The pelvic floor is a group of muscles that supports the bladder and bowel and helps maintain continence. Sphincter muscles help control the opening and closing of the urethra, which leads from the bladder and carries urine out of the body.
The pelvic floor
The pelvic floor is a group of muscles often described as being shaped like a hammock or sling. The outlets of the bladder and bowel – urethra and rectum – pass through the pelvic floor.
These muscles are attached to the spine's tailbone or coccyx and continue to the pubic bone at the front of the body.
The pelvic floor supports the bladder and bowel in men, passing just under the prostate gland. It supports the uterus, bladder and bowel in women.
We can consciously control these muscles through a system of nerves and electrical impulses sent from our brain to the muscles. When we want to tense or relax them we can.
Ordinarily, the pelvic floor muscles are tense, ensuring continence by keeping the outlets closed. When we go to the toilet we relax these muscles and the urethra opens.
The levator ani is a muscle group in pelvic floor group. This group is especially important for maintaining continence. The levator ani surrounds the vagina in women, and in both men and women it surrounds the anal canal and the urethra.
The urethral sphincters are also important for continence and control. In fact, for men, there are two. One is located in the bladder neck and is called the internal sphincter. It's a smooth muscle, which means there's no conscious control over it. You can't voluntarily squeeze it, that happens automatically.
Then there is the external sphincter, which both men and women have. It's a different type of muscle to the internal sphincter and we can voluntarily control it.
In men it's located just under the prostate at the base of the penis. For women, the external sphincter extends up to the bladder and encircles both the urethra and vagina.