Pelvic floor muscle and anatomy illustrations used with permission from Pelvic Guru and Your Pace Yoga

When we refer to the pelvic floor, it is often a shortcut to refer to the muscles that make up the pelvic basin. The pelvic floor also includes:

blood vessels
nerves
ligaments
fascia
fatty tissue
lymph
skin

This is all within the border of the pelvis.

Bony landmarks of the pelvis

The pelvic girdle is comprised of two halves to the pelvis, called innominate, which are made up of three fused bones:

pubis

ilium
ischium

Bony pelvis and hip joints with ligaments

Connecting these two pelvic halves in the back of the body are the sacrum (triangular bone at base of spine) and coccyx (tailbone).

There is a cartilage joint at the front of the pelvis that completes the pelvic ring called the pubic symphysis. This can get quite painful for some women during their pregnancy.

Where is the pelvic floor?

Let’s map out the area where your pelvic floor lives. If you are comfortable touching the bones that create the border as described above, please do. If not, just imagine where they are.

Find your pubic bone in the front of your pelvis.

Reach around to the very bottom of your spine where your tailbone (or coccyx) is (hint: it’s usually lower than we may think).

If you are sitting, lift your right butt cheek and find your sitz bone (or ischial tuberosity).

You have now mapped out the diamond shape of the bottom of your pelvis. Within this bony border you will find all of your pelvic floor muscles!

The pelvic floor muscles are comprised of three layers.

Layer 1 of the pelvic floor

First layer of pelvic floor muscles with vulvovaginal anatomy

This layer is the outermost layer. This layer has four muscles that can be palpated both externally and internally.

These muscles can be palpated internally on women and people with vulvovaginal anatomy at the dept ofhen one finger-knuckle-length. For those with penile anatomy these muscles will be palpated externally:

Bulbocavernosus/bulbospongiosus
Ischiocavernosus
Superficial transverse perineal
External anal sphincter

This layer helps to close around all of the tubes at the end of the urinary system (urethra), gastrointestinal system (anus), and the reproductive system (vagina for those who have them).

Additionally, this layer allows for sexual function with the erectile tissues of the clitoral and penis.

The tissue between the vagina and anus is called the perineal body. This tissue might suffer a tear during childbirth. Physical therapy while pregnant and after childbirth can help with this!

Layer 2 of the pelvic floor

Second layer of pelvic floor muscles with vulvovaginal anatomy

The closure around the tubes continues with layer 2. This layer is referred to as the deep perineal pouch.

It’s less obvious to pinpoint where the muscles are as compared the first and third layers, but for women with urinary urgency you can trigger this sensation when you palpate the compressor urethra muscle.

This layer is palpated at the depth of the second knuckle on the index finger . The muscles are:

Urethral sphincter
Deep transverse perineal
Compressor urethra (vulvovaginal anatomy only)
Sphincter urethrovaginalis (vulvovaginal anatomy only)

Layer 3 of the pelvic floor

Third layer of the pelvic floor muscles with vulvovaginal anatomy

This layer is the innermost layer of the pelvic floor muscles. This layer is also referred to as the pelvic diaphragm.

This muscular sling looks like a hammock, acting to provide support for the bladder, rectum, and for those who have one, a uterus.

This layer has a right and left side:

Pubococcygeus
Iliococcygeus
Coccygeus

Pelvic wall muscles

Not to be ignored are two important muscles that make up the pelvic walls: the piriformis and obturator internus.

The piriformis muscle is a hip external rotator (think turned out like a ballet dancer). It often gets press for causing pain in the sciatic nerve when it’s overactive or tight, but the problem could be with the obturator internus, which is also a hip external rotator. (The pelvic specialists reading this now have a magical glow about them. We love this muscle.)

The obturator internus is very often a culprit in deep vaginal, rectal or hip pain. Pelvic specialists love this muscle because when we palpate it, the patient will often say, “Yes, that’s exactly my pain. No one has been able to find that before.”

So, if you experience what you think is sciatica, it might actually be your obturator internus irritating your sciatic nerve, not the piriformis. The sciatic nerve is the cream in the Oreo cookie between the piriformis and the obturator internus and can be irritated by either muscle.

In Summary

All genders have three layers of pelvic floor muscles and the pelvic wall muscles. This musculature coordinates with intra-abdominal pressure and other muscles in the area (abdomen, back, hip, etc) to optimize core control and continence.

What is the pelvic floor?