Thankful for Tough Tissues: Big Head/ Little Head

Andrew Siegel MD   8/4/2018

Midas penis in cage

Image above from Phallological Museum in Reyjkavik that I recently visited


The toughest connective tissues in the human body, exclusive of bone and teeth (in order of strength) are:

  1. Dura mater (of brain and spinal cord)
  2. Tunica albuginea (of penis and clitoris)

Is it not fitting that the two toughest and hardiest connective tissues in the human body are located in the brain and genitals, providing protection and support to arguably two of our most vital and important human possessions? 

The hardest organs in the body are bones (calcium and other minerals) and teeth (enamel), but when it comes to connective tissue, the brain and penis/clitoris reign supreme. The brain and spinal cord are enveloped and protected by the dura mater (Latin, “hard mother”), the robust outermost membrane. The erectile chambers of the penis (and the clitoris, although on a miniaturized scale) are covered with a tough fibrous envelope called the tunica albuginea (Latin, “white membrane”).

The White Membrane

The tunica albuginea consists mostly of collagen with a sprinkling of elastin to allow it to stretch. It has an important role in maintaining both penile and clitoral erections.  When a penis is flaccid the tunica is 2 mm or so thick and with an erection it stretches to 0.25 to 0.5 mm thick.  At the time of erectile rigidity, the blood pressure in the penis exceeds 200 mm of mercury, the only place in the body where hypertension is desirable and necessary for proper function. The tunica albuginea supports the penis at these times of penile hypertension, allowing for full erectile rigidity and durability and protecting the penis against injury from the torquing and buckling stresses of sexual intercourse.

Acute Trauma to the White Membrane

On rare occasions, the tunica surrounding the erectile chambers of the penis ruptures under the force of a strong blow to the erect penis, a situation referred to as a penile fracture. It is not unlike the tire of a car being driven forcibly into a curb, resulting in a gash in the tread and deflation from the blow out. Such an acute blunt traumatic injury rarely occurs to the non-erect penis by virtue of its mobility, flaccidity, and 2 mm thick tunica. However, when the penis is rigid, there is peak tension and stretch on the white membrane. The leading cause of penile fractures is vigorous sexual intercourse, most often when the penis slips out of the vagina and strikes the perineum (area between the vagina and anus). She “zigs,” he “zags,” and a miss-stroke occurs of sufficient force as to rupture the white membrane.

Fracture can also occur under the circumstance of rolling over or falling onto the erect penis as well as any other situation that inflicts damage to the erect penis, such as walking into a wall in a poorly illuminated room or forcible masturbation.

Penile fracture is a medical emergency, and prompt surgical repair is necessary to maintain erectile function and minimize scarring of the erectile chambers that could result in permanent penile bending and angulation.

Chronic Trauma to the White Membrane

Chronic traumatic injuries to the white membrane are often asymptomatic for many years. Just the simple act of obtaining a rigid erection puts tremendous compression stress forces on the white membrane and the potential for micro-trauma to it increases exponentially when one inserts his erect penis into a vagina and two parties move, bump and grind, creating intense shearing stress forces on the penis. Certain positions angulate the penis and create more potential liability for injury than others. Even gentle sex can be rough with a single act of intercourse resulting in hundreds of thrusts with significant rotational, axial and torquing strains and stresses placed upon the erect penis with the potential for subtle buckling injuries.

Repeat performance perhaps a few times a week for many decades and by the time a man is in his 50s, on a cumulative basis, traumatic penile injuries—often asymptomatic in their developmental stages—can cause scarring to the white membrane, ultimately resulting in Peyronie’s disease.  This often manifests with a hard lump, shortening, curvature, narrowing, a visual indentation of the penis described as an hour-glass deformity, pain with erections and less erectile rigidity. Penile pain, curvature, and poor expansion of the erectile chambers contribute to difficulty in having a functional and anatomically correct rigid erection suitable for intercourse.

Bottom Line:  The human body is nothing short of amazing and should be accorded the greatest respect. We should be grateful for our dura mater and tunica albuginea that protect and allow function of our brains and penises/clitorides, respectively.  Given the service that our penises provide, it is surprising that penile fracture and Peyronie’s disease are not more common than they actually are.

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.

Dr. Siegel has authored the following books that are available on Amazon, iBooks, Nook and Kobo:

MALE PELVIC FITNESS: Optimizing Sexual & Urinary Health

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

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


These books are written for educated and discerning men and women who care about health, well-being, fitness and nutrition and enjoy feeling confident and strong.

Dr. Siegel is co-creator of the male pelvic floor exercise instructional DVD (female version is in the works): PelvicRx

New video on female pelvic floor exercises:  Learn about your pelvic floor

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