The nerve that allows the human clitoris to detect pleasurable touch contains thousands more nerve fibers than once estimated – about 10,000, up from 8,000. Medical researchers discovered this by doing some something that had never been done before: they actually counted the fibres.
Previously, it was widely believed that the clitoris contained around 8,000 nerve fibers, but the origins of this number are unclear, study lead author Dr Blair Peters (opens in a new tab)assistant professor of surgery at Oregon Health and Science University (OHSU) School of Medicine, Live Science told Live Science.
“The number 8,000, that wasn’t even a real scientific paper,” he said. The number comes from a line in a book called “The Clitoris” (opens in a new tab) (Warren H. Green, Inc., 1976) by physician Dr. Thomas P. Lowry and his then-wife Thea Snyder Lowry, in which the authors briefly mention a study of cow clitoris and extend its findings to humans.
“It was not based on human data”, Dr Rachel Rubin (opens in a new tab), an assistant clinical professor of urology at Georgetown University and a urologist and sexual medicine specialist in a DC-area private practice, told Live Science. The cow-derived statistic has been quoted many times unverified – until now.
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In their research, Peters and their colleagues looked at the two dorsal clitoral nerves, which are dense bundles of nerve fibers that relay sensory signals from the clitoris to the brain. These nerves run down either side of the clitoral shaft and transmit information about touch, pressure, and pain, while other nerves manage functions such as muscle tone and blood flow.
The dorsal nerves sampled contained between 4,926 and 5,543 nerve fibers each, an average of 5,140 fibers. With two dorsal nerves per clitoris, this translates to approximately 10,280 nerve fibers that allow sensation in the pleasure-producing organ. These results, which have not yet been peer-reviewed, were presented on October 27 at a joint scientific meeting (opens in a new tab) of the Sexual Medicine Society of North America and the International Society for Sexual Medicine.
What’s remarkable, Peters said, is that those 10,000 fibers all branch into the clitoral glans, the visible part of the clitoris located where the labia minora (inner lips) of the vulva meet. By comparison, the median nerve, which runs through the wrist and provides sensation to most of the hand, contains 18,000 nerve fibers. When you compare the surface area of the clitoral glans to that of the hand, “10,000 versus 18,000 becomes surprisingly high,” he said.
Peters pursued this research, in part, to inform his work as a plastic and reconstructive surgeon specializing in gender-affirming surgeries, including gender-affirming phalloplasty, or the surgical construction of a penis from other body tissues.
To create a penis capable of erogenous sensations, surgeons remove tissue from a nerve-rich area of the body, usually the forearm or thigh, according to the OHSU Transgender Health Program (opens in a new tab). Once the phallus is made, these nerves are then connected to the nerves in the pelvis and ideally the nerves grow together and begin to transmit sensory signals to the brain.
“I wanted to take a closer look, basically, at the nerves that we connect when we make a penis,” Peters told Live Science.
Generally speaking, research into the basic anatomy of the vulva, which includes the clitoris, could also aid in the diagnosis and treatment of nerve damage and help surgeons navigate procedures near the genitals without causing damage by inadvertently.
The new research was made possible by seven transmale patients who underwent phalloplasties and volunteered to donate samples of their clitoral tissue. These donated tissues were then stored, stained blue and magnified 1,000 times under a microscope so that image analysis software could count individual nerve fibers.
All patients had testosterone treatment before phalloplasty. There is some evidence that testosterone can stimulate nerve regeneration in the context of injury, but in normal, healthy nerves, the hormone shouldn’t change the number of fibers present, Peters said. “However, this study did not have controls without testosterone exposure,” they said, so it would be worth repeating the study with tissue samples from cisgender women who had never had testosterone. Such samples would likely come from corpses, rather than people undergoing surgery.
The new research highlights how little is known about the anatomy and function of the clitoris, Rubin said. This reflects historical biases in medical research that have left modern physicians with huge knowledge gaps.
“It’s likely that no doctor has ever examined your clitoris or asked about orgasm in a medical setting,” she said. “And it’s not because it’s not worth it.”