Sex Muscles Illustrated

Andrew Siegel MD     4/22/2023

In this entry, words will be kept to a minimum because the illustrations tell most of the story.  The images of the sex muscles, aka the superficial pelvic floor muscles, derive from the 1918 edition of Gray’s Anatomy of the Human Body (public domain), modified by Uwe Gille.

No matter your gender, two vital muscles, the bulbocavernosus (BC) and the and ischiocavernosus (IC), are the “motor” that drives genital sexual function.  Without these muscles, your penis or vagina would be non-functional putty!  Notice how remarkably similar the muscles are in both genders, the only difference being that the BC muscle is split in women, divided by the vagina.

The relationship of the BC and IC muscles to the vagina and penis parallels the relationship between the diaphragm and the lungs. Without a functioning diaphragm to move the lungs, your lungs would be non-functional bags of air.

Male BC (top) and IC muscles (bottom)

Functions of the Male BC and IC muscles

  • Transform “engorged” penis to “rigid” penis by compressing erectile chambers (responsible for penile high blood pressure)
  • Enable moving your erect penis up and down at will
  • Stabilize erect penis so it stays rigid and skyward-angled
  • Contract at sexual climax to forcibly expel semen

The only place in the body it is desirable to have high blood pressure is within the penis. The BP at the time of full rigidity is > 200 mm, the 80-100 mm increase over systolic BP achieved by virtue of contraction of these muscles.  Anywhere else it would be considered a hypertensive “crisis,” but in the penis it is simply an “erection.”

Female BC (top) and IC muscles (bottom)

Functions of the Female BC and IC muscles

  • Increase pelvic blood flow during arousal, contributing to lubrication and plumping of vulva
  • Transform clitoris from flaccid to erect
  • Enable tightening of the vagina at will
  • Contract at the time of climax, contributing to physical sensation of orgasm

Note that men and women capable of achieving “intense” orgasms most often have very strong, toned, supple, and flexible BC and IC muscles.

Bottom Line: In men, the IC and BC muscles function as the “erector penis” and “ejaculator penis,” respectively.   In women, these muscles function as the “erector clitoris,” “constrictor vagina,” and “climaxer maximus.”  No matter your gender, optimize the function of these muscles by doing Kegel exercises properly. 

Wishing you the best of health,

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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 AreaInside 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, one of the largest urology practices in the United States.  He is the co-founder of PelvicRx and Private Gym.  His latest book is 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 is now available at Audible, iTunes and Amazon as an audiobook read by the author (just over 6 hours). 

Dr. Siegel’s other books:

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


MALE PELVIC FITNESS: Optimizing Sexual and Urinary Health

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

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