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
- fatty tissue
This is all within the border of the pelvis.
Bony landmarks of the pelvis
We all have the bony ring of the pelvic girdle. There are two halves to the pelvis, called innominates, which are made up of three fused bones:
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.
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 when one is a finger-knuckle-length in:
- Superficial transverse perineal
- External anal sphincter
This layer helps to close around all of the tubes at the end of the urinary system (urethra), reproductive system (vagina), and gastrointestinal system (anus).
Additionally, this layer allows for sexual function via clitoral and penis erection.
The tissue between the vagina and anus is called the perineal body. This tissue might suffer a tear during childbirth.
What’s different in the cis-male (folks who were born male) pelvis? Without the vaginal canal, they have fewer muscles and a differently shaped perineal body (called bulbospongiosus; the equivalent of the bulbocavernosus in the cis-female).
Also, the upside down V of the pubic rami (the bone of the pelvis) is more shallow because they don’t need to push a little human out of the pelvic outlet.
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.
This layer is palpated when your finger is two knuckles in. The muscles are:
- Urethral sphincter
- Deep transverse perineal
- Compressor urethra (cis-women only)
- Sphincter urethrovaginalis (cis-women only)
This layer is the innermost layer of the pelvic floor muscles. This layer is also referred to as the pelvic diaphragm.