The vagina is an elastic muscular tube located between the bladder and rectum. It is about three inches long, and its internal walls are lined with specialized cells that produce lubricating fluids during sex and arousal. These cells also secrete mucus, which keeps the vagina moist. The vaginal opening is surrounded by a ring of muscle fibers known as the pubococcygeal sphincter, which controls the flow of urine from the bladder. When the sphincter contracts, it closes off the urethra to prevent urine from leaking out when coughing, laughing, or jumping. During intercourse, the vagina lengthens and widens to accommodate a penis, but it returns to its original size after orgasm.
Rugae are folds or ridges that line the inside of the vagina. They are made up of connective tissue, collagen, and elastin. Rugae provide support for the vagina and help maintain its shape during sexual activity. The rugae help to increase friction during intercourse, making it more pleasurable for both partners. Without them, the vagina would collapse inwards, creating a sensation similar to a tight fist. This can make intercourse uncomfortable or painful for some women.
There are several theories about how the rugae formed evolutionarily. One theory suggests that they evolved to allow females to stretch their vaginas to accommodate larger penises during intercourse. Another theory suggests that the rugae developed to prevent bacterial growth within the vagina. Still another theory posits that the rugae are remnants of an embryonic structure that were never fully eradicated during development.
The rugae can be seen on a woman's vulva during a gynecological examination. They may also be visible through the walls of the vagina when she is aroused or having sex. Some women find this fascinating while others consider it embarrassing. Some couples like to explore these folds with fingers or tongue during foreplay, while others prefer to keep things simple. Ultimately, whether to expose your vaginal rugae is a personal decision.