Porth's Essentials of Pathophysiology, 4e

1019

Disorders of the Female Genitourinary System

C h a p t e r 4 0

majus; the uterosacral ligaments , which run from the uterocervical junction to the sacrum; and the cardinal or transverse cervical ligaments, which are attached to the side of the uterus (Fig. 40-4). The wall of the uterus is composed of three layers: the perimetrium, the myometrium, and the endometrium. 2 The perimetrium, or outer serosal layer, is derived from the abdominal peritoneum. This outer layer merges with the peritoneum that covers the broad ligaments. Anteriorly, the perimetrium is reflected over the blad- der wall, forming the vesicouterine pouch ; posteriorly, it extends to form the rectouterine pouch (see Fig. 40-1). Because of the proximity of the perimetrium to the uri- nary bladder, a bladder infection often causes uterine symptoms, particularly during pregnancy. The myometrium , or middle muscle layer of smooth muscle fibers, forms the major portion of the uterine wall. It is continuous with the muscle layer of the uterine tubes and the vagina. The smooth muscle also extends into the ligaments connected to the uterus. The inner fibers of the myometrium run in various directions, giv- ing it an interwoven appearance. Contractions of these muscle fibers help to expel menstrual flow and the prod- ucts of conception during miscarriage or childbirth. The endometrium , or inner mucosal layer of the uterus, is continuous with the epithelial lining of the uterine tubes and vagina. It is actively involved in the menstrual cycle, differing in structure with each stage of the cycle (to be discussed). If conception occurs, the products of conception are implanted in this layer; if conception does not occur, the inner surface of this layer is shed through menstruation. The round cervix forms the neck of the uterus. The opening, or os, of the cervix forms a pathway between the vagina and the uterus. The vaginal opening is called

Fundus of uterus

Uterine horn

Uterotubal junction

Uterine tube

Uterine cavity Perimetrium Myometrium Endometrium

Body

Internal os Cervical canal

Isthmus

External os

Fornix of vagina

Supravaginal part Vaginal part

Cervix

Vagina

Vaginal orifice

Vestibule of vagina

FIGURE 40-3. Median section of the vagina and uterus. (From Moore KL, Agur AMR. Essential Clinical Anatomy. 2nd ed. Philadelphia, PA: Lippincott Williams &Wilkins; 2002:238.)

portion, called the body; and the inferior constricted part, called the cervix 1,2 (see Fig. 40-3). The uterus is supported on both sides by four sets of ligaments: the broad ligaments , which run laterally from the body of the uterus to the pelvic side walls; the round ligaments , which run from the fundus laterally into each labium

Ovarian ligament

Suspensory ligament of ovary

Frequent site of implantation

Site of fertilization

Uterine tube

Fundus

Fimbriae

Path of oocyte

Ovary

Ruptured ovarian follicle

Broad ligament

Round ligament of uterus

Uterosacral ligament

Cardinal ligament

A

Path of sperm

B FIGURE 40-4. Schematic drawing of female reproductive organs, showing (A) suspensory ligament of the ovary and the broad, uterosacral, and cardinal ligaments on the left, and (B) the path of the oocyte as it moves from the ovary into the fallopian (uterine) tube; the path of sperm is also shown, as is the usual site of fertilization.