FACTS & HINTS

High-Yield Facts

Clinical Points

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The thickness of the endometrium (vascular mucosal lining) changes throughout the menstrual cycle, undergoing thickening and shedding. Following menopause the uterus and vagina undergo atrophy

Because the upper two thirds of the vagina lie within the pelvic cavity, weakness of the pelvic floor muscles can lead to vaginal prolapse. The lumen of fallopian tubes communicates with the peritoneal cavityat its distal (ovarian) end.

The ovaryis covered onlybya thin layer of mesothelium, an extension of the mesovarium, to permit ovulation of the mature ovum into the peritoneal cavity.

Ectopic pregnancies are therefore possible within the peritoneum.

Fertilization of an ovum usuallyoccurs within the fallopian tubes at the ampulla (the widest part)

Ectopic pregnancies-implantation of a blastocyst other than in the uterine wall-can occur in the uterine tube (tubal pregnancy-most common ectopic pregnancy), into the ovary(ovarian pregnancy-rare) or into the abdominal wall (peritoneal pregnancy-veryrare)

Blockage of the uterine tubes as the result of disease is a common cause of infertility

Clinical Points

Cervical Cancer

Common between age 40 and 60 years

Was the leading cause of death of women in the United States until 1940, when detection of malignancies and premalignant conditions was made possible bythe development of Pap (Papanicolaou) smears.

Risk factors include: earlysexual activity, multiple sexual partners, human papillomavirus infection, and smoking Eighty-five percent to 90% are squamous cell carcinomas; 10% to 15% are adenocarcinomas

Fibroids

Benign tumors of smooth muscle cells of uterine myometrium

Occur in 30% all women

Can occur in anylocation within the uterus

Growth stimulated byestrogen and oral contraceptive pill

Symptoms usuallya result of compression effects

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37 Perineum and External Genitalia: Female

STUDYAIMS

At the end of your study, you should be able to:

Outline the general organization of the perineum

Describe the contents of the urogenital and anal triangles

Describe the central perineal tendon and perineal membrane

Outline the fascial layers and spaces of the perineum

Describe the anatomyof the clitoris, labia, and vestibule

Outline the blood supplyof the external genitalia

Outline the innervation of the female external genitalia

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GUIDE

Pelvis and Perineum: Perineum and External Genitalia: Female

[Plate 356, Female Perineum and External Genitalia (Pudendum or Vulva)]

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[Plate 358, Female Perineum and Deep Perineum]

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[Plate 359, Female Perineal Spaces]

Perineum

General organization (Same as male)

Narrow region between superior medial aspects of thigh

With lower limbs abducted in lithotomyposition, becomes a diamond-shaped area

Bounded bypelvic diaphragm superiorlyand superficial fascia and skin inferiorly

Anal canal, urethra, and vagina pass through the perineum

Boundaries:

Anteriorly: Pubic symphysis

Posteriorly: Inferior sacrum and coccyx

Anterolaterally: Ischiopubic rami

Laterally: Ischial tuberosities

Posterolaterally: Sacrotuberous ligaments

Divided into two triangles byimaginaryline between ischial tuberosities

Posteriorlyis anal triangle

Anteriorlyis urogenital triangle

Contents of the anal triangle (Same as male)

Anal canal and anus

External and internal anal sphincters

Ischiorectal fossa

Contents of urogenital triangle

Membranous and distal urethra

Vagina

Vulva (labia majora, labia minora, and clitoris)

Erectile bodies of vulva

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Central perineal tendon (perineal body) (Same as male)

Located at midpoint of the line dividing the urogenital from anal triangles

Mass of collagenous and elastic fibers

Deep to skin

Anterior to anal canal

Posterior to bulb of the penis (male) or vestibule (female)

Site of attachment for

Bulbospongiosus

Superficial transverse perineal muscles

Deep transverse perineal muscles

External anal sphincter

Fascicles of muscle from external sphincter urethrae and levator ani

Perineal membrane

Everything same as male, except

Sphincter urethrae (external urethral sphincter)

Mayexist in females

Some fibers extending to the ischiopubic rami (compressor urethrae) and some encircling the vagina as well Pierced byvagina and urethra

Fascia and spaces of the urogenital triangle

Everything same as male, except

Superficial perineal space (pouch)

Between membranous layer of superficial fascia and perineal membrane

Contains:

Crura of clitoris and associated muscles

Bulbs of vestibule and associated muscles

Superficial transverse perineal muscles

Branches of internal pudendal vessels and pudendal nerves

Greater vestibular glands

Deep perineal space (pouch)

Lies between perineal membrane and pelvic diaphragm

Ischioanal fossae extend anteriorlyinto this space

Contains:

Proximal part of urethra

External sphincter urethrae muscle

Deep transverse perineal muscles

Vessels and nerves

Female External Genitalia

Anatomical features

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Female external genitalia collectivelycalled the vulva

Female external genitalia include

Mons pubis

Labia majora

Labia minora

Clitoris

Vestibule of vagina

Bulbs of vestibule

Greater vestibular glands

Mons pubis

Fattytissue lying anterior to pubic symphysis and superior pubic rami

Skin continuous with anterior abdominal wall

After pubertyis covered with pubic hair

Labia majora

Longitudinal folds of skin containing fat, smooth muscle, and termination of round ligament of uterus

Lie on either side of pudendal cleft

Externallycontain sebaceous glands and are covered bypubic hair

Internallyare smooth and hairless

Unite anteriorlyas the anterior commissure

Form a posterior commissure posteriorly, which disappears after childbirth

Labia minora

Longitudinal folds of hairless skin without fat enclosed bylabia majora

Surrounds vestibule of vagina

Extend from clitoris around urethra and vagina

Meet anteriorlyas a small fold = frenulum of the clitoris, which passes deep to the clitoris

Posteriorlyunite as frenulum (fourchette)

Vestibule

Region enclosed bylabia minora

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Contains external urethral meatus, vaginal introitus (most inferior opening) and opening of ducts of paraurethral gland

Contains opening of ducts of greater vestibular (Bartholin's) glands One gland on either side of vestibule

Posterior to vaginal orifice

Ductal openings either side of vagina; secrete mucus during sexual arousal Contains bulbs of vestibule

Elongated masses of erectile tissue One on either side of vaginal introitus

Homologous to bulb of penis and corpus spongiosum

Clitoris

Resembles inverted 'V'

Composed of root and body, located where labia minora meet anteriorly

Lies 2 cm anterior to external urethral meatus

Bodycomposed of two crura, two corpora cavernosa, and glans clitoris

Highlyinnervated, becomes engorged during sexual arousal Prepuce of clitoris-anterior extension of labia minora

Vascular supply and innervation

[Plate 393, Nerves of Perineum and External Genitalia: Female]

Arterial supply

External pudendal arteries (branches of femoral artery)

Internal pudendal arteries

Labial and clitoral branches of internal pudendal artery

Venous drainage

Internal pudendal vein

Venae comitantes of internal pudendal artery

Lymphatic drainage

To superficial inguinal nodes

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Innervation

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Anterior labial nerves from ilioinguinal nerve

Perineal branch from posterior femoral cutaneous nerve

Posterior labial nerves from pudendal nerve

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