Pelvic Floor Muscle Control Research Articles

Gestational diabetes is associated with alteration on pelvic floor muscle activation pattern during pregnancy and postpartum: Prospective cohort using electromyography assessment.

Background and objectiveGestational diabetes mellitus (GDM) is a comorbidity which may cause acute and lifelong disorders to mother and child. Alterations in muscular and connective tissues have been associated with GDM in translation studies, characterizing gestational diabetic myopathy. Pregnancy-specific urinary incontinence and sexual disabilities, disorders that depend on the pelvic floor muscle (PFM) integrity, are also associated with GDM both during and after pregnancy. The aim was to compare PFM activation patterns between GDM and non-GDM women from 24–30 gestational weeks to 18–24 months postpartum during a standard clinical test during gestation and postpartum.MethodsWe conducted a prospective three-time-point cohort study from gestation (24–30 weeks—T1, and 36–38 weeks—T2) to 18–24 months postpartum (T3). PFM electromyography was recorded in primigravida or primiparous women with one previous elective c-section with or without the diagnosis of GDM according to the American Diabetes Association criteria. A careful explanation of the muscle anatomy and functionality of the PFM was given to participants before EMG assessment. The outcome measures were PFM activation patterns assessed during pregnancy and postpartum, comparing intra and between groups. PFM activation patterns were assessed by normalized electromyography signal at rest and during 1-second (sec) phasic, 10-sec hold, and 60-sec sustained contractions.ResultsDemographic and obstetric data showed homogeneity between groups. The GDM group achieved peak PFM EMG amplitudes similarly to the non-GDM group, but they took longer to return to baseline levels during the ~1-sec contraction (flicks). During 10-sec hold contractions, the GDM group sustained lower levels of PFM activation than the non-GDM group at both 36–38 weeks of gestation and 18–24 months postpartum when compared to the non-GDM group.ConclusionThe results suggest that GDM impaired PFM control mainly on 1-sec flicks and 10-sec hold contraction, which appears to develop during late pregnancy and extends long-term postpartum. This motor behavior may play a role on pelvic floor dysfunctions.

ID:16195 Cortical Neuromodulation of Pelvic Floor Muscle Tone: A Proof-of-Concept Study

In the human brain, supplementary motor area (SMA) is involved in the control of pelvic floor muscles (PFMs). SMA dysfunction has been implicated in several disorders involving PFMs, including urinary incontinence and urologic pelvic pain. Here, we aimed to provide a proof-of-concept study to demonstrate the feasibility of modulating resting PFM activity (tone) as well as SMA activity with noninvasive stimulation of SMA.

Effect of a Comprehensive Rehabilitation Program for Community Women with Urinary Incontinence: A Retrospect Cohort Study.

Urinary incontinence (UI) is a common problem affecting older adult women globally, but studies regarding combined treatments for all types of UI are still lacking. Here we evaluate the efficacy of a comprehensive rehabilitation program for women with UI. A comprehensive rehabilitation program was introduced that combines pelvic floor muscle (PFM) exercises, functional electrical stimulation, and timely biofeedback during the training process. Data of patients with stress (SUI), urgency (UUI), or mixed (MUI) urinary incontinence who participated in this program between 2016 and 2019 were reviewed retrospectively. Seventy-three subjects (mean age 59.2 ± 12.7 years) were enrolled. After 12 weeks of rehabilitation, vaginal pressure and control accuracy increased in all groups. PFM maximum recruitment increased significantly at week 12 in SUI and UUI, but not in MUI. At week 6, only the SUI group had achieved significant improvements in vaginal pressure, PFM maximum recruitment and control accuracy. The Short-form Urogenital Distress Inventory (UDI-6) and Incontinence Impact Questionnaire-7 (IIQ-7) scores declined dramatically after the program started, and significant improvements were maintained to week 48. The comprehensive rehabilitation program is effective and decreases urinary leakage episodes and improves quality of life in women with UI, especially SUI.

Motor cortical neuromodulation of pelvic floor muscle tone: Potential implications for the treatment of urologic conditions.

In the human brain, supplementary motor area (SMA) is involved in the control of pelvic floor muscles (PFMs). SMA dysfunction has been implicated in several disorders involving PFMs, including urinary incontinence and urologic pain. Here, we aimed to provide a proof-of-concept study to demonstrate the feasibility of modulating resting PFM activity (tone) as well as SMA activity with noninvasive stimulation of SMA. We studied six patients (3 women + 3 men) with Urologic Chronic Pelvic Pain Syndrome. Repetitive transcranial magnetic stimulation (rTMS) was applied to SMA immediately after voiding. We tested two rTMS protocols: high-frequency (HF-rTMS) which is generally excitatory, and low-frequency (LF-rTMS) which is generally inhibitory. PFM activity was measured during rTMS using electromyography. Brain activity was measured immediately before and after rTMS using functional magnetic resonance imaging. The rTMS protocols had significantly different effects on resting activity in PFMs (P = 0.03): HF-rTMS decreased and LF-rTMS increased pelvic floor tone. SMA activity showed a clear trend ( P = 0.06) toward the expected differential changes: HF-rTMS increased and LF-rTMS decreased SMA activity. We interpret the differential effects of rTMS at the brain and muscle level as novel support for an important inhibitory influence of SMA activity on pelvic floor tone after voiding. This preliminary study provides a framework for designing future studies to determine if neuromodulation of SMA could augment therapy for chronic urologic conditions.

MP27-19 A NEW CLINICAL PROTOCOL FOR DEMONSTRATION OF CORTICAL BRAIN ACTIVITY MAPPING DURING VOLUNTARY UROFLOW AND PELVIC FLOOR MUSCLE ACTIVITY USING FUNCTIONAL NEAR INFRA-RED SPECTROSCOPY (FNIRS)

You have accessJournal of UrologyUrodynamics/Lower Urinary Tract Dysfunction/Female Pelvic Medicine: Incontinence: Evaluation (Urodynamic Testing)1 Apr 2018MP27-19 A NEW CLINICAL PROTOCOL FOR DEMONSTRATION OF CORTICAL BRAIN ACTIVITY MAPPING DURING VOLUNTARY UROFLOW AND PELVIC FLOOR MUSCLE ACTIVITY USING FUNCTIONAL NEAR INFRA-RED SPECTROSCOPY (FNIRS) Lynn Stothers and Andrew Macnab Lynn StothersLynn Stothers More articles by this author and Andrew MacnabAndrew Macnab More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.898AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Control of micturition is dependent upon an extensive brain neural network. Cortical activity related to pelvic floor muscle (PFM) contractions has been demonstrated using fMRI but is not in routine clinical care due to expense, limited access and restriction to the supine position. Functional near infra-red spectroscopy (fNIRS) which detects changes in oxyhemoglobin (O2Hb) and deoxyhemoglobin (hHb) concentrations is non invasive, maps cortical activity in real time and allows upright posture. Objective: examine patterns of frontal cortical brain O2Hb using fNIRS during PFM contraction and relaxation at capacity and related to voluntary uroflow in natural voiding posture. METHODS N=12 studies; subjects, healthy volunteers, men (age 24-55 yrs), women (age 24-78 yrs). A protocol proving PFM control by fMRI was replicated then extended to include spontaneous voiding, uroflow and post void residual urine. fNIRS was performed using a 4x4 optode grid (Artinis Medical Systems) over the frontal cortex, at 10 Hz. At bladder capacity, following natural filling subjects imitated voiding by releasing or imitated interruption of voiding by contracting PFMs for 10 sec over 10 repetitions followed by voluntary voiding (seated or standing for males). O2Hb and hHb patterns were captured, then linked to uroflow in video format. RESULTS In men and women PFM contraction and relaxation induced a repetitive activation pattern in the frontal cortex with increases in ΔO2Hb evident. There was an increase in ΔO2Hb detectable in the lateral prefrontal area (Brodmann′s areas) following permission to void at capacity with urge. Fig 1: demonstration of cerebral O2Hb static images from fNIRS video before permission to void (A), following permission to void (B), at Q max (C) and following voiding (D). CONCLUSIONS A clinical protocol for fNIRS mapping to detect activation of the frontal cortical micturition region during voluntary uroflow and during PFM is presented for future clinical studies. To our knowledge, this is the first study confirming fNIRS activation patterns detected during micturition-related activity in cortical structures during natural voiding posture corresponding to those previously demonstrated in fMRI. © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e355 Advertisement Copyright & Permissions© 2018MetricsAuthor Information Lynn Stothers More articles by this author Andrew Macnab More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Use of Transabdominal Ultrasound Imaging in Retraining the Pelvic-Floor Muscles of a Woman Postpartum

Postpartum stress urinary incontinence (SUI) often compromises a woman's ability to participate in normal daily routines or physical activities. Pelvic-floor muscle (PFM) training has been shown to be effective in improving urinary incontinence. Transabdominal ultrasound (TAUS) imaging is a new, noninvasive method for assessing the function of the PFMs. This case report describes the use of TAUS imaging in the strengthening of a patient's PFMs. The patient was a 29-year-old woman experiencing SUI with high-impact activities following a history of 2 vaginal deliveries, 1 resulting in a grade III perineal laceration. Intervention included PFM training with the use of TAUS imaging. A 1-year follow-up examination was performed to assess the long-term functional outcomes experienced by the patient. The patient's ability to maintain a PFM contraction during motor tasks was documented throughout the course of treatment to demonstrate her gain in PFM control. The patient gained strength in her PFMs, enabling her to maintain a PFM contraction during various motor tasks. She was able to return to a running program with no SUI symptoms. Her satisfaction level was high at 1 year. The use of TAUS imaging was a helpful assessment and biofeedback tool for re-education and rehabilitation of the PFMs for this patient.

Gender differences in voluntary micturition control — An fMRI study

In the last decade functional imaging has gained substantial importance for identifying cortical and subcortical brain regions being involved in the micturition circuit. However, possible gender differences are still a matter of debate. In the present study we used functional magnetic resonance imaging (fMRI) to determine micturition related brain regions in healthy men and compared them with those in women to elucidate gender-related differences. fMRI was performed at 3 T in 12 healthy men with urge to void due to a filled bladder. In a non-voiding model they were instructed to contract or to relax the pelvic floor muscles repetitively. As previously reported in women, contraction and relaxation of pelvic floor muscles induced strong activations in the brainstem and more rostral areas in our group of healthy men. In general, men had stronger activations during contraction than women in nearly all identified areas. In contrast, results for the relaxation condition were similar. Some of the differences between contraction and relaxation, formerly detected in females, could be found in our group of males as well. The results suggest that in women and men the same cortical and subcortical networks exist for micturition control. Especially, the well located activations in the putative pontine micturition centre and the periaqueductal grey could be identified in both sexes. However, pelvic floor muscle control seems to induce different activation intensities in men and women.

Effect of Biofeedback Training on Paradoxical Pelvic Floor Movement in Children with Dysfunctional Voiding

Dynamic perineal ultrasonography to assess the function of the pelvic floor muscles in children with micturition complaints shows that many children with daytime incontinence or recurrent urinary tract infections use their pelvic floor paradoxically. They strain when asked to withhold urine, or they have no voluntary control of the pelvic floor muscles at all. The aim of this study was to record the pelvic floor function and evaluate the physical therapy regimens for children with dysfunctional voiding (DV) and paradoxical pelvic floor function. A total of 65 patients with DV, many who also had constipation, were diagnosed with paradoxical movement of the pelvic floor. The patients were asked to contract their pelvic floor muscles during a perineal dynamic ultrasound investigation. Of the 52 patients treated by physical therapists, 32 had a single 1-hour biofeedback session with rectal examination and anal balloon expulsion. In the remaining 20 patients, this was followed by 2 weeks of biofeedback balloon expulsion training at home. Forty control patients were observed. In 13 of the 65 patients, the diagnosis could not be confirmed by the physical therapists. At 6 to 10 months after training, 50 of the 52 other patients had normal voluntary pelvic floor muscle control. Of the 40 control patients, 39 had normal pelvic floor control. The results of this study have demonstrated that pelvic floor dysfunction occurs frequently in children with DV and can be cured by dedicated physical therapy. The clinical importance of this phenomenon is not yet clear. Prospective studies will teach us more about the true incidence and therapeutic effect of pelvic floor dysfunction on DV.

Activation of the supplementary motor area (SMA) during voluntary pelvic floor muscle contractions—An fMRI study

To identify cortical and subcortical regions involved in voluntary pelvic floor muscle control, functional magnetic resonance imaging (fMRI) was performed at 1.5 T in thirty healthy subjects (15 women, 15 men). The participants performed rhythmical (1 Hz) pelvic floor muscle contractions, which imitated the repetitive interruption of voiding. Since previous reports concerning the representation of pelvic floor muscles in the cortex of the medial wall are inconsistent, a conservative statistical threshold (FWE-corrected P<0.05) was used to detect the most robust foci of activation, and cytoarchitectonic probability maps were used to correlate the results with structural anatomical information. We found a strong and consistent recruitment of the supplementary motor area (SMA), with foci of peak activity located in the posterior portion of the SMA, suggesting that this region is specifically involved in voluntary pelvic floor muscle control. Further significant activations were identified bilaterally in the frontal opercula, the right insular cortex and the right supramarginal gyrus. They may reflect the attentive processing and evaluation of visceral sensations. Weaker signals were detected in the primary motor cortex (M1) and the dorsal pontine tegmentum. There was no significant correlation between bladder volumes and brain activation induced by pelvic floor muscle contractions. We found no significant gender-related differences.

Electromyography of pelvic floor muscles

Pelvic floor muscles (PFM) are intimately involved in function of lower urinary tract, the anorectum and sexual functions, therefore their neural control transcends the primarily important somatic innervation of striated muscle, as they are directly involved in “visceral activity”. Neural control of pelvic organs is affected by a unique co-ordination of somatic and autonomic motor nervous systems. Visceral and somatic sensory fibres supply sensory information from pelvic organs; their input influences through central integrative mechanisms also pelvic floor muscle activity. Anatomically, somatic afferent and efferent nerves of the sacral cord segments, reflexly integrated at the spinal cord and brainstem level, conduct neural control of PFM. The inputs from several higher centres influence the complex reflex control and are decisive for voluntary control, and for socially adapted behaviour related to excretory functions.

Voluntary pelvic floor muscle control—an fMRI study

Storage and periodic expulsion of urine by the bladder are controlled by central pathways and organized as simple on–off switching circuits. Several reports concerning aspects of micturition control have identified distinct regions in the brainstem, like the pontine micturition center (PMC) and the periaqueductal gray (PAG), as well as the cerebellum, basal ganglia, limbic system, and cortical areas that are organized in a widespread network. The present study focused on the involvement of these specific brain regions in pelvic floor muscle control. Functional magnetic resonance imaging (fMRI) was performed at 3 T in 11 healthy women with urge to void due to a filled bladder, who were instructed to either imitate voiding by releasing or to imitate interruption of voiding by contracting pelvic floor muscles. None of the subjects was able to start voiding during the experiments, presumably due to subconscious restraint resulting from the inconvenient situation. Relaxation and contraction of pelvic floor muscles induced strong and similar activation patterns including frontal cortex, sensory–motor cortex, cerebellum, and basal ganglia. Furthermore, well-localized activations in the PMC and the PAG were identified. To our knowledge, this is the first study using fMRI to demonstrate micturition-related activity in these brainstem structures. The presented approach proved to characterize the widespread central network in pelvic floor muscle control. Thus, in patients with voiding dysfunction, fMRI will be useful to elucidate the individual disturbance level.

Behavioral Treatment Options for Urinary Incontinence

Abstract Behavioral treatments improve bladder control by changing the incontinent patient's behavior, especially his or her voiding habits, and by teaching skills for preventing urine loss. These treatments are effective for most outpatient men and women with stress, urge, or mixed incontinence. The average reduction in the frequency of incontinence ranges from 57% to 86%. In long-term care settings, treatment is generally more challenging and yields more modest results. The advantages of behavioral interventions include the absence of side-effects, patient comfort, and high levels of patient satisfaction. Although most patients who receive behavioral treatment achieve significant improvement, most are not completely dry. Thus, there is a need for research to explore ways to enhance the effectiveness of these conservative therapies. Combining behavioral treatment with other treatments may have additive effects. Research is also needed to understand better the mechanisms of therapeutic change, the best methods for teaching pelvic floor muscle control, the optimal exercise regimens, the predictors of outcome, and the efficacy of behavioral treatments in men. Although behavioral interventions are more accepted today than 20 years ago, they are still not widely available or integrated into most clinical practices, and we know little of how effective they will be in these settings. Thus, it will be important to develop and evaluate creative modes of delivery, such as group intervention (especially by nonphysician providers), in a variety of clinical settings.

In addition to usual care, pelvic floor exercises commenced preoperatively reduce incontinence after prostatectomy

In men receiving usual post-operative care for radical prostatectomy, do additional pelvic floor exercises commenced preoperatively and continued postoperatively reduce incontinence? Randomised controlled trial with blinded assessors. Tertiary medical centre and private urology clinics in the USA. Men scheduled for elective radical prostatectomy. Exclusion criteria were prior prostatectomy, more than two episodes of incontinence in the previous six months, and impaired mental state. One hundred and twenty-five men were randomised to an intervention group (n = 63) or a control group (n = 62), from which six and seven men, respectively, were withdrawn because their surgery was cancelled. The intervention group received one session of biofeedback-assisted training in pelvic floor muscle control and instructions in a daily pelvic floor regimen. The regimen included three sessions of 15 pelvic floor muscle contractions, each held for up to ten seconds with two to ten seconds rest, and interruption or slowing of the urinary stream during voiding once per day. These men were encouraged to follow the regimen daily until the surgery and were reminded at catheter removal to resume the daily regimen. The control group received no preoperative intervention, brief verbal instructions after catheter removal to interrupt the urinary stream during voiding once daily, plus whatever instructions were given by the surgeon as part of usual care. The primary outcome was time to continence, assessed by one-day bladder diaries completed weekly and a seven-day bladder diary completed at six weeks, three months, and six months. Continence was defined as no leakage reported on three consecutive one-day diaries or on one seven-day diary. Questionnaires about severity of incontinence, pad use, return to work, and quality of life were also completed at six weeks, three months, and six months. At the sixmonth assessment, survival analysis showed significantly faster return to continence in the intervention group, median time to continence 3.5 months versus > 6 months, p = 0.04. Other benefits at six months included significant reductions in severe incontinence (Odds Ratio (OR) 0.29, 95% CI 0.09 to 0.94); pad use (OR 0.44, 95% CI 0.24 to 0.99); and incontinence with coughing (OR 0.29, 95% CI 0.13 to 0.66), sneezing (OR 0.38, 95% CI 0.17 to 0.86), and standing up from lying (OR 0.36, 95% CI 0.13 to 0.94). Quality of life, incontinence impact, and return to work and usual activities did not differ significantly between groups. For men undergoing radical prostatectomy with usual postoperative care, additional biofeedback-assisted training in pelvic floor muscle control and pre- and postoperative pelvic floor exercises reduce postoperative incontinence.

Pre- and postsynaptic localization of the 5-HT7 receptor in rat dorsal spinal cord: Immunocytochemical evidence

Several lines of evidence indicate that 5-HT7 receptors are involved in pain control at the level of the spinal cord, although their mechanism of action is poorly understood. To provide a morphological basis for understanding the action of 5-HT on this receptor, we performed an immunocytochemical study of 5-HT7 receptor distribution at the lumbar level. 5-HT7 immunolabelling is localized mainly in the two superficial laminae of the dorsal horn and in small and medium-sized dorsal root ganglion cells, which is consistent with a predominant role in nociception. In addition, moderate labelling is found in the lumbar dorsolateral nucleus (Onuf's nucleus), suggesting involvement in the control of pelvic floor muscles. Electron microscopic examination of the dorsal horn revealed three main localizations: 1) a postsynaptic localization on peptidergic cell bodies in laminae I-III and in numerous dendrites; 2) a presynaptic localization on unmyelinated and thin myelinated peptidergic fibers (two types of axon terminals are observed, large ones, presumably of primary afferent origin, and smaller ones partially from intrinsic cells; this presynaptic labelling represents 60% and 22% of total labelling in laminae I and II, respectively); and 3) 16.9% of labelling in lamina I and 19.8% in lamina II are observed in astrocytes. Labeled astrocytes are either intermingled with neuronal elements or make astrocytic "feet" on blood vessels. In dendrites, the labelling is localized on synaptic differentiations, suggesting that 5-HT may act synaptically on the 5-HT7 receptor. This localization is compared with other 5-HT receptor localizations, and their physiological consequences are discussed.

Behavioral treatment options for urinary incontinence

Behavioral treatments improve bladder control by changing the incontinent patient’s behavior, especially his or her voiding habits, and by teaching skills for preventing urine loss. These treatments are effective for most outpatient men and women with stress, urge, or mixed incontinence. The average reduction in the frequency of incontinence ranges from 57% to 86%. In long-term care settings, treatment is generally more challenging and yields more modest results. The advantages of behavioral interventions include the absence of side-effects, patient comfort, and high levels of patient satisfaction. Although most patients who receive behavioral treatment achieve significant improvement, most are not completely dry. Thus, there is a need for research to explore ways to enhance the effectiveness of these conservative therapies. Combining behavioral treatment with other treatments may have additive effects. Research is also needed to understand better the mechanisms of therapeutic change, the best methods for teaching pelvic floor muscle control, the optimal exercise regimens, the predictors of outcome, and the efficacy of behavioral treatments in men. Although behavioral interventions are more accepted today than 20 years ago, they are still not widely available or integrated into most clinical practices, and we know little of how effective they will be in these settings. Thus, it will be important to develop and evaluate creative modes of delivery, such as group intervention (especially by nonphysician providers), in a variety of clinical settings.

The Effects of a Progressive Exercise Program With Surface Electromyographic Biofeedback on an Adult With Fecal Incontinence

Fecal incontinence often compromises a person's ability to participate in work and recreational activities. Incontinence may also diminish a person's willingness to take part in social events, leading to feelings of isolation. This case report describes physical therapy designed to reduce a patient's pelvic-floor muscle dysfunction and fecal incontinence. The patient was a 30-year-old woman whose fecal incontinence began after the complicated vaginal birth of her first child that required a vacuum extraction and episiotomy. Intervention included soft tissue techniques, electromyographic biofeedback, strength training, relaxation training, patient education, and a home program. The patient completed a questionnaire at initial evaluation and at discharge to assess her perceived limitations in functional activities. Electromyographic analysis was used to measure changes in the patient's pelvic-floor muscle control. The social, occupational, and sexual domains, which the patient initially judged to be the most compromised, showed the greatest improvement. Electromyographic data for the final treatment session indicated improved strength, endurance, and control of her pelvic-floor muscles. The patient reported no episodes of fecal incontinence over the last month of the 3 months of therapy. The physical therapy program may have led to improved bowel continence and greater control of the pelvic-floor muscles, resulting in greater confidence and comfort in social and work situations and less restriction in the patient's physical relationship with her spouse.

The role of biofeedback in Kegel exercise training for stress urinary incontinence

This study examined the effectiveness of teaching pelvic floor exercises with use of bladder-sphincter biofeedback compared to training with verbal feedback based on vaginal palpation in 24 women with stress urinary incontinence. Verbal feedback training consisted of instructing the patient to squeeze the vaginal muscles around the examiner's fingers and providing her with verbal performance feedback. Biofeedback patients received visual feedback of bladder pressure, abdominal (rectal) pressure, and external anal sphincter activity. The biofeedback group improved the strength and selective control of pelvic floor muscles; the verbal feedback group did not. Both groups significantly reduced the frequency of incontinence. The biofeedback group averaged 75.9% reduction in incontinence, significantly greater than the 51.0% reduction shown by the verbal feedback group. Twelve of 13 patients in the biofeedback group improved by 60% or better. Six patients in the verbal feedback group improved by 68% or better, and five were less than 30% improved.

Spinal control of pelvic floor muscles

A prevalent notion in the literature is that the pelvic floor muscles behave as a unitary mass. We examined this proposition experimentally. In spinal cats, we recorded EMG activity from the following pelvic floor muscles: the sphincter ani externus (SAE), the abductor caudae internus (coccygeus), and the levator ani (pubiocaudalis) muscles. The epaxial sacrocaudalis dorsalis lateralis muscle was also exposed and prepared for recording. Electrical stimulation of S2 ventral roots elicited twitch responses of the sphincter ani externus and of the sacrocaudalis dorsalis lateralis muscles. Stimulation of S3 and Cx1 ventral roots elicited responses in the other two muscles studied, the levator ani and abductor caudae internus. Thus a clear segregation of the segmental motor neuron pools innervating the different pelvic floor muscles was demonstrated. The various muscles of the pelvic floor region could be reflexly activated either individually or as a mass unit depending on the intensity of stimulation. Tactile or electrical stimulation of pudendal regions on either side of the body elicited responses of the sphincter ani externus. In contrast, activation of the levator ani and abductor caudae internus muscles could be lateralized: tactile or electrical stimulation of the dorsolateral surfaces at the base of the tail region elicited ipsilateral responses from these muscles. Section of one pudendal nerve did not alter the level of tonic activity (2 to 4s) of the sphincter ani externus. However, bilateral section of the pudendal nerve entirely abolished both tonic activity and phasic responsiveness of the SAE without affecting the activity of the levator ani and abductor caudae internus muscles. Pudendal nerve stimulation elicited only polysynaptic reflex responses from S2 ventral roots. The results presented show that the neural apparatus of the striated musculature of the pelvic floor is capable of activating individually the different muscles that make up the system, and that the sphincter ani externus from one side, and muscles that conform the diaphragm pelvis from the other, are subserved by different neuronal circuits.