# A Critical Introduction to Human Sexuality

Lead Author(s): Nicole McNichols, Matt Numer

A modern, comprehensive and research-based exploration of human sexuality that incorporates real life perspectives on contemporary issues.

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## Comparison of Human Sexuality Textbooks

Consider adding Top Hat’s A Critical Introduction to Human Sexuality textbook to your upcoming course. We’ve put together a textbook comparison to make it easy for you in your upcoming evaluation.

### Top Hat

Nicole McNichols, Matthew Numer, “A Critical Introduction to Human Sexuality”, Only One Edition needed

### Oxford Press

Baldwin, Janice & John Baldwin & Simon LeVay, Discovering Human Sexuality (3rd ed.)

### McGraw-Hill

Hyde, Janet and John DeLamater, Understanding Human Sexuality (13th ed.)

### Pearson

Hock, Roger R., Human Sexuality (4th ed.)

### Pricing

Average price of textbook across most common format

#### $67.95 E-book ####$169.95

Hardcover print text only

#### $90 E-book ####$180

Hardcover print text only

E-book

E-book

#### $180 Hardcover print text only ### Pearson Hock, Roger R., Human Sexuality (4th ed.) ####$199.95

Hardcover print text only

## Always up-to-date content, constantly revised by community of professors

Constantly revised and updated by a community of professors with the latest content

### Top Hat

Nicole McNichols, Matthew Numer, “A Critical Introduction to Human Sexuality”, Only One Edition needed

### Oxford Press

Baldwin, Janice & John Baldwin & Simon LeVay, Discovering Human Sexuality (3rd ed.)

### McGraw-Hill

Hyde, Janet and John DeLamater, Understanding Human Sexuality (13th ed.)

### Pearson

Hock, Roger R., Human Sexuality (4th ed.)

## In-book Interactivity

Includes embedded multi-media files and integrated software to enhance visual presentation of concepts directly in textbook

### Top Hat

John Redden & Joe Crivello, Human Physiology, Only One Edition needed

### Oxford Press

Baldwin, Janice & John Baldwin & Simon LeVay, Discovering Human Sexuality (3rd ed.)

### McGraw-Hill

Hyde, Janet and John DeLamater, Understanding Human Sexuality (13th ed.)

### Pearson

Stuart Fox, Human Physiology (14th ed.)

## Customizable

Ability to revise, adjust and adapt content to meet needs of course and instructor

### Top Hat

John Redden & Joe Crivello, Human Physiology, Only One Edition needed

### Oxford Press

Baldwin, Janice & John Baldwin & Simon LeVay, Discovering Human Sexuality (3rd ed.)

### McGraw-Hill

Hyde, Janet and John DeLamater, Understanding Human Sexuality (13th ed.)

### Pearson

Hock, Roger R., Human Sexuality (4th ed.)

## All-in-one Platform

### Top Hat

John Redden & Joe Crivello, Human Physiology, Only One Edition needed

### Oxford Press

Baldwin, Janice & John Baldwin & Simon LeVay, Discovering Human Sexuality (3rd ed.)

### McGraw-Hill

Hyde, Janet and John DeLamater, Understanding Human Sexuality (13th ed.)

### Pearson

Hock, Roger R., Human Sexuality (4th ed.)

#### Nicole McNichols, Ph.DUniversity of Washington

Nicole McNichols is a lecturer in the Department of Psychology at the University of Washington in Seattle, where she also received her PhD in Social Psychology. Over the past five years, Nicole has built her class, The Diversity of Human Sexuality, into the University of Washington’s largest and most popular undergraduate course with over two thousand enrolled students each year. Nicole is frequently a guest lecturer and speaker regarding topics in human sexuality. She was at the forefront of the University of Washington’s push to adopt and develop active learning techniques and technologies to bring scientific subject matter to life in the classroom. Nicole is an active member of a variety of societies for teaching human sexuality and was recently the keynote speaker at the University of Washington’s Psychology graduation. Nicole received her BA from Cornell University and her MA from NYU.

#### Matthew Numer, Ph.DDalhousie University

Matthew Numer is an Assistant Professor in the School of Health and Human Performance at Dalhousie University and cross-appointed to the Gender and Women’s Studies Program. He has been funded by the Canadian Institutes of Health Research for his work in the areas of gender, sex and sexuality. His research interests include substance use, gay, bisexual and other men who have sex with men’s health, sexual health, online technologies, LGBTQ2S health, masculinities, Indigenous boys’ and men’s health, and post-secondary pedagogical practices. He has received numerous awards for his interactive teaching methods and is widely known as an innovator in the classroom. He is the former Chair of the Nova Scotia Rainbow Action Project, was a member of the board of directors for the Halifax Sexual Health Centre for eight years, and currently serves on the AIDS Coalition of Nova Scotia: Gay Men’s Health Advisory Committee.

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# Chapter 4: Female Sexual Anatomy

## 4.1 Learning Objectives

By the end of the chapter, you should be able to:

• Identify the location and function of the female reproductive/sexual structures, including the Vulva, Vagina, Uterus, Cervix, Oviducts and Ovaries and Breasts.
• Understand the G-spot and related topics.
• Attain an understanding of female sexual health, including types of common cancers and other illnesses.

## 4.2 Getting to Know the Female Body

Many people in western culture are too embarrassed to discuss their genitals or learn how they function. At best, this leads to ignorance and at worst, to feelings of fear or even disgust toward one's own body. Unfortunately, this can be especially true of females, who may have been taught that their genitals, like their sexuality, should always remain private and safe from self-exploration. Keep in mind that although this chapter aims to illustrate the diversity of the female form, not all self-identified women possess the anatomy presented below. We will examine some examples of intersex and transgender bodies in Chapter Six.   ​

## 4.3 The Vulva

The external female genitalia, referred to as the vulva, include the anatomical structures related to the genitals on the outside of the body. Most people are less familiar with these than they are with male external genitalia for cultural reasons as well as because they are less protrusive and obvious. The vulva consists of the inner and outer labia, the mons, the vaginal opening, and the clitoris. Many people mistakenly call this whole area the vagina, but the vagina is a separate and entirely internal structure. There is great diversity in the appearance of females' vulvas, and this mostly has to do with the length and proportion of the inner and outer labia.

### ​4.3.1 The Labia

The labia are the two pairs of skin that fold down and around the vulva. Whereas the outer labia (or labia majora) are filled with mostly fatty tissue and contain hair on their surface, the inner labia (or labia minora) are thin, hairless and are only fully visible after parting the outer labia. Many females report that the skin on the outer labia is less sensitive to erotic touch than the inner labia, and it is also usually darker in appearance. The inner labia contain more glands, blood vessels, and nerve endings than the outer labia, making them very sensitive to erotic touch.

As illustrated in the above video, the inner labia vary tremendously in length. In some females, they are virtually absent, whereas in others, they hang well beneath the outer labia. What does culture dictate in terms of what is deemed "attractive"? Interestingly, there are huge differences. In some cultures, a practice called labia stretching exists which serves to increase the length of the inner labia. In others, females undergo medically unnecessary surgeries to make their inner labia shorter. Unfortunately, this trend has begun to show in girls as young as age nine, who, as reported in this BBC article and interview after viewing images from social media and porn, believe that their own labia are somehow imperfect or unusual. Many gynecologists report that these girls then frequently inform their doctors that they "hate" their vaginas and wish to have labiaplasty, a cosmetic surgery that shortens the length of the inner labia.

### Question 4.01

Question 4.01

What is your opinion of labiaplasty? What do you think motivates women to have this surgery?

### 4.3.2 The Mons

Residing above the labia is the mons. The mons is covered with a thin layer of fat, which functions primarily as cushioning for the female during sex. In an adult female, the mons is covered in pubic hair, which is hair that appears on the genitalia of all sexes after puberty. Scientists believe that pubic hair primarily exists to trap bacteria in the region and, in the case of females, to prevent the bacteria from entering the introitus of the vagina. There is some evidence that pubic hair also vaporizes odors from sweat glands around the pubic area that are thought to contain pheromones, which are chemical substances released by all mammals that serve to attract other mammals of the same species. Despite these properties, a recent JAMA study reported that in the U.S. 62% of females completely remove their pubic hair and 84% report doing at least "some grooming" (Rowen et al., 2016). Younger women (age 18-34), the study found, were more likely to opt for total removal. Aside from the risk of causing skin irritation, there is nothing problematic from a medical standpoint in removing pubic hair (so long as one safely does so) and many females report that it improves or enhances their sexual functioning. The notion that it somehow makes a female "cleaner" or is required for hygienic purposes, however, is medically unfounded and an unfortunate consequence of a culture that has traditionally cast female sexuality in a "dirty," shameful light. As reported by Huffington Post, in response to this, and in an apparent pubic hair removal backlash, some females, including celebrity Amber Rose, are choosing to celebrate their un-removed pubic hair in a very public manner.

### 4.3.3 The Clitoris

The inner labia meet at the back and at the front of the vulva, encircling the vestibule which contains the vaginal opening, the urethral opening, and the clitoris. The size and distance of the clitoris from the vaginal introitus varies greatly from female to female. The most visible part of the clitoris, the glans, is located directly under the clitoral hood, which resides at the front of the vestibule where the inner labia meet. The shaft of the clitoris runs up from the glans toward the clitoral hood and can be felt although not easily seen. Similar to the penis, the glans and shaft becomes engorged with blood and erect during sexual arousal. The erectile tissue inside the glans is known as the corpus spongiosum and is responsible for making the size of the clitoris expand during sexual arousal. The erectile tissue within the shaft of the clitoris is composed of two corpora cavernosa, which operate to make the clitoris erect during sexual arousal. Descending downwards and back from the clitoral shaft are the crura (singular "crus"), which are approximately three inches long and give the clitoris a wishbone-like structure. The crura wrap partially around the urethra. The vestibular bulbs are curved masses residing beneath the crura. Like the glans, they are composed of corpus spongiosum tissue that becomes erect during sexual arousal. The erection of the vestibular bulbs helps to lengthen and stiffen the vagina during sexual arousal. Whereas the clitoral glans, hood, and shaft are all external, the crura and vestibular bulbs are considered to be the internal structures of the clitoris.

The clitoris is packed with sensory nerve fibers and its only function is to provide sexual pleasure. Stimulation of the clitoris is the typical way most females achieve orgasm. Its' erection involves both its inner and outer structures. (There is quite a bit of diversity in clitoral anatomy, however.) For some females, direct stimulation of the clitoris may feel too intense and stimulation of the clitoris through the hood is more apt to feel pleasurable. The clitoris is more erotically sensitive in its erect versus flaccid state. After orgasm, most females feel that their clitoris becomes temporarily too sensitive for touch.

Question 4.02

Historically, the clitoris was deliberately left out of most high school education classes. Did you learn about the clitoris in high school? Was it helpful? Do you wish you had learned more? Why do you think your school did or didn't teach you about the clitoris?

Unfortunately, female circumcision continues to be practiced, and at increasing rates around the world. To date,  it has impacted 80-120 million females alive today in 29 different countries. The World Health Organization (WHO) classifies female circumcision into four types: a) complete or partial excision of the clitoris, b) partial or complete excision of the inner labia together with the clitoris, c) infibulation (excision of clitoris and inner labia and subsequent fusion of the outer labia to narrow vaginal introitus, d) other genital mutilation procedures including use of corrosive substances, cauterization or piercing.

The purpose of the procedure is to suppress female responsiveness and preserve virginity. It is frequently performed by traditional "folk" practitioners who lack medical training. It carries extreme risks including infections and hemorrhaging, which can be fatal. In its extreme form, it can cause serious problems with urination, menstruation, childbirth, and intercourse. In addition, it frequently causes severe emotional distress and problems navigating relationships. Here is a an interesting look at four women's stories who were victims of female circumcision, and their journey as they sought reconstructive surgery to heal.

The practice occurs primarily in western, eastern, and north-eastern Africa, the middle east and Asia. Although it occurs in areas where Islam is the dominant religion, it has no religious basis. The African Union’s Protocol on the Rights of Women was ratified in 2005. It requires its 53 member states to prohibit female circumcision. Opponents to this law cited concerns with protecting cultural diversity.

Sadly, many females know little or nothing about the structure, function or appearance of their clitoris. It was not until 1981 that the Federation of Feminist Women's Health Clinics published anatomically correct images of the clitoris. In 2009 the first 3-D sonography of the stimulated clitoris was recorded by French researchers. Even today, it is frequently misrepresented in medical textbooks and downplayed in importance in medical fields. To combat ignorance, a social movement known as cliteracy (developed by conceptual artist Sophia Wallace) has taken root, aiming to educate people about the clitoris. As part of this movement, and as reported by The Atlantic, scientists have recently created the first 3D image of a clitoris which can be downloaded and printed for free using any 3D printer.  There is now even an interactive video game, called "Clit-Me" which can be downloaded as an app onto your phone and teaches the anatomy and functionality of the clitoris.

Question 4.03

Compared to the outer labia, the inner labia have more $\_\_\_\_\_\_\_$ and are more $\_\_\_\_\_\_\_$.

A

Nerves; erotically sensitive

B

Hair; insensitive to touch

C

Pigment; erotically sensitive

D

Porous openings; protected from irritation

Question 4.04

Which of the following is true about the mons?

A

It contains a pad of fat to provide cushioning during sex.

B

It contains pubic hair to protect the vagina from harmful bacteria.

C

It is the uppermost part of the vulva.

D

All of the above

Question 4.05

In the clitoris, the $\_\_\_\_\_\_\_$ contains corpus spongiosum and the shaft contains $\_\_\_\_\_\_\_$.

A

Vestibular bulbs; glands

B

Glans; corpus cavernosa

C

Vaginal introitus; hair

D

Inner labia; corpus spongiosum

Question 4.06

Match the part of the clitoris with its correct description.

Premise
Response
1

Glans

A

Connects to the glans to the more internal structures of the clitoris.

2

Crura

B

Becomes engorged and enlarges during sexual arousal.

3

Vestibular bulbs

C

Composed of corpus spongiosum tissue that becomes erect during sexual arousal.

4

Shaft

D

Internal structure that creates wishbone structure.

## 4.4 The Vaginal Introitus

At the rear of the vestibule is the vaginal introitus (opening). In newborn girls, this is usually covered with a membranous fold of skin called a hymen. Like vulvas, hymens come in a variety of shapes and sizes, but almost all have at least one opening that allows for the exit of menstrual blood after the onset of menses. In rare cases, a female may have an imperforate hymen, which completely covers the opening of the vagina and will have have to be surgically opened at puberty. The hymen usually stretches or even tears the first time a female has intercourse, which can sometimes lead to pain and even bleeding. The notion that the state of a female's hymen reveals her virginity is incorrect, however, because many females' hymens naturally tear during adolescence from physical activity and some females have fairly open hymens to begin with.

Question 4.07

The video "The Truth About Hymens and Sex" states that the hymen should be thought of as (a)?

A

Paper thin

B

Shielded membrane

C

Blocker

D

Balloon arch

The urethra resides between the vaginal opening and the clitoris, and its main function is to excrete urine from the bladder. It is a separate opening in the vulva exclusively for urine. This separation contrasts the male penis, which uses the same opening for urine and seminal discharge (more to come on that). The urethral opening connects to the urethra and bladder. Finally, the vaginal opening is the connecting point between the interior and exterior female genitalia. This opening, which is covered by the labia and sometimes the hymen, leads to the vaginal canal. Here is a picture of the vaginal opening.

Cystitis, also known as a urinary tract infection (UTI) can occur when E. coli bacteria invade the urethra and bladder, causing frequent, painful urination. It is often caused by irritation of the urinary meatus due to prolonged or frequent intercourse ("Honeymoon Cystitis") and also by the use of spermicides which can alter the vaginal flora, causing the proliferation of E. coli. Anal intercourse followed by vaginal intercourse can also cause UTIs.

Question 4.08

Which of the following is not a common cause of UTI infections?

A

Frequent intercourse

B

Anal intercourse followed by vaginal intercourse

C

Spermicides

D

Birth control pills

​This spotlight story discusses one person’s experience of Interstitial Cystitis. Her story focuses on diagnosing and managing this health issue in relation to sex. The Mayo Clinic provides an overview of the condition here. This story illustrates one (though there are many) conditions that can cause pain during sex.

### Question 4.09

Question 4.09

How comfortable would you be discussing a sexual function issue with a physician or other health practitioner?

### Question 4.10

Question 4.10

What factors might impact people’s ability to discuss sexual function with health care providers? Explain.

### Question 4.11

Question 4.11

If you were in a situation where your sexual function was impacting a sexual relationship, how comfortable would you be discussing it with partner(s)? Explain.

The perineum is the relatively flat area that resides between the vagina and anus and can be erotically sensitive for many females. Unfortunately, the perineum can also enable the transport of bacteria from the anus to the vagina, which is why it is recommended that females always wipe front to back.

Located on either side of the vaginal introitus are the openings to two glands called the Bartholin's gland. The Bartholin's glands are anatomically homologous to the bulbourethral glands in males and are responsible for secreting minute amounts of alkaline fluid into the vagina immediately prior to orgasm. This fluid is not the basis for vaginal lubrication, however, and its exact function is not known.

Residing beneath the vulva and connected to the deeper, internal portions of the clitoris are the pelvic floor muscles, which provide a sling that supports the pelvic organs. The pubococcygeus (PC) muscle is an especially important pelvic floor muscle that steadily contracts during sex and helps to stiffen the walls of the vagina, making them more erotically sensitive. During orgasm, the pubococcygeus muscle rhythmically contracts, producing feelings of intense pleasure. It is also believed that these contractions help to keep semen in the vagina, thereby increasing the chances of a pregnancy occurring. In addition, the pubococcygeus plays an important role in preventing urine from escaping. For all of these reasons, it is important for females to perform exercises, called Kegel exercises, to strengthen the pubococcygeus muscle, particularly after childbirth when it is naturally stretched out and weakened. Kegel exercises essentially involve repeatedly engaging the same muscle that is used to stop the flow of urine and can be done inconspicuously anytime and anywhere. In addition to helping prevent incontinence after childbirth, Kegel exercises are an excellent way to increase the intensity and pleasure of orgasm.

Question 4.12

Which of the following statements about the female hymen is correct?

A

All hymens cover the vaginal introitus to approximately the same degree.

B

The first time a female has intercourse her hymen will inevitably tear and cause bleeding.

C

Most hymens have at least one opening to allow for the passage of menstrual blood.

D

An imperforate hymen is one which is virtually absent.

Question 4.13

Strengthening of the pubococcygeus muscle leads to:

A

More intense orgasms.

B

C

Protection from uterine cancer.

D

A and B (but not C)

## 4.5 The Vaginal Canal

The main function of the vaginal canal is to provide a birth canal for a fetus and to help transport sperm up through the uterus into the oviducts to create a pregnancy. It is largely insensitive to stimulation, as it has few nerve endings. It is highly elastic, causing it to lengthen greatly during sexual arousal. In its unaroused state, the vagina is relaxed and collapsed and extends 2-4 inches up and toward the back of a female's body. Penetration of the vagina by a penis is referred to formally as coitus, or penis in vagina (PIV) sex.

### 4.5.1 The Layers of the Vagina

The vagina has three layers. The innermost layer contains a thin cellular lining called mucosa, which is responsible for producing lubrication during sexual arousal. The mucosa is surrounded by an intermediate muscular layer, which tightens in order to wrap more tightly around the penis during coitus. The outermost layer is more tough and elastic. All three layers of the vagina swell with blood during sexual arousal, producing a state called vasocongestion. The portion of the vagina that is closest to the outside of a female's body has significantly more nerves and blood vessels than the more inner portion, making it the most sexually erotic part of the vagina. Importantly, the vagina contains millions of "good" bacteria that help maintain its slightly acidic environment. This helps to prevent the growth of harmful bacteria (Ma et al., 2012). During a female's most fertile time in her cycle, the vagina becomes less acidic so as to not damage sperm as they travel through it.

The vagina is naturally self-cleaning and does so via an odorless discharge that changes in color and texture depending on where a female is in her cycle. Douching, which involves the rinsing of the vagina with various liquids, is therefore completely unnecessary and potentially harmful. By changing the PH level of the vagina, douching can allow the naturally occurring microbes in the vagina to overgrow, particularly the fungus Candida albicans. This fungus leads to a yeast infection known as candidiasis, which causes inflammation of the vaginal walls, itching and sometimes a thick, whitish discharge. Candidiasis is diagnosed by microscopic examination of the discharge and is treated with antifungal medications. Though unpleasant, candidiasis is not particularly harmful to a female's health, although repeated cases can suggest a compromised immune system. Other factors that can throw off the PH level of the vagina and cause candidiasis include stress, hormone changes related to pregnancy or birth control pills, diabetes and antibiotics.

Question 4.14

Which of the following is true regarding microbes in the vagina?

A

Attempting to remove them via douching is ineffective and unnecessary.

B

In certain amounts, they are healthy and beneficial.

C

An overgrowth of the fungus Candida Albicans can lead to yeast infections.

D

All of the above

### 4.5.2 The G-Spot

The Grafenberg spot (G-spot) was discovered by sexologist Ernst Grafenberg in the 1950s. It is located about two inches inside the vagina on the front wall (toward the female's abdomen) and can feel slightly more crinkled or rough than the surrounding area. Its stimulation can be very sexually arousing and many females find that it leads to more powerful orgasms than those brought on by clitoral stimulation.

There is some controversy regarding the G-spot with many scientists doubting its existence and others calling it a downright myth or lie (Puppo & Puppo, 2014; Hines, 2001). These researchers fear that stressing the existence of this "magical spot" will only frustrate females who search for it in vain hoping to find an easier path to orgasm. Other studies using ultrasound have claimed to have found strong supporting evidence for the G-spot, and argue it is absolutely a discrete anatomical structure (Buisson, 2010; Meston & Buss, 2009). Other studies have used vibrators to stimulate the G-spot to prove its existence as well as that of female ejaculation (Addeigo et al., 1981). There are even doctors who offer G-spot enhancement injections, although these treatments lack data to support their efficacy.

Assuming the G-spot does exist, at least in some females, there is another debate surrounding whether G-spot orgasms differ from those brought on by clitoral stimulation. As mentioned above, many females report that G-spot orgasms do differ in their intensity, and we will explore this further in future chapters. Most of the evidence suggests, however, that there is nothing distinctly different about an orgasm triggered via the clitoris versus the G-spot as both connect to the same underlying nerves and musculature.

Question 4.15

In the video "The G-Spot, Does it Exist", how many studies did the scientists cite suggesting there is no G-spot?

A

96

B

12

C

2012

D

69

Between the front wall of the vagina and the urethra are important glands known as the paraurethral glands (also known as the Skene's gland), which is anatomically comparable to the prostate gland in men. When a female has an orgasm via stimulation of her G-spot, the paraurethral glands sometimes release a fluid that is secreted from the glands into the urethra. This fluid, combined with some urine, are then pushed out of the urethral opening during orgasm in what is known as female ejaculation. The force and volume released during female ejaculation vary widely from female to female.

Although many females report with utmost certainty that the G-spot exists, some scientists believe it is a total myth.

Question 4.16

Which of the following is true regarding the G-Spot?

A

It resides on the back wall of the vagina.

B

When stimulated to orgasm, it activates the Skene's gland to release fluid.

C

It is located 6-7 inches inside the vagina.

D

When stimulated, it leads to an orgasm that is anatomically distinct from a clitoral orgasm.

## 4.6 The Anus

The anus is located behind the vagina. The anus is made up of internal and external sphincter muscles that control excretion. It is important to note that for sexual purposes, the inner sphincter is not under voluntary control. Therefore, penetrating the anus (whether male or female) requires most people to go slowly. The inner sphincter needs time to open and relax during anal intercourse. The exterior sphincter is voluntary, but many people require practice to relax this muscle during intercourse which can be achieved by bearing down. Beyond the anus, further into the body lies the rectum, which in females is located posterior to the vagina. Like the vagina, the rectum is lined with mucosa, although unlike the vagina this inner cellular lining does not produce any lubrication, making the area susceptible to tearing. Like the vagina, the outer portion of the anus has more nerves and blood vessels than the inner portion, making it more sexually erotic. Although the rectum serves to transport fecal matter out of the body, fecal matter is stored in the colon, not in the rectum. Many people, regardless of their sexual orientation, find the anus to be a highly erotic area.

## 4.7 The Uterus

Above the vagina, leading further into the female reproductive tract, is the uterus. In a non-pregnant female, the uterus is about the size and shape of an upside-down pear. It is capable of expanding to approximately 60 times that size during pregnancy.

Question 4.17

According to the video, how many layers does the vagina have?

A

3

B

2

C

1

D

4

### 4.7.1 The Layers of the Uterus

The uterus is suspended by a broad ligament in the abdominal cavity in a horizontal position, slanted slightly forward. A tipped uterus is one which slants instead toward the spine, usually as a result of genetics. In severe cases, a tipped uterus can make sex and childbirth more difficult, requiring that the uterus be repositioned via surgery. Like the vagina, it is comprised of three layers. The innermost layer is called the endometrium, which serves to help transport sperm up toward the site of fertilization and also serves as a source of nourishment for an implanted embryo. For this reason, the inner lining of the endometrium changes during a female's menstrual cycle. During the first part of a female's cycle, this lining tends to change from being thin and slippery to becoming thicker and richer. A portion of this lining is then shed during menstruation, exiting the body through the cervix and vagina. The middle layer of the uterus consists of a powerful muscular wall called the myometrium, which contracts during labor, orgasm, menstruation and occasionally ovulation. The perimetrium provides the last, outer covering of the uterus and separates it from the pelvic cavity.

Question 4.18

Match the layer of the uterus with its correct description.

Premise
Response
1

Endometrium

A

Powerful muscle that contracts during labor and orgasm.

2

Myometrium

B

Outermost part of the uterus.

3

Perimetrium

C

Innermost part of the uterus that grows increasingly thick in preparation for possible pregnancy.

### 4.7.2 The Cervix

The uterus connects downward with the vagina via the cervix. To feel her cervix, a female can insert one or two fingers deeply into her vagina. During the fertile times of her menstrual cycle, the cervix will feel soft and gently parted, almost like a pair of lips. During all other times of her cycle, it feels more firm and closed, like the tip of a nose.

### 4.7.3 Cervical Os

The cervical os refers to the portion of the cervix that connects the vagina with the cervical canal, which runs through the center of the cervix into the uterus. The cervical os contains numerous mucous glands, which excrete different types of mucus depending on where a female is in her menstrual cycle. This mucus is slightly acidic, which serves to preserve the sterile uterine environment. Immediately prior to ovulation, the cervical os excretes muscin ("fertile mucus") which is alkaline, clear, copious and stretchy, like raw egg white. The muscin facilitates the rapid transport of sperm into the uterus and oviducts, and it can allow pregnancy to occur even when sperm is deposited near (but not actually in) the vagina.

Question 4.19

Clear, stretchy, copious cervical mucus that occurs immediately prior to ovulation is called:

### 4.7.4 Cervical Cancer

The American Cancer Society predicts that in 2017 in the United States 12,820 women will be diagnosed with, and approximately 4210 women will die from, cervical cancer. Cervical cancer is 100% caused by the human papillomavirus (HPV), which is a sexually transmitted infection (STI). Fortunately, there is a vaccine that completely protects against HPV and cervical cancer called Gardasil, which we will discuss in more detail in Chapter 18. Rates of cervical cancer have declined by more than 50% in the last 40 years, due to the invention of the Pap test. During a Pap test, a small, usually plastic, spatula-like instrument is inserted through the vagina up to the cervix, where cells are gently scraped off the surface. These cells are then placed on a slide and examined by a technician for the presence for pre-cancerous lesions. Except in cases of very early detection, treatment usually involves removal of the entire uterus, as well as the cervix. Chemotherapy and/or radiation are usually prescribed as additional treatments. As discussed in Chapter 18, a vaccine is available that can prevent cervical cancer.

### 4.7.5 Endometrial Cancer

According to the American Cancer Society, endometrial cancer is the most common cancer of the female reproductive organs. ACS predicts that in 2017 in the United States 61,380 women will be diagnosed with, and 10,920 women will die from, endometrial cancer. Like cervical cancer, treatment for endometrial cancer usually involves removal of the entire uterus, and sometimes also the oviducts and ovaries when the disease is detected in later stages. Chemotherapy, radiation or both is also usually recommended.

### 4.7.6 Non-Cancerous Conditions Of The Uterus

In addition to cancer, other conditions that sometimes affect the uterus include fibroids, which are tumors of smooth muscle that tend to grow on the endometrium, in the myometrium or near the outer surface of the uterus. 20%-25% of females develop fibroids at some point in their lives; however, according to the MayoClinic, they almost never develop into cancer. When they occur, symptoms usually include pain and bleeding in the area. Often fibroids are only discovered during a routine pelvic exam. Removal of the fibroids in those cases is usually recommended, and in extreme cases, a full hysterectomy may be recommended. Another somewhat common condition of the uterus is endometriosis. This involves the growing of endometrial tissue in abnormal places, such as in the oviducts, the ovaries or other surfaces within the pelvic cavity. As this endometrial tissue grows it becomes stuck and causes pain, bleeding, and irritation to surrounding tissue. Prolapse involves the downward sagging of the uterus into the vagina and is caused by the weakening of the ligaments that support both it and the pelvic floor. In extreme cases, surgery may be required and a small ring can be inserted to help keep the uterus in place. In less severe cases, Kegel exercises can help strengthen the muscles needed to support the uterus.

Question 4.20

Match the medical condition with its correct description.

Premise
Response
1

Endometritis

A

Inner lining of the uterus begins growing in other parts of reproductive tract including the oviducts.

2

Tipped Uterus

B

Non-cancerous tumors that grow on the surface or middle layer of the uterus.

3

Cervical Cancer

C

Caused by the Human Papillomavirus Virus.

4

Fibroid

D

A uterus that is slanted toward the spine.

## 4.8 The Oviducts

At the very top of the uterus, forming a pathway between the uterus and ovaries, are two symmetrical branches called the oviducts, or fallopian tubes. Each oviduct is about four inches long and connects to one ovary. Oviducts are lined with cells called cilia, which are tiny, hairlike structures that function to push the ovum (egg) along as it makes its way toward the uterus.  Although these cilia push in the opposite direction from that in which sperm try to travel, they usually do not offer a serious impediment to sperm.

As the oviducts approach the ovaries, each widens into a flared opening with fingerlike extensions, known as fimbria. Although the fimbria brush against the ovaries, they are not attached to them. The fimbria are lined with cilia that gently sweep the ovum into the oviducts, where fertilization usually occurs.

In a normal pregnancy, the fertilized ovum will travel down the oviducts into the uterus before implanting in the endometrial lining. Occasionally, however, especially when an infection is present, the embryo may get stuck and implant in the lining of the oviduct, causing an ectopic pregnancy.  Since the oviducts are not designed to support a developing embryo, sharp pain and bleeding usually result, and termination of the pregnancy will be required to prevent rupturing and serious damage to the female.

## 4.9 The Ovaries

The ovaries are two round structures each measuring about 1.5 inches in diameter. Ovaries and men's testicles are about the same size and shape, and both are considered gonads since they produce ova or sperm as well as sex hormones. These sex hormones include estrogens, androgens, and progestins and are secreted in a complex sequence which guides the stages of the menstrual cycle. (We will discuss this sequence in great detail when we discuss fertility in a later chapter.) Each ovary contains a number of follicles, and inside each follicle is an ovum, or egg cell, surrounded by fluids and supporting cells. Each individual ovum bears an X chromosome, unlike sperm, which have either an X or Y chromosome. In addition to follicles, ovaries contain theca and granulosa cells, both of which produce sex steroids.

During the menstrual cycle, a group of follicles will all start to develop, or ripen. Finally, one (usually) follicle ripens fully and releases its ovum into the oviducts in a process called ovulation. After discharging its ova, the remaining follicle then becomes a corpus luteum and assumes sex steroid production. The remaining follicles (that didn't fully ripen) then disintegrate and are reabsorbed by the body.

Unlike sperm, which are constantly regenerated, girls are born with their lifetime supply of ova. Most females are born with about a million ova in each ovary. This supply slowly declines as a female ages. During her reproductive life, a female usually releases one ova per cycle, from either ovary, meaning that the vast majority of a female's eggs never make it to the point of ovulation. Ovaries do not trade off turns ovulating in perfect order each month - it is a random process where, on average, each ovary ovulates 50% of the cycles.

Question 4.21

Which of the following is not a sex hormone produced by the ovaries?

A

Estrogen

B

Androgens

C

Progestins

D

Oxytocin

## 4.10 The Breasts

The breasts (or mammary glands) are considered to be a secondary sex characteristic in that they only appear after puberty but are not directly part of the reproductive system. (Pubic hair is another example of a secondary sex characteristic.) Breast tissue resides between the skin and muscle of the chest wall and in some cases, expands up toward the armpits. Like all other parts of female sexual anatomy, breasts vary considerably in size and shape from female to female, and often from left side to right side. Occasionally, males have a certain amount of breast tissue that may resemble a female breast but usually lacks the functionality to produce milk.

Each breast consists of approximately 15-20 lobes (lobules) that contain clusters of alveoli. Each alveolus is lined with glandular cells, whose chief function is to produce milk during times when a female is lactating (usually following childbirth). To exit the breast, an infant's sucking triggers the mother's breast to "let down" milk, whereby it travels from the alveoli down through ducts that connect to the nipple and then out of the mother's body via multiple ducts in the nipple. There is no relationship between breast size and the ability to produce milk. Even females with very small breasts have plenty of glandular tissue to breastfeed an infant.

Typically, each breast contains one nipple that is situated in a circular patch of darker skin known as the areola. Nipples may become erect from sexual arousal and also cold. Occasionally, however, both females and males may have extra nipples, which are usually located between the breast and the armpit, or else the abdomen. Many females have sparse hair growing around the areola.

Many people, especially in Western culture, place a huge emphasis on the sexual nature of breasts. Stimulation of the breasts or nipples via touching or kissing, in the right context, can be highly erotic. There is great diversity, however, in how females respond to having their breasts stimulated. In some females, breast stimulation is extremely pleasurable and can even directly cause orgasm. For other females, the reaction is indifference. Sometimes, females may even dislike having their breasts touched,  such as after childbirth when they are breastfeeding and may feel as if their breasts are already overstimulated. Other females find that their breasts are especially tender and don't want to be touched at certain times during their menstrual cycle, or as a side effect from taking the birth control pill.

Western culture also places a giant emphasis on the idea of large breasts being more sexually erotic than smaller breasts, causing many females to fear that their own breasts are too small or are otherwise inadequate. This causes many females to pursue elective surgeries to augment or change the look of their breasts, in hopes of bringing their bodies into alignment with the ideals pushed onto them by the media and society.

UK-based photographer Laura Dodson gives an excellent overview of the variety of breast shapes and sizes in her project, "Bare Reality." in which she photographs over 100 females' breasts. Dodson explains “We see images of breasts everywhere, but they’re unreal. They create an unflattering comparison but also an unobtainable ideal. I wanted to rehumanize women through honest photography.”

Question 4.23

In each breast, there are 15-20 lobes, each of which contains clusters of $\_\_\_\_\_\_\_$ lined with $\_\_\_\_\_\_\_$ which produce milk.

A

Glandular cells; alveoli

B

Alveoli; glandular cells

C

Cilia; mucosa cells

D

Mucosa cells; cilia

### 4.10.1 Breast Cancer

The American Cancer Society estimates that in 2017 in the United States, 252,710 new cases of invasive breast cancer will be diagnosed in females and that  40,610 females will die from the disease. Based on these numbers, one in eight American females will be diagnosed with breast cancer in their lifetime.

Breast cancer starts when cells in the breast begin to grow out of control and start to form a tumor in the breast. Most breast lumps are not cancer and are benign, meaning that they are not abnormal growths and will not spread outside of the breast. The lump (tumor) is malignant (causing cancer) if the cells can grow into (invade) surrounding tissues or spread (metastasize) to distant areas of the body. Breast cancers typically begin in the ducts that carry milk to the nipple; however, some start in the lobes, which are the glands that make breast milk. Symptoms usually include a lump in the breast, discharge from the nipple, and/or reddened, wrinkled skin on the breast. If left unchecked, breast cancer can easily move into the lymph nodes and soon spread to other parts of the body.

The high occurrence of breast cancer makes early detection important. Learning to do a self-exam of your own or your partner's breast at mid-cycle to detect lumps is critical. (See the video below for how to perform a self-exam.) Mammograms, which involve taking an X-ray of the breast to detect tumors are typically recommended beginning at age 40.

Breast cancer treatment usually involves a lumpectomy or mastectomy, which includes removal of part or all of the breast tissue. Radiation, chemotherapy and hormone therapy are usually also recommended to kill off any remaining cancer cells.

Question 4.24

Which of the following is not a symptom of breast cancer?

A

Reddened skin on the breast

B

Discharge leaking from the nipple

C

Hair around the areole

D

A lump in the breast

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## 4.11 References

Berg, R. C., Underland, V., Odgaard-Jensen, J., Fretheim, A., & Vist, G. E. (2014). Effects of female genital cutting on physical health outcomes: a systematic review and meta-analysis. BMJ Open, 4(11). doi:10.1136/bmjopen-2014-006316

Carroll, J. L. (2012). Sexuality now: embracing diversity(4th ed.). Belmont, CA: Wadsworth Publishing.

Chung, K. W., PhD, & Chung, H. M., MD. (2012).Gross anatomy (7th ed.). Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins.

Farage, M. A., & Maibach, H. I. (2016). The vulva anatomy, physiology, and pathology. New York, NY: Informa Healthcare.

Foldes, P., & Buisson, O. (2009). REVIEWS: The Clitoral Complex: A Dynamic Sonographic Study.The Journal of Sexual Medicine, 6(5), 1223-1231. doi:10.1111/j.1743-6109.2009.01231.x

Ginger, V. T. (2011). Chapter 2: Functional Anatomy of the Female Sex Organs. In J. P. Mulhall, L. Incrocci, I. Goldstein, & R. Rosen (Authors), Cancer and Sexual Health (pp. 13-23). New York, NY: Springer Publishing.

Levay, S., Baldwin, J., & Baldwin, J. (2015). Discovering human sexuality (3rd ed.). Oxford, UK: Oxford University Press.

Lloyd, E. (2005). The Case of the Female Orgasm: Bias in the Science of Evolution. Cambridge, MA: Harvard University Press.

Lloyd, J., Crouch, N. S., Minto, C. L., Liao, L., & Creighton, S. M. (2005). Female genital appearance: ‘normality’ unfolds. BJOG: an International Journal of Obstetrics and Gynaecology, 112, 643-646. Retrieved November 29, 2017, from http://www.newviewcampaign.org/userfiles/file/BJOG%2005-normal-genitalia.pdf

Momoh, C. (2005). Female Genital Mutilation. In C. Momoh (Author), Female Genital Mutilation (pp. 5-12). London, UK: Radcliffe Publishing.

Morris, D. (2007). The naked woman: a study of the female body. New York, NY: Macmillan.

Nzegwu, N. (2011). 'Osunality' (or African eroticism). In S. Tamale (Author), (pp. 253-270). Oxford, UK: Pambazuka Press.

O'Connell, H. E., Sanjeevan, K. V., & Hutson, J. M. (2005). Anatomy of the clitoris. The Journal of Urology, 174(4), 1189-1195.

Puppo, V. (2011). Anatomy of the Clitoris: Revision and Clarifications about the Anatomical Terms for the Clitoris Proposed (without Scientific Bases) by Helen O’Connell, Emmanuele Jannini, and Odile Buisson. ISRN Obstetrics and Gynecology2011, 261464. http://doi.org/10.5402/2011/261464

Sundahl, D. (2003). Female ejaculation & the G-spot: Not your mother's orgasm book! Alameda, CA: Hunter House.

Telleen, S. (2016, February 11). The Female Reproductive System. Retrieved November 29, 2017, from http://cnx.org/contents/Rxiox2r4@1/The-Female-Reproductive-System

World Health Organization. (1998). Female genital mutilation: an overview. Geneva, CH: World Health Organization.

## 4.12 Answers to Discussion Question

Many students will report that labioplasty is an unfortunate reflection of pressures put on young women by society, in particular the porn industry, to look a certain way. Other students may feel that labioplasty empowers a woman to feel good about herself physically and that women should not feel ashamed doing something that makes her feel more confident.

Answers will vary but should include a discussion of experiences (or lack thereof) discussion sexual issues with physicians.

Answers may vary but may include discomfort in talking about sex generally, health care providers level of comfort/knowledge, inability to express concerns and more.

Answers will vary but may include their own level of comfort in acknowledging the issue. May also discuss partner’s level of comfort.

## 4.13 Image Credits

[1] Image courtesy of Lamilli in the Public Domain.

[2] Image courtesy of Labioplasty under CC BY-SA 3.0.

[3] Image courtesy of Wikipicturesxd under CC BY-SA 4.0.

[4] Image courtesy of Hic et nunc under CC BY-SA 3.0.

[5] Image courtesy of Bebop7 under CC BY-SA 3.0.