Posts Tagged ‘wellness’

Penile Erection Geometry

June 7, 2014




(Illustration credited to Dr. Henry Gray, Gray’s Anatomy of the Human Body, 20th edition, original publication 1918, public domain)

Blog # 156

A flaccid penis is soft like a marshmallow and dangles limply from its attachment to the pubic bone. With stimulation, the penis fills, firms, and increases in length and girth, as tumescence turns to rigidity. Not only does the penis undergo a metamorphosis into a rigid erection, but it also starts angling up towards the heavens—majestically pointing towards the sky, a marvel of human hydraulic engineering in defiance of the laws of gravity. At its extreme, the erect penis can touch the abdominal wall. A young man’s erection can easily support the weight of a towel.

Who Knew? Birthday and New Year’s Eve party blowouts—those party toys that when blown unfurl and extend outwards—are a useful means of thinking about erections. In the flaccid state, the erectile cylinders are very similar to the party blowout when it is not being blown into; in the erect state, the erectile cylinders are comparable to the party blowout when it is being blown into.  In the flaccid state, there is an acute bend at the junction of the external and internal penis. With a rigid erection, this acute angle is lost and the external penis develops an obtuse angle relative to the internal penis.

Analogous to penile size, there is a great amount of variability in the angle of the erect penis relative to the body (the pubo-penile angle). Like belly buttons that can be “outies” or “innies,” erections can be “uppies” or “outies,” depending on a number of factors. “Flagpoles” can be vertical, horizontal, or any angle in between.

Who Knew? In summer camp there was always that smart aleck camper who cited a complex equation of the physics of erection intensity, involving the “angle of the dangle,” “the heat of the meat,” “the direction of the erection,” “the dimension of the extension,” “the torque of the pork,” etc. Who knew that there was actually validity to some of these factors in determining the angle of erection!

The pubo-penile angle is determined by the following factors: the tension in the suspensory ligaments of the penis; the attachments of the penis to the pelvic bones; the size of the penis; the extent of the erection; and the tone and strength of the ischiocavernosus (IC) and bulbocavernosus (BC) muscles.

The suspensory ligaments support and maintain the erect penis in an upright position, essentially anchoring the base of the penis to the pubic bone. The tighter the ligaments are, the greater the potential upward angulation of the erect penis.

Who Knew? In an effort to increase penile length, some surgeons perform a procedure in which the suspensory ligaments of the penis are cut. What this actually does is to expose some of the internal penis, allowing more of the penis to hang outside the body. The price one pays for this sleight of hand is that one’s erection will no longer point majestically to the heavens. Essentially, one gains a bit of flaccid length and loses angle—robbing your Peter to pay Paul, literally!

As the suspensory ligaments provide support and anchorage of the external penis from above, so the attachments of the erectile cylinders to the pelvic bones provide support and anchorage of the internal penis from below. Every individual has different anatomy, and the variations in pelvic anatomy and support can engender variations in erectile angulation. In general, the more firm and secure the attachments are from below, the greater the potential foundation of support and the greater the potential upward angulation of the erect penis.

Who Knew? The internal, concealed penis that is attached to the pelvic bones can be thought of as the roots of a tree. Similarly, the external penis can be considered in terms of the trunk of a tree. Without a solid root system—the foundation—no tree can assume a tall and erect stature. But with a solid foundation, the penis, like the tree, has the support to point high to the heavens.

Penile size is generally inversely proportional to the potential for upward angulation. Largely due to the force of gravity, there is a tendency for less upward angulation with longer and heavier penises.

Conceptually easy to understand, if flaccid is considered a 0% erection and full rigidity is 100%, the greater the magnitude and extent of the erection, the greater the upward angulation.

There are two particularly important pelvic floor muscles called the bulbocavernosus (BC) and ischiocavernosus (IC) muscles. These muscles are crucial to male sexual function. There are a total of 3 erectile cylinders that form the bulk of the tissue of the penis. The solitary erectile cylinder known as the “corpus spongiosum” (“spongy body”) runs from the perineum (the area between the scrotum and anus)” through the length of the penis to the “glans,” the head of the penis. Its innermost, protuberant portion is known as the “bulb.” The corpus spongiosum contains the urethra (urinary channel) and during sexual stimulation, the corpus spongiosum and the glans become swollen and plump. The BC is the muscle that covers the penile “bulb.” The “corpora cavernosa” (“cave-like bodies”) are the paired erectile cylinders are responsible for rigid erections. The IC refers to the muscle that covers the inner, deep aspects of the corpora cavernosa.

Bulbocavernosus and ischiocavernosus muscle strength can factor strongly into erectile angulation. A voluntary contraction of the BC and IC muscles will cause the erect penis to deflect in an upwards direction. As the BC and IC muscles are flexed, one can easily observe movement of the external penis towards the heavens as the increased blood filling of the erectile cylinders nudges the external penis up. The better the tone and conditioning the BC and IC muscles, the greater the potential upward angulation of the erect penis.

We must accept what nature has given us regarding our suspensory ligaments, our attachments of the penis to the pelvic bones, and the size of our penises. However, the factors that we can modify are the extent of our erections and the strength of our IC and BC muscles. So if we want to maximize our pubo-penile angle, PFM exercises become of paramount importance

An erection needs to be hard enough to penetrate, but flexible enough to be able to negotiate the various “acrobatic” requirements of different sexual positions. So, although an erection that points to the heavens is a wonderful phenomenon, one that is so angled to the extent that it is inflexible will not help one’s performance in the bedroom.

Who Knew? The vagina is shaped like a banana, with its innermost and deepest part angling downwards toward the sacral bones. In order to accommodate female anatomy and position, a penis needs to be both rigid and flexible at the same time—“flexible rigidity,” to use an oxymoronic phrase. If one has a highly angled, inflexible erection, sexual positions such as the reverse cowgirl or woman on top leaning backwards can be painful and can potentially inflict damage to the penis, as well as prove uncomfortable for the woman.


Andrew Siegel, MD


The aforementioned is largely excerpted from my new book: Male Pelvic Fitness: Optimizing Sexual and Urinary Health; available in e-book (Kindle, iBooks, Nook) and coming soon in paperback.


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