Blood Supply To And Lymphatic Drainage Of The Female Reproductive Tract

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Blood supply

The internal pudendal artery is the arterial trunk supplying blood to all of the perineal structure inferior to the pelvic diaphragm. It begins as a branch of the internal iliac, which is located subperitoneally in the lateral pelvis. It exits the bony pelvis, crosses the sacrospinous ligament and enters the ischiorectal fossa. At this point the artery, along with the internal pudendal vein and nerve, becomes enclosed by the obturator fascia, forming the pudendal canal. As the artery enters the pudendal canal it gives off an inferior rectal artery which supplies the anorectal junction. The remaining portion of the internal pudendal artery reaches the base of the urogenital diaphragm and gives off a series of perineal branches. These supply the contents of both superficial and deep perineal spaces, including the vagina, urethra and clitoris.

The venous drainage of both perineal triangles parallels the arterial supply. There is also a rich submucosal venous plexus in the distal vagina. Distension of these submucosal veins can produce vaginal or vulvar varices. The inferior rectal veins join the internal pudendal vein just as it leaves the ischiorectal fossa at the lesser sciatic foramen. Both the rectal and the vaginal submucosal plexuses penetrate the pelvic diaphragm, to communicate with the endopelvic space. Here, vaginal veins may anastomose with uterine veins and inferior rectal veins with middle rectal veins.

The blood supply of the uterus and the upper vagina is via a single arterial trunk, the internal iliac artery. This arises from the division of the common iliac artery at the junction of the sacrum and the ilium. Descending in the lateral pelvis subperitoneally it gives off a series of visceral branches, including rectal, uterine and vesical. These course medially to enter the endopelvic space at the base of the broad ligament. Before reaching the isthmus of the uterus, the uterine artery crosses superior to the ureter and gives branches to the vaginal fornix and cervix. Turning superiorly in the parametrial space of the broad ligament, a series of arterial branches is given to the body of the uterus until the artery anastomoses with the ovarian artery at the uterotubal junction.

The uterine vein is usually plexiform, coursing laterally in the base of the broad ligament before reaching the lateral pelvic wall. Here the plexus of veins forms a series of tributaries entering the internal iliac vein, which in turn empties into the inferior vena cava. Other veins in the endopelvic space include middle rectal veins draining the rectum.

The normal route of rectal venous flow is into the internal iliac vein. During pregnancy the fetus may partially occlude the inferior vena cava when the woman is recumbent, increasing venous resistance and diminishing pelvic venous flow into the inferior vena cava. Because the middle rectal veins also communicate with the superior rectal branches of the inferior mesenteric vein, there is the potential for pelvic blood to ascend via the portal circulation. None of the pelvic veins contains valves, which allows blood to take the path of least resistance. Middle rectal veins also communicate with inferior rectal veins; these are tributaries of the internal pudendal vein, which drains into the iliac veins before entering the inferior vena cava. Increased blood flow in these vessels, particularly in the last trimester of pregnancy, is a well known cause of hemorrhoids.

The ovarian arteries arise as lateral branches from the abdominal aorta, descend in the retroperitoneal space, cross the ala of the sacrum and enter the suspensory ligament of the ovary. As the ovarian artery enters the lateral edge of the broad ligament it courses medially between the two layers of the ligament, giving branches to the ovary and uterine tube.

The venous drainage of the structures in the superior part of the broad ligament is via the ovarian vein, which parallels the ovarian artery as the vein ascends in the retroperitoneal space. On the right side of the ovarian vein is a tributary of the inferior vena cava, whereas on the left side it drains into the left renal vein.

Lymphatic drainage

As a general rule the lymphatic drainage follows the blood supply of a region. However, the lymphatic drainage of the perineum differs in this respect because there is a dual pathway. Deep lymphatics course upward, following the pudendal vein, draining the deep parts of both the urogenital and the anal triangles. However, superficial lymphatics from the skin overlying the vulvar and anal areas course to the medial thigh, where they communicate with superficial inguinal lymph nodes. Adenopathy of the superficial inguinal nodes is well known in many vulvar and anal infections, as well as in carcinoma of these regions.

A plexus of uterine lymphatics parallels the course of uterine veins, entering regional lymph nodes along the internal iliac artery. From these nodes lymph trunks ascend to para-aortic nodes in the retroperitoneum.

Afferent lymphatics from the ovarian and fallopian tube accompany ovarian vessels to para-aortic lymph nodes in the retroperitoneum. The fundus of the uterus is drained in part by this same route, but also sends lymphatic vessels anteriorly, paralleling the course of the round ligaments of the uterus. This bilateral course carries afferent lymphatics to inguinal lymph nodes on both sides of the pelvis.

Genitalia

The Penis

There are two parts of the penis: the base, which is attached to the pubis, and the pendular portions. Underlying the penile skin there are cavernous erectile bodies and the paired corpora cavernosa, which are primarily concerned with erection, and the corpus spongiosum which contains the urethra. These erectile bodies are separate structures at the base of the penis but are bound by fascia along its shaft. The corpora cavernosa are cylindrical bodies in the shaft region but taper markedly at the base, where they attach to the pubic ramus and perineal membrane. The corpus spongiosum has three parts: beginning at the perineum there is the bulb of the penis, the spongy portion, and the glans at the tip of the penis (Figure 3.4).

The base and proximal portion of the penile shaft are covered by the muscles. The paired ischiocavernosus muscles overlie the crura and corpus cavernosa. Another pair of muscles, the bulbospongiosus, overlies the corpus spongiosum.

Urethra and Glans

The urethra is divided into bulbous, spongy and glandular portions. The bulbous and spongy parts are lined by a pseudostratified columnar epithelium, except at the tip of the penis, termed the fossa navicularis, which is lined by stratified squamous epithelium. The epithelium contains small acini of mucous

Corpus -spongiosus

Corpus cavernosus

Glans -

Fossa navicularis

IviGCUUO

Corpus -spongiosus

Corpus cavernosus

Glans -

Fossa navicularis

-Prostate

— Seminal vesicle

- Rectal fold

Ejacuiatory duct

IviGCUUO

FIGURE 3.4 Sagittal section of pelvis and male reproductive system.

-Prostate

- Urogenital diaphragm, bulbourethral y gland, duct

— Seminal vesicle

- Rectal fold

Ejacuiatory duct

FIGURE 3.4 Sagittal section of pelvis and male reproductive system.

Ureter

- Bladder

Corpus spongiosus Corpus cavernosus

Urethral glands

---Fossa navicularis

FIGURE 3.5 Coronal section of penis and urethra viewed anteriorly.

Ureter

- Bladder

-—Ureteral orifice

Prostatic duct openings

______Verumontanum with utricle (blind pouch) and ejaculatory ducts

Urogenital diaphragm with bulbourethral glands (Cowper) Bulb

Opening of bulbourethral gland Crus

Corpus spongiosus Corpus cavernosus

Urethral glands

---Fossa navicularis

FIGURE 3.5 Coronal section of penis and urethra viewed anteriorly.

cells (glands of Littre), as well as mucosal and submucosal glands, termed urethral or periurethral glands (Figure 3.5). These glands can become infected and form abscesses.

On the superior surface of the corona of the glans penis, as well as on the undersurface near the frenulum, there are sebaceous glands, the glands of Tyson. These secrete a white cheesy type of material which, with desquamating epithelial cells, forms the smegma, a substance that accumulates between the prepuce and glands in uncircumcised men.

Scrotum

The scrotum may have small sebaceous cysts which may be multiple and, on occasion, become quite large or develop infections. The scrotum has two compartments which are divided in the midline. Each side is the mirror image of the other. The testis is the most anterior intrascrotal structure and must be examined carefully. The second most important structure is the epididymis, which lies immediately posterior to the testis.

Testis

The testis has two main functions: it produces sperm and it secretes male hormones. Sperm production takes place in the seminiferous tubules, whereas the production of testosterone, the major male hormone, takes place in the tissue located between the tubules. Each testis contains approximately 400-600 seminiferous tubules. Individual tubules are up to 70 cm in length and are coiled along most of this in order to be accommodated in a fascial compartment of the testis. These compartments are extensions of the outer fibrous capsule of the testis, the tunica albuginea. The seminiferous tubules join to form the rete testis, which is the connection to the excretory duct system. The lining of the seminiferous tubules contains two main types of cells, the developing sperm cells and the Sertoli cells, which support and presumably 'nurse' the sperm cells during the development process. Sperm are continuously produced in the testis from puberty to senility, following an orderly sequence of events. In the testis this process takes about 64 days. However, when they leave the testis the sperm cells are immature and unable to fertilize an egg.

Excretory Ducts

The excretory ducts transport sperm from the testis to the end of the male reproductive tract. They are composed of five components: the efferent ducts, the epididymis, the vas, the ejaculatory duct and the urethra.

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