Previous: Iceland and the Phallological Museum
Next: More on Condoms



View count:618,919
Last sync:2021-10-30 03:30
You asked for it, you got it. The Penis!

Support Sexplanations by becoming a sexpla(i)naut:

Go to to get your very own Want/Will/Won't Poster:

You can ask Lindsey Questions at:

Host: Dr. Lindsey Doe

Directing/Filming/Editing: Nicholas Jenkins

Titles: Michael Aranda

Executive Producer: Hank Green

Penis, penis, penis, penis!




Imagine, if you will, that I am a penis, a human penis. I would have seven main parts; a head, shaft, roots that go inside the body, skin that covers the shaft and head, a urethra with an opening like this, and two types of spongy tissue: corpus spongiosum and corpus carvenosa.

 The Inside

Like this, with a urethra on the inside. This is a tube that transports urine, pre-cum, and semen. If there are other things coming out, a urologist would be the doctor to ask. Urologist.

Around the urethra, all the way up to the tip, is the corpus spongiosum. It forms the glans, or the head of the penis. The corpus cavernosa is the spongy tissue on both sides of the penis, the left and right, that fills with blood during erections. This is what the penis looks like on the inside if we did a cross section. Urethra, corpus spongiosum, corpus cavernosa.

Here's how I remember the difference. The head stays kind of spongy during erection so, corpus spongiosum. And the cavernosa are two spongy tissues that create a cavern around the corpus spongiosum. I'm sticking with it! If you have better suggestions, you know where to comment.

There are veins in here too, and this is all wrapped up with skin.

 The Foreskin

This portion of skin is called the prepuce or foreskin. It folds in on itself like a sleeve and can end here, here, here or here. Underneath it are tiny glands that produce a waxy lubrication so it can mmmm. If this substance accumulates for a few days or longer, it can turn white, and thick, what we call smegma. It's the same stuff that builds up under the foreskin of the clitoris. Simple. Pull back, rinse off. The foreskin is quite important to penis design and sexual performance. It keeps the head moisturized, transports blood, matches the lubrication of the vagina, and reads sensations with over 15 square inches of super-packed nerve endings.

 The outside

When the penis becomes erect, it fills with blood and the skin stretches so that the foreskin actually gathers here at the bottom or becomes taut. This reveals the glans, or the head. Like my head, there's and opening to the urethra called the meatus. Ahhhh! There's also a ridge like my chin called the corona, and it is thought to have the function of removing another persons semen, scooping it out. It is definitely not referring to the beer. The beer, the corona of the penis, the corona of the sun, they're all referring to the Spanish word for crown.

Here, on the underbelly of the penis, is where the foreskin is or was attached to the glans. It's called the frenulum. This is very similar to the part right here where the tongue is connected to the bottom on your mouth. So sensitive.

This part of my penis self is the shaft. This is the base. Further inside the body are the crura, or the roots, so that there is a sturdy foundation for raising the flagpole.  This part of the penis can be felt or stimulated between the legs in the perineum. And all of this can get an erection.


An erection might mean that the penis becomes harder! Longer, longer, longer! Thicker, higher. An erection happens when blood flows into the spongy tissue, filling them up until they press up against the veins that would carry the blood out. More blood going in than going out enlarges the penis. Kind of like an inner tube, kind of. Researchers think that the size of the veins and the density of the sponge tissue is what determines how erections will look.

 Heredity and Erections

If the person's lineage originated in a hot weather place, then the penis might be hanging longer, dispersing the heat and roaming the bush. Then for arousal it'll raise up, just not change as much in shape as a penis from a descendant of cooler climates. This penis is more likely to stay tucked away, conserving heat and dodging wind. We playfully call these showers, and these growers.

How the penis looks is not a determinant of masculinity, sexual prowess, domination, power or worth. It may indicate heredity, dad's side, or how much the person smokes, certainly not their ability or inability to perform. The purposes of these penises are to urinate, ejaculate, inseminate, and hopefully experience pleasure.


If you have one, it's your responsibility to protect it. Wash it, lube it, treat infections, adorn it with good quality condoms and pick up after its messes. Like toilet seats, just sayin'.

Stay curious.