A Complex System of Anatomy, Neural Pathways, and Psychological Processes
Curator’s Note: The recent study in Sexual Medicine explores the complexities of anal sex practices and the biological underpinnings of pleasure for women and men. Authored by a team of sexual health scientists, it challenges the notion of the rectum as a uniform organ by identifying distinct regions associated with sensations and pleasure. Findings reveal that sexual arousal involves a network of anatomical and psychological factors, not just localized stimulation. The variability in orgasmic responses between genders highlights sociocultural influences and individual experiences. Ultimately, the study advocates for a nuanced understanding of human sexuality, emphasizing the interplay of anatomy, neurophysiology, psychology, and personal variation in sexual pleasure. This sexual health story was written by Dr Michael Broadly a retired health scientist and public health consultant for educational purposes.
Dear Subscribers,
As a retired health scientist and public health professional, I have learned that the most misunderstood aspects of human biology are the ones we discuss the least. Therefore, I decided to create an educational series by reviewing scholarly literature to provide evidence-based content for my readers.
Sexuality, particularly less openly discussed aspects of our misunderstanding as a taboo topic in some cultures, has long suffered from a curious paradox: it is widely practiced, yet poorly understood in scientific and public discourse.
In this post, I will share some insights from a recent peer-reviewed study published in Sexual Medicine, which offers a rare and thoughtful exploration of this domain.
The paper is titled “Anal sex practices and rectal erogenous zone maps among men and women of diverse sexual orientations: an anatomic-map based questionnaire study.
This scholarly paper, citing 38 outstanding scientific and review studies, was authored by sexual health scientists and practitioners, including Michael Zaliznyak, Alexander B. Walton, Jenna Stelmar, Dylan Isaacson, Thomas W. Gaither, Gail Knudson, and Maurice M. Garcia.
Rather than focusing on pathology or risk, as much of the historical literature has done, it examines something far more human: pleasure, variation, and the biological underpinnings of experience.
What emerges in this study is not a simple story, but a layered one, which I will explain and simplify for you under multiple sections.
The Rectum Is Not a Passive Structure
One of the most important contributions of this research is its challenge to a long-standing implicit assumption that the rectum is a relatively uniform organ in terms of sensation.
Using anatomical mapping, researchers divided the rectum into four regions and asked participants to identify where they experienced pleasure. What they found was remarkably consistent across genders: the superficial anterior region was most frequently associated with pleasurable sensation.
This finding is not arbitrary. Anatomically, this region lies adjacent to key structures involved in sexual function. In individuals with a prostate, it corresponds closely with the position of this gland, which has long been implicated in sexual pleasure. In individuals with a clitoris, internal extension (referred to as the crura) extends toward this same anterior space.
Additionally, the pudendal nerve, a major conduit of sexual sensation, travels along this region. Its branches innervate the external genitalia, perineum, and anal sphincter, contributing to the integration of sensory signals that can culminate in arousal and orgasm.
In simple terms, the body is not improvising; it is following well-established neuroanatomical pathways.
Pleasure Is Multisource, Not Localised
The study reinforces a concept well known in sexual medicine but often overlooked in public narratives: sexual pleasure does not arise from a single anatomical point.
Participants reported that sensation during receptive anal stimulation may derive from several mechanisms, including:
- Direct stimulation of adjacent organs (such as the prostate)
- Stretching of the anal sphincters and pelvic floor muscles
- Distension of the rectal walls
- Neural signaling through shared pathways, such as the pudendal nerve
This finding aligns with broader physiological understanding. The pelvic region is a highly integrated system in which organs, muscles, and nerves overlap both structurally and functionally.
Such integration explains why stimulation in one area can produce sensations perceived elsewhere, a phenomenon sometimes described as “referred pleasure,” analogous to referred pain in clinical medicine.
Orgasm: A Combined Physiological and Psychological Event
For me, an important insight from the study is that orgasm cannot be reduced to anatomy alone. While a proportion of participants reported the ability to achieve orgasm from anal stimulation alone, this was far from universal.
Men were significantly more likely than women to report this outcome, with approximately 39% of men versus 19% of women indicating orgasm from anal stimulation alone. However, the more telling statistic is elsewhere.
Approximately half of both men and women reported requiring co-stimulation, that is, simultaneous stimulation of other erogenous areas to achieve orgasm.
This finding reflects decades of research in sexual physiology: orgasm is not a purely local reflex, but a network event involving:
- Peripheral nerve activation
- Spinal cord integration
- Brain processing, including emotional and cognitive centers
Psychological factors such as comfort, familiarity, expectation, and emotional context play a critical role. The study itself acknowledges that self-esteem, desire, and prior experience may significantly shape outcomes.
In clinical terms, this reinforces a simple but overlooked truth: the brain is not just involved in sexual function. It is central to it.
Why Differences Between Individuals Are Expected
One of the more interesting findings of the study is the variability in reported experiences.
A substantial proportion of women reported never achieving orgasm from anal stimulation, even with additional stimulation. Men, by contrast, reported higher success rates.
This difference may, in part, be explained by anatomy, particularly the presence of the prostate and its associated neurovascular structures. However, the authors also highlight broader explanations, including sociocultural influences and differences in sexual conditioning and expectations.
Importantly, this variability should not be interpreted as dysfunction. In medicine, variability is the rule rather than the exception. Just as individuals differ in pain thresholds, metabolism, or response to medication, so too do they differ in sexual response.
The danger is not in the variation itself, but in the assumption that there is a single “correct” pattern.
A Comparative Anatomical Perspective on Receptive Structures
From a physiological standpoint, some individuals, particularly those with experience across different forms of sexual practice, may observe certain parallels between vaginal and rectal stimulation.
While these structures differ fundamentally in biological function, selected similarities in their anatomical and neurophysiological characteristics can help explain overlapping sensory experiences.
Both the vagina and the rectum are embedded within the pelvic floor, a complex network of muscles, connective tissues, and nerves that play a central role in continence, support, and sexual function.
Surrounding these structures are muscular components capable of contraction and relaxation, including the vaginal walls and the internal and external anal sphincters. These muscles contribute to variations in pressure, tone, and tactile sensation during stimulation.
Another point of convergence is in their proximity to highly sensitive erogenous regions. The anterior wall of the rectum is anatomically adjacent to the prostate in males, a gland well documented to be involved in sexual response.
In females, the vaginal canal is in close relation to internal clitoral structures and the anterior vaginal wall, areas frequently associated with heightened sensitivity. Both regions are functionally linked through shared neural pathways, particularly branches of the pudendal nerve, which transmits sensory information from the perineum and external genitalia.
In addition, both structures are associated with rich sensory innervation, although the nature and distribution of nerve endings differ. The rectum contains visceral and somatic sensory pathways capable of detecting pressure, stretch, and, in some individuals, pleasurable stimuli. The vagina similarly responds to mechanical stimulation, with sensitivity influenced by hormonal, vascular, and neurological factors.
An important physiological distinction, however, relates to lubrication. Vaginal tissue naturally lubricates in response to arousal, mediated by vascular and glandular mechanisms. The rectum lacks this mechanism, so external lubrication plays a critical role in reducing friction and maintaining tissue integrity.
Both regions are also situated near the perineum, an anatomically dense area of sensory and motor innervation. Stimulation of this region can facilitate the integration of sensory signals across the pelvic floor, further underscoring the interconnected nature of sexual response.
I’d like to emphasize that, despite these areas of overlap, the rectum and vagina are structurally and functionally distinct. The rectum is not specialized for sexual function and may be more susceptible to mechanical stress or injury if not approached with appropriate care.
From a clinical and educational perspective, recognizing both the similarities and the differences allows for a more balanced and informed understanding of human sexual physiology.
Ultimately, these observations reinforce a broader principle: sexual sensation is not confined to isolated organs, but emerges from a coordinated system involving muscles, nerves, adjacent structures, and the central nervous system, including the brain and mind.
Clinical and Health Implications
While the topic may seem purely experiential, the implications extend into clinical practice. The rectum and surrounding structures are frequently affected by medical conditions and interventions, including:
- Inflammatory bowel diseases
- Infections
- Pelvic or colorectal surgery
- Radiation therapy
These conditions can alter anatomy, nerve function, and tissue sensitivity. The study suggests that understanding the rectum as a region with distinct functional zones rather than a uniform organ may help clinicians better anticipate and explain changes in sensation following treatment.
This perspective represents a shift from a purely disease-focused model toward a more holistic understanding of patient experience, including quality of life.
A More Mature Understanding of Human Sexuality
What this research ultimately offers is not a sensational conclusion, but a mature one. A single structure, pathway, or outcome does not govern human sexual response. An interplay of anatomy, neurophysiology, psychology, and experience manifests it.
The rectum, like many parts of the body, participates in this system in ways that are both biologically grounded and individually variable.
For some, it may contribute significantly to sexual pleasure. For others, it may play little or no role. Both outcomes are consistent with the underlying science.
As scientists, clinicians, educators, and individuals, we value not prescribing a uniform experience but understanding the diversity of human physiology. In doing so, we replace myth with knowledge and, more importantly, uncertainty with clarity.
Selected Scholarly References
Levin, R. J. (2018). Prostate-induced orgasms: A concise review illustrated with a highly relevant case study. Clinical Anatomy, 31(1), 81–85. https://doi.org/10.1002/ca.23006
Gaither, T. W., Vincent, N. W., Piqueiras, E., et al. (2023). Atlas of the receptive anal sex experience among people with prostates. The Journal of Sexual Medicine, 20(2), 126–138. https://doi.org/10.1093/jsxmed/qdac024
Stelmar, J., Zaliznyak, M., Sandhu, S., et al. (2025). Anatomic maps of erogenous and aversive sensation zones of the breasts, vulva, and vagina: A questionnaire-based study. The Journal of Sexual Medicine, 22(1), 7–13. https://doi.org/10.1093/jsxmed/qdae143
Mazloomdoost, D., & Pauls, R. N. (2015). A comprehensive review of the clitoris and its role in female sexual function. Sexual Medicine Reviews, 3(4), 245–263. https://doi.org/10.1002/smrj.61
O’Connell, H. E., Eizenberg, N., Rahman, M., & Cleeve, J. (2008). The anatomy of the distal vagina: Towards unity. The Journal of Sexual Medicine, 5(8), 1883–1891. https://doi.org/10.1111/j.1743-6109.2008.00875.x
McBride, K. R., & Fortenberry, J. D. (2010). Heterosexual anal sexuality and anal sex behaviors: A review. The Journal of Sex Research, 47(2–3), 123–136. https://doi.org/10.1080/00224490903402538
Laan, E. T. M., Klein, V., Werner, M. A., van Lunsen, R. H. W., & Janssen, E. (2021). In pursuit of pleasure: A biopsychosocial perspective on sexual pleasure and gender. International Journal of Sexual Health, 33(4), 516–536. https://doi.org/10.1080/19317611.2021.1965689
Mah, K., & Binik, Y. M. (2005). Are orgasms in the mind or the body? Psychosocial versus physiological correlates of orgasmic pleasure and satisfaction. Journal of Sex & Marital Therapy, 31(3), 187–200. https://doi.org/10.1080/00926230590513401
Frederick, D. A., John, H. K. S., Garcia, J. R., & Lloyd, E. A. (2018). Differences in orgasm frequency among gay, lesbian, bisexual, and heterosexual men and women in a U.S. national sample. Archives of Sexual Behavior, 47(1), 273–288. https://doi.org/10.1007/s10508-017-0939-z
Dickstein, D. R., Edwards, C. R., Rowan, C. R., et al. (2024). Pleasurable and problematic receptive anal intercourse and diseases of the colon, rectum and anus. Nature Reviews Gastroenterology & Hepatology, 21(6), 377–405. https://doi.org/10.1038/s41575-024-00932-1
About the Author
I’m a retired healthcare scientist in my late-70s. I have several grandkids who keep me going and inspire me to write on this platform. I am also the chief editor of the Health and Science publication on Medium.com. As a giveback activity, I volunteered as an editor and content curator for Illumination publications, supporting many new writers. I will be happy to read, publish, and promote your stories. You may connect with me on LinkedIn, Twitter, and Facebook, where I share stories I read. You may subscribe to my account to get my stories in your inbox when I post. You can also find my distilled content on Substack: Health Science Research by Dr Mike Broadly.
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