De-mystifying the Erection

The penis is one of the most contemplated organs of the body; it’s the source of pride, ego, pleasure, and at times, pain. For all the emotions and energy spent thinking about the penis and its functions many people don’t really know how it works. I’m here to help clear a few things up for you.

The Basicserection cross section

A penis is made up of 3 cylinders; 2 larger cylinders which are the main erectile bodies called the corpora cavernosa.

The third cylinder is smaller and contains the urethra (where urine passes through), and is called the corpora spongiosum.

This cylinder has some component of erectile tissue and is in continuity with the head of the penis.

How it works

When a man receives pleasurable stimulation (manual, visual, mental… a stiff breeze in some instances) nerves in the penis become stimulated and allow blood to enter the penis through the erectile tissue. This arterial blood then fills the 3 cylinders (including the glans or head of penis) until it is fully erect. The blood is held in place through collapsible small veins that become closed off once the erection occurs.  When the erection becomes relaxed the blood leaves the cylinders through these veins which leads to a flaccid state.

What about…

  • Penile fractures: the penis has great tensile strength and elasticity, but yes the penis can fracture. As mentioned in the basics there aren’t any bones in the penis so how does it fracture? Penile tensile strength at full erection is around 1200-1500 mmHg. If the penis is bent at a severe angle with an erection the tunica (or tissue covering the cylinders) can tear and potentially lead to permanent scar tissue and bending of the penis. The most common situations where fracture occurs are when the penis slips out of the vagina during intercourse and is driven into the pubic bone instead. “Doggystyle” or “woman on top” are the most common reported positions that cause fractures. Immediate medical evaluation is recommended if this occurs.
  • Penile curvature: this can be caused from a fracture as I mentioned above but is more commonly from small micro traumas to the tunica (cylinder cover layer) over many years, and some people are born with penile curvature. Curvature generally doesn’t decrease the effectiveness so if your partner is a man don’t be shy if there’s an angle to the dangle. If the angulation is severe, which is less common, it can be repaired surgically.
  • Priapism: An erection that lasts more than 4 hours is potentially a big problem. Fight your inclination to be proud of this feat. After 4 hours the penile tissue needs fresh blood and a new supply of oxygen to survive. These erections are usually caused from either drug use both legal (viagra, some psych meds) and illegal (meth) or naturally. As penile tissue is suffocating, damage occurs in the penis and can lead to permanent erectile dysfunction, so don’t mess around, go into emergency room right away.

Sex doesn’t have to be a mystery, and your body shouldn’t be either. Know your body, raise up your sex ed game.

– Dr. Amy

Dr. Amy Schlaifer is a urologic surgeon practicing in Phoenix, AZ.

Thumbnail image via WeHeartIt