Internal female sexual anatomy consists of the vagina, cervix, uterus, and ovaries. These are discussed in the following sections. Refer to I Figure 3.4 for cross-section and front views of the female pelvis.
Endometrium
The Vagina
The vagina is a canal that opens between the labia minora and extends into the body, angling upward toward the small of the back, to the cervix and uterus. Most women have never seen inside their own vaginas, but it is possible to do so during their regular pelvic exams. The health-care practitioner can use a mirror to show a woman her vagina while the speculum is holding the vaginal walls open. Women who are unfamiliar with their anatomy can have a difficult time when they first try inserting a tampon into the vagina:
Female Sexual Anatomy and Physiology
YOUR SEXUAL
HEALTH
No matter how hard I tried, I couldn’t get a tampon in until I inserted a finger and realized that my vagina slanted backward. I had been pushing straight up onto the upper wall. (Authors’ files)
The unaroused vagina is approximately 3 to 5 inches long. The analogy of a glove is often used to illustrate the vagina as a potential rather than an actual space, with its walls able to expand enough to serve as a birth passage. In addition, the vagina changes in size and shape during sexual arousal, as we will discuss in Chapter 6.
The vagina contains three layers of tissue: mucous, muscle, and fibrous tissue. All these layers are richly endowed with blood vessels. The mucosa (myoo-KOH-suh) is the layer of mucous membrane that a woman feels when she inserts a finger inside her vagina. The folded walls, or rugae (ROO-jee), feel soft, moist, and warm, resembling the inside of one’s mouth. The walls normally produce secretions that help maintain the chemical balance of the vagina. During sexual arousal, a lubricating substance exudes through the mucosa.
Most of the second layer, composed of muscle tissue, is concentrated around the vaginal opening. These muscles contract rhythmically at orgasm and contribute to the pleasurable sensations women experience during orgasm. One research study found that women are more likely to be aware of the vaginal contractions at orgasm during manual clitoral stimulation than during intercourse (Carrobles & Gamez, 2007).
Because of the concentration of musculature in the outer third and the expansive ability of the inner two thirds of the vagina, a situation often develops that can be at best funny and at worst embarrassing. During headstands and certain yoga or intercourse positions with the pelvis elevated, gravity causes the inner two thirds to expand and draw air into the vagina. The outer muscles tighten, and the trapped air is forced back out through the tightened muscles, creating a sound we usually associate with a different orifice. The occurrence is popularly known as “queef,” although one student has suggested calling this phenomenon “varting,” because the sound is similar to that of
chapter 3
a fart (fortunately, there is no unpleasant smell). Surrounding the muscular layer is the innermost vaginal layer, composed of fibrous tissue. This layer aids in vaginal contraction and expansion and acts as connective tissue to other structures in the pelvic cavity.