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The female reproductive system consists of the ovaries, uterine tubes, uterus, vagina, and external genitalia. These organs remain underdeveloped for about the first 10 years of life. During adolescence, sexual development occurs and menses first occur (menarche). Cyclic changes occur throughout the reproductive period, with an average cycle length of approximately 28 days. These cycles cease at about the fifth decade of life (menopause), at which time the reproductive organs become atrophic.
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The ovaries are the primary female sex organ because they produce eggs (ovum or oocytes) and sex hormones (e.g., estrogen). The ovaries are located within the pelvic cavity.
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The paired uterine tubes are also called fallopian tubes, or oviducts, and extend from the ovaries to the uterus (Figure 14-1A and B). The luminal diameter of the uterine tubes is very narrow and, in fact, is only as wide as a human hair.
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- Infundibulum and fimbriae. The infundibulum is the funnel-shaped, peripheral end of the uterine tube. The infundibulum has fingerlike projections called fimbriae. The fimbriated end of the uterine tube is not covered by peritoneum, which provides open communication between the uterine tube and the peritoneal (pelvic) cavity. In contrast to the male reproductive system, where the tubules are continuous with the testes, the uterine tubes are separate from the ovaries. Oocytes are released (ovulation) into the peritoneal cavity. The beating of the fimbriae may create currents in the peritoneal fluid, which carry oocytes into the uterine tube lumen.
- Ampulla. The ampulla is a region of the uterine tube where fertilization usually occurs.
- Isthmus. The isthmus is the constricted region of the uterine tube where each tube attaches to the superolateral wall of the uterus.
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An
ectopic pregnancy occurs when a fertilized egg implants in the uterine tube or peritoneal cavity. The uterine tubes are not continuous with the ovaries, and therefore, there is also a risk that fertilization and implantation will occur outside of the uterine tubes in the peritoneal cavity. Ectopic pregnancies usually result in loss of the fertilized ovum and in hemorrhage, putting the health of the woman at risk.
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The uterus, known as the womb, resembles an inverted pear and is located in the pelvic cavity between the rectum and the urinary bladder (Figure 14-1A and B). The uterus is a hollow organ that functions to receive and nourish a fertilized oocyte until birth. Normally, the uterus is flexed anteriorly, where it joins the vagina; however, the uterus may also be retroverted (flexed posteriorly). The pelvic and urogenital diaphragms support the uterus. The uterus consists of the following subdivisions:
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- Fundus. The rounded superior surface between the uterine tubes.
- Body. The main part of the uterus located between the uterine tubes and isthmus. The lumen of the uterus is triangular in the coronal section and continuous with the uterine tubes and vaginal canal.
- Isthmus. The narrow region between the body and the cervix.
- Cervix. The outlet that projects into the vagina. The internal os is the junction of the cervical canal and the uterine body; the external os communicates with the vaginal canal.
- Arterial supply. From branches of the internal iliac artery (uterine arteries) and aorta (ovarian arteries).
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Cervical cancer is a common form of cancer that occurs in women aged 30 to 55 years. This cancer usually arises from the epithelium that covers the cervix. The most effective method of detecting cervical cancer is by a
Papanicolaou (Pap) smear, in which cervical epithelial cells are scraped from the cervix and examined to determine if the cells are abnormal.
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The uterine tubes and uterus are covered by a layer of peritoneum on the anterior, superior, and posterior surfaces (Figure 14-1C). Inferior to the uterine tube and lateral to the uterus, the peritoneal membrane is fused into a double layer called the broad ligament.
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- Mesosalpinx. The uterine tubes course along the upper edge of the broad ligaments. This portion of the broad ligament is called the mesosalpinx.
- Suspensory ligament of the ovary. The ovarian arteries and veins course between the double layers of the broad ligament. This portion of the broad ligament is called the suspensory ligament.
- Round ligament. The round ligament is a fibrous cord that courses from the uterus through the deep inguinal ring and inguinal canal, exits the superficial inguinal ring, and attaches to the labia majora. The round ligament courses between the double layers of the broad ligament.
- Ovarian ligament. This ligament is a fibrous cord that connects the ovary to the uterine body.
- Mesovarium. The ovary is partially covered by a separate posterior fold of the broad ligament called the mesovarium.
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The vagina serves as the inferior region of the birth canal. It also serves as the passageway for the sloughed endometrium that results from menstruation and is the receptacle for the penis during sexual intercourse. The recesses between the cervix and the vaginal wall are known as the fornices. The vascular and lymphatic supply for the vagina is as follows (Figure 14-2A and B):
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- Vascular supply. Receives blood supply from the vaginal branches of the uterine artery and the internal iliac artery.
- Lymphatic drainage. Lymph drains in two directions. The lymphatics from the upper region drain into the internal iliac nodes. Lymphatics from the lower region of the vagina drain into the superficial inguinal nodes.
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The deep perineal space is located between the superior and inferior fascia of the urogenital diaphragm (Figure 14-2C and D). The urogenital diaphragm stretches between the paired pubic rami and the ischial rami. The urethra and the vagina pierce the urogenital diaphragm. The urogenital diaphragm consists of the deep transverse perineal muscle and the internal urethral sphincter, both of which are covered by fascia (superior and inferior fascia of the UG diaphram). The perineal branch of the internal pudendal nerve innervates both muscles. The space also contains the internal pudendal vessels and the pudendal nerve.
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Superficial Perineal Space
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The superficial perineal space is the region inferior and parallel to the urogenital diaphragm (Figure 14-2C and D). The superior boundary is the inferior fascia of the urogenital diaphragm. The inferior boundary is the superficial perineal (Colles') fascia. The superficial perineal space contains the ischiocavernosus, bulbospongiosus, and the superficial transverse perineal muscles (Figure 14-2C).
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- Ischiocavernosus muscle. Covers the inferior surface of the corpus cavernosum (the crus of the clitoris) and is innervated by the perineal branch of the pudendal nerve.
- Bulbospongiosus muscle. Arises from the perineal body and inserts into the corpus spongiosum. The perineal branch of the pudendal nerve innervates the bulbospongiosus muscle. This muscle compresses the erectile tissue of the vestibular bulbs and constricts the vaginal orifice.
- Superficial transverse perineal muscle. Attaches to and supports the perineal body. The perineal branch of the pudendal nerve innervates the superficial perineal muscle.
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The perineal body is a fibromuscular mass located at the center of the perineum, between the anus and vagina. The perineal body serves as an attachment site for the superficial and deep perineal muscles and the bulbospongiosus, levator ani, and external anal sphincter muscles.
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The follow structures form the external genitalia of the female reproductive system (Figure 14-2A):
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- Mons pubis. A rounded area superficial to the pubic symphysis containing adipose tissue.
- Labia majora. Paired longitudinal ridges of skin that are inferior and posterior to the mons pubis. The outer surfaces are covered with pubic hair. The round ligaments of the uterus are attached to the labia majora.
- Labia minora. Paired hairless skin ridges flanking a midline space known as the vestibule. The vestibule contains the urethra and the vagina. Flanking the vaginal opening are small greater vestibular glands, which release mucus into the vestibule that helps to keep the vagina lubricated during sexual intercourse.
- Clitoris. The junction of the labia minora folds. The clitoris consists of erectile tissue that is continuous with two crura (corpora cavernosa), and a glans. The clitoris, which is richly innervated with sensory nerve endings sensitive to touch, become engorged with blood and erect with blood during tactile stimulation, contributing to sexual arousal in the female. The female urinary and reproductive tracts are completely separate, with neither running through the clitoris. In contrast, the urethra in the male carries both urine and semen and courses through the penis.
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An
episiotomy is a surgical incision made between the posterior edge of the vagina and the perineal body to enlarge the superficial opening of the birth canal. The incision can be midline or at an angle. An episiotomy is performed to prevent random tearing of the perineal structures, particularly across the external anal sphincter during childbirth. If the external and sphincter is torn, rectal incontinence can occur.