Female Pelvis and Perineum

The muscles, nerves, and vessels of the female perineum are almost identical with those of the male, with 4 major differences:

(1) the vagina pierces the urogenital diaphragm
(2) the urethra is in the anterior wall of the vagina
(3) the clitoris does not contain any part of the urethra
(4) the embryonic labioscrotal and urogenital folds remain unfused and form the labia majora and minora, respectively

Vulva – general term for female external genitalia

Mons pubis – fatty protuberance anterior to the pubic symphysis (gets fatty during puberty, less so after menopause)

Labia majora – paired folds of skin filled with fat – provide protection for the opening of the vestibule of the vagina

Labia minora – thin paired delicate folds of hairless skin, medial and internal to the labia majora

contain a core of spongy tissue with many small blood vessels but no fat; contain sebaceous and sweat glands
meet superior to the clitoris to form the prepuce (clitoral hood); meet inferiorly to clitoris to form the frenulum of the labia minora

Vestibule of the Vagina – space enclosed by the labia minora

the urethra, vagina, and the ducts of the greater vestibular (Bartholin’s) glands open into the vestibule
the paraurethral glands and their ducts are located on either side of the urethral opening

Clitoris – female erectile organ; homologous to penis, although it has neither a corpus spongiosum nor a urethral segment

highly sensitive; it will enlarge with tactile stimulation and is very important in the sexual arousal of the female
the clitoris contains a root and a body consisting of two deep crura, two corpus cavernosa and a centrally located glans

Bulbs of the Vestibule – 3cm elongated masses of erectile tissue along each side of the vaginal orifice

Innervation – nerves to the vulva include branches of ilioinguinal, genital branch of the genitofemoral, perineal branch of femoral cutaneous nerve of the thigh, and the perineal nerve (off the pudendal)

Pelvic Viscera

Ureters – travel on the lateral wall of the pelvis minor and are crossed superiorly by the uterine arteries

passes close to the fornix of the vagina and enters the posterosuperior angle of the bladder

Urinary Bladder – similar to the male except the path of the urethra is shorter and takes it to the vestibule of the vagina

blood supply is from the vaginal arteries (recall that male bladder is supplied by vesicular arteries)

Urethra – shorter than in the male; the external urethral orifice is located in the vestibule of the vagina

superior ½ corresponds to male prostatic urethra, inferior ½ corresponds to the male membranous urethra
the paraurethral glands (Skene's glands), homologous to the male prostate, are located on either side of the external urethral orifice

Vagina – muscular tube about 9.5 cm long, posterior to the bladder in the midline

vagina communicates with the outside of the body at the vestibule and with the uterus at the cervix

fornices – grooves that surround the cervix; posterior fornix is anterior to the rectum and close to the retrounterine pouch
vaginal walls contain muscles: pubovaginalis, bulbspongiosus, deep transversus perinei, and sphincter urethae

Uterus – located immediately superior the vagina; normally bent forward

external os – cervical opening of the vagina

internal os – inside the uterus at the point at which the isthmus widens out into the body

fundus – the rounded superior portion of the uterus between where the uterine tubes enter on either side at the horns

Uterine tubes – muscular tubes that extend laterally from the uterus in the peritoneal cavity – divided into four parts

(1) infundibulum (most distal) – contains finger-like fimbrae

(2) ampulla – where fertilization takes place

(3) isthmus – where the tubes enters the horn

(4) uterine part – where the tubes pass through the myometrium (intramural)

Ovaries – almond shaped glands (3cm x 1.5cm x 1cm) that are located close to the pelvic walls

smooth in pre-adolescents but get progressively irregular with ovulation
surface of the ovaries in not covered by peritoneum; during ovulation, the oocyte is expelled into the peritoneal cavity where it is trapped by the fimbrae of the uterine tubes

Peritoneal Folds

Vesicouternine pouch – lies between the urinary bladder and the uterus

Retrouterine pouch – between the uterus and the rectum; separated from the posterior fornix of the vagina by thin tissue

Broad ligament – the peritoneal fold that invests the uterus and attaches it to the lateral body wall – several parts:

Round ligament – embedded in the broad ligament and is attached to the superior aspect of the uterus

Mesosalpinx – the part of the broad ligament that invests the uterine tube

Mesometrium – invests the uterus

Mesovarium – invests the ovaries

Suspensory ligament of the ovary – contains the ovarian vessels, suspends the ovary from the lateral wall

Ligament of the ovary – attaches the ovary to the uterus.

there are peritoneal folds on the anterior abdominal wall, just as in the male

Lymphatics – external genitalia drain locally to the inguinal nodes, uterus to the internal iliac, ovary to abdominal nodes

Female vs. Male Pelvis – female pelvis is modified to allow childbirth

female hips are wider than male (greater trochanters of femur stick out more); females also have a broader pubic body
ischial spines and sacrum are oriented so as not to be in the way of the birth canal

Childbirth – episiotomy is a surgical incision made to control tearing of the perineum during childbirth

damage to perineum can result in uterine prolapse, cystocele (urinary bladder prolapse) and rectocele (rectal prolapse)