The human clitoris is a scientific iceberg, both physically and figuratively.
The clitoris is often said to house 8,000 nerve endings – 'double' that of the penis – but new findings, presented at a scientific meeting in October, suggest that's a serious underestimation of both sex organs.
The study is not yet peer-reviewed, but at least the results are on track to be properly scrutinized.
The numbers most often cited for the innervation of the glans penis and glans clitoris derive from old studies on – wait for it – cows; the results were simply co-opted for human anatomy.
And so those numbers have persisted for decades. Blair Peters, a plastic surgeon at Oregon Health and Science University's School of Medicine, thinks it's about time scientists found the correct number.
Peters specializes in gender-affirming care, and his work depends on a deep understanding of human sex organs. To conduct further research, Peters obtained clitoral nerve tissue from seven transmasculine volunteers undergoing gender-affirming genital surgery in his practice.
Under a microscope, Peters and his colleagues counted an average of 5,140 nerve fibers in the dorsal clitoral nerve, and the clitoris has two of these.
Taking into account the full range of samples studied, the total number of nerve endings innervating the entire wishbone-shaped organ ranges from 9,852 to 11,086 fibers.
Peters's study is the first to report the number of nerve fibers in the human dorsal clitoral nerve and approximate the number of nerve fibers innervating the human clitoris.
"It's startling to think about more than 10,000 nerve fibers being concentrated in something as small as clitoris," says Peters. "It's particularly surprising when you compare the clitoris to other, larger structures of the human body. "
The median nerve, which runs through the hand, is known for having high nerve fiber density, explains Peters. It has about 18,000 nerve fibers, but it's also a whole lot bigger than a roughly 10-centimeter-long (4 inches) pleasure organ.
So how's that innervation compare to the head of a male penis? Peters plans on finding out.
While it's often said that the clitoris is twice as sensitive as a penis, there's more nuance to the numbers than that. Both sex organs have the same embryological origin, which means they probably contain roughly similar numbers of total nerve endings.
What is most likely different is how densely concentrated these nerve endings are in certain spots.
Initial studies suggest, for instance, that the tip of the clitoris has greater variability in nerve density than the glans of the penis. In simple terms, that probably means some parts of the clitoris are extra sensitive.
Peters hopes that a better understanding of how sex organs are innervated can ultimately help surgeons with successful reconstructions of the clitoris and penis, not only for gender-affirming purposes but also for repairing instances of genital mutilation.
"There's something profound about the fact that gender-affirming care becoming more commonplace also benefits other areas of health care," Peters says.
"A rising tide lifts all boats. Oppressing or limiting transgender health care will harm everyone."
Peters presented the findings at a joint scientific meeting of the Sexual Medicine Society of North America and the International Society for Sexual Medicine.