A p p e n d i x
A
Human Sexual
Anatomy
I
becomes engorged with blood during arousal,
causing it to increase in size—and a glans, a
f you are to understand sexual rela- highly sensitive tip, about the size of a pea
tions between individuals, you need to be ■ the urethra, the opening through which urine
aware of both the anatomy and physiology of passes from the bladder to the outside
sex and the attitudes and emotions that shape people’s ■ the vestibule, or entryway to the vagina
feelings about their own sexuality and that of others.
■ the perineum, the area between the vestibule and
In Appendix A we will consider the first of these ele-
the anus (the opening from the rectum and
ments, the anatomy and physiology of sex. We will
bowel)
look at female and male sexual anatomy and describe
the genitalia, or external reproductive parts, and then ■ the hymen, a ring of tissue that partially covers
the internal reproductive systems of each sex. the vaginal opening. The hymen contains small
blood vessels that may bleed the first time the tis-
sue is broken: at first intercourse, first insertion
of a tampon, during masturbation, or as a result
■ Female Genital Structures ■
of some accidental injury. The main internal
The external genitalia of a woman are technically re- structures of the female reproductive system are
ferred to as the vulva. The vulva is composed of the the vagina, the cervix, the uterus, the fallopian
following structures: tubes, and the ovaries (see Figure A.1).
■ the mons veneris, or pubic mound: an area of The vagina is the passageway from the uterus to
fatty tissue above the pubic bone the external genitalia. It is a potential space within a
woman’s body. Usually, the vaginal walls touch one an-
■ the labia majora (Latin for “greater lips”): two
other, but the vagina is elastic and capable of opening
rounded folds of skin and, within them, the labia
wide enough to allow a baby to pass through during
minora (or “lesser lips”)
birth. Such stretching would be extremely painful if
■ the prepuce, or clitoral hood: a fold of skin that the vagina had the same number of nerve endings as
covers the clitoris when it is not erect and is many of the structures of the vulva. Therefore, the
formed where the labia minora join vagina is not so sensitive to feeling.
■ the clitoris, which consists of an internal shaft At the top of the vagina is the cervix: the neck of
composed of erectile tissue—tissue that the uterus (cervix means “neck” in Latin). The uterus,
,A-2 Human Sexual Anatomy APPENDIX A
Fallopian
tube
Ovary
Uterus
Cervix
Bladder
Urethra Vagina
Clitoris
Hymen
Mons veneris
Vaginal orifice
Labia majora (greater lips)
Labia minora (lesser lips)
FIGURE A.1
Female urogenital system
or womb, is a cavity whose purpose is to cradle a fetus The egg released in ovulation then travels along the
until birth. Leading from the uterus are two passage- fallopian tubes to the uterus.
ways, called fallopian tubes, that connect a woman’s In preparing to receive the egg, the lining of the
uterus to her ovaries. uterus, called the endometrium, thickens with a layer
Ovaries are female gonads, or sex glands. of tissue and blood (see Figure A.2). This tissue can
Women have two ovaries, one on each side of their nourish an embryo during the early stages of preg-
bodies. They produce reproductive cells (ova, or eggs) nancy if the egg becomes fertilized during its passage
and two female sex hormones: estrogen and proges- from the ovaries. When fertilization does not occur,
terone. Ordinarily, the ovaries alternate in producing the egg and the unused endometrial tissue and blood
one ovum per month, in a process called ovulation.1 are discarded during menstruation.2
2. Menstruation occurs in monthly cycles, ranging from about
twenty-one to thirty-five days. Travel, anxiety, illness, extreme ath-
1. Sometimes, women produce more than one egg at a time. This is letic activity, or change in diet can make menstrual periods more or
one way that twins or higher multiples are conceived. less frequent.
, F E M A L E G E N I TA L S T R U C T U R E S A-3
Fallopian tube
Ovary
Uterine lining
Uterus
Mature ovum
Immature ova
a Vagina
Blood and other fluids
Uterine lining thickens
Ovum is released (ovulation)
b Vagina
Blood and other fluids
Lining continues to thicken
Ovum’s journey through tube
c Vagina
Disintegration of
unfertilized ovum;
Menstruation occurs
(uterine lining sloughs
off and is discharged from
body in menstrual fluid)
d Vagina
FIGURE A.2
The menstrual cycle: (a) During the early part of the cycle, an ovum matures in an
ovary; the endometrium, or uterine lining, begins to thicken. (b) About fourteen days
after the onset of the last menstruation, a mature ovum is released; the endometrium
is thick and spongy. (c) The ovum travels through one of the fallopian tubes; blood
and other fluids engorge the uterine lining. (d) If the ovum is not fertilized, the endo-
metrium breaks down and sloughs off in a form of bleeding (menstruation).
, A-4 Human Sexual Anatomy APPENDIX A
Bladder
Seminal vesicle
Prostate gland
Penis
Urethra
Corona
Glans Perineum
Meatus
Frenum Scrotum Testis
FIGURE A.3
Male urogenital system
■ Male Genital Structures ■ the penis, which rests against the scrotum, is the
frenum, the place where the foreskin is or was con-
The external male genitalia are the penis and the scro- nected to the penis. The frenum, even more than the
tum (see Figure A.3). Like the female clitoris, the penis corona, is sensitive to tactile stimulation.
is composed of an erectile shaft and a sensitive tip, or When a man is not sexually aroused, his penis
glans. The glans is especially sensitive to touch at the is flaccid. When erect, penises vary somewhat in size
corona: a crownlike ridge at its base. If a male has not and are usually about six inches in length and about
been circumcised, the glans is covered by a thin mem- an inch and a half in diameter. The urethra runs
brane, the foreskin, when his penis is not erect. In cir- through the penis and carries male reproductive cells
cumcision, this foreskin is removed.3 On the side of and urine, though never at the same time.4 This open-
3. In the United States, circumcision is commonly performed and the
procedure is done shortly after a male baby’s birth. For some—par- assessment of the advantages and disadvantages of circumcision.
ticularly Jews and Muslims—circumcision is an important religious “It is legitimate for the parents to take into account cultural, reli-
or cultural ritual. gious, and ethnic traditions, in addition to medical factors, when
Conclusions about whether there are significant health or hy- making this choice” (American Academy of Pediatrics 1999).
giene benefits to circumcision have varied over the years (Haas and As circumcision has become less routine, rates have declined. In
Haas 1993, p. 99; Greenberg, Bruess, and Haffner 2002, pp. 143– 1999, only 65 percent of male infants were circumcised, compared
145). Current thinking is that “the medical benefits aren’t as com- to 90 percent in the 1970s. White rates, which had been much
pelling as once believed” (Blecher 2001). Also, beginning in the higher than those of other racial/ethnic groups, have almost con-
1970s, the circumcision of male babies has been challenged by verged with black rates now (66% of white baby boys and 64% of
those who argue—with some research evidence—that there is black babies were circumcised in 1999). Circumcision is less com-
enough pain to pose a psychological trauma to the infant (Green- mon for Latino or Asian babies (Blecher 2001; Rubin 2001; U.S.
berg et al. 2002, pp. 142–145; Blecher 2001). National Center for Health Statistics 2002). Some Jews have
In 1999 the American Academy of Pediatrics ceased recom- adopted a substitute circumcision ritual in which there is no actual
mending circumcision as a medically advantageous routine proce- surgery performed (Blecher 2001).
dure. Instead, it is AAP policy that parents should determine what 4. A man’s urethra cannot carry urine while his penis is erect because
is in the best interest of the child. Parents should be given accurate erection automatically blocks the opening from his bladder to his
information and then make an individual decision based on their urethra.
A
Human Sexual
Anatomy
I
becomes engorged with blood during arousal,
causing it to increase in size—and a glans, a
f you are to understand sexual rela- highly sensitive tip, about the size of a pea
tions between individuals, you need to be ■ the urethra, the opening through which urine
aware of both the anatomy and physiology of passes from the bladder to the outside
sex and the attitudes and emotions that shape people’s ■ the vestibule, or entryway to the vagina
feelings about their own sexuality and that of others.
■ the perineum, the area between the vestibule and
In Appendix A we will consider the first of these ele-
the anus (the opening from the rectum and
ments, the anatomy and physiology of sex. We will
bowel)
look at female and male sexual anatomy and describe
the genitalia, or external reproductive parts, and then ■ the hymen, a ring of tissue that partially covers
the internal reproductive systems of each sex. the vaginal opening. The hymen contains small
blood vessels that may bleed the first time the tis-
sue is broken: at first intercourse, first insertion
of a tampon, during masturbation, or as a result
■ Female Genital Structures ■
of some accidental injury. The main internal
The external genitalia of a woman are technically re- structures of the female reproductive system are
ferred to as the vulva. The vulva is composed of the the vagina, the cervix, the uterus, the fallopian
following structures: tubes, and the ovaries (see Figure A.1).
■ the mons veneris, or pubic mound: an area of The vagina is the passageway from the uterus to
fatty tissue above the pubic bone the external genitalia. It is a potential space within a
woman’s body. Usually, the vaginal walls touch one an-
■ the labia majora (Latin for “greater lips”): two
other, but the vagina is elastic and capable of opening
rounded folds of skin and, within them, the labia
wide enough to allow a baby to pass through during
minora (or “lesser lips”)
birth. Such stretching would be extremely painful if
■ the prepuce, or clitoral hood: a fold of skin that the vagina had the same number of nerve endings as
covers the clitoris when it is not erect and is many of the structures of the vulva. Therefore, the
formed where the labia minora join vagina is not so sensitive to feeling.
■ the clitoris, which consists of an internal shaft At the top of the vagina is the cervix: the neck of
composed of erectile tissue—tissue that the uterus (cervix means “neck” in Latin). The uterus,
,A-2 Human Sexual Anatomy APPENDIX A
Fallopian
tube
Ovary
Uterus
Cervix
Bladder
Urethra Vagina
Clitoris
Hymen
Mons veneris
Vaginal orifice
Labia majora (greater lips)
Labia minora (lesser lips)
FIGURE A.1
Female urogenital system
or womb, is a cavity whose purpose is to cradle a fetus The egg released in ovulation then travels along the
until birth. Leading from the uterus are two passage- fallopian tubes to the uterus.
ways, called fallopian tubes, that connect a woman’s In preparing to receive the egg, the lining of the
uterus to her ovaries. uterus, called the endometrium, thickens with a layer
Ovaries are female gonads, or sex glands. of tissue and blood (see Figure A.2). This tissue can
Women have two ovaries, one on each side of their nourish an embryo during the early stages of preg-
bodies. They produce reproductive cells (ova, or eggs) nancy if the egg becomes fertilized during its passage
and two female sex hormones: estrogen and proges- from the ovaries. When fertilization does not occur,
terone. Ordinarily, the ovaries alternate in producing the egg and the unused endometrial tissue and blood
one ovum per month, in a process called ovulation.1 are discarded during menstruation.2
2. Menstruation occurs in monthly cycles, ranging from about
twenty-one to thirty-five days. Travel, anxiety, illness, extreme ath-
1. Sometimes, women produce more than one egg at a time. This is letic activity, or change in diet can make menstrual periods more or
one way that twins or higher multiples are conceived. less frequent.
, F E M A L E G E N I TA L S T R U C T U R E S A-3
Fallopian tube
Ovary
Uterine lining
Uterus
Mature ovum
Immature ova
a Vagina
Blood and other fluids
Uterine lining thickens
Ovum is released (ovulation)
b Vagina
Blood and other fluids
Lining continues to thicken
Ovum’s journey through tube
c Vagina
Disintegration of
unfertilized ovum;
Menstruation occurs
(uterine lining sloughs
off and is discharged from
body in menstrual fluid)
d Vagina
FIGURE A.2
The menstrual cycle: (a) During the early part of the cycle, an ovum matures in an
ovary; the endometrium, or uterine lining, begins to thicken. (b) About fourteen days
after the onset of the last menstruation, a mature ovum is released; the endometrium
is thick and spongy. (c) The ovum travels through one of the fallopian tubes; blood
and other fluids engorge the uterine lining. (d) If the ovum is not fertilized, the endo-
metrium breaks down and sloughs off in a form of bleeding (menstruation).
, A-4 Human Sexual Anatomy APPENDIX A
Bladder
Seminal vesicle
Prostate gland
Penis
Urethra
Corona
Glans Perineum
Meatus
Frenum Scrotum Testis
FIGURE A.3
Male urogenital system
■ Male Genital Structures ■ the penis, which rests against the scrotum, is the
frenum, the place where the foreskin is or was con-
The external male genitalia are the penis and the scro- nected to the penis. The frenum, even more than the
tum (see Figure A.3). Like the female clitoris, the penis corona, is sensitive to tactile stimulation.
is composed of an erectile shaft and a sensitive tip, or When a man is not sexually aroused, his penis
glans. The glans is especially sensitive to touch at the is flaccid. When erect, penises vary somewhat in size
corona: a crownlike ridge at its base. If a male has not and are usually about six inches in length and about
been circumcised, the glans is covered by a thin mem- an inch and a half in diameter. The urethra runs
brane, the foreskin, when his penis is not erect. In cir- through the penis and carries male reproductive cells
cumcision, this foreskin is removed.3 On the side of and urine, though never at the same time.4 This open-
3. In the United States, circumcision is commonly performed and the
procedure is done shortly after a male baby’s birth. For some—par- assessment of the advantages and disadvantages of circumcision.
ticularly Jews and Muslims—circumcision is an important religious “It is legitimate for the parents to take into account cultural, reli-
or cultural ritual. gious, and ethnic traditions, in addition to medical factors, when
Conclusions about whether there are significant health or hy- making this choice” (American Academy of Pediatrics 1999).
giene benefits to circumcision have varied over the years (Haas and As circumcision has become less routine, rates have declined. In
Haas 1993, p. 99; Greenberg, Bruess, and Haffner 2002, pp. 143– 1999, only 65 percent of male infants were circumcised, compared
145). Current thinking is that “the medical benefits aren’t as com- to 90 percent in the 1970s. White rates, which had been much
pelling as once believed” (Blecher 2001). Also, beginning in the higher than those of other racial/ethnic groups, have almost con-
1970s, the circumcision of male babies has been challenged by verged with black rates now (66% of white baby boys and 64% of
those who argue—with some research evidence—that there is black babies were circumcised in 1999). Circumcision is less com-
enough pain to pose a psychological trauma to the infant (Green- mon for Latino or Asian babies (Blecher 2001; Rubin 2001; U.S.
berg et al. 2002, pp. 142–145; Blecher 2001). National Center for Health Statistics 2002). Some Jews have
In 1999 the American Academy of Pediatrics ceased recom- adopted a substitute circumcision ritual in which there is no actual
mending circumcision as a medically advantageous routine proce- surgery performed (Blecher 2001).
dure. Instead, it is AAP policy that parents should determine what 4. A man’s urethra cannot carry urine while his penis is erect because
is in the best interest of the child. Parents should be given accurate erection automatically blocks the opening from his bladder to his
information and then make an individual decision based on their urethra.
