What is the Pelvic Floor
Anatomy | Berrin Boyce | muscles | Pelvic Floor | sex | sexual function

February 9, 2020

This is part 1 of a three part series written by guest blogger Berrin Boyce, PT

What is the pelvic floor?

Broadly defined, the pelvic floor is a group of small muscles, comprised of 3 separate layers that line the inside of the pelvis. These muscles primarily attach to the bony structures of the pelvis, the pubic bone in the front, sitz bones or ischial tuberosities on each side, and the tailbone or coccyx in the back. Together they create the floor of the pelvis, and provide a number of functions. At rest, they create a hammock that separates the outside of the pelvis from the inside.

As a pelvic floor physical therapist, I typically describe the functions of the pelvic floor as the 5 “S”s including:

  • support to pelvic organs: sling to support the bladder, rectum, and uterus (if applicable)
  • sphincteric closure at urethra and anus: control over when we pee, poop, and pass gas
  • sump-pump: for lymphatic drainage/swelling
  • stability of bony structure: support around pelvic and hip joints
  • sexual function: increased blood flow, muscle contraction during orgasm

This small group of muscles work together to perform many tasks we do on a daily basis related to urination, defecation, sexual function and pelvic stability that we rarely think about until a problem arises.

How does the pelvic floor work?

As a physical therapist, I specialize in understanding the anatomy and function of muscles all over the body. Muscles in general work to move our limbs and provide stability, but they also work to increase blood flow when they contract and relax, and in some cases constrict or tighten to maintain increased blood flow in certain areas of the body (hello erection!). During sexual arousal erectile tissue in both male and female genitals maintains increased blood flow through muscle contraction. Pelvic floor muscles must also be able to relax for fluid and stool to be eliminated from the body and to allow for penetration.

A healthy muscle has the ability to contract and relax, and we need to have good awareness or proprioception to know how to control that muscle. When we have weak muscles, the job that muscle is supposed to perform goes to a neighboring muscle or groups of muscles, known as compensation. Abdominal muscles work together with the pelvic floor muscles during sexual activity to create and maintain increased intra-abdominal pressure which is in part responsible for tension that builds during sexual arousal.The first layer of muscles in the pelvic floor is made up of the ischiocavernosus, bulbocavernosus (bulbospongiosus in males), superficial transverse perineal, and external anal sphincter. Their primary function is to contract to close the holes of the pelvic floor and to relax to open the urethra, and anal sphincters in both males and females. Both ischiocavernosus, and bulbocavernosus play an important role in increasing and maintaining blood flow to the clitoris and penis during sexual arousal. In men, the bulbospongiosus contracts for ejaculation.

The second layer of muscles consists of the compressor urethrae and the deep transverse perineum. They also provide support to internal structures in the vaginal canal and round the base of the penis.

The third layer of muscles includes the pubococcygeus, iliococcygeus, coccygeus, and obturator internus. They offer more broad support and act more as the sump-pump function to reduce normal swelling that occurs during the sexual response cycle.

About the Author:

Berrin Boyce is a pelvic health physical therapist, who received her bachelor’s degree in Human Physiology at the University of Oregon and her doctorate of physical therapy from Northeastern University in Boston. She currently works in the Denver Metro area at N2 Physical Therapy treating a wide variety of conditions including: persistent abdominal and back pain, persistent pelvic pain conditions, sexual dysfunction, urinary incontinence, pelvic organ prolapse, fecal incontinence, constipation, and pregnancy/post-partum related musculoskeletal conditions. She enjoys working with both women and men to address any pelvic floor issues related to the musculoskeletal system. In her free time she is an avid cyclist and runner, and has practiced yoga for over 15 years.



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