An Erection is a Symphony

Andrew Siegel MD   7/18/2020

One’s ability to obtain and maintain a penile erection is often taken for granted, as many bodily functions are. An erection is thought of as a normal, healthy, simple act of nature. The truth of the matter is that erections are normal, healthy, and natural, yet anything but simple. 

The transformation from flaccid to rigid is a complex bio-chemical-physical event that involves the intact and coordinated orchestration of the central and peripheral nervous system, blood vessel system, erectile smooth muscles and erectile skeletal muscles. To deconstruct this complexity and simplify the understanding of this elaborate and intricate process, the symphony orchestra is used as a metaphor.  

gaga_symphony_orchestra1(Gaga Symphony Orchestra live at Palazzo Zuckermann, Padua, Italy; photo taken by Carlo Alberto Cazzuffi, September 2012; Permission to copy and distribute under the terms of the GNU Free Documentation License)


An erection is a symphony that results from the interplay of four orchestral sectionsstring instruments (nerves), percussion instruments (blood vessels), woodwind instruments (erectile smooth muscle), and brass instruments (erectile skeletal muscle, a.k.a. pelvic floor muscles). The conductor of the orchestra is the brain (the main sex organ). Although each musician within the orchestral sections has a unique role, all work together harmoniously to create a beautiful synergy. If any individual musician or orchestral section is off key, the disharmony can cause the symphony to be flawed, resulting in a sub-par performance.


NervesThink of the nerves as the string instruments (violin, viola, cello and double bass) vibrating in sync.

The penis has a rich supply of nerves that connect with the spinal cord and brain. Without these nerves and connections, the penis would be without sensation, isolated from the rest of the body and incapable of responding to touch or erotic stimulation. The paired cavernous nerves that convey the message to the penis to fill with blood are anatomically intimate with the prostate gland.

How things work when nerves are functioning well:

  • When the penis is stimulated by touch, nerves relay information to spinal cord centers, which then relay the message to the penile arteries to increase blood flow, resulting in the penis becoming engorged with blood.
  • Touch to the penis is also conveyed directly to the brain, enhancing the reflex spinal cord response.
  • Erotic stimulation (visual cues, sounds, scents, touch, thoughts, memories, etc.) further stimulates the penis from excitatory nerve pathways that descend from the brain.
  • With touch stimulation of the head of the penis, a reflex contraction of the pelvic floor muscles occurs, causing more blood to flow into the penis, leading to a fully rigid erection.

Blood vesselsThink of the blood vessels as the percussion instruments (piano, xylophone, cymbals, drums, etc.) pulsing rhythmically.

Inflation of the penis is all about blood inflow and trapping. When there are issues with the influx or trapping of blood, it becomes challenging to obtain and/or maintain an erection.

How things work when the blood vessels are functioning well:

  • With touch or erotic stimulation, the cavernous nerves convey the message to the penile arteries to relax, increasing penile blood flow substantially within nanoseconds.

Erectile smooth muscleThink of the erectile smooth muscle as the woodwind instruments (piccolos, flutes, oboes, clarinets and bassoons).

The erectile smooth muscle within the sinuses of the erectile chambers governs the inflation/deflation status of the penis. When the smooth muscle is contracted (squeezed), the penis cannot inflate with blood, but when the muscle relaxes, blood gushes into the sinuses and inflates the penis.

As we age, smooth muscle in all arteries of the body stiffens, causing high blood pressure (essential hypertension); paralleling this, there is an age-related stiffness of the erectile smooth muscle, which can cause difficulty obtaining and/or maintaining an erection.

How things work when the erectile smooth muscle is functioning well:

  • With touch or erotic stimulation, the cavernous nerves cause relaxation of the smooth muscle within the sinuses of the erectile chambers, allowing blood to flow into and fill the sinuses.
  • As the sinuses approach complete filling, veins that drain them are pinched off, trapping blood within the sinuses.
  • This smooth muscle relaxation and venous trapping results in penile blood pressure becoming equal with the systolic blood pressure (normally 120 millimeters) and an engorged penis, plump but not rigid.

Erectile skeletal muscles (pelvic floor muscles)Think of the erectile skeletal muscles as the brass instruments (trumpets, French horns, trombones, and tubas), which are capable of the loudest sounds in the orchestra. These instruments are particularly important to the most booming, powerful and exciting portions of the music, corresponding to the role of the pelvic floor muscles that are the muscles of penile rigidity and also the drivers of ejaculation and climax.

The pelvic floor muscles are the “rigidity” muscles, necessary for transforming the plump penis into a rock-hard penis. These muscles surround and compress the deep, internal roots of the penis, causing back flow of pressurized blood into the penis, responsible for obtaining and maintaining full rigidity.  When the penis is erect, it is these pelvic floor muscles that are responsible for the ability to lift one’s penis up and down as the muscles are contracted and relaxed. These muscles are also responsible for ejaculation—compressing the urethra rhythmically to cause the expulsion of semen.

The pressure in the penis at the time of a fully rigid erection is > 200 mm, the only organ in the body where high blood pressure is both acceptable and necessary for healthy function. If the systemic blood pressure were this high, it would be considered a “hypertensive crisis.”  This explains why blood pressure pills are the most common medications associated with erectile dysfunction.

How things work when the pelvic floor muscles are functioning well:

  • With touch stimulation of the head of the penis, there is a reflex contraction of the pelvic floor muscles; every time the head of the penis is squeezed, the pelvic floor muscles contract reflexively.
  • The pelvic floor muscles surround the internal roots of the penis and as they compress and squeeze the penile roots with each contraction, blood within the roots is forced back into the external penis. This pushes more blood into the penis and causes increased clamping of venous outflow, a tourniquet-like effect resulting in penile high blood pressure and full-fledged rigidity—a brass-hard penis.

BrainThink of the brain as the conductor of the orchestra—the maestro—who has the vital role of unifying and coordinating the individual performers, setting the tempo, executing meter, “listening” critically and shaping the sound of the ensemble accordingly. The conductor is the key player and if he is having an off day and does not bring his “A” game, there will be disharmony in the orchestra and the symphony will be flat and unimpressive.

Psychological and emotional factors have a significant impact on erectile function. Mood, stress, anxiety, fears, interpersonal and relationship issues, etc.—acting via the mind-body connection and mediated via the release of neuro-chemicals—can influence erectile function for better or worse. Stress, for example, induces the adrenal glands to release a surge of adrenaline. Adrenaline constricts blood vessels, which has a negative effect on erections, the basis for the common occurrence of adrenaline-fueled performance anxiety.

Bottom Line: An erection is a complex “symphony,” orchestrated by the main sex organ—the brain—and executed at the level of the penis via the individual performances of the “orchestral members” who comprise the orchestral sections—the nerves, blood vessels, erectile smooth muscle and the pelvic floor muscles. All orchestral members play a vital role in the creation of a magical synergy, resulting—when all sections and performers are working optimally—in a spirited, powerful, passionate performance that climaxes in a tension-releasing “symphonic finale.”

It is important to know that if there are dissonant musicians in the orchestra leading to a suboptimal performance, the situation can often be rectified so that ultimately harmony can be achieved; in other words, the problem is often remediable. More about this in future entries. 

Wishing you the best of health,

2014-04-23 20:16:29


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Dr. Andrew Siegel is a physician and urological surgeon who is board-certified in urology as well as in female pelvic medicine and reconstructive surgery.  He is an Assistant Clinical Professor of Surgery at the Rutgers-New Jersey Medical School and is a Castle Connolly Top Doctor New York Metro Area, Inside Jersey Top Doctor and Inside Jersey Top Doctor for Women’s Health. His mission is to “bridge the gap” between the public and the medical community. He is a urologist at New Jersey Urology, the largest urology practice in the United States.  Today’s entry is excerpted from his latest book, Prostate Cancer 20/20: A Practical Guide to Understanding Management Options for Patients and Their Families. 

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Video trailer for Prostate Cancer 20/20

Preview of Prostate Cancer 20/20

Andrew Siegel MD Amazon author page

Prostate Cancer 20/20 on Apple iBooks

PROSTATE CANCER 20/20: A Practical Guide to Understanding Management Options for Patients and Their Families is now on sale at Audible, iTunes and Amazon as an audiobook read by the author (just over 6 hours). 

Dr. Siegel’s other books:

FINDING YOUR OWN FOUNTAIN OF YOUTH: The Essential Guide to Maximizing Health, Wellness, Fitness and Longevity

PROMISCUOUS EATING— Understanding and Ending Our Self-Destructive Relationship with Food

MALE PELVIC FITNESS: Optimizing Sexual and Urinary Health

THE KEGEL FIX: Recharging Female Pelvic, Sexual, and Urinary Health




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One Response to “An Erection is a Symphony”

  1. First-line Approach to Improved Sexual Function | Our Greatest Wealth Is Health Says:

    […] sexual functioning is based upon many body components working harmoniously (central and peripheral nerves, hormones, blood vessels, smooth and skeletal muscles), the initial […]

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