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Background : This study aimed to assess the penile circumference in its flaccid and erect states using a Rigiscan monitoring device and Audiovisual Sexual Stimulation (AVSS) within a large Chinese male cohort to establish an objective standard. Methods : 1,134 men participated between January 2019 and June 2021. 803 men, achieving a hardness of 80% or more, were included. Circumferences of the penis' base and tip in its flaccid and erect states were documented, and averages were compared across age groups and Chinese regions. Age-related correlations were explored. Results : Flaccid penile base and tip averaged 7.25 ± 0.60 cm and 7.20 ± 0.71 cm. At 80% erection, they were 9.70 ± 0.65 cm and 9.65 ± 0.75 cm. The increase in circumference from flaccid to 80% erect for the base and tip was approximately 25.31% and 25.47%, respectively. Correlations between flaccid and erect states were significant (tip: R  = 0.807, base: R  = 0.828, both p  < 0.01). No significant age or regional variations in penile circumference were found. Conclusion : Our data on 803 subjects measured with Rigiscan showed that penile circumferences in flaccid and erect states show a strong correlation, in Chinese population. Penile size does not seem significantly influenced by age or region.

Most men believe that the average length of an erect penis is greater than 6 inches (15.24 cm). This belief is due, in part, to several often-cited studies that relied on self-reported measurements, with means of about 6.2 inches (15.75 cm) for heterosexual men and even greater for gay men. These studies suffered from both volunteer bias and social desirability bias. In this review, the combined mean for 10 studies in which researchers took measurements of erect penises was 5.36 inches (13.61 cm; n = 1,629). For 21 studies in which researchers measured stretched penises, the mean was approximately 5.11 inches (12.98 cm; n = 13,719). Based on these studies, the average length of an erect penis is between 5.1 and 5.5 inches (12.95-13.97 cm), but after taking volunteer bias into account, it is probably toward the lower end of this range. Studies show that a majority of men wish they were larger, with some choosing penile lengthening surgery. These surgeries are considered by the American Urological Association to be risky. Most men seeking surgery have normal sized penises. Counseling with factual information about penis size might be effective in alleviating concerns for the majority of men who worry about having a small penis.

Data regarding the size of the adult penis is of great importance to both clinicians and researchers. Currently, there is no consensus regarding the preferred method for the evaluation of penile size. Various and conflicting methods are reported in the literature. We review the data on measurement methods of the flaccid, stretched, and erected penis with the aim of constructing a recommendation for best practice. A systematic search for articles on penile length and girth measurement techniques was performed using PubMed, Google Scholar, and Cochran Library. Only peer-reviewed articles published in English before August 2018 were reviewed. All authors evaluated the methods and results sections presented in each publication. Relevant, demonstrative publications are reported in this review. We did not find definitive evidence favoring one measuring method over the other. Therefore, we advocate the use of our recommendations for penile size measurement in future publications.

Introduction: Peyronie's disease (PD) is associated with penile length loss due to atrophy that occurs as a result of fibrous inelastic scarring. Studies have shown diminished penile length and girth, as well as the inability to participate in sexual activity, can lead to decreased quality of life, emotional challenges, and sexual dissatisfaction in a large percentage of men., Aim: To provide a summary of the new developments in the surgical techniques available for the PD patient, with a focus on procedures that provide penile size restoration., Methods: A MEDLINE PubMed search was used to identify articles related to surgical treatments for PD, including plication procedures, penile prosthesis placement, and techniques for size restoration., Main Outcome Measure: Types of surgical treatments for PD and their outcomes regarding penile length and patient satisfaction., Results: The Nesbit procedure, among other plication procedures, and penile prosthesis placement with modeling or plication are likely to decrease penile length. Although plaque incision with grafting offers restoration of penile length, it carries a risk of postoperative erectile dysfunction (ED). For men with concomitant ED and severe curvature not amenable to prosthesis with modeling or plication, options include grafting, circumferential tunical incisions, subcoronal prosthesis placement, and the sliding technique with its modifications, allowing for management of both PD and ED while restoring penile length. Adjunct procedures, such as ventral phalloplasty and suspensory ligament release, have also been shown to restore length in PD patients. Novel therapies continue to evolve with the goal of preserving length while treating curvature., Conclusion: There are numerous surgical options for correcting penile curvature in PD patients, with or without concomitant ED treatment. When determining the optimal procedure, it is important to consider possible preservation of penile length and to discuss possible complications to increase patient satisfaction and improve quality of life. Barrett-Harlow B, Clavell-Hernandez J, Wang R. New Developments in Surgical Treatment for Penile Size Preservation in Peyronie's Disease. Sex Med Rev 2019;7:156-166., (Copyright © 2018 International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved.)

Yafi et al. have conducted a study that will be of great interest to the lay community and also of import to practicing urologists who routinely encounter patients with concerns about the appearance of their phallus [1]. In one study 14% of men expressed dissatisfaction with their genitals with flaccid penile length being the most common source of dissatisfaction [2]. The concerns of such men tend to be the perception that their penis is small, or at least smaller than the penises of other men.

The aim of this study is to assess the impact of objective (stretched) and subjective penile size in the erectile function in a urological check-up program on a cross-sectional study including 689 men aged 35-70 years. IIEF-5 questionnaire, physical examination (penile length, prostate volume, blood pressure, body mass index-BMI), metabolic syndrome (MS), comorbidities, habits (sexual intercourse frequency, physical activity, alcohol, and tobacco use), level of education, serum glucose, total testosterone, estradiol, PSA, lipid profile, and self-perceptions (ejaculation time and subjective penile size) were examined in multivariate models using logistic and linear regressions. Penile objective mean length was 13.08 cm ± 2.32 and 67 (9.72%) patients referred small penis self-perception. Seventy-six (11.03%) participants had severe erectile dysfunction (ED), 75 (10.88%) had mild to moderate and moderate ED, 112 (16.25%) had mild ED and 426 (61.83%) had no ED. Risk factors for ED that held statistical significance were self-perceived small penis (OR = 2.23, 95% CI 1.35-3.69, p = .0017), sexual intercourse frequency (per week) (OR = 0.45, 95% CI 0.38-0.52, p < .0001), satisfactory ejaculation time (no vs. yes, OR = 2.06, 95% CI 1.46-2.92, p < .0001), comorbidity (yes vs. no, OR = 2.01, 95% CI 1.46-2.76, p < .0001), age >65 years (OR = 2.93, 95% CI 1.53-5.61, p < .0001), tobacco use (yes vs. no, OR = 1.41, 95% CI 1.02-1.96, p < .0375), regular physical activity (no vs. yes, OR = 1.59, 95% CI 1.13-2.23, p < .0083), serum total testosterone < 200 ng/dl (OR = 3.48, 95% CI 1.69-7.16, p = 0.0009), serum glucose > 100 mg/dl (OR = 1.69, 95% CI 1.18-2.43, p = 0.0044) and systolic blood pressure > 130 mmHg (OR = 1.60, 95% CI 1.16-2.19, p = 0.0037). Results suggest that in addition to previously reported risk factors, patient's subjective impressions of penile size negatively impacts sexual life in about 10% of men considered healthy, while objective penile length does not play significant role in erectile function.

Short periods of testosterone suppression have been shown to reduce trabecular smooth muscle content and increase interstitial connective tissue accumulation in animal models. However, the long-term effects of testosterone suppression remain unclear. The aim of this study was to evaluate the long-term effects of testosterone suppression on penile structure and erectile function in rats. Subjects were divided into two groups by observation period (short-period group (group I), 12 weeks; long-period group (group II), 20 weeks). Each group comprised three different subgroups (10 rats each): sham-operated control, surgical castration, and testosterone replacement (4 weeks after an 8-week castration period). Group II subgroups included a sham control, surgical castration, and testosterone replacement (4 weeks after a 16-week castration period). Erectile function was assessed by measuring intracavernosal pressure in response to cavernous nerve stimulation, and expression of the endothelial nitric oxide synthase (eNOS) protein was determined by western blot analysis. Serum testosterone values were measured via radioimmunoassay. The results indicated that serum testosterone level, penile length and girth, cavernosal smooth muscle content, and eNOS activity decreased significantly in castrated animals. These effects were rescued by testosterone undecanoate injection. Erectile function was normalized over 4 weeks in rats that received androgen replacement. Expression of eNOS was decreased in the corpus cavernosum of castrated animals compared with controls, while androgen replacement normalized the expression of eNOS. These results were consistently observed regardless of the duration of androgen deprivation. Thus, these data suggest that androgen regulates the expression of eNOS in the rat penile corpus cavernosum and confirm the importance of androgens in the maintenance of erectile function. Additionally, long-term androgen deprivation does not induce irreversible structural or erectile functional changes in sexually mature adult male rats.

Peyronie's disease is an abnormal curvature of the penis that affects sexual intercourse. The treatment options include injection therapy into the scar or surgical correction of the curvature using plication or grafting., (Copyright © 2018 European Association of Urology. Published by Elsevier B.V. All rights reserved.)

Introduction: Congenital ventral penile curvature without hypospadias is often treated surgically in childhood. The history of untreated ventral curvature is unknown., Objective: This study's aim was to examine the association of untreated ventral penile curvature with various sexual and psychosexual outcomes., Study Design: An electronic survey was advertised to men older than 18 years on Facebook. Men with possible ventral penile curvature identified themselves by choosing sketches that most closely represented their anatomy. Outcomes assessed included: Sexual Health Inventory for Men, difficulty of intercourse because of curvature, International Prostate Symptom Score, Penile Perception Score, psychosexual milestones, paternity, infertility, sitting to urinate, and the CDC HRQOL-4 module., Results: Among participants, 81 out of 684 men (11.8%) reported untreated ventral penile curvature. Participants with self-reported curvature noted more difficulty with intercourse because of curvature (4.5 vs 4.9, p < 0.001), more unhealthy mental days (8.6 vs 6.2, p = 0.02), and increased dissatisfaction with penile self-perception compared with men without reported curvature (8.6 vs 9.5, p < 0.001)., Discussion: Men with possible untreated ventral curvature reported worse penile perception scores, more mentally unhealthy days, and increased difficulty with intercourse secondary to curvature compared with men without curvature. A limitation to this study is selection bias; responses collected were self-reported from survey volunteers. Additionally, the question identifying ventral penile curvature is not validated but performed well in pretesting. Most questions were from validated surveys, but some were modeled after validated surveys and/or contained high face validity types of questions., Conclusion: Men with possible untreated ventral penile curvature reported more dissatisfaction with penile appearance, increased difficulty with intercourse, and more unhealthy mental days. Given high success rates, low complications, and improved outcomes after surgical correction of penile curvature reported in the literature, our results support correction of congenital penile curvature in childhood., (Copyright © 2015 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Objective: The gracilis was once applied in reconstructing erectile function but its appearance was bulky. We aimed to design a model meeting the requirements of both reducing volume and retaining function., Materials and Methods: The gracilis muscles of 6 rabbits were harvested, applied colorful vascular perfusion and modified Sihler's intramuscular nerve staining. According to their intramuscular nerves and blood vessels, 9 rabbit right gracilis muscles were then longitudinally split into two halves. The anterior muscle bundle was selected as the functional unit and blood supply., Results: The intramuscular nerves and vessels were simultaneously presented on a same specimen. Their relationship suggested gracilis muscle to be composed of two relatively independent subunits. The reconstructed penis survived well, simulating erectile action satisfactorily., Discussion: The penis model reconstructed with longitudinally split rabbit segmental gracilis myocutaneous flap had met the requirements of both restoring erectile function and improving the appearance.

Introduction: Many men seek penile augmentation treatments-a standard tool for their counseling is to inform them of what is "normal." Although some studies suggest good correlation between stretched and erect penile length, those that have measured stretched and erect length simultaneously have shown significant variability., Aim: To assess the accuracy of differing penile measurements with multiple observers., Methods: We recruited 201 adult men (mean age 49.6 years) who achieved full erection using intracavernosal injection., Main Outcome Measures: Penile measurements were taken by one of seven andrology specialists in a private, temperature-controlled (21°C, 72°F) environment. Stretched flaccid and erect length and circumference were measured. We analyzed the accuracy of each flaccid measurement using the erect measurements as a reference, for the overall patient population and for each observer., Results: The mean underestimate of length from stretched flaccid to erect was 2.64 cm (21.4%) and girth 2.27 cm (19.5%). Interobserver variability ranged from a mean underestimate of 16-27% (length) and 15-27% (girth)., Conclusions: In this large, multicenter, multi-observer study of penis size, flaccid measurements underestimated erect size. It also seems likely that there is significant interobserver variability. We believe erect penis measurements should be used for men being considered for treatment of small penis anxiety., (© 2015 International Society for Sexual Medicine.)

Objective: To systematically review and create nomograms of flaccid and erect penile size measurements., Methods: Study key eligibility criteria: measurement of penis size by a health professional using a standard procedure; a minimum of 50 participants per sample., Exclusion Criteria: samples with a congenital or acquired penile abnormality, previous surgery, complaint of small penis size or erectile dysfunction. Synthesis methods: calculation of a weighted mean and pooled standard deviation (SD) and simulation of 20,000 observations from the normal distribution to generate nomograms of penis size., Results: Nomograms for flaccid pendulous [n = 10,704, mean (SD) 9.16 (1.57) cm] and stretched length [n = 14,160, mean (SD) 13.24 (1.89) cm], erect length [n = 692, mean (SD) 13.12 (1.66) cm], flaccid circumference [n = 9407, mean (SD) 9.31 (0.90) cm], and erect circumference [n = 381, mean (SD) 11.66 (1.10) cm] were constructed. Consistent and strongest significant correlation was between flaccid stretched or erect length and height, which ranged from r = 0.2 to 0.6., Limitations: relatively few erect measurements were conducted in a clinical setting and the greatest variability between studies was seen with flaccid stretched length., Conclusions: Penis size nomograms may be useful in clinical and therapeutic settings to counsel men and for academic research., (© 2014 The Authors. BJU International © 2014 BJU International.)

Introduction: Accurate data regarding the size of the erect penis are of great importance to several disciplines working with male patients, but little high-quality research exists on the subject, particularly in different ethnic groups and for erect penis size., Aim: The aim of this study was to create a nomogram of erect penile dimensions in a large sample of Middle Eastern men., Methods: A retrospective cohort study of 778 men (mean age 43.7; range 20-82) attending urological outpatient clinics in Saudi Arabia was conducted. Exclusion criteria were age under 18 years, a presenting complaint of small or short penis, Peyronie's disease or complaint of congenital curvature, clinical hypogonadism, and previous penile surgery or trauma., Main Outcome Measures: Three erect penile dimensions following induction of erection using intracavernosal injection of Quadrimix., Results: Mean patient body mass index (BMI) was 29.09 (standard deviation [SD] 5.76). The mean suprapubic skin-to-penile tip erect length was 12.53 cm (SD 1.93); the mean erect length from the symphysis pubis to the penile tip was 14.34 cm (SD 1.86); and the mean erect shaft circumference was 11.50 cm (SD 1.74). A nomogram was constructed and statistical analysis performed, demonstrating a weak negative correlation between BMI and erect penile length measured from the suprapubic skin (r = -0.283, P < 0.000) but not from bone to tip, and a weak negative correlation between age and both erect penile length measurements (skin to tip r = -0.177, P < 0.0005; bone to tip r = -0.099, P = 0.006)., Conclusion: A nomogram for Middle Eastern men can be used as a standard when advising men with small penis anxiety. The importance of measuring erect size and allowing for infra-pubic fat interference in measurement is emphasized. We envisage that this tool can be used to educate and reassure concerned men about the size of their penises., (© 2015 International Society for Sexual Medicine.)

The description of the nerve-sparing technique of radical prostatectomy by Walsh was one of the major breakthroughs in the surgical treatment of prostate cancer in the 20(th) century. However, despite this advance and consequent technological refinements to nerve-sparing surgery, a large proportion of men still suffer from erectile dysfunction (ED) as a complication of prostatectomy. A plethora of therapeutic approaches have been proposed to optimize erectile function recovery in these patients. Several preclinical and translational studies have shown benefits of therapies including PDE5 inhibitor (PDE5I) treatment, immunomodulation, neurotrophic factor administration, and regenerative techniques, such as stem cell therapy, in animal models. However, most of these approaches have either failed to translate to clinical use or have yet to be studied in human subjects. Penile rehabilitation with PDE5Is is currently the most commonly used clinical strategy, in spite of the absence of solid clinical evidence to support its use.

Introduction: Innervation of the penis supports erectile and sensory functions., Aim: This article aims to study the efferent autonomic (visceromotor) and afferent somatic (sensory) nervous systems of the penis and to investigate how these systems relate to vascular pathways., Methods: Penises obtained from five adult cadavers were studied via computer-assisted anatomic dissection (CAAD)., Main Outcome Measures: The number of autonomic and somatic nerve fibers was compared using the Kruskal-Wallis test., Results: Proximally, penile innervation was mainly somatic in the extra-albugineal sector and mainly autonomic in the intracavernosal sector. Distally, both sectors were almost exclusively supplied by somatic nerve fibers, except the intrapenile vascular anastomoses that accompanied both somatic and autonomic (nitrergic) fibers. From this point, the neural immunolabeling within perivascular nerve fibers was mixed (somatic labeling and autonomic labeling). Accessory afferent, extra-albugineal pathways supplied the outer layers of the penis., Conclusions: There is a major change in the functional type of innervation between the proximal and distal parts of the intracavernosal sector of the penis. In addition to the pelvis and the hilum of the penis, the intrapenile neurovascular routes are the third level where the efferent autonomic (visceromotor) and the afferent somatic (sensory) penile nerve fibers are close. Intrapenile neurovascular pathways define a proximal penile segment, which guarantees erectile rigidity, and a sensory distal segment., (© 2015 International Society for Sexual Medicine.)

Objective: To report penile integrity measures, including stretched penile length (SPL), from a randomized, double-blind, double-dummy, placebo-controlled trial evaluating treatment with tadalafil initiated after nerve-sparing radical prostatectomy (nsRP)., Methods: Patients aged ≤ 68 years were randomized after nsRP 1:1:1 to 9-month double-blind treatment (DBT) with tadalafil 5 mg once daily (OaD), 20-mg tadalafil on-demand ("pro-re-nata"; PRN), or placebo, followed by 6-week drug-free washout and 3-month open-label OaD treatment. Secondary outcome measures included the change in SPL from pre-nsRP to the end of DBT (analysis of covariance adjusting for treatment, country, baseline, age, and nerve-sparing score), responses to Sexual Encounter Profile (SEP) questions 1-3 (mixed models for repeated measures adjusting for treatment, country, visit, visit-treatment-interaction, age), and Standardized Morning Erection Question (Cochran-Mantel-Haenszel test adjusted for age and country)., Results: Four hundred twenty-three patients were randomized to tadalafil OaD (N = 139), tadalafil PRN (N = 143), and placebo (N = 141). Greater retainment of SPL was observed with tadalafil OaD vs placebo at the end of DBT (least-square mean [95% confidence interval] difference OaD vs placebo, 4.1 mm [0.4 to 7.8 mm]; P = .032). No significant effects on SPL were found for tadalafil PRN vs placebo, or for the nerve-sparing score. Penile tumescence (SEP1) and ability for vaginal insertion (SEP2) significantly improved vs placebo at the end of double-blind and open-label treatment for patients randomized to tadalafil OaD only. The ability for successful sexual intercourse (SEP3) significantly improved with tadalafil OaD vs placebo only during DBT. The distribution of Standardized Morning Erection Question responses was different at the end of DBT (P = .045); 34.2% of patients on tadalafil OaD, 50.0% on tadalafil PRN, and 56.5% on placebo reported absence of morning erections., Conclusion: These data suggest the early initiation of tadalafil OaD protects from penile length loss and may contribute to protection from structural cavernosal changes after nsRP., (Copyright © 2015 Elsevier Inc. All rights reserved.)

The baculum (os penis) has been extensively studied as a taxon-specific character in bats and other mammals but its mechanical function is still unclear. There is a wide consensus in the literature that the baculum is probably a sexually selected character. Using a novel approach combining postmortem manipulation and three-dimensional (3D) imaging, we tested two functional hypotheses in the common noctule bat Nyctalus noctula, the common pipistrelle Pipistrellus pipistrellus, and Nathusius' pipistrelle Pipistrellus nathusii: (i) whether the baculum can protect the distal urethra and urethral opening from compression during erection and copulation; and (ii) whether the baculum and corpora cavernosa form a functional unit to support both the penile shaft and the more distal glans tip. In freshly dead or frozen and thawed bats, we compared flaccid penises with artificially 'erect' penises that were inflated with 10% formalin. Penises were stained with alcoholic iodine and imaged with a lab-based high-resolution x-ray microtomography system. Analysis of the 3D images enabled us to compare the changes in relative positions of the baculum, corpora cavernosa, urethra, and corpus spongiosum with one another between flaccid and 'erect' penises. Our results support both functional hypotheses, indicating that the baculum probably performs two different roles during erection. Our approach should prove valuable for comparing and testing the functions of different baculum morphologies in bats and other mammals. Moreover, we have validated an essential component of the groundwork necessary to extend this approach with finite element analysis for quantitative 3D biomechanical modeling of penis function., (© 2015 Anatomical Society.)

Introduction: Penile size continues to receive popular and empirical attention. Little is known about the process of self-measurement and whether the behaviors a man engages in to become erect for self-measurement are associated with his erect penile dimensions., Aims: The article aims to assess men's erect penile dimensions in a study in which the men would presumably be motivated to report accurate information about their penis size; and to explore associations between men's erect penile dimensions, their method of measurement, and their demographics., Methods: Data are from an Internet-based baseline phase of a large prospective daily diary study that compared men's use of a standard-sized condom to men's use of a condom sized to fit their erect penis., Main Outcome Measures: The main outcomes are participant characteristics, activities engaged in during self-measurement process, and self-reported erect penile length and circumference., Results: For this sample of 1,661 men, the mean erect penile length was 14.15 cm (SD = 2.66; range = 4 to 26 cm), and the mean erect penile circumference was 12.23 cm (SD = 2.23; range = 3 to 19). Participant characteristics were not associated with measured length or circumference. Most men measured their penis while alone, using hand stimulation to become erect., Conclusions: In this sample of men who measured their erect penile length and circumference for the purposes of receiving a condom sized to fit their erect penis, we found a mean erect penile length of 14.15 cm and a mean erect penile circumference of 12.23 cm. The self-reported erect penile dimensions in this study are consistent with other penile dimension research. Also, findings suggest that mode of getting an erection may influence erect penile dimensions. Additionally, how a man becomes erect for self-measurement may be associated with his erect penile length and/or circumference., (© 2013 International Society for Sexual Medicine.)

The aim of this study was to identify the functional-anatomical structures of the canine penis during and after erection to demonstrate the respective changes to provide a basis for further examinations of pathological conditions like priapism. Additionally, a gray-scale analysis was performed to quantify results from the ultrasound examination. In total, 80 dogs were examined. In group (Gr.) A, 44 intact or castrated dogs were examined, and in Gr. B, 36 dogs were examined during erection and after complete detumescence of the penis. The following parameters were assessed: (1) using physical measurements: length of the Pars longa glandis [Plg] and length of the Bulbus glandis [Bg]; and (2) using ultrasound: total penile diameter, width of the erectile tissue of the Plg, diameter of the Corpus spongiosum [Cs] including the penile bone and urethra, vertical diameter, circumference of the penis, cross-sectional area, and area of the Cs including the urethra. The mentioned parameters could be assessed in all dogs of Gr. A and Gr. B with the only exception being the urethra that could be visualized using ultrasound in some dogs only and predominantly in the erected penis (Gr. B). Concomitantly, the erectile tissue of the Plg and the Cs was more heterogenous and hypo- to anechoic during erection compared with dogs in Gr. A and Gr. B after detumescence. Comparing the results in Gr. B, the length of the Plg and the Bg were decreased approximately 40.6% and 38.0%, the total width of the penis 40.5%, the total width of the erectile tissue of the Plg 48.0%, and the width of the Cs 15.6% during detumescence compared with erection. Comparing the decrease in size at the different locations (apex penis, middle of Plg, middle of Bg) for vertical diameter, total circumference, and cross-section area, it was largest at the Bg. B-mode ultrasound is a suitable tool to investigate not only the morpho-functional structures of the resting canine penis, but also of the erected and detumescent penis, and to investigate the underlying changes during erection and detumenscence., (Copyright © 2013 Elsevier Inc. All rights reserved.)

The intromittent organs of most amniotes contain variable-volume hydrostatic skeletons that are stored in a flexible state and inflate with fluid before or during copulation. However, the penis in male crocodilians is notable because its shaft does not seem to change either its shape or bending stiffness as blood enters its vascular spaces before copulation. Here I report that crocodilians may have evolved a mechanism for penile shaft erection that does not require inflation and detumescence. Dissections of the cloaca in sexually mature male American alligators (Alligator mississippiensis) show that the cross section of the proximal shaft of the alligator penis contains dense collagenous tissues that do not significantly change shape when fluid is added to the central vascular space. The large amount of collagen in the wall and central space of the alligator penis stiffen the structure so it can be simply everted for copulation and rapidly retracted at its completion. Because no muscles insert directly onto the penis, eversion and retraction must be produced indirectly. My results suggest that the contraction of paired levator cloacae muscles around the anterior end of the cloaca rotates the penis out of the cloacal opening and strains the ligamentum rami that connect the base of the penis to the ischia. When the cloacal muscles relax, the elastic recoil of the ligamentum rami can return the penis to its original position inside the cloaca., (Copyright © 2012 Wiley Periodicals, Inc.)

Objective: To demonstrate the effect of the size of the resultant tunical defect after plaque excision on postoperative erectile function of patients with Peyronie's disease., Methods: The results of 38 patients with plaque excision and dermal grafting were reviewed from April 2007 to June 2011. History, physical examination, self-shot photograph, color duplex ultrasonography were done preoperatively, and the risk factors for erectile dysfunction were evaluated. The tunical defects were ≥ 3 cm for group 1 and <3 cm for group 2. The postoperative need for phosphodiesterase type 5 inhibitors was noted for both groups. The International Index of Erectile Function-5 questionnaire was completed by all patients., Results: Overall, phosphodiesterase type 5 inhibitors were necessary for 13 (34%) of 38 patients; 7 (58.3%) of 12 in group 1 and 6 (23%) of 26 in group 2. The risk factors for postoperative erectile dysfunction were statistically similar for both groups. If patients with ventral defects were excluded from group 2, the number of patients requiring phosphodiesterase type 5 inhibitors was 4 (17%) of 24. The patients in group 2 answered the fifth question (4.6 ± 0.55) significantly different from those in group 1 (3.7 ± 0.88)., Conclusion: Plaque excision and dermal grafting can be recommended only for highly selected patients with Peyronie's disease with good erectile capacity, with a degree of angle not suitable for only plication or Nesbit techniques, for patients who do not accept any significant shortening of the penis, and if the size of the tunical defect will be <3 cm. Additional techniques on the opposite aspect of the lesion are advocated for the remaining curvatures, not to enlarge the tunical defect >3 cm., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The reproductive system of the male agouti is not well documented. This study describes the specific anatomical features of the free part of the penis occurring during penile erection in the agouti. Electro-ejaculation was used to induce erection in three male agoutis that had previously produced offspring. Results proved that there were four stages in the erection process. Stage 1 involved protrusion of the penis from the preputial orifice. The lateral penile cartilages were then spread (stage 2). During stage 3, there was the blooming of the head of the glans penis (penile flower) and eversion of the intromittent sac. The protrusion of the keratinaceous styles and ejaculation occurred during stage 4. This information could assist in semen collection for use in reproductive techniques for the agouti such as artificial insemination., (© 2012 Blackwell Verlag GmbH.)

Recent studies substantiate a model of the tunica albuginea of the corpora cavernosa as a bi-layered structure with a 360° complete inner circular layer and a 300° incomplete outer longitudinal coat spanning from the bulbospongiosus and ischiocavernosus proximally and extending continuously into the distal ligament within the glans penis. The anatomical location and histology of the distal ligament invites convincing parallels with the quadrupedal os penis and therefore constitutes potential evidence of the evolutionary process. In the corpora cavernosa, a chamber design is responsible for facilitating rigid erections. For investigating its venous factors exclusively, hemodynamic studies have been performed on both fresh and defrosted human male cadavers. In each case, a rigid erection was unequivocally attainable following venous removal. This clearly has significant ramifications in relation to penile venous surgery and its role in treating impotent patients. One deep dorsal vein, 2 cavernosal veins and 2 pairs of para-arterial veins (as opposed to 1 single vein) are situated between Buck's fascia and the tunica albuginea. These newfound insights into penile tunical, venous anatomy and erection physiology were inspired by and, in turn, enhance clinical applications routinely encountered by physicians and surgeons, such as penile morphological reconstruction, penile implantation and penile venous surgery.

Purpose: Prospective evaluation of sexual outcomes after prostate brachytherapy with iodine-125 seeds as monotherapy at a tertiary cancer care center., Methods and Materials: Subjects were 129 men with prostate cancer with I-125 seed implants (prescribed dose, 145 Gy) without supplemental hormonal or external beam radiation therapy. Sexual function, potency, and bother were prospectively assessed at baseline and at 1, 4, 8, and 12 months using validated quality-of-life self-assessment surveys. Postimplant dosimetry values, including dose to 10% of the penile bulb (D10), D20, D33, D50, D75, D90, and penile volume receiving 100% of the prescribed dose (V100) were calculated., Results: At baseline, 56% of patients recorded having optimal erections; at 1 year, 62% of patients with baseline erectile function maintained optimal potency, 58% of whom with medically prescribed sexual aids or drugs. Variables associated with pretreatment-to-posttreatment decline in potency were time after implant (p = 0.04) and age (p = 0.01). Decline in urinary function may have been related to decline in potency. At 1 year, 69% of potent patients younger than 70 years maintained optimal potency, whereas 31% of patients older than 70 maintained optimal potency (p = 0.02). Diabetes was related to a decline in potency (p = 0.05), but neither smoking nor hypertension were. For patients with optimal potency at baseline, mean sexual bother scores had declined significantly at 1 year (p < 0.01). Sexual potency, sexual function, and sexual bother scores failed to correlate with any dosimetric variable tested., Conclusions: Erections firm enough for intercourse can be achieved at 1 year after treatment, but most men will require medical aids to optimize potency. Although younger men were better able to maintain erections firm enough for intercourse than older men, there was no correlation between potency, sexual function, or sexual bother and penile bulb dosimetry., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Introduction: Sexuality is a sensitive issue that may be difficult to explore through surveys involving direct contact. Epidemiological studies in this domain are scarce. Online surveys may provide more anonymity and less direct contact encouraging participation. The Global Online Sexuality Survey (GOSS) reports on different aspects of male and female sexuality. The Global Online Sexuality Survey-Arabic-Males (GOSS-AR-M) is the Arabic version reporting on male sexuality., Aim: To evaluate male ejaculatory function, penile size and contraceptive trends among Arabic speakers in the Middle East., Methods: The survey was randomly offered online to web surfers in the Middle East., Main Outcome Measures: Prevalence of premature ejaculation, ejaculatory latency, penile size and their correlation with erectile function., Results: A total of 82.6% reported various degrees of premature ejaculation, associated with a statically significant decline in erectile function, despite a median intravaginal ejaculatory latency time (IELT) of 5 minutes, 95% confidence interval (CI) of 8.4-9.8. Adjusted to the World Standard Population by the World Health Organization, the collective prevalence was 83.7%. Local anesthetics gave better results and tolerance in delaying ejaculation. Self-measured erect penile length from symphysis pubis to glans was 15.6 cm ± 4.1, 95% CI = 15.4-15.9, yet, 30% were dissatisfied with size, mainly in the flaccid state, with dissatisfaction being inversely proportional with erectile function. Intrauterine device was the method mostly used by couples, and condoms had a high dissatisfaction rate., Conclusion: The prevalence of premature ejaculation appears to surpass that of erectile dysfunction, despite the possibility that it may be overreported considering the acceptable IELT of the population surveyed. Premature ejaculation and concerns over genital size may be considered as risk factors for ED. More male contraceptive measures should be introduced and popularized. Alleviating dissatisfaction with condom utility via health education should be a priority., (© 2011 International Society for Sexual Medicine.)

Introduction: Elastin fibers confer passive recoil to many tissues including the lung, skin, and arteries. In the penis, elastin is present in sinusoids, arterioles, and in the tunica albuginea. Although decreased penile elastin has been reported in men with erectile dysfunction, the exact role of elastin in physiologic processes integral to erection remains speculative., Aim: The aim of this study was to characterize erectile function in elastin-deficient mice., Methods: Elastin haploinsufficient mice (Eln(+/-) ) and aged match Eln(+/+) (Wt) mice were used. Cavernosum was removed from some mice for quantification of elastin, collagen, and smooth muscle actin. Ex vivo assessment of contractile force generation was performed by myography. In vivo assessment of intracorporal pressure normalized to mean arterial pressure in response to electrical stimulation of the cavernosal nerve was measured. Veno-occlusive function was determined by cavernosography., Main Outcome Measures: The main outcome measures of this study were the in vitro and in vivo assessment of cavernosal vasoreactivity, veno-occlusive function and erection in mice deficient in elastin., Results: Eln (+/-) mice exhibited ∼33% less penile elastin than Wt mice, with no change in collagen. Cavernosal tissue from Eln(+/-) mice has a significantly heightened contractile response, explained in part by increased smooth muscle cell content. Veno-occlusive function was significantly altered in Eln(+/-) mice. Interestingly, erectile function was impaired only at submaximal voltage (1 V) stimulation (there was no impairment during the higher 2-V stimulus)., Conclusions: Eln (+/-) mice display a cavernosal phenotype consistent with developmental changes attributable to the loss of elastin. These alterations confer a degree of altered erectile function that is able to be overridden by maximal stimulatory input. Altogether, these data suggest that elastin is important for erectile function., (© 2011 International Society for Sexual Medicine.)

Erectile dysfunction (ED) is common and a significant contributor to poor quality of life and psychosocial morbidity in men. Normal erectile function requires effective co-ordination between a number of complex neural pathways. Penile tumescence occurs in response to rapid arterial inflow to the corpora cavernosa with simultaneous venous outflow restriction due to expansion of the lacunar spaces. This process is under both central and local neuromediation. Endothelins are potent vasoconstrictor peptides that cause strong, slowly developing but sustained contraction of trabecular smooth muscles cells of the corpora cavernosa. Multiple mechanisms of action are proposed, including transmembrane calcium flux, mobilisation of inositol triphosphate sensitive intracellular calcium stores and calcium sensitisation through the Rho-Rho kinase pathway. The exact role of endothelins in the pathogenesis of ED currently remains unclear. Elevated endothelin-1 levels are found in patients with diabetes mellitus and this alone may be sufficient to cause ED. However, this is not borne out in clinical studies. The resultant elevated intracellular calcium may, however, modulate gene expression sufficiently to cause smooth muscle proliferation. Alternatively, alterations in endothelin receptor sensitivity in conditions such as diabetes and hypertension may enhance vasoconstrictor processes. Currently there is contradictory evidence for the role of endothelin receptor antagonists in ED. Animals studies suggest they inhibit corporal vasoconstriction, improve erectile function and protect against diabetes-induced smooth muscle apoptosis. However, the results of clinical studies in ED have been less promising. Uncertainty regarding the exact role of endothelin in penile erection hampers progress in this area. It is possible that the endothelin system may only be relevant to ED in certain conditions where global endothelial dysfunction exists (e.g. diabetes mellitus, systemic sclerosis) and the use of endothelin antagonists in these patient groups may yield improved outcomes., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Purpose: To review and to summarize the literature on anatomy and physiology of erection in the past three decades, especially the work done in our institution., Methods: A search of the PubMed database was performed using keywords erection, anatomy and erectile dysfunction (ED). Relevant articles were reviewed, analyzed and summarized., Results: Penile vascularisation and innervation vary substantially. Internal pudendal artery is the major source of penile blood supply, but a supralevator accessory pudendal artery that may originate from inferior vesical or obturator or external iliac arteries is not uncommon. Section of this artery during radical prostatectomy (RP) may adversely affect postoperative potency. Anastomoses between the supra and the infralevator arterial pathways are frequent. The cavernous nerves (CNs) contain parasympathetic and sympathetic nerve fibers and these nerves lie within leaves of the lateral endopelvic fascia. Anastomoses between the CNs and the dorsal nerve of the penis are common. Nitric oxide released from noradrenergic, noncholinergic neurotransmission of the CN and from the endothelium is the principal neurotransmitter-mediating penile erection. Interactions between pro-erectile and anti-erectile neurotransmitters are not completely defined. Finally, medial preoptic area and paraventricular nucleus are the key structures in the central control of sexual function and penile erection., Conclusions: The surgical and functional anatomy of erection is complex. Precise knowledge of penile vascularisation and innervation facilitates treatment of ED especially after RP.

Previous biomechanical models of the penis simulated penile erections utilizing 2D geometry, simplified 3D geometry or made inaccurate assumptions altogether. These models designed the shaft of the penis as a one-compartment pressurized vessel fixed at one end when in reality it is a two-compartment pressurized vessel in which the compartments diverge as they enter the body and are fixed at two separate anatomic sites. This study utilizes the more anatomically correct two-compartment penile model to investigate erectile function. Simplified 2D and 3D models of the erect penis were developed using the finite element method with varying anatomical considerations for analyzing structural stresses, axial buckling, and lateral deformation. This study then validated the results by building and testing corresponding physical models. Finally, a more complex and anatomically accurate model of the penis was designed and analyzed. When subject to a lateral force of 0.5 N, the peak equivalent von Mises (EVM) stress in the two-compartment model increased by about 31.62%, while in the one-compartment model, the peak EVM stress increased by as high as 70.11%. The peak EVM stress was 149 kPa in the more complex and anatomically accurate penile model. When the perforated septum was removed, the peak EVM stress increased to 455 kPa. This study verified that there is significant difference between modeling the penis as a two- versus a one-compartment pressurized vessel. When subjected to external forces, a significant advantage was exhibited by two corporal based cavernosal bodies separated by a perforated septum as opposed to one corporal body. This is due to better structural integrity of the tunica albuginea when subjected to external forces.

The penis physiological states of flaccidity or erection, result from the contraction or relaxation, respectively, of smooth muscle cells in the corpora cavernosa (CSMCs). They result from the interaction of various inter and intracellular molecular signaling pathways. During the more usual state of flaccidity seems to predominate a tonic sympathetic activity, releasing noradrenaline (NA) and other agonists that generate contractile signals in the CSMCs, with the likely cooperation of endothelium-derived messengers. Through activation of membrane receptors in the CSMCs they raise the intracellular messengers inositol triphosphate (IP3) and diacylglycerol (DAG). This results in a transient increase in cytosolic calcium concentration [Ca2+]i that starts the contractile response which is further sustained by the parallel agonist-induced activation of a "calcium sensitizing" mechanism involving the RhoA/Rho-kinase pathway. Overexpression of the latter might contribute to several vascular disorders as hypertension, vasospasm or erectile dysfunction. On sexual stimulation the cavernous nerves release nitric oxide (NO) that starts the erectile response. They also release acetylcholine that stimulates the endothelium to generate a more sustained release of NO. NO diffuses into CSMCs and increases their intracellular levels of cyclic guanosin monophosphate (cGMP) which decreases [Ca2+]i and deactivates the calcium sensitizing mechanism, thus relaxing CSMCs. This main physiological pathway for CSMCs relaxation is helped by the cyclic adenosin monophosphate (cAMP) pathway activated by various intercellular messengers from neural or paracrine sources, including prostaglandins E (PGE). Different phosphodiesterase enzymes (PDEs) inactivate the cyclic nucleotides thereby limiting their erectogenic action. Indeed the pharmacological inhibition of PDEs, especially the cGMP-specific PDE5, greatly enhances the erectile responses. There are crosstalk mechanisms between the cGMP and cAMP signaling pathways that offer additional possibilities for the pharmacotherapy of erectile dysfunction.

Introduction: Erectile dysfunction (ED) represents a common quality-of-life issue of any treatment used for prostate cancer, including high-intensity focused ultrasound (HIFU) and targeted cryoablation of the prostate (TCAP). There is a paucity of comparative studies regarding the difference in the erectile function and penile size of patients undergoing HIFU or TCAP., Aim: The aim of this study is to compare the erectile function and penile size of patients undergoing HIFU or TCAP., Methods: Patients with a preoperative erectile function domain of the International Index of Erectile Function (IIEF-EF) score ≥ 26 were prospectively included. All patients were preoperatively evaluated by IIEF-EF and penile color Doppler ultrasound. Penile length and circumference were measured in flaccidity and at maximum erection. At 6, 12, 18, 24, 36 months after surgery, patients were assessed with the same protocol., Main Outcome Measures: IIEF-EF score, penile color Doppler ultrasound, penile length, and circumference at different time points., Results: There were 55 patients in the HIFU group and 47 in the TCAP group. At each time point, there were significant differences in mean IIEF-EF scores and penile color Doppler results between the two groups. At 36 months, TCAP patients experienced lower erectile function recovery rate compared with HIFU patients (TCAP=46.8%; HIFU=65.5%; P=0.021). No significant decreases in penile length and circumference were found in the two groups (all P values ≥ 0.05)., Conclusions: Our data demonstrate TCAP caused significantly decreased erectile function than HIFU. We found no change in penile size after HIFU or TCAP. The option of HIFU may be more attractive to the patient who wants to avoid ED afterward, to maintain their quality of life., (© 2010 International Society for Sexual Medicine.)

Introduction: The aim of this prospective study was to evaluate the usefulness of measurement of axial penile rigidity, compared with radial penile rigidity., Patients and Methods: Twenty-two patients, aged 21-75 years old (a mean of 50), with erectile dysfunction underwent axial penile rigidity measurements by the digital inflection rigidometer (DIR) as well as radial penile rigidity measurements by the RigiScan Plus during intracavernous pharmacological erection testing., Results: A significant correlation was recognized between axial rigidity, and radial rigidity at the tip (p = 0.0024) and base (p = 0.0098) of the penis. In 10 patients, the DIR revealed axial rigidity of 550 g or more, and they also had radial rigidity of 60% or more at the tip and base. In 14 and 17 subjects, radial rigidity of 60% or more was observed at the tip and base, respectively. Four of the former 14 and 7 of the latter 17 had axial rigidity <550 g., Conclusions: A RigiScan results of radial rigidity of 60% or more should be interpreted cautiously and not necessarily regarded as normal., (Copyright (c) 2010 S. Karger AG, Basel.)

In many cultures, the erect penis has been a symbol of masculine qualities. Because of this symbolism, a penis that is less than average size can cause insecurity or embarrassment. This series reports the authors' 18-year experience in the management of 60 men with a complaint of a small penis. For 44 of these 60 men, counseling was sufficient; the other 16 had surgery, and of these, 9 were satisfied with the result. Despite limitations, the authors conclude that those men who already achieve a penis length of no less than 7.5 cm (2.95 in) in erection, have only limited benefit from penis-enhancing surgery. This particular patient category should therefore be dissuaded from surgery.

Objective: To assess a commonly marketed brand of penile extender, the Andro-Penis(R) (Andromedical, Madrid, Spain), widely used devices which aim to increase penile size, in a phase II single-arm study powered to detect significant changes in penile size, as despite their widespread use, there is little scientific evidence to support their potential clinical utility in the treatment of patients with inadequate penile dimensions., Patients and Methods: Fifteen patients were required to test the efficacy of the device, assuming an effect size of >0.8. Eligible patients were counselled how to use the penile extender for at least 4 h/day for 6 months. Penile dimensions were measured at baseline and after 1, 3, 6 and 12 months (end of study). The erectile function (EF) domain of the International Index of EF was administered at baseline and at the end of the study. Treatment satisfaction was assessed using an institutional unvalidated five-item questionnaire., Results: After 6 months the mean gain in length was significant, meeting the goals of the effect size, at 2.3 and 1.7 cm for the flaccid and stretched penis, respectively. No significant changes in penile girth were detected. The EF domain scores improved significantly at the end of study. Treatment satisfaction scores were consistent with acceptable to good improvement in all items, except for penile girth, where the score was either 'no change' or 'mild improvement'., Conclusions: Penile extenders should be regarded as a minimally invasive and effective treatment option to elongate the penile shaft in patients seeking treatment for a short penis.

Introduction: Pilot experiences have suggested that tension forces exerted by a penile extender may reduce penile curvature as a result of Peyronie's disease., Aim: To test this hypothesis in a Phase II study using a commonly marketed brand of penile extender., Methods: Peyronie's disease patients with a curvature not exceeding 50 degrees with mild or no erectile dysfunction (ED) were eligible. Fifteen patients were required to test the efficacy of the device assuming an effect size of >0.8, consistent with an "important" reduction in penile curvature. Changes in penile length over baseline and erectile function (EF) domain scores of the International Index of Erectile Function (IIEF) constituted secondary end points., Main Outcome Measures: Patients were counselled on the use of the penile extender for at least 5 hours per day for 6 months. Photographic pictures of the erect penis and measurements were carried out at baseline, at 1, 3, 6, and 12 months (end of study). The IIEF-EF domain scores were administered at baseline and at the end of study. Treatment satisfaction was assessed at end of study using a nonvalidated institutional 5-item questionnaire., Results: Penile curvature decreased from an average of 31 degrees to 27 degrees at 6 months without reaching the effect size (P = 0.056). Mean stretched and flaccid penile length increased by 1.3 and 0.83 cm, respectively at 6 months. Results were maintained at 12 months. Overall treatment results were subjectively scored as acceptable in spite of curvature improvements, which varied from "no change" to "mild improvement.", Conclusions: In our study, the use of a penile extender device provided only minimal improvements in penile curvature but a reasonable level of patient satisfaction, probably attributable to increased penile length. The selection of patients with a stabilized disease, a penile curvature not exceeding 50 degrees, and no severe ED may have led to outcomes underestimating the potential efficacy of the treatment.

Priapism, abnormally prolonged penile erection in the absence of sexual excitation, is associated with ischemia-mediated erectile tissue damage and subsequent erectile dysfunction. It is common among males with sickle cell disease (SCD), and SCD transgenic mice are an accepted model of the disorder. Current strategies to manage priapism suffer from a poor fundamental understanding of the molecular mechanisms underlying the disorder. Here we report that mice lacking adenosine deaminase (ADA), an enzyme necessary for the breakdown of adenosine, displayed unexpected priapic activity. ADA enzyme therapy successfully corrected the priapic activity both in vivo and in vitro, suggesting that it was dependent on elevated adenosine levels. Further genetic and pharmacologic evidence demonstrated that A2B adenosine receptor-mediated (A2BR-mediated) cAMP and cGMP induction was required for elevated adenosine-induced prolonged penile erection. Finally, priapic activity in SCD transgenic mice was also caused by elevated adenosine levels and A2BR activation. Thus, we have shown that excessive adenosine accumulation in the penis contributes to priapism through increased A2BR signaling in both Ada -/- and SCD transgenic mice. These findings provide insight regarding the molecular basis of priapism and suggest that strategies to either reduce adenosine or block A2BR activation may prove beneficial in the treatment of this disorder.

Penile erection involves a complex interaction between the central nervous system and local factors. It is a neurovascular event modulated by psychological and hormonal factors. The discovery of nitric oxide (NO) as an intercellular messenger or neurotransmitter paved the way for identifying important mechanisms underlying physiological and pathophysiological events in the penis, in addition to providing the knowledge for the development of new therapeutics based on a novel concept of molecule and cell interaction. Despite the fact that sinusoidal endothelial cells also produce and release NO in response to chemical and possibly physical stimuli, roles of neurogenic NO in penile erection appear to be more attractive and convincing, since the pharmacological neuromodulation represents an essential step to attaining penile erection. Erectile dysfunction (ED) is caused by a variety of pathogenic factors, particularly impaired formation and action of NO. Hence, a thorough knowledge of the physiology of erection is essential for future pharmacological innovations in the field of male ED, particularly targeting NO or intracellular cyclic GMP, which represent the most promising therapeutic approach to treat patients with ED.

The male is often troubled by concerns that his penis is not large enough to satisfy his partner or himself. He is ashamed to have others view his penis, especially in the flaccid state. Such concerns might be unfounded in reality and might be a presentation of social anxiety or some other clinical problem, such as erectile dysfunction. Concern over the size of the penis, when such concern becomes excessive, might present as the 'small penis syndrome', an obsessive rumination with compulsive checking rituals, body dysmorphic disorder, or as part of a psychosis. However, it is often a worry that can be described as within the normal experience of many men. Various potential causal factors are considered. A thorough assessment, normalizing the worry and then exploring the treatment options in detail with the man, is essential to allow the matter to be consolidated satisfactorily within the male ego.

The objective of this study was to identify the cerebral correlates of the early phase, and of low to moderate levels, of penile tumescence using for the first time a volumetric measure of the penile response. We hypothesized that (i) regions whose response had been found correlated with circumferential penile responses in previous studies would be identified with volumetric plethysmography and (ii) that other brain regions, including the amygdalae, would be found using the more sensitive volumetric measurement. In ten healthy males, functional magnetic resonance imaging (fMRI) was used to study brain responses to sexually stimulating photographs and to various categories of control photographs. Both ratings of perceived erection and penile plethysmography demonstrated an erectile response to the presentation of sexually stimulating photographs. Regions where the BOLD signal was correlated with penile volumetric responses included the right medial prefrontal cortex, the right and left orbitofrontal cortices, the insulae, the paracentral lobules, the right ventral lateral thalamic nucleus, the right anterior cingulate cortex and regions involved in motor imagery and motor preparation (supplementary motor areas, left ventral premotor area). This study suggests that the development of low levels of penile tumescence in response to static sexual stimuli is controlled by a network of frontal, parietal, insular and cingulate cortical areas and that penile tumescence reciprocally induces activation in somatosensory regions of the brain.