FEMALE REPRODUCTIVE ANATOMY AND REPRODUCTIVE FUNCTION doc

21
FEMALE REPRODUCTIVE ANATOMY
The female reproductive system is composed of the external and
internal genitalia. The external genitalia (Fig. 2-1) are collectively
termed the pudendum or vulva and are directly visible.
The internal genitalia include the vagina, cervix, uterus, uter-
ine (fallopian) tubes, and ovaries (Figs. 2-2 and 2-3). Special in-
struments are required for inspection of the internal genitalia. Sim-
ple specula or other instruments allow direct visualization of the
vagina and cervix, but the intraabdominal group can be inspected
only by invasive methods (laparotomy, laparoscopy, or culdoscopy)
or by sophisticated imaging techniques (ultrasonography, CT scan,
or magnetic resonance imaging).
EXTERNAL GENITALIA
MONS PUBIS (MONS VENERIS)
The mons veneris, a rounded pad of fatty tissue overlying the
symphysis pubis, develops from the genital tubercle. It is not an
organ but a region or a landmark. Coarse, dark hair normally ap-
pears over the mons early in puberty. During reproductive life,
the pubic hair is abundant, but after the menopause, it becomes
sparse. The normal female escutcheon is typically a triangle with
the base up, in contrast to the triangle with the base down pat-
tern in males.
The skin of the mons contains sudoriferous and sebaceous
glands. The amount of subcutaneous fat is determined by heredity,
age, nutritional factors, and possibly, steroid hormone factors.
2
FEMALE REPRODUCTIVE
ANATOMY AND REPRODUCTIVE
FUNCTION
CHAPTER

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FIGURE 2-1. External female genitalia.
BENSON & PERNOLL’S
22 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
Innervation
The sensory nerves of the mons are the ilioinguinal and gen-
itofemoral nerves.
Blood and Lymph Supply
The mons is supplied by the external pudendal artery and vein. The
lymphatics merge with those from other parts of the vulva and from
the lower abdomen. The crossed lymphatic circulation of the labia
within the mons is clinically important because it permits metasta-
tic spread of cancer from one side of the vulva to the inguinal glands
of the opposite as well as to the affected side.
FIGURE 2-2. Internal female genitalia (superior view).
Clinical Importance
Dermatitis is common in the pubic area, and it is important to ob-
serve closely if infestation with Phthirus pubis (lice, crabs) is sus-
pected. Edema can occur secondary to infections, vulvar varicosi-
ties, trauma, or carcinomatous infiltration of the lymphatics. Cancer
elsewhere in the vulva also can involve the mons.
LABIA MAJORA
In the adult female, these two raised, rounded, longitudinal folds of
skin are the most prominent features of the external genitalia. They
are homologous to the male scrotum. They originate from the gen-
ital swellings extending posteriorly and dorsally from the genital
tubercle. From the perineal body, they extend anteriorly around the
labia minora to merge with the mons. The labia normally are closed
in nulliparous women but later open progressively with succeeding
vaginal deliveries and become thin and atrophic with sparse hair in

later life.
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FEMALE REPRODUCTIVE ANATOMY
23
BENSON & PERNOLL’S
24 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
The skin of the lateral surfaces of the labia majora is thick and
often pigmented. It is covered with coarse hair similar to that of the
mons. The skin of the inner labia majora is thin and contains no
hairs. The labia majora are made up of connective and areolar tis-
sue, with many sebaceous glands. A thin fascial layer similar to the
tunica dartos of the scrotum is present within the labia just below
the surface. The round ligament of the uterus passes through the in-
guinal canal (canal of Nuck) to end in a fibrous insertion in the an-
terior portion of the labia majora.
Small and large coiled subcutaneous sweat glands are situated
all over the body except beneath mucocutaneous surfaces, that is,
the labia minora or vermilion border of the lips. Normally, the fluid
secretion of small coiled (eccrine) sweat glands, which have no re-
lationship to hairs, has no odor. Large coiled (apocrine) sweat
glands that open into hair follicles are found over the mons, the
labia majora, and the perineum as well as the axilla. These glands,
which begin to secrete an odorous fluid at puberty, are more active
during menstruation and pregnancy. The sweat glands are controlled
by the sympathetic nervous system.
FIGURE 2-3. Internal female genitalia (midsagittal view).
Sebaceous glands are associated with and open into hair folli-
cles. On the labia minora, where hairs are absent, however, seba-
ceous glands open on the surface. At puberty, an oily secretion with
a slight odor is produced. The fluid lubricates and protects the skin

from irritation by vaginal discharge. Gland secretion is mediated by
hormonal and psychic stimuli. The activity of the sebaceous glands
diminishes in older women.
Innervation
Anteriorly, the labia majora are supplied by the ilioinguinal and pu-
dendal nerves. Laterally and posteriorly, they are innervated by the
posterior femoral cutaneous nerve.
Blood Supply
The labia majora are supplied by the internal pudendal artery (de-
rived from the anterior parietal division of the internal iliac or hy-
pogastric artery) and by the external pudendal artery (from the
femoral artery). Drainage is via the internal and external pudendal
veins.
Clinical Importance
The labia majora serve no special function. A cyst of the canal
of Nuck often is mistaken for an indirect inguinal hernia. Adher-
ence of the labia in infants may indicate vulvitis. External force
or the complications of labor can cause vulvar hematoma. Hidrade-
nomas are tumors that originate in aprocrine sweat glands, but
they become malignant only rarely. Sebaceous cysts, almost
invariably benign but often infected, develop from sebaceous
glands.
LABIA MINORA
The labia minora are small, narrow, elongated folds of skin between
the labia majora and the vaginal introitus. They are derived from
the skin folds beneath the developing clitoris. Normally, the labia
minora are in apposition in nulliparas, concealing the introitus. Pos-
teriorly, the labia minora merge at the fourchette. The labia are sep-
arate from the hymen, the structure marking the vaginal entrance,
or introitus. Anteriorly, each labium merges into a median ridge that

fuses with its mate to form the clitoral frenulum, an anterior fold
that becomes the prepuce of the clitoris.
The lateral and anterior surfaces of the labia minora usually are
pigmented. Their inner aspect is pink and moist, resembling the
vaginal mucosa.
The labia minora have neither hair follicles nor sweat glands
but are rich in sebaceous glands.
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FEMALE REPRODUCTIVE ANATOMY
25
BENSON & PERNOLL’S
26 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
Innervation and Blood Supply
The innervation of the labia minora is via the ilioinguinal, puden-
dal, and hemorrhoidal nerves. The labia minora are not truly erec-
tile, but a generous vasculature permits marked turgescence with
emotional or physical stimulation. They are supplied by the exter-
nal and internal pudendal arteries and veins.
Clinical Importance
The labia minora tend to close the introitus. They increase in size
in response to ovarian hormonal stimulation. Indeed, without es-
trogen stimulation, they all but disappear. Squamous cell carcinoma
of the vulva often originates in the labia, as do sebaceous cysts. The
presence of adherent labia minora in the infant is usually due to
inflammation. Fusion, however, may indicate sexual maldifferenti-
ation.
CLITORIS
This 2–3 cm long homolog of the penis is found in the midline
slightly anterior to the urethral meatus. It is composed of two small,
erectile corpora, each attached to the periosteum of the symphysis

pubis, and a diminutive structure (glans clitoridis) that is gener-
ously supplied with sensory nerve endings. The glans is partially
hooded by the labia minora.
Innervation and Blood Supply
The clitoris is supplied by the hypogastric and pudendal nerves,
pelvic sympathetics, and by the internal pudendal artery and vein.
Clinical Importance
Cancer of the clitoris is rare, but it is extremely serious because of
problems of wide extension and early metastases. The inguinal and
femoral nodes usually are involved first.
VESTIBULE AND
URETHRAL MEATUS
The triangular area between the labia minora anteriorly onto which
the urethra opens, bounded posteriorly by the vaginal orifice, is the
vaginal vestibule. It is derived from the urogenital sinus and is cov-
ered by delicate stratified squamous epithelium.
The urinary meatus is visible as an anteroposterior slit or an
inverted V. Like the urethra, it is lined by transitional epithelium.
The vascular mucosa of the meatus often pouts or everts. This
makes it appear more red than the neighboring squamous vaginal
mucosa.
Innervation and Blood Supply
The vestibule and terminal urethra are supplied by the pudendal
nerve and by the internal pudendal artery and vein.
Clinical Importance
Urethral caruncles, as well as squamous cell or transitional cell car-
cinoma, can develop in the urethrovestibular area.
PARAURETHRAL GLANDS
(SKENE’S GLANDS)
Immediately within the urethra, on its posterolateral aspect, are two

small orifices leading to the shallow tubular ducts or glands of
Skene, which are wolffian duct remnants. The ducts are lined by
transitional cells and are the sparse equivalent of the numerous male
prostate glands.
Innervation and Blood Supply
Like the vestibule and urethral meatus, Skene’s glands are supplied
by the pudendal nerve and by the internal pudendal artery and vein.
Clinical Importance
Skene’s glands, which supply minor amounts of mucus, are espe-
cially susceptible to gonococcal infection, which may be first evi-
dent here. After successful antigonorrheal therapy, nonspecific in-
fection with other purulent organisms is common and results in
recurrent skenitis. Destruction of the duct using electrocautery or
laser may be necessary.
PARAVAGINAL OR VULVOVAGINAL
GLANDS AND DUCTS
(BARTHOLIN’S GLANDS
AND DUCTS) AND HYMEN
Just external to the hymen are paravaginal, vulvovaginal glands, or
Bartholin’s glands, the counterpart of Cowper’s glands in the male.
On either side are two tiny apertures. A narrow duct, 1–2 cm long,
connects each of these apertures with a small, flattened, mucus-
producing gland that lies between the labia minora and vaginal wall.
The hymen is a thin, moderately elastic barrier that usually partially
but rarely completely occludes the vaginal canal. It is an incomplete
double-faced epithelial plate covering a matrix of fibrovascular tissue.
Innervation and Blood Supply
The hymen and area of the Bartholin’s glands are supplied by the
pudendal and inferior hemorrhoidal nerves, arteries, and veins.
CHAPTER 2

FEMALE REPRODUCTIVE ANATOMY
27
BENSON & PERNOLL’S
28 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
Clinical Importance
Bartholinitis can occur with sexually transmitted diseases, espe-
cially gonorrhea, and an abscess of Bartholin’s duct can require mar-
supialization.
A tight hymen can result in painful intercourse (dyspareunia),
in which case, hymenotomy or dilatation will be required. The rem-
nants of the lacerated hymen following intercourse or delivery are
called carunculae hymenales (myrtiformes). Hymenal or perineal
scars also can cause dyspareunia.
PERINEAL BODY, FOURCHETTE,
AND FOSSA NAVICULARIS
The perineal body includes the skin and underlying tissues between
the anal orifice and the vaginal entrance. The perineal body is sup-
ported by the transverse perineal muscle and the lower portions of
the bulbocavernosus muscle.
The labia minora and majora converge posteriorly to form a
low ridge called the fourchette. Between this fold and posterior
to the hymen is a shallow depression termed the fossa navicu-
laris.
Innervation and Blood Supply
These structures are supplied by the pudendal and inferior hemor-
rhoidal nerves, arteries, and veins.
Clinical Importance
The perineal body or fourchette often is lacerated during childbirth
and can require repair. Because of vascularity, an early or deep epi-
siotomy can result in the loss of several hundred milliliters of blood.

Faulty repair can be followed by dyspareunia or by reduced sexual
satisfaction.
INTERNAL GENITALIA
VAGINA
The vagina (Fig. 2-3) is a thin, muscular, partially collapsed rugose
canal 8–10 cm long and about 4 cm in diameter. It extends from
the hymen at the urogenital cleft to the cervix and curves upward
and posteriorly from the vulva. The cervix protrudes several cen-
timeters into the upper vagina to form recesses called the fornices.
The posterior fornix is usually deeper than the anterior fornix. The
lateral fornices are similar in size. The vaginal dimensions are reduced
during the climacteric, and all fornices, especially the lateral ones,
become more shallow.
The vagina lies between the urinary bladder and the rectum and
is supported principally by the transverse cervical ligaments (car-
dinal ligaments) and the levator ani muscles.
The peritoneum of the posterior cul-de-sac (pouch of Douglas)
is closely approximated to the posterior vaginal fornix, a detail of
surgical importance.
The vagina is lined by stratified squamous epithelium, which is
thick and folded transversely in nulliparas. Many of these rugae are
lost with repeated vaginal delivery and after the menopause. Nor-
mally, no glands are present in the vagina.
Innervation and Blood Supply
The nerve supply to the vagina is via the pudendal and hemor-
rhoidal nerves and the pelvic sympathetic system (Fig. 2-4). The
blood supply is from the vaginal artery (a descending branch of the
uterine artery) and from the middle hemorrhoidal and internal pu-
dendal arteries. It is drained by the pudendal, external hemor-
rhoidal, and uterine veins.

CHAPTER 2
FEMALE REPRODUCTIVE ANATOMY
29
FIGURE 2-4. Arteries and nerves of female genitalia.
BENSON & PERNOLL’S
30 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
The lymphatic drainage of the lower vagina is via the superfi-
cial inguinal nodes; that of the upper vagina is to the presacral, ex-
ternal iliac, and hypogastric nodes. This is important in vulvo-
vaginal infections and cancer spread.
Clinical Importance
Vaginal discharge is common and can be due to local or systemic
disorders. Infections of the lower reproductive tract are the most
common cause of leukorrhea. Estrogen depletion (senile or atrophic
vaginitis) and estrogen or psychic stimulation are other causes.
Primary cancer of the vagina is very rare, but secondary spread from
cervical cancer is not uncommon.
CERVIX
The cervix of the nonpregnant uterus (Fig. 2-3) is a conical, mod-
erately firm organ about 2–4 cm long and some 2.5 cm in outside
diameter, with a central, spindle-shaped canal. About half the length
of the cervix is supravaginal and close to the bladder anteriorly.
Childbirth lacerations account for most cervical distortions. The
external os, which is initially round and only a fraction of a cen-
timeter in diameter, may gape and be much longer as a result of
these tears. Even in the absence of distortions, however, it is cus-
tomary to refer to the cervix as having anterior and posterior lips.
The cervix is supported by the uterosacral ligaments and trans-
verse cervical ligaments (cardinal ligaments).
The intravaginal portion of the cervix is covered by stratified

squamous cells, which usually extend to approximately the exter-
nal os. The cervical canal is lined by secretory columnar epithe-
lium. The juncture of these two epithelia is variable and is subject
to continual revision under the influence of infections, hormones,
and trauma. The countless crevices that give the cervical canal a
honeycombed appearance on transverse section are infoldings of
the mucus-secreting membrane.
Excluding the epithelial covering and the cervical canal, the
cervix is composed of approximately 85% connective tissue and
15% smooth muscle fibers that join the uterine myometrium above.
The anatomic structure of the cervix undergoes marked alteration
during pregnancy, labor, and delivery.
Innervation and Blood Supply
Innervation of the cervix is via the second, third, and fourth sacral
nerves and the pelvic sympathetic plexus (Fig. 2-4). The right and
left cervical artery and vein, major branches of the uterine circula-
tion, carry most of the blood to and from the cervix.
Clinical Importance
The red appearing, more friable columnar epithelium over the endo-
cervix is responsible for ectropion and may contribute to postcoital
bleeding and infection. Additionally, the squamocolumnar junction is
the site of Ͼ90% of squamous cell carcinomas of the cervix. Cervi-
cal cancer is the second most common female genital malignant neo-
plastic disease. (Endometrial cancer is the most common.) Cervical
infection may be a contributor to infertility. Leukorrhea often is due
to inflammation of the mucus-secreting membrane.
UTERUS
The uterus (Figs. 2-2 and 2-3) is an inverted, pear-shaped muscu-
lar organ with a narrow central cavity situated deep in the true pelvis
between bladder and rectum. The central cavity, which is lined by

endometrium, is roughly triangular with the base up and is markedly
compressed in the anterior-posterior. Each of the upper apices is
connected to an oviduct, and the lower apex merges with the cer-
vical canal.
The uterine tubes join the uterus, one on either side, about two
thirds of the distance to the top of the uterus. That portion of the
uterus above the tubal insertion is called the fundus. Below the in-
sertion is the body (corpus) of the uterus, which is continuous with
the supravaginal segment of the cervix. In contrast to the cervix,
the uterine substance (myometrium) is 85% smooth muscle and only
15% connective tissue. Except for the anteroinferior portion of the
corpus, which is invested by the bladder, the uterus is covered by
peritoneum.
The adult nonpregnant uterus weighs about 90 g and is about
7–8 cm long and about 4 cm in its widest diameter. However, con-
siderably larger sizes and increased weight occur with hormonal
stimulation and after childbirth. During pregnancy, the uterus, which
increases to weigh about 1000 g, literally balloons to accommodate
the gestation.
The uterus is supported by three paired ligaments. Uppermost
are the round ligaments, which pass from the uterine fundus ante-
rior to the uterine tube to the internal inguinal canal. Laterally on
each side from inferior to the uterine tube extending to the cervix
and attached to the pelvic side wall are the cardinal ligaments. The
uterosacral ligaments extend from each sacral attachment to the
posterior uterocervical juncture.
In the nulliparous woman, the uterus and cervix usually are di-
rected forward at almost a right angle with the long axis of the
vagina. However, 25%–35% of women normally have retroverted
or retroflexed uteri.

CHAPTER 2
FEMALE REPRODUCTIVE ANATOMY
31
BENSON & PERNOLL’S
32 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
Innervation and Blood Supply
The nerves to the uterus include the superior hypogastric plexus,
the inferior hypogastric plexus, the nervi erigentes, the common il-
iac nerves, and the hypogastric ganglion (Fig. 2-5).
The uterine artery (a terminal branch of the hypogastric) is the
primary souce of blood to the uterus, and the ovarian artery is a
contributor. The uterine artery passes anterior to the ureter lateral
to, but near, the uterocervical junction. This is a very important
anatomical land mark! The veins draining the uterus are primarily
the uterine veins and secondarily the ovarian veins.
Lymphatic drainage may be through the cervix to the external
iliac chain or via the isthmus to the lateral sacral nodes. Lymph
drainage within the round ligaments may extend to the superifical
inguinal nodes, then to the femoral, and finally, to the external il-
iac chain. Drainage through the suspensory ligament of the ovary
proceeds to the lumbar nodes along the aorta, above or below the
kidney.
Clinical Importance
The uterus performs its reproductive function with remarkable ef-
ficiency. Although menstrual problems are common, they are not
FIGURE 2-5. Parturition pain pathways. Afferent pain impulses from the
cervix and uterus are carried by nerves that accompany sympathetic fibers
and enter the neuraxis at T10, T11, T12, and L1. Pain pathways from the per-
ineum travel to S2, S3, and S4 via the pudendal nerve.
(From J.J. Bonica, The nature of pain of parturition. Clin Obstet Gynecol 1975;2:511.)

usually of uterine origin. Occasionally, congenital (e.g., subsep-
tate uterus, uterus unicollis) or acquired defects (e.g., Asherman’s
syndrome) make pregnancy difficult. With the exception of child-
birth, the uterus is infrequently subject to infection. The my-
ometrium is rarely the site of malignancy. Endometrial cancer,
however, is the most common female genital cancer. The my-
ometrium is very commonly the site of benign uterine leiomyomas
and, less frequently, is locally honeycombed by endometrium, re-
sulting in adenomyosis.
UTERINE TUBES
(FALLOPIAN TUBES)
Both uterine tubes function to convey the ova to the uterus from the
ovary. Bilaterally, these tubes lie in the peritonealized superior
border of the broad ligament termed the mesosalpinx. Each tube is
7–14 cm in length and generally is horizontal near the uterus. On
reaching the lower ovarian pole, it courses around the ovary to ter-
minate by contact with the ovarian medial posterior surface.
Each tube is divided into the isthmus, ampulla, and infundibu-
lum. The most medial segment is the isthmus. It is narrow in di-
ameter, ending its uterine intramural course with an ostium of
ϳ1 mm. More distal to the isthmus is the ampulla, which is more
tortuous and wider. The ampulla terminates distally in the funnel-
shaped infundibulum, which has as its most distal margin a series
of fingerlike diverging processes, the fimbriae. The funnel-shaped
mouth of the infundibulum, excluding the widely reaching fimbriae,
is about 3 mm in diameter and opens into the peritoneal cavity. The
infundibulum is loosely supported by the infundibulopelvic liga-
ment (suspensory ligament of the ovary).
The tubal wall consists of serous (peritoneal), subserous or ad-
ventitial (vascular and fibrous), muscular, and mucous components.

The muscular layer is composed of outer longitudinal and inner cir-
cular smooth muscle layers. The mucosa is a ciliated columnar se-
cretory epithelium arranged in longitudinal folds that become more
complex in the ampullae. Its ciliary motion is directed toward the
uterus.
Innervation and Blood Supply
The oviductal nervous supply is from the pelvic and ovarian
parasympathetic and sympathetic plexuses. The tubal blood supply
is from the tubal branch of the uterine artery and from the ovarian
branch of the uterine artery. The venous drainage is through the
tubal veins accompanying the arteries. The lymphatic drainage be-
comes retroperitoneal to the lumbar aortic nodes.
CHAPTER 2
FEMALE REPRODUCTIVE ANATOMY
33
BENSON & PERNOLL’S
34 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
Clinical Importance
Tubal pregnancy and either intraluminal (usually gonococcal or
chlamydial) or peritubal (often streptococcal) infections are the most
common clinical concerns relative to the uterine tubes. Tubal dis-
tortion from peritubal scarring by endometriosis or infection, as well
as intraluminal problems, can predispose to infertility. Tubal can-
cer is very uncommon but serious.
OVARIES
The ovaries are a pair of slightly flattened, ovoid organs that ap-
pear mottled pearly white with many surface irregularities. They lie
below the pelvic brim and are supported by the ovarian ligaments
(which extend from the uterus to the medial ovarian pole) and the
infundibulopelvic ligaments. The ovaries rest in a fossa on the pelvic

sidewall lined by peritoneum. They are bounded above by the ex-
ternal iliac vessels, below by the obturator nerve and vessels, pos-
teriorly by the ureter and uterine artery and vein, and anteriorly by
the pelvic attachment of the broad ligament. The uterine tubes are
draped over the medial surface of the ovaries.
The ovaries weigh 4–8 g each and are usually 2.5Ϫ5 ϫ
1.5Ϫ3 ϫ 0.7Ϫ1.5 cm. They are covered by a cuboidal or low colum-
nar epithelium and are divided into a medulla (consisting of nu-
merous blood vessels, lymphatics, nerves, connective tissue, and
smooth muscle) and a cortex (consisting of fine areolar stroma,
many blood vessels, and scattered epithelial cells arranged in fol-
licles).
The graafian follicles contain the oocytes, which with matura-
tion (i.e., selection for ovulation) enlarge sufficiently to protrude
visibly from the ovarian surface. When fully mature, the ovum is
released and the follicle is transformed into a corpus luteum. This,
in turn, is replaced by scar tissue (termed corpus albicans).
Innervation and Blood Supply
The ovarian nerve supply is from the lumbosacral sympathetic chain
and passes to the ovary along the ovarian artery. The ovarian ar-
tery (usually a branch of the abdominal aorta, although the left not
infrequently arises from the left renal artery) is the primary blood
supply to the ovary. However, blood is also supplied from the anas-
tomosing ovarian branch of the uterine artery. The veins follow the
arteries to form the pampiniform plexus within the mesovarium. The
right ovarian vein empties into the vena cava, whereas the left ovar-
ian vein usually enters the left renal vein. The lymphatics drain
retroperitoneally to the aortic lumbar nodes.
Clinical Importance
The principal functions of the ovaries include hormone production

and the development of ova for the achievement of pregnancy. These
functions can be interrupted by many factors. The ovaries are a fre-
quent site of benign and malignant ovarian tumors. Torsion can oc-
cur, leading to vascular insufficiency and necrosis. Ovarian infec-
tions also occur, usually in premenopausal women.
THE PELVIC FLOOR
The pelvic floor (Figs. 2-6 and 2-7) consists of muscles, ligaments,
and fascia arranged in such a manner as to support the pelvic vis-
cera; provide sphincterlike action for the urethra, vagina, and rec-
tum; and permit the passage of a term infant. It is composed of the
upper and lower pelvic diaphragms and the vesicovaginal and rec-
tovaginal septa, which connect the two diaphragms, the perineal
body, and the coccyx. Other structures contributing to the integrity
CHAPTER 2
FEMALE REPRODUCTIVE ANATOMY
35
FIGURE 2-6. Fascial planes of the pelvis.
(Modified after Netter.)
BENSON & PERNOLL’S
36 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
of the pelvic floor include the transverse cervical (cardinal or
Mackerrodt’s) ligaments and the gluteus maximus muscles.
The upper pelvic diaphragm is a musculofascial structure made
up of endopelvic fascia, the uterosacral ligaments, and the levator
ani muscles (including the pubococcygeus portion). The lower mus-
culofascial pelvic diaphragm includes the urogenital diaphragm and
the sphincter muscles at the vulvar outlet (ischiocavernosus, bul-
bocavernosus, and transverse perineal muscles).
All parts of the upper and lower musculofascial diaphragms an-
chor into the perineal body directly or indirectly, like spokes into

FIGURE 2-7. Pelvic musculature (inferior view).
the hub of a wheel or shroud lines into the ring of a parachute. For
reciprocal support, the layers of the pelvic diaphragms are inter-
woven and superimposed. They are not fixed but move upon one
another. This makes it possible for the birth canal to dilate during
passage of the fetus and to close postpartum.
The pelvic floor is perforated centrally by three tubular struc-
tures: urethra, vagina, and rectum. Each traverses the pelvic floor
at a different angle, which enhances the sphincterlike action of the
pelvic muscles.
The different tissues of the musculofascial diaphragm play an
important role in providing both support and resilience. The con-
nective tissue provides support but no recoil, the fascia gives
strength but no elasticity, the elastic tissue has resilience but little
strength, and the voluntary and smooth muscles provide stretch and
recoil but with limited tolerances.
Weakness or relaxation of the pelvic floor can be due to a neu-
ropathy or an injury during childbirth, or it can be of congenital or
involutional origin.
THE BONY PELVIS
The bony pelvis is composed of four bones, the sacrum and coccyx
(posterior) and the two innominate bones laterally and anteriorly.
The spinal column articulates (through an arthrodial joint) with the
sacrum at L5. Bilaterally, the innominate bones rest on the femurs,
articulating by enarthroses (Figs. 2-8, 2-9, 2-10, and 2-11). Within
the pelvis itself are two types of joints, a synchondrosis uniting the
two pubic bones and diarthroses between the sacrum and ilium and
between the sacrum and coccyx. The innominate bones have three
major sections: ilium, ischium, and pubis.
The ilium is composed of the upper part (ala or wing) and a

lower part (body) that forms the upper part of the acetabulum, unit-
ing with the ischium and pubis. Medially, the ala of the ilium pre-
sents a smooth concave area that anteriorly is the iliac fossa and pos-
teriorly is the iliac tuberosity (superior) and the sacral articulation
(inferior). The superior border of the ilium (crest) is bounded by the
anterior and posterior superior iliac spines and serves to attach the
following muscles: external oblique, internal oblique, transversus
(anterior two thirds), latissimus dorsi, quadratus lumborum (poste-
rior), sacrospinalis, tensor fascia latae, and sartorius muscles. The
lateral surface of the ilium provides attachments for the gluteal mus-
cles. The posterior border of the iliac is marked by the posterior por-
tion of the greater sciatic notch. Blood supply to the ilium is from
the iliolumbar, deep circumflex iliac, obturator, and gluteal arteries.
CHAPTER 2
FEMALE REPRODUCTIVE ANATOMY
37
BENSON & PERNOLL’S
38 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
The ischium has a body, superior and inferior rami, and a
tuberosity. The body joins with the ilium and pubis to form the
acetabulum. The inner surface is smooth and contiguous with the
body of the ilium (above), forming the posterior portion of the lateral
FIGURE 2-9. The bony pelvis (superior view).
FIGURE 2-8. The bony pelvis (posterior view).
wall of the true pelvis. The posterior border forms the anterior por-
tion of the greater sciatic notch. The ischial tuberosity is the most
prominent portion of the bone and is the bony portion on which the
human sits. The lesser sciatic notch occupies the posterior border
CHAPTER 2
FEMALE REPRODUCTIVE ANATOMY

39
FIGURE 2-11. The bony pelvis (inferior view).
FIGURE 2-10. The bony pelvis (anterior view).
BENSON & PERNOLL’S
40 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
of the superior ramus. The inferior ramus joins the inferior ramus of
the pubis to form the pubic arch. The ischial spine is an important
obstetric landmark, being the narrowest portion of the pelvis, and
is located along the inferior ramus. The sacrospinous ligament is
found between the ischial spine and the sacrum. The pudendal nerve
and vessels pass under the lateral portion of this ligament. Blood
comes to the ischium from the obturator, medial, and lateral cir-
cumflex arteries.
The pubis has a body and superior and inferior rami. The body
contributes to the acetabulum. The rami meet in the midline to form
the symphysis pubis, and medially this is marked by the pecten
ossis pubis, an irregular ridge. The pubic tubercle is found ϳ2 cm
from the medial edge of the superior ramus. The inferior aspect of
the superior ramus is the obturator sulcus. The pubis receives blood
from the obturator, medial, and lateral circumflex arteries.
The sacrum is formed by union of 5–6 sacral vertebrae. The
fifth lumbar articulates (and occasionally fuses) with the first sacral
vertebra. Their anterior portions form the sacral promontory. The
posterior surface of the sacrum is convex, the midline forming the
median sacral crest (fused spinal processes) and the fused laminae
of the sacral vertebrae forming a flattened area laterally. This rough
area is marked by absence of the laminae of the fifth and often, even
the fourth and third sacral vertebrae. This opening of the dorsal wall
of the sacral canal is the sacral hiatus. The lateral portions of the
sacrum (from fusion of the sacral vertebrae transverse process) ar-

ticulate with the ileum. The lower body of the fifth sacral verte-
brae articulates with the coccyx. The sacrum receives its blood sup-
ply from the middle and lateral (usually 4) sacral arteries.
The coccyx is formed by 4 (occasionally 3 or 5) coccygeal ver-
tebrae, which are most frequently fused into a single bone, and re-
ceives its blood supply from the middle sacral artery.
The bony pelvis is divided into two cavities by the iliopectineal
line of the innominate bones. The upper cavity, which is larger and
shallower, is the false pelvis, and the lower, which is smaller and
deeper, is the true pelvis.
THE PELVIC MUSCLES, THEIR NERVES
AND BLOOD SUPPLY
Muscles important to the pelvis include those of the abdomen, back,
buttock, perineum, and upper extremity. Because many of the mus-
cles have been functionally detailed in preceding portions of this
chapter, Table 2-1 summarizes their nerves and blood supply.
CHAPTER 2
FEMALE REPRODUCTIVE ANATOMY
41
TABLE 2-1
MOTOR NERVE AND BLOOD SUPPLY
TO ABDOMINAL AND PELVIC MUSCLES
Motor
Muscle Nerve(s) Blood Supply
ABDOMINAL
External oblique T7–L4 Inferior epigastric
Internal oblique T7–L4 Inferior epigastric,
deep circumflex iliac
Transversus T7–L1 Deep circumflex
abdominus iliac

Rectus abdominus T7–L1 Inferior epigastric
Pyramidalis T12 Inferior epigastric
PELVIC AND LOWER EXTREMITY
Cremasteric Genitofemoral Inferior epigastric
remnant
Psoas minor L1–L2 Lumbar branch of
ileolumbar
Psoas major L2–L3 Lumbar branch of
ileolumbar
Iliacus Femoral Iliac branch of
ileolumbar
Sartorius Femoral Muscular branch of
femoral
Rectus femoris Femoral Lateral femoral
circumflex
Vastus lateralis Femoral Lateral femoral
circumflex
Vastus medialis Femoral Femoral, profunda
femoris, popliteal
(genicular branch)
Vastus intermedius Femoral Lateral femoral
circumflex, obturator
Pectineus Femoral Medial femoral
circumflex, obturator
Gracilis Obturator Profunda femoris,
obturator, medial
femoral circumflex
(Continued)
BENSON & PERNOLL’S
42 HANDBOOK OF OBSTETRICS AND GYNECOLOGY

TABLE 2-1
(Continued)
Motor
Muscle Nerve(s) Blood Supply
Abductor longus Obturator Medial femoral
circumflex, obturator
Abductor brevis Obturator Medial femoral
circumflex, obturator
Abductor magnus Obturator, Medial femoral
sciatic circumflex,
obturator, profunda
femoris, popliteal
Biceps femoris Sciatic Profunda femoris,
popliteal
Tensor fascia latae Superior Lateral femoral
gluteal circumflex, superior
gluteal
Gluteus maximus Inferior Superior and
gluteal inferior gluteal,
profunda femoris
Gluteus medius Superior Superior gluteal
gluteal
Gluteus minimus Superior Superior gluteal
gluteal
Obturator internus Obturator Superior gluteal
internus
gemellus
superior
Gemellus superior Obturator Inferior gluteal
internus

gemellus
superior
Gemellus inferior Quadratus Inferior gluteal
femoral
gemellus
inferior
Quadratus femoris Quadratus Medial femoral
femoris circumflex
gemellus
inferior
Piriformis Superior Superior and inferior
gluteal gluteal, pudendal
CHAPTER 2
FEMALE REPRODUCTIVE ANATOMY
43
PERINEAL
Transverse Perineal Pudendal
perinaei
Bulbocavernosus Perineal Pudendal
Sphincter urethrae Perineal Pudendal
Levator ani S–4, pudendal Inferior pudendal,
inferior
hemorrhoidal,
inferior gluteal
Sphincter ani Pudendal Inferior
externus hemorrhoidal,
transverse perineal
Coccygeus Pudendal Inferior pudendal,
inferior gluteal
TABLE 2-1

(Continued)
Motor
Muscle Nerve(s) Blood Supply
MENSTRUATION
Menstruation, or normal periodic uterine bleeding, is a physiologic
function occurring only in female primates. It is basically a cata-
bolic process and is under the influence of pituitary and ovarian
hormones. Its onset, the menarche, usually occurs at age 8–13 years.
Its termination, the menopause, normally ensues at age 49–50.
However, medical (e.g., gonadotropin releasing hormone agonists),
radiation, or surgical intervention may cause artificial menopause
at an earlier age.
The interval between menstrual periods varies according to age,
physical and emotional well-being, and environment. The normal
menstrual cycle is commonly stated to be 28 days, but intervals of
24 to 32 days are considered normal unless the cycles are grossly
irregular. At both the beginning and the end of reproductive life,
the cycle is likely to be irregular and unpredictable due to failure
of ovulation. This provides a natural example of the difference be-
tween ovulatory and anovulatory menstruation. On reaching matu-
rity, approximately two thirds of women maintain a reasonably reg-
ular periodicity, barring pregnancy, stress, or illness.
BENSON & PERNOLL’S
44 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
The average duration of menstrual bleeding is 3–7 days, but
this also may vary.
The average blood loss in a normal menstrual period is ap-
proximately 35–90 mL. About three quarters of this blood is lost
during the first 2 days of the period. Women Ͻ35 years tend to lose
more blood than those Ͼ35.

Menstrual discharge contains blood, desquamated endometrial
and vaginal epithelial cells, cervical mucus, and bacteria.
Prostaglandins have been recovered from menstrual blood, together
with enzymes and fibrinolysins from the endometrium. The last pre-
vent clotting of menstrual blood unless bleeding is excessive.
Nonetheless, small fragile, fibrin-deficient vaginal clots may form
because of the presence of mucoprotein and glucose in an alkaline
moiety.
The following factors all can influence menstrual bleeding:
(1) fluctuations in ovarian hormones, pituitary hormones,
prostaglandin, and enzyme levels; (2) variability of the autonomic
nervous system; (4) vascular changes (stasis, spasm-dilatation); and
(5) other factors (e.g., unusual nutritional and psychologic states).
(Also see p. 707)
THE TYPICAL MENSTRUAL CYCLE
The menstrual cycle is mediated by complex neuroendocrine mech-
anisms. A single releasing hormone, gonadotropin-releasing hor-
mone (GnRH), has been identified for the gonadotropins follicle-
stimulating hormone (FSH) and luteinizing hormone (LH). GnRH
is produced in the hypothalamus and transmitted to the anterior pi-
tuitary (where the gonadotropins are produced) via the periportal
vascular system (Fig. 2-12).
Normal menstrual cycles are carefully regulated by go-
nadotropin secretion from the anterior pituitary into the systemic
circulation. With the onset of each cycle, follicles ready for matu-
ration are stimulated to develop by FSH. One (rarely more) out-
strips the others to form a prominent graafian follicle. Regression
of the remaining follicles then ensues. Meanwhile, estrogen is pro-
duced by the theca lutein cells of the follicles. The principal ovar-
ian estrogens are estrone (E1), estradiol (E2), and a small amount

of estriol (E3). On the eighth and ninth days of the cycle, the es-
trogen level stops rising, and LH and FSH levels begin to fluctu-
ate. On about the 14th day, a sudden LH surge triggers rupture of
the follicle and ovulation (extrusion of the ovum). Slight bleeding
occurs, and the empty follicle soon becomes filled with blood, which
clots (hemorrhagic follicle). LH and possibly, prolactin, stimulate
FIGURE 2-12. Menstrual cycle (hormones, histologic changes, and basal body temperature).
45