Tuesday, November 29, 2016

The Fabulous(?) Fornix

I recently got a request for information about the cervical fornix and the role it can play in having good sex. This reader wanted to know if it's true that some women get extreme pleasure from having the fornix stimulated, and wanted more information about its location and what was required to stimulate it.

There have been a rash of web posts in the last few years claiming nearly magical properties for this "spot," with some people claiming that simply having the head of the penis enter into the fornix causes an instant orgasm for the woman that is more intense than any other. With claims like that floating around, it seems like a good idea to take a serious look at the subject.


Let's start with some real anatomy, because there's a lot of bad pseudo-anatomy running around on the internet with respect to the fornix. This diagram from a med school anatomy course shows two views of the female internal genitals:

In the second view, the woman is facing to the left and she has a normal (forward-tilted) uterus.  (Compare this with the first view in the image below.)

Notice that the fornix is not a "spot." It is the entire ring-shaped depression that goes all the way around the base of the cervix. What we call the "anterior fornix" or "the A-spot" is just the front-most part of the fornix.  What we call the "posterior fornix" or "the P-spot" is just the rear-most part of the fornix.

Similarly, the lateral fornices (shown in the left hand drawing) are just the left and right quadrants of the fornix. In spite of the way they are usually drawn and talked about, the four "fornices" aren't separated from each other, they are just names for four arbitrary segments of a ring.

Is the uterus "tipped"?

Now look at the location of the cervix and the location and depth of the anterior and posterior fornices in these two images from the Mayo Clinic's website, showing the two most common positions for the uterus:

In this case, the woman is facing to the right in both images, so the posterior fornix (or P-spot) is on the left, toward the rectum, and the anterior fornix (or A-spot) is on the right, right next to the bladder.

As you can see, the uterus isn't just flipped toward the rear in the second image. It also connects to the vagina at a different point. That means that the cervix is in a different location – more at the far end of the vagina instead of being on the front wall – and it is oriented at a very different angle. As a result, the anterior and posterior fornices are very different in location, depth, and angle.

In particular, notice that in the "normal" position for the uterus, shown on the left, the anterior fornix is quite a bit shallower and closer to the vaginal opening than the posterior fornix.  But in the image on the right, both fornices are the same distance from the entrance, and the anterior fornix is actually somewhat deeper.  This can have a major effect on whether a penis "fits" into either fornix in a particular position.

Roughly half of all women have a uterus that is tilted forward and rests on the bladder. Around 30% have one that is tilted back, resting against the rectum. And the rest have a uterus that is in-between, so it's not leaning against either the bladder or the rectum. (If you have a uterus and you don't already know which way it tilts, your GYN can probably tell you.)

These aren't the only variations. Sometimes the uterus has a bend in the middle (called retroflex or anteflex, depending on which way it bends). This can increase or decrease how far the cervix is displaced toward the front or back wall of the vagina.

Finally, women who are not on hormonal birth control and are not post-menopausal will often notice that the cervix is lower for several days around the time of ovulation.  Sometimes this means an increased chance of painful cervix hits just on those days when your sex drive is greatest, which can be really annoying if your partner doesn't know how to adjust his position!

The position, shape, and orientation of the fornix

So there's quite a lot of variation in the position of the cervix and the angle at which it sticks into the vagina, whether it's on the front (anterior) wall of the vagina, or it's right at the end of the vagina, or it's somewhat on the back (posterior) wall. It can be more extremely forward or back than the above images show, or it can be anywhere in-between. And since the fornix is the space around the base of the cervix, variations in the location and angle of the cervix create large differences in the location and shape of the fornix as well.

Getting sexually aroused causes the uterus to lift up a bit into the lower abdomen, helping to lengthen and straighten out the vagina. The vagina also "tents," or gets larger at the inner end.

Both of these changes open up and alter the shape of the fornices a lot, but they don't change the relative position of the cervix very much. Tenting creates a fairly large potential space all around the cervix - including the space we call the fornix - and the width, depth, and shape of the fornix in an aroused woman's vagina will vary all the way around the cervix. Furthermore, its shape at any particular point varies a lot from woman to woman.

Genital "fit" in different positions

Then there's the question of penis width, length, and curvature. A shorter penis may be able to reach the anterior fornix but not the the posterior fornix, particularly if a woman has a longer vagina and a uterus that is tilted forward. If a woman has a shorter vagina, on the other hand, a longer penis can easily get trapped in the anterior fornix and poke painfully into the cervix if it is driven to full depth, and yet feel good if angled past the cervix into the posterior fornix.

Similarly, a penis with a large head (glans) may be too large to fit into the anterior fornix and hit the cervix instead. And a curved penis that is just the right length for a particular woman may fit snugly into one part of her fornix in one specific position and still miss her entire fornix in all other positions.

As this indicates, positions matter a lot. For most couples in most rear-entry positions, for example, the head of the penis presses against the front wall of the vagina and strokes across the g-spot into the anterior fornix. This is one reason why many women like doggie, and especially like pronebone, where the penis enters the vagina at a steep angle to the vaginal axis.

On the other hand, most couples find that it takes an extreme angle in a rear-entry position for the penis to reach past the cervix and connect with the posterior fornix. The woman can stand and rest her hands on the floor or a piece of furniture so that she is bent completely over, with her chest against her thighs. Or, if she is comparatively tall and flexible, she can drop her chest to the bed in doggie and raise her butt as high as possible to duplicate the same pelvic angle. Even in these cases, though, the man must enter low and angle his penis upward for it to work for most women. (An upwardly-curved penis helps.)

In missionary, the penis is normally aligned more or less with the main axis of the vagina, not pressing one part of the vaginal wall more than any other. However, if the woman's butt is raised – e.g., if she grasps her knees and pulls them toward her shoulders, lifting her hips off the bed – the penis can be angled toward the front wall, sliding across the g-spot and aiming toward the anterior fornix.

Conversely, the woman can extend her legs flat on the bed and the man can slide forward along the woman's body in a "pelvic override" or "coital alignment" position, forcing his penis to aim more vertically downward toward the bed. This causes the head of the penis to press against the back wall of the vagina and slide along it into the posterior fornix (if the penis is long enough).  This works best when the uterus is "tipped" toward the rear.

Experimenting in the "cowgirl" position

Cowgirl (woman on top) is in many ways the most flexible position in terms of angle, and it gives control to the person best able to determine if the penis is in some "magic spot." So if you're the female partner, get on top in the normal cowgirl position, with your vaginal opening centered around the base of his penis, and then shift your whole body forward or back, causing the head of his penis to press in the same direction.

Specifically, if you sit up straight and slide your body forward toward his waist about an inch or two, you'll press the head of his penis against the front wall of your vagina, where it will stroke your g-spot and slide into your anterior fornix. If, instead, you lean forward and slide your whole body backward a little bit toward his thighs, you'll press the head of his penis against the back wall of your vagina, and it will slip into your posterior fornix if it's long enough.

(As is true for the coital alignment position, this creates extra pressure and friction between the shaft of his penis and the front of your vaginal opening. This feels good and may pull your labia and clitoral hood downward, creating extra stimulation for the clitoris.)

You can also shift to the left or right. Don't tilt to the side; stay upright or tilted forward while you move your whole body sideways an inch or two. This will angle his penis toward one of your lateral fornices. If his penis is too long for your anterior fornix, and too short for your posterior fornix, and it keeps hitting your cervix in the middle and hurting you, try a sideways shift. Aiming his penis toward one of your lateral fornices might turn out to be the perfect answer.

Summing it up

There are many people for whom none of this matters. Whether the tip of the penis fits "just right" into the fornix at some point around its circumference makes no difference in how PiV feels to them.

However, some people really, really like that feeling, and if you're one of them, it's worth giving some thought to anatomical differences and the geometry that makes for a good fit for you and your partner. In particular, finding a good "fornix fit" can add almost electric intensity to "yab-yum," the period of motionless penetration that many couples who practice tantric sex include near the end of the ritual.

The PiV positions that allow for that "fitting snugly into the socket" feeling will depend on the length, angle, and shape of the vagina, the location of the cervix, and the length, width, and curvature of the penis. And all of these things vary widely from one person to the next.

This means that there are no "best" positions for every couple. You will just have to experiment with your partner. The best positions for the two of you will depend entirely on how your bodies fit together in different positions at different angles and depths.

To help you figure out what's going on in there, a reader recommended this website, http://beautifulcervix.com/ as "a great way to visualize exactly how things look internally." It's a great resource!

But you shouldn't rely just on pictures and generalizations. Knowing the location of your (or your partner's) cervix and the tilt of your (her) uterus can help you understand what's going on in there and really help you visualize which way to move. For most women, the cervix is in reach of a finger, so go have fun "playing doctor"!



  1. having a smaller than average penis ( about 4.5" without pressing into the fat pad) i don't think i have ever reached the posterior fornix, nor the cervix.
    So i don't know how i should feel.
    Stating this area would be a lot more pleasurable put even more pressure on guys like me, and on women who can't climax from this stimulation for whatever reason.

    1. I've clearly stated my skepticism about the "magic fit" hype about the fornix. Maybe it really does feel special for a few rare couples, or maybe it's all BS. There's no way to tell.

      But so what? I've had orgasms so intense I've almost blacked out – and a lot of those have been with no penetration at all!

      If it can't get any better than that – and it really can't – then why worry about some sort of possibly-mythical fornix fit?

      > ( about 4.5" without pressing into the fat pad)

      Why do it wrong when you can do it right? Press the ruler firmly against the pubic bone to get an accurate length. That will put you at around 5" which is very close to average.

      I have small hands, and even I can touch my own cervix. Yes, there's variation in vaginal size and the location of the cervix, so you certainly won't be able to reach the posterior fornix for many women, but you should be able to reach the anterior fornix for almost all women. It is almost never more than 4" deep.

      Please go read "How Much Does Penis Size Matter?" http://moderntantra.blogspot.com/p/penis-size.html before you waste any more time worrying about a quarter inch or so in length that simply isn't going to make any difference in bed.

      And think about this: Lesbians consistently have many more orgasms and report having better sex than straight women do.

      Your penis is probably the least important part of your tool kit for satisfying a woman. If you can be a great lover without one (and you can), then the size of the one you've got has almost nothing to do with whether you can make a woman happy.

  2. Hi Shakti, thanks for writing this up. Some really good points here, especially the part about there being only one fornix that goes around the cervix, which almost always gets overlooked by people thinking in terms of 2D diagrams.

    Anyhow, what's your verdict on this allegedly magical orgasm zone? My own take is that it's somewhere between really terrible science and an outright scam. The discussion under "Notability" and "A Scam?" outlines why pretty well: https://en.wikipedia.org/wiki/Talk%3AAnterior_fornix_erogenous_zone

    Now, I don't doubt that some women are aroused by this, since people can be aroused by pretty much anything, and it's been shown by sex researchers that women often can't tell the difference between orgasm and a high state of arousal, nor pinpoint what precisely caused their orgasm, which is why any time a new "spot" or "zone" is "discovered" and announced in the press, you'll suddenly have women claiming to orgasm from it all the time (and men claiming to cause it). It's a kind of placebo effect imo. But it just doesn't make any sense from an anatomical or embryological point of view, from what I can tell, for the fornix to be some kind of orgasm-causing erogenous zone in the way that the clitoris is.

    1. Sorry for the late reply. My hunch is that it's somewhere between an outright hoax and an interesting demonstration of the power of suggestion.

      However, it might work for some couples, and the interest it has generated serves as a good hook for an anatomy lesson, so I thought it was worth exploring.

  3. Hi Shakti,

    I'm the guy from Reddit who recommended the beautiful cervix website, and wanted to say that you have written a marvelous article about my favorite spot!

    I would also like to add a couple of ways to better access those deepspots. My favorite method is something I call "nudgefucking". It's basically the range of motion you can safely stroke in and out of the vagina without ever going shallower than the cervix. This way, the cervix never gets hit with a head-on bump.

    The second method is by cowgirl, and by using belly dancing hips to swirl around the penis rather than bounce up and down. The grinding round and round provides equal stimulation to everything deep. Here's one my favorite examples:


    1. Hi, Wayne. Thanks for the suggestions. I hope others read down far enough to see them.

      The angle in the gif may be too demanding for most people who aren't that athletic, but it's possible to do basically the same thing in a more vertical position. I described it like this in my cowgirl tutorial [http://moderntantra.blogspot.com/2014/08/woman-on-top-sex-tips-in-cowgirl.html]:

      > When you lift your body up just a bit and then move your whole torso forward an inch or two without tilting yourself forward, it makes his penis slant sharply inside your body, with the tip pressing hard against the G-spot on the front vaginal wall.

      > If you now move your hips in a circle horizontally, just above his hips, you will make the head of his penis make a circle inside you, pressing first against the front wall of your vagina, then against one of the sides, then against the back wall, and so on. At the same time the lower shaft of the penis is pressing against the opposite side of the vaginal entrance, stretching and rubbing the tissues there in the other direction.

      > This circular stretching and pressure on the kegel muscles at the entrance is different from the usual vaginal sex and feels very good. The pulse of pressure across the G-spot every cycle adds an extra spike to it.

      I find it easiest to do this while holding onto my guy's arms, so I'm anchored and have something to alternately pull on and push against on each side. It feels really nice!

  4. Really good article! It's interesting how these types of things work.

    I know based on your reaction to the other Anonymous poster that you might not like this question, but is it possible for a penis in the below average range to actually stimulate this spot? At around 4-5 inches?

    If so, how on earth is it possible? I keep reading posts on Reddit and other forums with women saying that only certain ex-boyfriends with specific shaped and sized penises can stimulate this spot during sex, which is upsetting. I know it may depend on the woman, but the general consensus it that it seems to have to be quite a bit above average (6.5-7.5) to stimulate this area, and I'm ashamed that due to the amount of tissue in my penis I won’t be able to provide that pleasure naturally. Unless of course I were to use toys, which can be extremely depressing as it would *only* be because I’m not big enough :(

    While using toys to (specifically) make up for my lack of size will always be depressing, I'm more than capable to put on a poker face when doing so to provide great sexual pleasure for my partner. However, is it at all possible to reach this zone with a small penis? And if so how? Because it seems almost impossible from all other accounts...

    Also you mentioned that a penis with a big head might not be able to stimulate this spot very well either.... That's another problem to add to the list of my penis dimensions.... Is there a way around that or am I basically defective in almost every way? And I'm specifically talking about the a-spot. I understand that there are other spots I could stimulate, but I don't want to stimulate lesser spots *just* because I'm not the best size/shape to stimulate others.

    I know I may sound a bit rash, but a lot of men have this issue as you know. Thank you for writing these posts they’re informative and a lot of people can benefit from reading them. I will share.

  5. I think a lot of people are writing stuff on Reddit and elsewhere that makes them feel special. They're doing it because they want to pretend to be better than everyone else.

    Vaginas vary a lot in size and shape, but the anterior fornix ("A-spot") is almost never more than 4" inside, even when the woman is aroused. I have small hands and I can easily reach mine.

    Most men don't have a problem being long enough to reach it. Instead they are TOO long. In deep penetration positions like missionary or doggie the head of the penis either slams into the cervix or slides past it.

    One reason I don't like doggie is that my guy is especially likely to bang my cervix in that position. Pronebone, on the other hand, is a basically similar position that PREVENTS deep penetration, and he ends up pressing comfortably into my anterior fornix with each stroke. So that works for us.

    But the best sex in the world doesn't depend on being a certain length or girth. Lesbians can have great sex, as can couples where the man can't get hard. You're wasting your time worrying about something that you can't change and that probably won't ever matter to your partner anyway.