New research from OHSU looked at human tissue to try to understand how many nerve fibers are contained in the clitoris. It seems to be the first time that this has ever been studied (a previous estimate was made using bovine tissue). The study found over 10,000 nerve fibers, which is 25% more than previously thought. Dr. Blair Peters is the author of the study and an assistant professor of plastic surgery and urology at OHSU. Peters joins us to talk about why more research on the clitoris, and the vulva in general, would help surgeons and scientists to understand that region of the body and how it relates to pleasure.
Editor’s note: This post was corrected to reflect that number of clitoral nerves identified is 25% more than previously thought.
This transcript was created by a computer and edited by a volunteer.
Dave Miller: This is Think Out Loud on OPB. I’m Dave Miller. We start today with new research out of OHSU. Scientists there studied tissue samples to learn how many nerve fibers are contained in a human clitoris. It seems to be the first time this has ever been studied in humans. The scientists found over 10,000 nerve fibers. That’s 20% more than previously thought. Blair Peters is the lead author of the study. He is a plastic and reconstructive surgeon at OHSU. He joins us to talk about both this study and the broader surgical issues that it connects to. Blair Peters, welcome.
Blair Peters: Hello! Thanks for having me. I’m happy to be here.
Miller: Thanks for joining us. Why did you and this team set out to do this study?
Dr. Peters: That’s an interesting evolution. I myself am a gender-affirming surgeon. So I perform a lot of genital surgery for trans and gender diverse individuals, and I initially started looking into the innervation of the clitoris in the context of a procedure called phalloplasty, or the creation of a penis. And the reason I did that is that we often will take one of the nerves that supplies the clitoris and then we take that and we put it into the penis to provide for erogenous or sexual sensation.
It’s a rare opportunity in that surgery to actually have access to clitoral nerve tissue, and I work very closely with colleagues in Urology and Gynecology who specialize in more comprehensive sexual health and sexual medicine. Through our kind of conversations, enjoying advocacy efforts for more marginalized groups, we realized that we have an opportunity here to actually, for the first time, quantify the innervation of the human clitoris, which has much broader implications just beyond the work that I’m specifically doing with the trans-community.
Miller: And we’re going to get into those implications as we go. What was the previous understanding of the number of nerve fibers?
Dr. Peters: There’s this book from the 1970s that just has one line in it, saying that the clitoris has 8,000 nerve fibers or nerve endings, and that line got repeated so many times and so often, kind of in the mainstream media, that it just became accepted as fact. But if you actually go back and look at the origins of this, it was never really a formally published study and it was actually done on cows. The interesting thing about that is the statement ‘the Clitoris has 8,000 nerve fibers’ has really become almost a focal point, or a rallying point for advocates for more research, attention and education about the clitoris, and really speaking to its sort of historical erasure. And I think there’s something really ironic or something to be said about the fact that even that rallying cry, and really that statement itself, is based off of misinformation and was never actually studied.
Miller: Can you put this new number, 10,000 nerves, in perspective – how does that compare to other parts of the human body?
Dr. Peters: That’s a great question. So you hear 10,000? What does that actually mean? Those 10,000 nerve fibers are just innervating the glans of the clitoris, which is sort of the visible external aspect, maybe the size of a marble or so, for context. Most people have probably heard of carpal tunnel syndrome, in the hand. The nerve that causes carpal tunnel syndrome is called the median nerve, and that nerve has 18,000 nerve fibers. But that nerve is responsible for innervating the majority of the human hand.
If you compare the size of the glans of the clitoris, a marble size, to the size of a human hand - 10,000 nerve fibers innervating a marble versus 18,000 nerve fibers innervating a hand - it’s pretty extreme in terms of its density of innervation. So it really speaks to just how densely innervated the organ is, and really sort of speaks to its sort of critical, central role in sexual pleasure.
Miller: Are all sensory nerves the same or endings the same? So can we compare the nerves innervating a hand or a clitoris and say, numerically, that if something pretty small has 10,000 and something much larger has 18,000, that it really is a clear comparison?
Dr. Peters: I don’t know if y’all, at some point in high school, remember that cartoon image of a brain and then superimposed on the surface of the brain is all the human body parts. And you sort of see how much of the brain is, you know, taken out by each sort of represented part of the body, and the hand is a huge portion of it, as is the tongue for sort of taste and as is the genitals for sort of erogenous or sexual sensation. So the number of nerve fibers is super important, and it’s something that we actually use in peripheral nerve surgery for example.
If someone has a nerve injury or you’re trying to restore function to a lost area, you’re often trying to connect nerves that have similar nerve counts to make sure you have enough nerve fibers, to sort of power or give the function you want. So it does have direct relevance to surgical decision making.
Miller: What do you know, as a surgeon, and somebody who has obviously had to study a lot of anatomy, about the full shape of this organ and how it extends into and connects to the rest of the pelvic region?
Dr. Peters: It’s really interesting. The full anatomy of the clitoris wasn’t actually delineated until the early 2000s. I believe the year was 2005, by an Australian neurologist, which if you kind of think about that, that’s not really that long ago, if you compare our understanding of penile anatomy, for example. But the visible part of the clitoris, like I mentioned earlier, is just the glans or sort of that marble-sized structure that’s at the upper portion of the vulva. But it actually extends beneath the skin on either side and its ultimate shape is more like a wishbone. So the whole structure is actually a lot larger than we ever appreciated, and there’s a lot of interesting sort of context as to why did it take until 2005 to even really have proper anatomy of what is a vital organ to 51% of the population?
Miller: Well, let’s turn to that now. How much more, for example, were you taught in medical school about a penis compared to a clitoris?
Dr. Peters: I think to anyone listening, thinking back even to your high school, like sexual education, you probably remember many times that the word ‘penis’ was uttered. I’d be surprised if the word ‘clitoris’ ever even came up. And really, if we think about the sexual education that we kind of give people in society, it’s very much geared towards cisgender people and very much geared towards heterosexual people. Sex is really defined as penile penetration when we know it’s so much more than that. And that same sort of societal attitude still really shapes even mainstream and modern medical education. Formal teaching in medical schools about the clitoris is still very little.
I think it’s alarming when you sort of realize that vulvar surgery, or surgery around the clitoris, has been happening for many decades and there’s tons of surgical procedures that are intimately close to the anatomy of the clitoral nerves. Yet they’re coarse, and the really fine details of that anatomy have only really been well described in about the last 10 years. And as a surgeon that operates on those nerves maybe once a week or so, it wasn’t until I started doing genital surgery during my fellowship that I even learned that anatomy.
There’s lots of urologists, lots of gynecologists, lots of plastic surgeons that operate in that area all the time, and have never actually seen the clitoral nerves or even understand where they are. When you put that into context, well what does that mean for people? There’s a lot of people out there that have had damage to these nerves during surgery. Part of that really is a lack of education, which stems from just kind of neglect of female sexuality, and sexual health for people that have vulvar anatomy.
Miller: It seems like one of the inescapable pieces here is that the clitoris is intimately tied to pleasure, which is separate from questions of reproduction. How does this question of pleasure get talked about in medical settings?
Dr. Peters: It honestly doesn’t, a lot of the time. It’s surprising how many people in healthcare are still sort of reluctant to talk about sex in clinical spaces, like the whole medicine environment can often be very sterile. But we know sex is so critical to people’s quality of life. And I think a lot of us that are earlier in our academic careers are really trying to bring sex into medicine. We see you know, the Sexual Medicine Society of North America, and a lot of efforts to really make the point that sexual health is health and sexual medicine is medicine and we all need to be talking to our patients about that.
But it’s pretty shocking when you think about if you had to pick one specialty that you think would have a very intimate knowledge of the clitoris and clitoral conditions and vulvar health, you would think obstetrics and gynecology. But you kind of alluded to it already, that whole specialty is very reproduction focused; a lot of time, effort and energy focuses on conception and the uterus and the cervix, and the actual vulva and the clitoris itself gets very little attention.
I have a best friend who is a gynecologist and she specializes in sexual health. And she graduated a couple of years ago and had to actually go to a lot of meetings almost seek out her own private education to become competent and trained in sexual health for people with vulvas, despite doing an entire gynecology residency. And it really again speaks to how societal attitudes or perceptions shape what we pay attention to in medicine. We’re really at the beginning stages of really understanding a lot about female or trans masculine sexual pleasure.
Miller: As you just noted, this friend of yours, it’s not like she went to medical school 40 years ago. She recently graduated and this is still the status quo.
Dr. Peters: This is absolutely still the status quo. I think a good example is I was just at a sexual medicine meeting for the International Society of Sexual Medicine this past weekend, and if you just look at the lists of abstracts or the list of projects being presented, the vast majority have to deal with erectile dysfunction or something to do with a penis. And although it’s getting better, and there is now a category of abstracts or papers or projects that speak to female sexual dysfunction or sexual issues in the transgender, gender-diverse population, those talks are still in tiny rooms. All the talks about penises are in the main stage and the main auditorium. All of the industry dinners and all of the research dollars, it’s all very much put towards the penis, still, because that’s where the money is. So, even in the most inclusive specialty, ‘Sexual Health,’ that is really trying to center sex for all people, it is still so penis dominant.
Miller: Well, what was the response at this recent conference when you arrived saying, ‘Hey folks, it’s not 8,000, it’s 10,000?’
Dr. Peters: Yeah, it’s been really intense and really interesting. It’s been a good opportunity to do a lot of education and a lot of advocacy. I think people are really excited about it and I think it’s really challenged a lot of dogma and challenged people to just question things. There’s so many, even advocates for vulvar health, that themselves have used this 8,000 quote time and time again, and that’s been debunked. If that is something that we all accepted as fact, and that’s based off of misinformation, well, what else is based off of misinformation, what else do we not know, or are we thinking of completely wrong?
I think it sort of lays the foundation to really make the point that we need to normalize talking about female sexual pleasure and understand that all human beings have sex and deserve to feel good in their bodies, regardless of gender identity. And I think it really puts us on the track of having to start taking down all of this misinformation and relearning how we think about sexuality, so we can do the proper research and answer the right questions going forward.
Miller: I want to go back to broader questions about pelvic surgeries. Could you give us an example of the really serious complications, life altering complications, that could follow and might regularly follow, from some surgery, because of a lack of attention to clitoral anatomy?
Dr. Peters: I think first and foremost, these are inadvertent injuries. It’s something that unfortunately, when it happens - by no means, I don’t have any mal-intent - but there are a lot of surgical procedures that come close or right on top of the anatomy of these clitoral nerves. Some examples would be any surgery in the pubic region. So a lot of people after massive weight loss, if they get skin tightening procedures, or tummy tucks, that lower incision comes really close to that area. The most sort of pertinent in terms of what’s in the media right now is cosmetic labial surgery. You may have heard the term like labiaplasty, that is very frequently increasing. Again, the nerves at that level are just under the skin.
There’s certainly many people that are very active on social media or in advocacy spaces, talking about their experience with those procedures and having completely lost sexual sensation, which is devastating. Especially when you lose sexual sensation in a world where no one pays attention to the clitoris, and there’s very few treatment options or even places for you to seek help out there. And I don’t think we really even fully understand how many people are out there with these injuries and how many times it’s happened. And I think these are the questions and conversations we need to keep having.
Miller: Obviously, with any surgery, there’s a possibility of complications and unintended consequences and bad things happening. So, in some ways, we’re talking here about lowering the number of the frequency of those bad outcomes. What do you think it would take to make those bad outcomes less likely?
Dr. Peters: It takes education. I followed this work up with making a video abstract or basically a tutorial on ‘how did I suck out the clitoral nerves,’ because there’s not such a thing out there. And it’s something that comes down to, again, equitable representation for all people. Medicine treats everybody and everyone needs to be represented equally. And I think we have to shift our attitudes in order for everything to truly be equitable with how it’s represented.
Like you said, any surgery has a known complication rate. But the clitoris, specifically, is so neglected, and so not thought of, that for half of these procedures where it would be a real risk. It’s not even on the consent form because people aren’t even thinking about it, let alone talking about it. So I think we have to really back up and change the way that we’re even teaching sex and educating about anatomy in medical schools. The whole history of the clitoris is very interesting, because if you follow it through, and look at what was happening socially at the time, it’s not until the feminist era that the clitoris even started showing up in medical textbooks. And then as times got more oppressive it gets erased and deleted from medical images. So it’s become very taboo in a lot of ways to talk about pleasure for anyone other than the cis man in a sexual relationship.
Miller: What do you hope to study next?
Dr. Peters: A few things. Next, I’m actually planning to quantify in the same way, the number of nerve endings in the penis, because that is, again, something that hasn’t fully been done, and I think would be very interesting to be able to directly compare to the clitoris. Specifically in my orbit, I plan to use that information that I’ve gained about clitoral innervation to better identify ways to optimize sensation and erogenous experiences for my trans-masculine patients that are undergoing phalloplasty. It’s my next big step forward.
Miller: Blair Peters. Thanks very much for joining us.
Dr. Peters: Thank you for having me.
Miller: Blair Peters is a plastic and reconstructive surgeon at OHSU, and the lead author of this new study that, for the first time, has counted the number of nerve fibers in a human clitoris. It is about 10,000.
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