束（NVB）与周围组织器官的关系。方法对10例成人男性盆腔器官标本作盆丛、NVB大体解剖,1例43岁成人新鲜盆腔脏器作连续切片,观察盆丛、NVB与周围组织器官的关系。结果盆丛位于腹膜后、直肠的侧壁,呈网络状,精囊腺的后外侧,由盆丛发出的阴茎海绵体神经在前列腺后外侧走行,这些神经与前列腺被膜血管组成NVB。NVB的密度沿前列腺下行时逐渐变稀,在膜部尿道的外侧和后外侧分布于尿道旁的横纹肌中。结论明确盆丛、NVB位置以及与盆腔器官的毗邻关系,有助于术中有效鉴别和保护盆丛和NVB,达到保留性神经的盆腔、会阴部手术的目的。     

Mechanical properties and innervation of the smooth muscle layers of the urethra of greyhounds

OBJECTIVE: To investigate the properties of the smooth muscle layers in the urethral wall of male and female greyhounds, and to consider their roles in continence and micturition. MATERIALS AND METHODS: The distribution and innervation of the smooth muscle layers of the prostate capsule and membranous urethra of male greyhounds were assessed. Strips of smooth muscle from these regions were used to determine the neuropharmacological properties by assessing the excitatory and inhibitory responses to nerve stimulation, and the effects of blocking agents. These were compared with strips from the proximal urethra and from the female urethra. RESULTS: The smooth muscle of the membranous urethra comprised 9% of the wall and received its innervation exclusively in branches from the pelvic plexus. The cholinergic innervation in the male produced 80% of the total contractile response in the longitudinal membranous urethra, 50% in the prostate capsule and 13% in the circular muscle of the proximal urethra. In the female all areas had poor contractile responses. Inhibitory fibres produced relaxation in all parts of male and female urethrae with the major effect caused by nitric oxide. Adrenergic nerves contributed to both residual excitation (alpha receptors) and inhibition (beta receptors). CONCLUSIONS: The longitudinal smooth muscle of the male membranous urethra probably shortens the urethra during micturition, through the activity of cholinergic nerves, whereas the circular smooth muscle of the proximal urethra, under adrenergic control, may be contracted during continence and ejaculation. In the female, the smooth muscle plays a minor role.     

Anatomic and functional studies of the male and female urethral sphincter

A total of 28 human specimens (14 male, 14 female) was used to perform macro- and microscopic studies on the morphologic basis of the urethral continence mechanism. Furthermore, functional studies were performed in six sheep, with the aim of looking at the pudendal and autonomic innervation of the urethra and the rhabdosphincter, as well as the changes of autonomic innervation after selective denervation. Transurethral ultrasound was performed in 34 continent patients, in order to visualize the contractions of the rhabdosphincter. The membranous urethra is innervated by branches of the autonomic pelvic plexus. The rhabdosphincter is an omega-shaped loop of striated muscle fibers that is innervated by the pudendal nerves. These results are supported by the results of animal experiments that show that the autonomic nerves predominantly innervate and regulate the upper part of the urethra, whereas stimulation of the pudendal nerves leads to a contraction of the lower part of the sheep urethra. In electron-microscopy, marked degeneration of the smooth muscle cells could be seen in the sheep with bilateral denervation.     

Anatomic study of pelvic urethra in women: value of its conservation in radical cystectomy

The vascularization of the different layers of the pelvic urethra was studied in 12 females urethras, in which the vascular system was injected with gelatinous inda ink. The arterial vascularization of the striated muscle is essentially tributary of the sub-mucosal network by the intermediary of fascicular and interfascicular arteries which anastomose to form an intermuscular plexus. This plexus also anastomoses with the subserosal network. The submucosal layer is a true vascular crossroad form by an intricate plexus of blood vessel, both arterial and veinuous. The sympathic, para-sympathic and somatic voluntary's nerves supply to the pelvic urethra.     

男性盆丛解剖标志在下尿路手术中的意义

为探寻下尿路手术中避免损伤盆丛的解剖标志，对１０个盆腔器官标本作盆丛大体解剖或大切片，观察盆丛与盆腔器官的毗邻关系，结果表明，盆丛位于直肠的前外侧，精囊腺的后外侧，在前列腺基底部与前列腺外侧的血管形成神经血管束，于尿道感染部的外侧和后外仙穿过尿生殖膈，认为精囊腺和神经血管束可作为下尿路术中避免损伤盆丛的解剖标志，文中还对盆丛的解剖分布及其与医源性阳萎的关系进行了讨论。     

INNERVATION OF THE STRIATED MUSCLE OF THE MEMBRANOUS URETHRA OF THE MALE DOG

Purpose

To identify the functional innervation of the striated muscle layer of the post-prostatic urethra of male dogs.

Materials and Methods

Detailed anatomic dissection of the pelvic and pudendal nerves was carried out. The pressure and contractile responses to stimulation of these nerves were recorded in vivo and in vitro.

Results

Small branches of the pelvic nerve entered the membranous urethra but passed through the striated muscle to the inner smooth muscle layer. Stimulation of the nerve with 1 msec pulses at 10 Hz produced a slow contraction of the urethra which was unaffected by d-tubocurarine. Pudendal nerve branches entered the striated layer from the caudal end. Stimulation produced a rapid, visible contraction that was abolished by d-tubocurarine. Field stimulation of isolated strips of striated muscle resulted only in rapid, d-tubocurarine sensitive contractions.

Conclusions

The striated muscle of the membranous urethra is innervated exclusively by the pudendal nerve.     

Precise localization of the autonomic nerves from the pelvic plexus to the corpora cavernosa: a detailed anatomical study of the adult male pelvis

The anatomical location of the branches of the pelvic plexus that innervate the corpora cavernosa has been identified previously in stillborn male neonates and fetuses. Based upon these observations, the techniques of radical retropubic prostatectomy and cystectomy have been modified to avoid injury to the autonomic innervation of the corpora cavernosa. However, the exact anatomical relationships of these nerves to the prostate, urethra and other pelvic structures in adults are unclear, since the initial anatomical studies of the pelvic plexus were performed in stillborn neonates in whom the accompanying vessels and fascia had been removed. Because these nerves are microscopic in size and can only be identified by their association with other pelvic structures, it was believed that a more refined understanding of the anatomy was necessary. In an effort to identify precisely the relationship of the cavernous branches of the pelvic plexus to the lateral pelvic fascia and the branches of the prostatovesicular arteries and veins, the following study was performed. Shortly after death a 60-year-old man was perfused completely with Bouin's fixative solution. The entire bladder, prostate, urethra, penis, corpora cavernosa, rectum, and pelvic sidewall fascia and musculature were removed en bloc. The specimen was serially sectioned transversely at 10 mu thickness, and every tenth section was stained with hematoxylin and eosin. An anatomical reconstruction in 3 dimensions was performed and illustrated. Thus, the specific location of the nerves that innervate the corpora cavernosa and their important relationships to the urethra, prostatic capsule, Denonvilliers' fascia and pelvic floor vasculature have been identified.     

The nature of urethral injury in cases of pelvic fracture urethral trauma

PURPOSE: We examine the urethral injury associated with pelvic fracture that is said to be due to a shearing force through the membranous urethra which inevitably destroys the urethral sphincter mechanism. MATERIALS AND METHODS: A total of 20 asymptomatic cases were prospectively studied, including symptomatically, radiologically, endoscopically and urodynamically, 1 to 4 years after an apparently successful anastomotic repair of a pelvic fracture urethral distraction defect. RESULTS: There was evidence of urethral sphincter function, including urodynamically in 11 (55%), endoscopically in 13 (65%) and functionally in 17 (85%) patients. CONCLUSIONS: These findings, coupled with surgical observation, suggest that the urethral injury associated with pelvic fracture is avulsion of the membranous urethra from the bulbar urethra rather than a shearing through the membranous urethra, and that some degree of urethral sphincter function is preserved in a significant percentage of patients.     

Urethral rupture--primary repair and reconstruction]

Whether the posterior urethra can successfully be reconstructed depends mainly on the primary care, especially in the case of strictures secondary to trauma. Prior to surgery, primary care of the lesion is mandatory, including open suprapubic fistula, drainage of the cavum retii and of the perineal space, repositioning of the urethra and immediate stabilization of the pelvic ring by means of elastic procedures. In a second step, between 1978 and 1990 we performed bulbo-prostatic surgery in 27 patients with traumatic rupture of the posterior urethra. Based on extensive anatomic be studies on the relationship of the membranous urethra to the pelvic floor and to the arteries, veins and nerves, an operative approach via the perineal body was developed. Of 18 patients followed up, only 4 had flow rates of less than 15 ml/s. Retrograde urethrograms and micturition cystograms showed good results.     

Reconstruction of Membranous Urethral Strictures

Purpose of Review

Due to the proximity of the rhabdosphincter and cavernous nerves to the membranous urethra, reconstruction of membranous urethral stricture implies a risk of urinary incontinence and erectile dysfunction. To avoid these complications, endoscopic management of membranous urethral strictures is traditionally favored, and bulboprostatic anastomosis is reserved as the main classical approach for open reconstruction of recalcitrant membranous urethral stricture. The preference for the anastomotic urethroplasty among reconstructive urologists is likely influenced by the familiarity and experience with trauma-related injuries. We review the literature focusing on the anatomy of membranous urethra and on the evolution of treatments for membranous urethral strictures.

Recent Findings

Non-traumatic strictures affecting bulbomembranous urethra are typically sequelae of instrumentation, transurethral resection of the prostate, prostate cancer treatment, and pelvic irradiation. Being a different entity from trauma-related injuries where urethra is not in continuity, a new understanding of membranous urethral anatomy is necessary for the development of novel reconstruction techniques. Although efficacious and durable to achieve urethral patency, classical bulboprostatic anastomosis carries a risk of de-novo incontinence and impotence. Newer and relatively less invasive reconstructive alternatives include bulbar vessel-sparing intra-sphincteric bulboprostatic anastomosis and buccal mucosa graft augmented membranous urethroplasty techniques. The accumulated experience with these techniques is relatively scarce, but several published series present promising results. These approaches are especially indicated in patients with previous transurethral resection of the prostate in which sparing of rhabdosphincter and the cavernous nerves is important in attempt to preserve continence and potency. Additionally, introduction of buccal mucosa onlay grafts could be especially beneficial in radiation-induced strictures to avoid transection of the sphincter in continent patients, and to preserve the blood supply to the urethra for incontinent patients who will require artificial urinary sphincter placement. The evidence regarding erectile functional outcomes is less solid and this item should be furtherly investigated.

     

NADPH-diaphorase in glandular cells and nerves and its relation to acetylcholinesterase-positive nerves in the male reproductive tract of man and guinea-pig

The presence of NADPH-diaphorase activity and acetylcholinesterase in the testis, epididymis, vas deferens, seminal vesicle, pelvic plexus, prostate and urethra of man and guinea-pig was investigated with the nitro blue NADPH technique and the thiocholine method, respectively. In human material NADPH-diaphorase activity was found in the Leydig cells, Sertoli cells and the epithelial linings of the rete testis, the excretory ducts, seminal vesicle, prostate and urethra. The guinea-pig material showed staining of the Leydig cells and spermatozoa and similar epithelial staining of the tract as man. Nerves beneath the epithelium and in the muscle layers of cauda epididymis, vas deferens, seminal vesicle, prostate and urethra were also stained. NADPH-diaphorase-positive nerve cells were seen in the pelvic plexus. Some cells also displayed acetylcholinesterase activity but others showed activity for only one of the enzymes or no activity for either enzyme. In the cauda epididymis, vas deferens, seminal vesicle, prostate and urethra acetylcholinesterase-positive nerve fibres formed a plexus beneath the secretory cells. It is concluded that NADPH-diaphorase, generally accepted as a nitric oxide synthase, is present in glandular cells of the male genital tract. The enzyme is also present in nerves, where it is partly co-localized with acetylcholinesterase. Received: 15 January 1997 / Accepted: 18 September 1997     

Surgical anatomy of the male and female urethra.

The urethra is lined by transitional and stratified columnar epithelium. The urethra can be divided into both anatomic (prostatic, membranous, bulbar, and pendulous) and functional (anterior and posterior) segments. In the male, the anterior urethra is contained within the corpus spongiosum and penis. The urethra in the male and female is located within the urogenital triangle and pierces the superficial and deep perineal spaces of the pelvic floor. The urethra is surrounded by perineal and pelvic musculature that provide support and also form the urethral sphincter mechanism. Cancers of the anterior urethra preferentially drain into superficial inguinal lymph node channels. Those of the posterior urethra (prostatic, membranous, and bulbar segments in the male and the proximal two thirds of the urethra in the female) generally drain into pelvic lymphatic channels. A thorough knowledge of urethral and regional anatomy allows for complete tumor excision, optimal reconstruction, and in selected cases, restoration of urinary tract function.     

Bulboprostatic anastomotic urethroplasty with preservation of potency: anatomical study, operative approach and clinical results

OBJECTIVE. To identify the precise anatomy of the membranous and bulbous urethrae and their relation to the neurovascular bundles (cavernous nerves and vessels). Based on the findings, a modified surgical technique was developed to preserve potency by avoiding injury to the neurovascular bundles during surgery on the posterior urethra. MATERIAL AND METHODS: The material for this study consisted of 10 male cadavers. We injected eight cadavers with a mixture of red latex and lead oxide. By means of meticulous dissection we removed the bladder, prostate, urethra, penis, surrounding vessels and nerves. We also identified the anatomical relations between various urogenital structures and the vessels and nerves. We examined the specimens radiologically. In the other two cadavers, we removed the membranous urethrae and subjected them to histological examination. We used haematoxylin-eosin and Verhoeff von Gieson stains to study the elastic tissues. RESULTS: The membranous urethra measured 2.5-3 cm in length. It originated from the lower third of the anterior surface of the prostate (and not from the apex) as a continuation of the prostatic urethra. The wall of the membranous urethra contained abundant elastic fibres. The neurovascular bundles were located posterolateral to the mid-portion of the prostate and prostatic apex. Near the apex the neurovascular bundle divided into two parts: a larger anterior part and a smaller posterior part. The anterior part crossed the membranous urethra, then the bulb of the penis at the 1 and 11 o'clock positions and finally entered the corpus cavernosum. The posterior part crossed the membranous urethra more posteriorly to enter the bulb of the penis. Between 1992 and 2003 we managed 22 patients (age range 16-50 years) with posterior urethral obstruction secondary to pelvic fracture by means of bulboprostatic anastomosis. We managed 17 patients via the perineal route and five via a combined perineoabdominal-transpubic route. All of these patients were potent before the operation, which proved the integrity of the neurovascular bundles. We could spare the anterior divisions of the neurovascular bundles (greater cavernous nerves and vessels) during their crossing of the bulb of the penis by cutting and dissecting within the bulb (not outside it) before dismembering it from the urogenital diaphragm. We also refrained from any dissection of the apex and the posterolateral surfaces of the prostate to avoid injury to the neurovascular bundles. At 6-year follow-up (range 1-10 years) 21/22 patients preserved their potency, giving a success rate of 95.45%. Of the 22 patients, two became temporarily impotent after the operation but regained potency within a period of 4-6 months. CONCLUSION: Our technique of neurovascular bundle preservation during bulboprostatic anastomotic urethroplasty may solve the problem of postoperative impotence.     

女性解剖性前盆腔脏器清除术对控尿机制的影响

目的:探讨女性解剖性前盆腔脏器清除术对控尿机制的影响,以进一步指导相关临床工作和研究。方法:对符合研究需要的成人女性尸体20具进行控尿神经的大体解剖,然后模拟行经耻骨后解剖性前盆腔脏器清除术,以明确可能会损伤控尿神经的操作,并提出相应的防范措施。结果:女性盆丛的阴道丛和尿道丛有神经分支进入尿道,其中膀胱尿道丛量较少,紧贴盆侧壁几乎与尿道上缘平行走向尿道。阴部神经的阴蒂背神经和阴部神经发出神经支配尿道,以阴部神经为主要。明确上述控尿神经,模拟手术表明:紧贴盆壁的操作、尿道近端切除>0.5cm、吻合尿道-新膀胱进针过深等均易于损伤控尿神经和肌肉操作。结论:手术中应针对易于损伤的控尿神经、肌肉操作因素进行防范,有助于女性控尿机制的保护。     

Urodynamics in spinal shock patients

We investigated 17 spinal shock patients with traumatic complete cord lesions with cystometry, urethral pressure profile, anal and rectal pressure recordings, and electromyography of the pelvic floor sphincters. Bladder filling was accompanied by an elevation of resistance in the bladder neck area, with a concomitant increase of pressure in the external sphincter zone but without a simultaneous increase of the electromyographic activity. These results indicate an increased sympathetic activity in the smooth muscle component of the entire urethra. In the majority of patients the continuous withdrawal pressure profile had higher values in the membranous urethra than the interrupted withdrawal pressure profile had higher values in the membranous urethra than the interrupted withdrawal pressure profile, revealing the importance of sensory afferents from the urethral mucosal receptors in producing artifactual reflex activity in the pelvic floor muscles. In the majority of interrupted withdrawal urethral pressure profiles higher pressures were recorded in the juxtabulbous region than in the mid part of the membranous urethra. A somewhat decreased electromyographic activity was found in the anal and urethral sphincters at rest. It did not often relate to the amount of resistance recorded in either sphincter. High urethral sphincter pressures and somatic activity of the conus medullaris reflexes show that external urethral and anal sphincters escape spinal shock, the primary characteristic of which is areflexia.     

经会阴修复重建男性尿道的应用解剖

目的探讨经会阴修复重建男性尿道的解剖学基础,寻求减少损伤的方法. 方法防腐成年男尸12具,经会阴逐层解剖至尿道前列腺尖部,观察层间结构和联系、尿道前列腺尖部和膜部周围结构,测量有关数据;另用新鲜男尸3具,模拟经会阴修复重建男性尿道手术操作. 结果支配阴囊、会阴及尿道球部的动、静脉及神经均是从两外侧走向中线;前尿道海绵体的腹、背侧与相邻组织间有致密纤维组织相连接.阴茎海绵体神经呈网状紧贴前列腺表面从底部走向尖部,穿过尿生殖膈,呈网格状展开,神经束网宽为(12.11±2.32) mm. 结论会阴结构复杂,手术时靠中线操作可减少损伤;在膜部尿道外侧5 mm的范围内操作,从前外侧紧贴前列腺表面分离前列腺尖部组织,可避免损伤神经束.     

Role of striated and smooth muscle components in the urethral pressure profile in traumatic neurogenic bladders: a neuropharmacological and urodynamic study. Preliminary report

Urodynamic investigations with urethral pressure profile, and vesical, intrarectal and anal pressure recordings were performed in 37 patients with spinal cord lesions. The recordings were done before and after phentolamine injections and/or pudendal nerve blocks to evaluate the respective contribution of sympathetic and somatic innervation to the maximum urethral closure pressure in the mid and distal portions of the membranous urethra. A pressure gradient was demonstrated in the membranous urethra with higher values in the distal than in the mid portion. These results emphasize that the interrupted withdrawal technique is superior to the continuous technique in patients with upper motor neuron bladders. Mid urethral striated and smooth muscle components were shown to represent approximately 60 and 30 per cent of the maximum urethral closure pressure, respectively. In the distal urethra striated and smooth components are more abundant than in the mid portion and contribute in equal proportion to the maximum urethral closure pressure. No substantial role was found for the vascular bed in the maximum urethral closure pressure. The greatest pressure decrease in the mid and distal urethra of patients with lower motor neuron bladders was believed to be an effect of denervation supersensitivity. The results of pudendal blocks showed sphincter dyssynergia to be mediated through pudendal nerves via spinal reflex arcs. Phentolamine effects on bladder activity suggest that blockade of alpha-adrenergic receptors inhibits primarily the transmission in vesical and/or pelvic parasympathetic ganglia and acts secondarily through direct depression of the vesical smooth muscle. Our neuropharmacological results raise strong doubts as to the existence of a sympathetic innervation of the striated urethral muscle in humans.     

A study of the myelinated fibres in the branches of the pelvic plexus

In a 20-year-old human female specimen the nerves to the pelvic organs were dissected and analysed. The gross anatomy of the branches of the pelvic plexus was described. The composition of these nerves was studied and the sizes and distribution of the diameter of a great part of the myelinated nerve fibres were measured and analysed. It was confirmed that the ventral roots S2 and S3 contain many nonmyelinated nerve fibres. There are direct connections between the sacral sympathetic chain and the pelvic plexus. They contain myelinated fibres with sizes as large as 11 μm. There are two different groups of fibres which supply the bladder, one on the dorsal side, mainly nonmyelinated (postganglic sympathetic?), and another group to the lateral side which contains many thin myelinated fibres (parasympathetic preganglionic?). The pelvic plexus and its branches are fixed to the vagina and the rectum. Surgical interventions in this area and perhaps also childbirth can damage the nerve supply to the bladder and the urethra. The functional disturbances of the bladder after such interventions can depend on what group of nerve fibres is most seriously damaged. The large number of thick myelinated fibres which reach the ventro lateral side of the urethra makes it highly probable that these fibres innervate the intrinsic striated urethral musculature. The large number of nonmyelinated nerve fibres in the nerves to the m. levator ani probably innervate smooth muscle tissue which is found in the fasciae of the pelvic floor.     

Magnetic resonance imaging of the male pelvic floor: The anatomical configuration and dynamic movement in healthy men

The male pelvic organs and the rhabdosphincter were visualized using magnetic resonance imaging (MRI) in five young male volunteers (mean age, 25.6 years). The prostate was crescent-shaped in three subjects and doughnut-shaped in two subjects. The external urethral sphincter (EUS) was located anterior to and lateral to the urethra but was rare on the rectal side. The membranous urethral length measured 28–35 mm (average, 31.0 mm). The pubourethral portion of the levator ani embraced the urinary bladder, the prostate, and the membranous urethra, and the most distal portion of the levator was thickened. During anal contraction, the EUS became thinner on both coronal and sagittal images and the levator was approximated closer to the urethra. Consequently, the prostate and the bladder base were elevated and the membranous urethra was elongated by 0–12mm (average, 5.6 mm). On sagittal images, the prostate, the membranous urethra, and the rectum were pulled closer to the pubic bone by anal contraction and the retropubic area became narrower. This study clearly demonstrated that MRI was useful in examining the anatomical configuration of the male pelvic floor and its dynamic movement during anal contraction. Neurourol. Urodynam. 17:591–597, 1998. © 1998 Wiley-Liss, Inc.