The pelvic floor is formed by several soft tissues that fill the outlet of the pelvis. The most important of these is a strong sheet of muscles, slung like a hammock from the walls of the pelvis. Through these muscles pass the urethra, the vagina and the anal canal. There are 2 layers to the pelvic floor muscles, the superficial layer and the deep layer.
Image 1-15 shows the superficial layer composed of five muscles. These may be injured during childbirth.
Image 1-16 shows the deep layer composed of three pairs of muscles, collectively known as the levator ani muscles. They support the pelvic organs of the rectum, uterus and bladder.
The pelvic floor muscles support the weight of the intestines, your uterus and unborn baby. They control urination, bowel movements and affect sensations during sexual intercourse. These muscles soften and weaken to a degree during pregnancy, due to the progesterone hormone, helping this area stretch for birth. However, when extra pressure is put onto the pelvic floor during pregnancy (say when you cough, laugh or sneeze), urine may be passed involuntarily because of a more relaxed pelvic floor.
During labour and birth the pelvic floor muscles guide the baby through the vagina to help them to be born. This natural process can further weaken the pelvic floor, although women who have had a Caesarean can also experience a weakened pelvic floor due to carrying the pregnancy. This is why pelvic floor exercises are important for all women throughout their lives, especially during and after pregnancy. You may wish to read pelvic floor exercises.
Updated November 2007
Stables D. and Rankin J. Physiology in Childbearing with Anatomy and Related Biosciences. 2004, Bailliere Tindall, Edinburgh.
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