The organs that occupy the female pelvis (Figs. 1–19 to 1–21) are the bladder, the ureters, the urethra, the uterus, the uterine (fallopian) tubes or oviducts, the ovaries, the vagina, and the rectum.* With the exception of the inferior portion of the rectum and most of the vagina, all lie immediately beneath the peritoneum. The uterus, uterine tubes, and ovaries are almost completely covered with peritoneum and are suspended in peritoneal ligaments. The remainder are partially covered. These organs do not completely fill the cavity; the remaining space is occupied by ileum and sigmoid colon.
* The rectum is not described in this chapter.
The urinary bladder is a muscular, hollow organ that stores urine and lies posterior to the pubic bones and anterior to the uterus and broad ligament. Its form, size, and position vary with the amount of urine it contains. When empty, it takes the form of a somewhat rounded pyramid, having a base, a vertex (or apex), a superior surface, and a convex inferior surface that may be divided by a median ridge into 2 inferolateral surfaces.
The superior surface of the bladder is covered with peritoneum that is continuous with the medial umbilical fold, forming the paravesical fossae laterally. Posteriorly, the peritoneum passes onto the uterus at the junction of the cervix and corpus, continuing upward on the anterior surface to form the vesicouterine pouch. When the bladder is empty, the normal uterus rests upon its superior surface. When the bladder is distended, coils of intestine may lie upon its superior surface. The base of the bladder rests below the peritoneum and is adjacent to the cervix and the anterior fornix of the vagina. It is separated from these structures by areolar tissue containing plexiform veins. The area over the vagina is extended as the bladder fills. The inferolateral surfaces are separated from the wall of the pelvis by the potential prevesical space, containing a small amount of areolar tissue but no large vessels. This surface is nonperitoneal and thus suitable for operative procedures. Posterolateral to the region facing the symphysis, each of the inferolateral surfaces is in relation to the fascia of the obturator internus, the obturator vessels and nerve, the obliterated umbilical artery above, and the fascia of the levator ani below. Posteriorly and medially, the inferior surface is separated from the base by an area called the urethrovesical junction, the most stationary portion of the bladder.
Fascia, Ligaments, & Muscle
The bladder is enclosed by a thin layer of fascia, the vesical sheath. Two thickenings of the endopelvic fascia, the medial and lateral pubovesical or puboprostatic ligaments, extend at the vesicourethral junction abutting the levator ani muscle from the lower part of the anterior aspect of the bladder to the pubic bones. Similar fascial thickenings, the lateral true ligaments, extend from the sides of the lower part of the bladder to the lateral walls of the pelvis. Posteriorly, the vesicourethral junction of the bladder lies directly against the anterior wall of the vagina.
A fibrous band, the urachus or medial umbilical ligament, extends from the apex of the bladder to the umbilicus. This band represents the remains of the embryonic allantois. The lateral umbilical ligaments are formed by the obliterated umbilical arteries and are represented by fibrous cords passing along the sides of the bladder and ascending toward the umbilicus. Frequently, the vessels will be patent, thus forming the superior vesical arteries. The peritoneal covering of the bladder is limited to the upper surface. The reflections of the peritoneum to the anterior abdominal wall and the corresponding walls of the pelvis are sometimes described as the superior, lateral, and posterior false ligaments. The muscle (smooth) of the bladder is represented by an interdigitated pattern continuous with and contiguous to the inner longitudinal and anterior circumferential muscles of the urethra. No distinct muscle layers are apparent.
The mucous membrane is rose-colored and lies in irregular folds that become effaced by distention. The 3 angles of the vesical trigone are represented by the orifices of the 2 ureters and the internal urethral orifice. This area is redder in color and free from plication. It is bordered posteriorly by the plica interureterica, a curved transverse ridge extending between the orifices of the ureters. A median longitudinal elevation, the uvula vesicae, extends toward the urethral orifice. The internal urethral orifice is normally situated at the lowest point of the bladder, at the junction of the inferolateral and posterior surfaces. It is surrounded by a circular elevation, the urethral annulus, approximately level with the center of the symphysis pubica. The epithelial lining of the bladder is transitional in type. The mucous membrane rests on the submucous coat, composed of areolar tissue superficial to the muscular coat. There is no evidence of a specific smooth muscle sphincter in the vesical neck.
Arteries, Veins, & Lymphatics
The blood supply to the bladder comes from branches of the hypogastric artery. The umbilical artery, a terminal branch of the hypogastric artery, gives off the superior vesical artery prior to its obliterated portion. It approaches the bladder (along with the middle and inferior vesical arteries) through a condensation of fatty areolar tissue, limiting the prevesical "space" posterosuperiorly, to branch out over the upper surface of the bladder. It anastomoses with the arteries of the opposite side and the middle and inferior vesical arteries below. The middle vesical artery may arise from one of the superior vessels, or it may come from the umbilical artery, supplying the sides and base of the bladder. The inferior vesical artery usually arises directly from the hypogastric artery—in common with or as a branch of the uterine artery—and passes downward and medially, where it divides into branches that supply the lower part of the bladder. The fundus may also receive small branches from the middle hemorrhoidal, uterine, and vaginal arteries. The veins form an extensive plexus at the sides and base of the bladder from which stems pass to the hypogastric trunk.
The lymphatics, in part, accompany the veins and communicate with the hypogastric nodes. They also communicate laterally with the external iliac glands, and some of those from the fundus pass to nodes situated at the promontory of the sacrum. The lymphatics of the bladder dome are separate on the right and left sides and rarely cross, but extensive anastomoses are present among the lymphatics of the base, which also involve those of the cervix.
The nerve supply to the bladder is derived partly from the hypogastric sympathetic plexus and partly from the second and third sacral nerves (the nervi erigentes).
The ureter is a slightly flattened tube that extends from the termination of the renal pelvis to the lower outer corner of the base of the bladder, a distance of 26–28 cm. It is partly abdominal and partly pelvic and lies entirely behind the peritoneum. Its diameter varies from 4–6 mm, depending on distention, and its size is uniform except for 3 slightly constricted portions.
The first of 3 constrictions is found at the junction of the ureter with the renal pelvis and is known as the upper isthmus. The second constriction—the lower isthmus—is at the point where the ureter crosses the brim of the pelvis minor. The third (intramural) constriction is at the terminal part of the ureter as it passes through the bladder wall.
The pelvic portion of the ureter begins as the ureter crosses the pelvic brim beneath the ovarian vessels and near the bifurcation of the common iliac artery. It conforms to the curvature of the lateral pelvic wall, inclining slightly laterally and posteriorly until it reaches the pelvic floor. The ureter then bends anteriorly and medially at about the level of the ischial spine to reach the bladder. In its upper portion, it is related posteriorly to the sacroiliac articulation; then, lying upon the obturator internus muscle and fascia, it crosses the root of the umbilical artery, the obturator vessels, and the obturator nerve.
In its anterior relationship, the ureter emerges from behind the ovary and under its vessels to pass behind the uterine and superior and middle vesical arteries. Coursing anteriorly, it comes into close relation with the lateral fornix of the vagina, passing 8–12 mm from the cervix and vaginal wall before reaching the bladder. When the ureters reach the bladder, they are about 5 cm apart. The ureters open into the bladder by 2 slitlike apertures, the urethral orifices, about 2.5 cm apart when the bladder is empty.
The wall of the ureter is approximately 3 mm thick and is composed of 3 coats: connective tissue, muscle, and mucous membrane. The muscular coat has an external circular and an internal longitudinal layer throughout its course and an external longitudinal layer in its lower third. The mucous membrane is longitudinally plicated and covered by transitional epithelium. The intermittent peristaltic action of the ureteral musculature propels urine into the bladder in jets. The oblique passage of the ureter through the bladder wall tends to constitute a valvular arrangement, but no true valve is present. The circular fibers of the intramural portion of the ureter possess a sphincter like action. Still, under some conditions of overdistention of the bladder, urine may be forced back into the ureter.
Arteries, Veins, & Lymphatics
The pelvic portion of the ureter receives its blood supply from a direct branch of the hypogastric artery, anastomosing superiorly in its adventitia with branches from the iliolumbar and inferiorly with branches from the inferior vesical and middle hemorrhoidal arteries. Lymphatic drainage passes along the hypogastric vessels to the hypogastric and external iliac nodes, continuing up the ureters to their middle portion where drainage is directed to the periaortic and interaorticocaval nodes.
The nerve supply is provided by the renal, ovarian, and hypogastric plexuses. The spinal level of the afferents is approximately the same as the kidney (T12, L1, L2). The lower third of the ureter receives sensory fibers and postganglionic parasympathetic fibers from the Frankenhäuser plexus and sympathetic fibers through this plexus as it supplies the base of the bladder. These fibers ascend the lower third of the ureter, accompanying the arterial supply. The middle segment appears to receive postganglions of sympathetic and parasympathetic fibers through and from the middle hypogastric plexus. The upper third is supplied by the same innervation as the kidney.
The female urethra is a canal 2.5–4 cm long. It extends downward and forward in a curve from the neck of the bladder (internal urethral orifice), which lies nearly opposite the symphysis pubica. Its termination, the external urethral orifice, is situated inferiorly and posteriorly from the lower border of the symphysis. Posteriorly, it is closely applied to the anterior wall of the vagina, especially in the lower two-thirds, where it actually is integrated with the wall, forming the urethral carina. Anteriorly, the upper end is separated from the prevesical "space" by the pubovesical (puboprostatic) ligaments, abutting against the levator ani and vagina and extending upward onto the pubic rami.
The walls of the urethra are very distensible, composed of spongy fibromuscular tissue containing cavernous veins and lined by submucous and mucous coats. The mucosa contains numerous longitudinal lines when undistended, the most prominent of which is located on the posterior wall and termed the crista urethralis. Also, there are numerous small glands (the homologue of the male prostate, paraurethral and periurethral glands of Astruc, ducts of Skene) that open into the urethra. The largest of these, the paraurethral glands of Skene, may open via a pair of ducts beside the external urethral orifice in the vestibule. The epithelium begins as transitional at the upper end and becomes squamous in the lower part.
External to the urethral lumen is a smooth muscle coat composed of an outer circular layer and an inner longitudinal layer in the lower two-thirds. In the upper third, the muscle bundles of the layers interdigitate in a basketlike weave to become continuous with and contiguous to those of the bladder. The entire urethral circular smooth muscle acts as the involuntary sphincter. In the region of the juncture of the middle and lower thirds of the urethra, decussating fibers (striated in type) form the middle heads of the bulbocavernosus and ischiocavernosus muscles and encircle the urethra to form the sphincter urethrae (voluntary sphincter).
The arterial supply is intimately involved with that of the anterior vaginal wall, with cruciate anastomoses to the bladder. On each side of the vagina are the vaginal arteries, originating in part from the coronary artery of the cervix, the inferior vesical artery, or a direct branch of the uterine artery. In the midline of the anterior vaginal wall is the azygos artery, originating from the coronary or circular artery of the cervix. Approximately 5 branches traverse the anterior vaginal wall from the lateral vaginal arteries to the azygos in the midline, with small sprigs supplying the urethra. A rich anastomosis with the introitus involves the clitoral artery (urethral branches) as the artery divides into the dorsal and superficial arteries of the clitoris, a terminal branch of the internal pudendal artery. The venous drainage follows the arterial pattern, although it is less well defined. In the upper portion of the vagina, it forms an extensive network called the plexus of Santorini.
The nerve supply is parasympathetic, sympathetic, and spinal. The parasympathetic and sympathetic nerves are derived from the hypogastric plexus; the spinal supply is via the pudendal nerve.
The uterus is a pear-shaped, thick-walled, muscular organ, situated between the base of the bladder and the rectum. Covered on each side by the 2 layers of the broad ligament, it communicates above with the uterine tubes and below with the vagina. It is divided into 2 main portions, the larger portion or body above and the smaller cervix below, connected by a transverse constriction, the isthmus. The body is flattened so that the side-to-side dimension is greater than the anteroposterior dimension and larger in women who have borne children. The anterior or vesical surface is almost flat; the posterior surface is convex. The fallopian tubes join the uterus at the superior (lateral) angles. The round portion that extends above the plane passing through the points of attachment of the 2 tubes is termed the fundus. This portion is the region of greatest breadth.
The cavity of the body, when viewed from the front or back, is roughly triangular with the base up. The communication of the cavity below with the cavity of the cervix corresponds in position to the isthmus and forms the internal orifice (internal os uteri). The cervix, also called the portio vaginalis, is somewhat barrel-shaped and is 2–4 cm in length, its lower end joining the vagina at an angle varying from 45–90 degrees. It projects into the vagina and is divided into a supravaginal and a vaginal portion by the line of attachment. About one fourth of the anterior surface and half of the posterior surface of the cervix belong to the vaginal portion. At the extremity of the vaginal portion is the opening leading to the vagina, the external orifice (external os uteri), which is round or oval before parturition but takes the form of a transverse slit in women who have borne children. The cavity of the cervix is fusiform in shape, with longitudinal folds or furrows, and extends from the internal to the external orifice. The endocervical canal is composed of columnar, mucus-secreting cells, whereas the external cervix is lined by nonkeratinizing squamous epithelium. The junction between these 2 areas is called the squamocolumnar junction or transitional zone.
The size of the uterus varies, under normal conditions, at different ages and in different physiologic states. In the adult woman who has never borne children, it is approximately 7–8 cm long, 4–5 cm at its widest point, and 30–40 g in weight. In the prepubertal period, it is considerably smaller. In women who have borne children, it is larger. Its shape, size, and characteristics in the pregnant state become considerably modified depending on the stage of gestation.
The wall of the uterus is very thick and consists of 3 layers: serous, muscular, and mucous. The serous layer (perimetrium) is simply the peritoneal covering. It is thin and firmly adherent over the fundus and most of the body, and then thickens posteriorly and becomes separated from the muscle by the parametrium. The muscular layer (myometrium) is extremely thick at about 1.5–2.5 cm and continuous with that of the tubes and vagina. It also extends into the ovarian and round ligaments, into the cardinal ligaments at the cervix, and minimally into the uterosacral ligaments. Two principal layers of the muscular coat can be distinguished: (1) the outer layer, which is weaker and composed of longitudinal fibers; and (2) a stronger inner layer, the fibers of which are interlaced and run in various directions, having intermingled within them large venous plexuses. The muscle layer hypertrophies with the internal os to form a sphincter.
The cervix, from the internal os distally, progressively loses its smooth muscle, finally to be entirely devoid of smooth muscle and elastic in its distal half. It is, in fact, the "dead-end tendon" of the uterus, at which point, during the active component of labor, both the uterus and the vagina direct their efforts. The mucous layer (endometrium) is soft and spongy, composed of tissue resembling embryonic connective tissue. The surface consists of a single layer of ciliated columnar epithelium. The tissue is rather delicate and friable and contains many tubular glands that open into the cavity of the uterus.
Position & Axis Direction
The direction of the axis of the uterus varies greatly. Normally, the uterus forms a sharp angle with the vagina so that its anterior surface lies on the upper surface of the bladder and the body is in a horizontal plane when the woman is standing erect. There is a bend in the area of the isthmus, at which the cervix then faces downward. This position is the normal anteversion or angulation of the uterus, although it may be placed backward (retroversion), without angulation (military position), or to one side (lateral version). The forward flexion at the isthmus is referred to as anteflexion, or there may be a corresponding retroflexion or lateral flexion. There is no sharp line between the normal and pathologic state of anterior angulation.
Anteriorly, the body of the uterus rests upon the upper and posterior surfaces of the bladder, separated by the uterovesical pouch of the peritoneum. The whole of the anterior wall of the cervix is below the floor of this pouch, and it is separated from the base of the bladder only by connective tissue. Posteriorly, the peritoneal covering extends down as far as the uppermost portion of the vagina; therefore, the entire posterior surface of the uterus is covered by peritoneum, and the convex posterior wall is separated from the rectum by the rectouterine pouch (cul-de-sac or pouch of Douglas). Coils of intestine may rest upon the posterior surface of the body of the uterus and may be present in the rectouterine pouch.
Laterally, the uterus is related to the various structures contained within the broad ligament: the uterine tubes, the round ligament and the ligament of the ovary, the uterine artery and veins, and the ureter. The relationships of the ureters and the uterine arteries are very important surgically. The ureters, as they pass to the bladder, run parallel with the cervix for a distance of 8–12 mm. The uterine artery crosses the ureter anterosuperiorly near the cervix, about 1.5 cm from the lateral fornix of the vagina. In effect, the ureter passes under the uterine artery "as water flows under a bridge."
Although the cervix of the uterus is fixed, the body is free to rise and fall with the filling and emptying of the bladder. The so-called ligaments supporting the uterus consist of the uterosacral ligaments, the transverse ligaments of the cervix (cardinal ligaments, cardinal supports, ligamentum transversum colli, ligaments of Mackenrodt), the round ligaments, and the broad ligaments. The cervix is embedded in tissue called the parametrium, containing various amounts of smooth muscle. There are 2 pairs of structures continuous with the parametrium and with the wall of the cervix: the uterosacral ligaments and the transverse (cardinal) ligament of the neck, the latter of which is the chief means of support and suspends the uterus from the lateral walls of the pelvis minor. The uterosacral ligaments are, in fact, the inferior posterior folds of peritoneum from the broad ligament. They consist primarily of nerve bundles from the inferior hypogastric plexus and contain preganglionic and postganglionic fibers and C fibers of the sympathetic lumbar segments, parasympathetic in part from sacral components and in part from sensory or C fibers of the spinal segments.
The cardinal ligaments are composed of longitudinal smooth muscle fibers originating superiorly from the uterus and inferiorly from the vagina, fanning out toward the fascia visceralis to form, with the internal os of the cervix, the primary support of the uterus. There is a natural defect in the muscle at its sides (hilum of the uterus) and at the cervical isthmus (internal os), where the vasculature and nerve supply enter the uterus.
The round ligaments of the uterus, although forming no real support, may assist in maintaining the body of the uterus in its typical position over the bladder. They consist of fibrous cords containing smooth muscle (longitudinal) from the outer layer of the corpus. From a point of attachment to the uterus immediately below that of the ovarian ligament, each round ligament extends downward, laterally, and forward between the 2 layers of the mesometrium, toward the abdominal inguinal ring that it traverses and the inguinal canal, to terminate in a fanlike manner in the labia majora and become continuous with connective tissue. The round ligament is the gubernaculum (ligamentum teres uteri), vestigial in the female. It is accompanied by a funicular branch of the ovarian artery, by a branch from the ovarian venous plexus, and, in the lower part of its course, by a branch from the inferior epigastric artery (Sampson's artery), over which it passes as it enters the inguinal ring. Through the inguinal canal, it is accompanied by the ilioinguinal nerve and the external spermatic branch of the genitofemoral nerve.
The broad ligament, consisting of a transverse fold of peritoneum that arises from the floor of the pelvis between the rectum and the bladder, provides minimal support. In addition to the static support of these ligaments, the pelvic diaphragm (levator ani) provides an indirect and dynamic support. These muscles do not actually come in contact with the uterus, but they aid in supporting the vagina and maintain the entire pelvic floor in resisting downward pressure. The effectiveness of these muscles depends on an intact perineum (perineal body, bulbocavernosus muscle and body), for if it is lacerated or weakened the ligaments will gradually stretch and the uterus will descend. The uterus and its components and the vagina are, in fact, one continuous unit.
The blood supply to the uterus is from the uterine and ovarian arteries. As a terminal branch of the hypogastric artery, the uterine artery runs downward and medially to cross the ureter near the cervix. It then ascends along the lateral border of the uterus in a tortuous course through the parametrium, giving off lateral branches to both uterine surfaces. Above, it anastomoses to join with the ovarian artery in the mesometrium, which creates the main accessory source of blood. The uterine arteries within the uterus form a series of arches over the fundus, creating cruciate anastomoses with the opposite side.
Branches of the arcuate arteries (radial) penetrate the myometrium at right angles to terminate in the basilar arterioles for the basilar portion of the endometrium and in the spinal arteries of the endometrium. The spinal arteries are tortuous in structure, not because of endometrial growth but because, ontogenically, an organ carries its arterial supply with it as it changes size and position. Therefore, the spiral arteries are able to maintain adequate arterial flow to the placenta while it is attached within the uterus.
On the other hand, the veins of the endometrium are a series of small sinusoids that connect to the larger sinusoids of the myometrium, the latter coalescing into the larger veins of the uterine complex. It is useful here to note the significance of the muscular role of the uterus in helping to control venous bleeding during parturition.
The arterial supply to the cervix is primarily through the cervical branches of the right and left uterine arteries, which form a rete around the cervix (coronary artery), creating the azygos artery in the midline anteriorly and posteriorly. Anastomoses between this artery and the vaginal artery on both sides afford cruciate flow on the anterior wall, whereas on the posterior wall of the vagina, anastomoses occur with the right and left middle hemorrhoidal arteries as they supply the wall and the rectum.
The veins form a plexus and drain through the uterine vein to the hypogastric vein. There are connections with the ovarian veins and the inferior epigastric by way of the vein accompanying the round ligament.
Lymphatic drainage involves several chains of lymph nodes. From the subperitoneal plexus, the collecting trunks of the lower uterine segment may drain by way of the cervix to the external iliac chain or by way of the isthmus to the lateral sacral nodes. Drainage along the round ligament progresses to the superficial inguinal nodes, then to the femoral, and finally to the external iliac chain. Drainage laterally to the suspensory ligament of the ovary involves the lumbar pedicle and progresses in a retroperitoneal manner across and anteriorly to the ureter, to the lumbar nodes (interaorticocaval) that lie along the aorta, and inferiorly to the kidney.
Fallopian Tubes (Uterine Oviducts)
The fallopian tubes serve to convey the ova (eggs) to the uterus. They extend from the superior angles of the uterus to the region of the ovaries, running in the superior border of the broad ligament (mesosalpinx). The fallopian tubes and ovaries are collectively referred to as the adnexa. The course of each tube is nearly horizontal at first and slightly backward. Upon reaching the lower (uterine) pole of the ovary, the tube turns upward, parallel with the anterior (mesovarian) border, then arches backward over the upper pole and descends posteriorly to terminate in contact with the medial surface. Each tube is 7–12 cm long and may be divided into 4 parts: isthmus, ampulla, infundibulum, and interstitial.
The isthmus is the narrow and nearly straight portion immediately adjoining the uterus. It has a rather long intramural course, and its opening into the uterus, the uterine ostium, is approximately 1 mm in diameter. Following the isthmus is the wider, more tortuous ampulla. It terminates in a funnel-like dilatation, the infundibulum. The margins of the infundibulum are fringed by numerous diverging processes, the fimbriae, the longest of which, the fimbria ovarica, is attached to the ovary. The funnel-shaped mouth of the infundibulum, the abdominal ostium, is about 3 mm in diameter and actually leads into the peritoneal cavity, although it probably is closely applied to the surface of the ovary during ovulation. The interstitial is the portion of the tube that lies within the uterine wall. The innermost portion is seen from the uterine cavity as the tubal ostea.
The wall of the tube has 4 coats: serous (peritoneal), subserous or adventitial (fibrous and vascular), muscular, and mucous. Each tube is enclosed within a peritoneal covering except along a small strip on its lower surface, where the mesosalpinx is attached. At the margins of the infundibulum and the fimbriae, this peritoneal covering becomes directly continuous with the mucous membrane lining the interior of the tube. The subserous tissue is lax in the immediate vicinity of the tube. The blood and nerve supply is found within this layer. The muscular coat has an outer longitudinal and an inner circular layer of smooth muscle fibers, more prominent and continuous with that of the uterus at the uterine end of the tube. The mucous coat is ciliated columnar epithelium with coarse longitudinal folds, simple in the region of the isthmus but becoming higher and more complex in the ampulla. The epithelial lining extends outward into the fimbriae. The ciliary motion is directed toward the uterus.
The blood supply to the tubes is derived from the ovarian and uterine arteries. The tubal branch of the uterine artery courses along the lower surface of the uterine tube as far as the fimbriated extremity and may also send a branch to the ligamentum teres. The ovarian branch of the uterine artery runs along the attached border of the ovary and gives off a tubal branch. Both branches form cruciate anastomoses in the mesosalpinx. The veins accompany the arteries.
The lymphatic drainage occurs through trunks running retroperitoneally across and anterior to the ureter, into the lumbar nodes along the aorta, and inferior to the kidney.
The ovaries are paired organs situated close to the wall on either side of the pelvis minor, a little below the brim. Each measures 2.5–5 cm in length, 1.5–3 cm in breadth, and 0.7–1.5 cm in width, weighing about 4–8 g. The ovary has 2 surfaces, medial and lateral; 2 borders, anterior or mesovarian and posterior or free; and 2 poles, upper or tubal and lower or uterine. When the uterus and adnexa are in the normal position, the long axis of the ovary is nearly vertical, but it bends somewhat medially and forward at the lower end so that the lower pole tends to point toward the uterus. The medial surface is rounded and, posteriorly, may have numerous scars or elevations that mark the position of developing follicles and sites of ruptured ones.
The ovary is covered by cuboid or low columnar epithelium and consists of a cortex and a medulla. The medulla is made up of connective tissue fibers, smooth muscle cells, and numerous blood vessels, nerves, lymphatic vessels, and supporting tissue. The cortex is composed of a fine areolar stroma, with many vessels and scattered follicles of epithelial cells within which are the definitive ova (oocytes) in various stages of maturity. The more mature follicles enlarge and project onto the free surface of the ovary, where they are visible to the naked eye. These are called graafian follicles. When fully mature, the follicle bursts, releasing the ovum and becoming transformed into a corpus luteum. The corpus luteum, in turn, is later replaced by scar tissue, forming a corpus albicans if pregnancy is not achieved that particular menstrual cycle.
The upper portion of this surface is overhung by the fimbriated end of the uterine tube, and the remainder lies in relation to coils of intestine. The lateral surface is similar in shape and faces the pelvic wall, where it forms a distinct depression, the fossa ovarica. This fossa is lined by peritoneum and is bounded above by the external iliac vessels and below by the obturator vessels and nerve; its posterior boundary is formed by the ureter and uterine artery and vein, and the pelvic attachment of the broad ligament is located anteriorly.
The mesovarian or anterior border is fairly straight and provides attachment for the mesovarium, a peritoneal fold by which the ovary is attached to the posterosuperior layer of the broad ligament. Because the vessels, nerves, and lymphatics enter the ovary through this border, it is referred to as the hilum of the ovary.
The ovary is suspended by means of the mesovarium, the suspensory ligament of the ovary (infundibulopelvic [IP] ligament), and the ovarian ligament. The mesovarium consists of 2 layers of peritoneum, continuous with both the epithelial coat of the ovary and the posterosuperior layer of the broad ligament. It is short and wide and contains branches of the ovarian and uterine arteries, with plexuses of nerves, the pampiniform plexus of veins, and the lateral end of the ovarian ligament. The suspensory ligament of the ovary is a triangular fold of peritoneum and is actually the upper lateral corner of the broad ligament, which becomes confluent with the parietal peritoneum at the pelvic brim. It attaches to the mesovarium as well as to the peritoneal coat of the infundibulum medially, thus suspending both the ovary and the tube. It contains the ovarian artery, veins, and nerves after they pass over the pelvic brim and before they enter the mesovarium.
The ovarian ligament is a band of connective tissue, with numerous small muscle fibers, that lies between the 2 layers of the broad ligament on the boundary line between the mesosalpinx and the mesometrium, connecting the lower (uterine) pole of the ovary with the lateral wall of the uterus. It is attached just below the uterine tube and above the attachment of the round ligament of the uterus and is continuous with the latter.
The ovarian artery is the chief source of blood for the ovary. Though both arteries may originate as branches of the abdominal aorta, the left frequently originates from the left renal artery; the right, less frequently. The vessels diverge from each other as they descend. Upon reaching the level of the common iliac artery, they turn medially over that vessel and ureter to descend tortuously into the pelvis on each side between the folds of the suspensory ligament of the ovary into the mesovarium. An additional blood supply is formed from anastomosis with the ovarian branch of the uterine artery, which courses along the attached border of the ovary. Blood vessels that enter the hilum send out capillary branches centrifugally.
The veins follow the course of the arteries and, as they emerge from the hilum, form a well-developed plexus (the pampiniform plexus) between the layers of the mesovarium. Smooth muscle fibers occur in the meshes of the plexus, giving the whole structure the appearance of erectile tissue.
Lymphatic channels drain retroperitoneally, together with those of the tubes and part of those from the uterus, to the lumbar nodes along the aorta inferior to the kidney. The distribution of lymph channels in the ovary is so extensive that it suggests the system may also provide additional fluid to the ovary during periods of preovulatory follicular swelling.
The nerve supply of the ovaries arises from the lumbosacral sympathetic chain and passes to the gonad along with the ovarian artery.
The vagina is a strong, hollow, fibromuscular canal approximately 7–9 cm long that extends from the uterus to the vestibule of the external genitalia, where it opens to the exterior. Its long axis is almost parallel with that of the lower part of the sacrum, and it meets the cervix of the uterus at an angle of 45–90 degrees. Because the cervix of the uterus projects into the upper portion, the anterior wall of the vagina is 1.5–2 cm shorter than the posterior wall. The circular cul-de-sac formed around the cervix is known as the fornix and is divided into 4 regions: the anterior fornix, the posterior fornix, and 2 lateral fornices. Toward its lower end, the vagina pierces the urogenital diaphragm and is surrounded by the 2 bulbocavernosus muscles and bodies, which act as a sphincter (sphincter vaginae).
The vaginal wall is composed of a mucosal layer and a muscular layer. The smooth muscle fibers are indistinctly arranged in 3 layers: an outer longitudinal layer, circumferential layer, and a poorly differentiated inner longitudinal layer. In the lower third, the circumferential fibers envelop the urethra. The submucous area is abundantly supplied with a dense plexus of veins and lymphatics. The mucous layer shows many transverse and oblique rugae, which project inward to such an extent that the lumen in transverse section resembles an H-shaped slit. On the anterior and posterior walls, these ridges are more prominent, and the anterior column forms the urethral carina at its lower end, where the urethra slightly invaginates the anterior wall of the vagina. The mucosa of the vagina is lined throughout by nonkeratinized squamous epithelium. Even though the vagina has no true glands, there is a secretion present. It consists of cervical mucus, desquamated epithelium, and, with sexual stimulation, a direct transudate.
Anteriorly, the vagina is in close relationship to the bladder, ureters, and urethra in succession. The posterior fornix is covered by the peritoneum of the rectovaginal pouch, which may contain coils of intestine. Below the pouch, the vagina rests almost directly on the rectum, separated from it by a thin layer of areolar connective tissue. Toward the lower end of the vagina, the rectum turns back sharply, and the distance between the vagina and rectum greatly increases. This space, filled with muscle fibers, connective tissue, and fat, is known as the perineal body. The lateral fornix lies just under the root of the broad ligament and is approximately 1 cm from the point where the uterine artery crosses the ureter.
The remaining lateral vaginal wall is related to the edges of the anterior portion of the levator ani. The vagina is supported at the introitus by the bulbocavernosus muscles and bodies, in the lower third by the levator ani (puborectalis), and superiorly by the transverse (cardinal) ligaments of the uterus. The ductus epoophori longitudinalis (duct of Gartner), the remains of the lower portion of the wolffian duct (mesonephric duct), may often be found on the sides of the vagina as a minute tube or fibrous cord. These vestigial structures often become cystic and appear as translucent areas.
The chief blood supply to the vagina is through the vaginal branch of the uterine artery. After forming the coronary or circular artery of the cervix, it passes medially, behind the ureter, to send 5 main branches onto the anterior wall to the midline. These branches anastomose with the azygos artery (originating midline from the coronary artery of the cervix) and continue downward to supply the anterior vaginal wall and the lower two-thirds of the urethra. The uterine artery eventually anastomoses to the urethral branch of the clitoral artery. The posterior vaginal wall is supplied by branches of the middle and inferior hemorrhoidal arteries, traversing toward the midline to join the azygos artery from the coronary artery of the cervix. These branches then anastomose on the perineum to the superficial and deep transverse perineal arteries. The veins follow the course of the arteries.
The lymphatics are numerous mucosal plexuses, anastomosing with the deeper muscular plexuses. The superior group of lymphatics joins those of the cervix and may follow the uterine artery to terminate in the external iliac nodes or form anastomoses with the uterine plexus. The middle group of lymphatics, which drain the greater part of the vagina, appears to follow the vaginal arteries to the hypogastric channels. In addition, there are lymph nodes in the rectovaginal septum that are primarily responsible for drainage of the rectum and part of the posterior vaginal wall. The inferior group of lymphatics forms frequent anastomoses between the right and left sides and either courses upward to anastomose with the middle group or enters the vulva and drains to the inguinal nodes.
The innervation of the vagina contains both sympathetic and parasympathetic fibers. Only occasional free nerve endings are seen in the mucosa; no other types of nerve endings are noted.