THE FEMALE REPRODUCTIVE TRACT

April 5, 2010

OBJECTIVES Review the anatomy of the external and

internal female reproductive tract with descriptive illustrations

Provide some clinical correlations, i.e. physiologic changes and implications

THE EXTERNAL FEMALE GENITALIA

VULVA OR PUDENDA

from the mons pubis anteriorly to the rectum posteriorly and from one lateral genitocrural fold to the other

keratinized, stratified squamous epithelium; becomes thicker, more pigmented, and more keratinized as the distance from the vagina increases

Mons Pubis (mons veneris) fat-filled cushion; directly anterior and superior

to the symphysis pubis rounded eminence that becomes hairy after

puberty; escutcheon is triangular, but may vary due to genetic and racial differences A diamond (male) pattern can be found in one of four

women

Labia Majora two large, longitudinal,

cutaneous folds of adipose and fibrous tissue.

approximately 7 to 8 cm in length and 2 to 3 cm in width; extend from the mons pubis anteriorly to become lost in the skin between the vagina and the anus in the area of the posterior fourchette

Skin: pigmented and covered with hair follicles - inner surface does not have hair follicles but has many sebaceous glands.

Usually the labia atrophy after menopause. The labia majora are homologous to the scrotum in the male.

Labia Minora (nymphae) small, red cutaneous folds

situated between the labia majora and the vaginal orifice

more delicate, shorter, and thinner than the labia majora

Divide anteriorly at the clitoris to form the prepuce superiorly and inferiorly the frenulum of the clitoris

Histologically composed of dense connective tissue with erectile tissue and elastic fibers, rather than adipose tissue.

Skin: less cornified and has many sebaceous glands but no hair follicles or sweat glands

relatively more prominent in children and postmenopausal women

homologous to the penile urethra and part of the skin of the penis in males.

Clitoris short, cylindrical, erectile

organ at the superior portion of the vestibule

normal adult glans clitoris has a width less than 1 cm, with an average length of 1.5 to 2 cm

Size affected by previous childbearing NOT age, weight, and oral contraceptive

glans: distal one third; has many nerve endings

consists of a base of two crura, attached to the periosteum of the symphysis pubis;

Body: has two cylindrical corpora cavernosa composed of thin-walled, vascular channels that function as erectile tissue

The clitoris is the female homologue of the penis in the male.

Vestibule the lowest portion of the

embryonic urogenital sinus; the cleft between the labia minora visualized when the labia are held apart

extends from the clitoris to the posterior fourchette

Fossa navicularis posterior portion of the

vestibule between the fourchette and the vaginal opening

Urethra membranous conduit for

urine In females: measures

3.5 to 5 cm in length; distal orifice: 4-6mm in

diameter proximal two thirds:

mucosa composed of stratified transitional epithelium

distal one third: stratified squamous epithelium and the mucosal edges grossly appear everted.

Skene's Glands (paraurethral glands) branched, tubular glands adjacent to the distal

urethra; usually run parallel to the long axis of the

urethra for approximately 1 cm before opening into the distal urethra, or may open into the area just outside the urethral orifice

the largest of the <paraurethral> glands; many smaller glands are also present

homologous to the prostate in the male.

Bartholin's Glands vulvovaginal glands located

beneath the fascia at about 4 and 8 o'clock, on the posterolateral aspect of the vaginal orifice

about the size of a pea; open into a groove between the hymen and the labia minora

Histologically composed of cuboidal epithelium, with ducts lined by transitional epithelium approximately 2 cm in length.

Homologous to Cowper's glands in the male

http://upload.wikimedia.org/wikipedia/commons/b/b8/Skenes_gland.jpg

Vestibular Bulbs two elongated masses of erectile tissue on either

side of the vaginal orifice immediately below the bulbocavernosus muscle;

the distal ends of the vestibular bulbs are adjacent to Bartholin's glands

homologous to the bulb of the penis in the male

Hymen a thin, usually perforated membrane at the

entrance of the vagina variations in the structure and shape of the

hymen

histologically covered by stratified squamous epithelium on both sides, with fibrous tissue and a few small blood vessels

carunculae myrtiformes: tags, or nodules, of firm fibrous material; remnants of the hymen identified in adult females.

VAGINA

Vagina a thin-walled, distensible,

fibromuscular tube that extends from the vestibule of the vulva to the uterus.

The walls of the vagina are normally in apposition and flattened in the anteroposterior diameter; but the potential space of the vagina is larger in the middle and upper thirds.

held in position by the surrounding endopelvic fascia and ligaments

Upper portion close to the horizontal plane

when a woman is standing supported by the upper

portions of the cardinal ligaments and the parametria

Middle portion supported by the levator ani

muscles and the lower portion of the cardinal ligaments

Lower portion in close relationship with

the urogenital and pelvic diaphragms

Rugae numerous transverse folds,

prominent in the lower third, in reproductive age women; provide accordion-like distensibility

Fornices spaces between the cervix and

attachment of the vagina; the posterior fornix is considerably larger than the anterior fornix, thusa anterior vaginal length ~6 to 9 cm posterior vaginal length ~8 to 12

cm

Histology: composed of four distinct layers:

Mucosa: stratified, nonkeratinized squamous epithelium May become keratinized Similar to the exocervix, but has larger and more

numerous papillae does not normally have glands

Lamina propria (tunica): fibrous connective tissue collagen and elastic tissue, with a rich supply of

vascular and lymphatic channels The muscular layer: many interlacing fibers; with an

inner circular layer and an outer longitudinal layer Cellular areolar connective tissue: large plexus of

blood vessels.

VASCULAR SUPPLY Arterial supply: extensive

anastomotic network throughout the vaginal length vaginal artery: originates

either directly from the uterine artery or as a branch of the internal iliac artery

may be multiple on each side of the pelvis

with an anastomosis with the cervical branch of the uterine arteries azygos arteries

Also has contributions from the internal pudendal, inferior vesical, and middle hemorrhoidal

Venous drainage: complex, accompanies the arterial system

Pudendal veins: principal drainage below the pelvic floor

Vaginal, uterine, vesical veins, as well as those around the rectosigmoid, provide drainage of the venous plexuses surrounding the middle and upper vagina

Lymphatics characterized by wide distribution

and frequent crossovers between the right and left sides of the pelvis

Upper third of the vagina: external iliac nodes

Middle third of the vagina: common and internal iliac nodes

Lower third: complex and variable distribution, including the common iliac, superficial inguinal, and perirectal nodes

NERVE SUPPLY The nerve supply of the vagina comes from

the autonomic nervous system's vaginal plexus, and sensory fibers come from the pudendal nerve.

Pain fibers: enter the spinal cord in sacral segments two to four;

With a paucity of free nerve endings in the upper two thirds of the vagina

PERINEUM Pelvic diaphragm

forms the inferior border of the abdominopelvic cavity; composed of a broad, funnel-shaped sling of fascia and muscle

it extends from the symphysis pubis to the coccyx and from one lateral sidewall to the other

the primary muscles of the pelvic diaphragm are the levator ani and the coccygeus

Urogenital Diaphragm also called the triangular ligament; a strong, muscular

membrane that occupies the area between the symphysis pubis and ischial tuberosities

external and inferior to the pelvic diaphragm

suspends the urethra from the pubic bone by continuations of the fascial layers

the free edge of the diaphragm is strengthened by the superficial transverse perineal muscle

inserts posteriorly into the central point of the perineum

Perineal Body the median raphe of the levator ani, between the

anus and the vagina, reinforced by the central tendon of the perineum.

the bulbocavernosus, superficial transverse perineal, and external anal sphincter muscles also converge on the central tendon

CLINICAL CORRELATIONS Susceptibility to infection, especially along the

intertriginous areas

Changes post-menopause

Bartholin’s duct cyst – most common enlarged cyst of the vulva; abscess and urethral diverticula formation

Vulvar trauma, i.e. due to saddle injuries or childbirth and the blood supply

Continuity between the labia majora, mons pubis, and anterior abdominal wall via the subcutaneous tissue

CLINICAL CORRELATIONS The posterior fornix as an important surgical landmark

The distal course of the ureter as an important consideration in vaginal surgery, and the anatomic proximity and interrelationships of the vascular and lymphatic networks of the bladder and vagina

Gartner's duct cyst (cystic dilation of the embryonic mesonephros) vs. large urethral diverticula

Vaginal lubrication during intercourse and the rich vascularization of the organ

The anatomic relationship between the long axis of the vagina and other pelvic organs when altered by pelvic relaxation, i.e. from the trauma of childbirth

Atrophy or weakness of the endopelvic fascia and the development of a cystocele, rectocele, or enterocele. rare complication : massive hemorrhage from the inferior gluteal or pudendal

arteries

REFERENCES Katz et al. (2007). Comprehensive

Gynecology, 5th ed.

Cunningham et al. Williams Obstetrics, 22nd edition.