Pelvic Floor Muscle Anatomy
This diagram depicts the numerous muscles of the pelvic floor. I drew it myself!
A lot of pelvic health issues arise because, just like any other muscle in the body, these pelvic floor muscles can become weak or tight and even have painful trigger points and areas of spasm.
This view is of a person lying on their back and looking from the feet up. All of the coloured parts are different muscles and they all work very closely together.
The pelvic floor muscles attach to all sides of the pelvis, therefore contributing to the stability of the joints, (sacro-iliac and pubic symphysis joints included). If a person has increased laxity in any of the pelvic joints and poor muscular control by the external muscles (think core, hip and gluteal musculature), this can cause the muscles to work overtime and subsequently become tight/spasmed, creating more pain.
They also attach to the coccyx and can cause tailbone pain (coccydynia) if the muscles are very tight and constantly pulling on the joint. This may or may not go hand-in-hand with bowel issues like constipation and incomplete evacuation because, once again, if the muscles are super tight then they are unlikely to be able to fully relax and let go to allow for complete bowel movements.