Female Genital Organschapter 1

The reproductive system of woman is described in two parts – external reproductive organ and internal reproductive organ.

The part of female reproductive organs that can be seen from outside is external reproductive organ. The main parts are: mons veneris or mons pubis – the swollen fat filled area covering the pubic symphysis is mons veneris. It is covered by luxuriant growth of black curly hair.

Labia majora extends downwards and backwards from the mons pubis. Posteriorly the two labia majora of either side joint in the midline together to form the posterior commissure. In children and in nulliparous women they cover the underlying parts. These are two skin folds filled with fat.

Labia minora are two folds of tissue inside the labia majora. They meet at the upper end of vulva and posteriorly meet at the middle to form fourchet. In nulliparous women, they are covered by the labia majora.

Clitoris is situated in the midline just above the labia minora. It is a small erectile body homologous of the penis. Like the penis it consists of a glans, a body and two crura. It is very sensitive.

The area enclosed by the labia minora is vestibule. It extends from the clitoris anteriorly to the fourchet posteriorly. It is perforated by the urethra and vagina. Besides these there are openings of two skene's ducts and openings of the Bartholin's glands.

Urethra opens at the urethral meatus in the midline of the vestibule. It is situated above the vaginal opening. The orifice appears as a vertical slit.

Vaginal opening is situated at the lower part of the vestibule. Its size and shape is variable. In virgin it is almost closed by hymen, a membrane. The hymen may be perforated at places. During the first coitus the hymen ruptures. After child birth the remnants of hymen form cicatrized nodules called myrtiform caruncles (caruncle myrtiformes).

Vagina is a musculomembranous tube, interposed between the urinary bladder and rectum. It extends from vulva to the cervix of the uterus. In the upper part vagina is blind and the lower portion of the cervix projects into it. The blind end is called vault. The vault is divided into anterior, posterior and lateral fornices. Posteriorly vagina is attached to the cervix at a higher level than on the anterior, so the posterior fornix is deeper than the anterior one. Length of vagina varies, anteriorly it is about 6–8 cm and posteriorly is about 7–10 cm. The vaginal canal is usually H-shaped.

The area between the posterior fourchette and the anus is perineum. Perineum is made up of superficial perineal muscles and external anal sphincter. The median raphe of levator ani reinforced by these muscles form the perineal body.

Uterus: The uterus is a pear-shaped muscular organ. Usually the length of the uterus is 7.5 cm, breath is 5 cm and 2.5 cm thick. In non-pregnant state uterus is situated inside the pelvic cavity. The urinary bladder is situated anteriorly and the rectum posteriorly. The upper part is wide narrowing gradually downwards. The triangular upper part is body and cylindrical lower portion is cervix. The two fallopian tubes enter the uterus at its two upper corners laterally. The part of the uterus above the attachment of the fallopian tubes is called the fundus of the uterus. A small segment between the body and the cervix is known as isthmus.

The uterine and the ovarian arteries supply the uterus. Uterine artery is a branch of internal iliac artery, and the ovarian artery comes directly from the abdominal aorta. Arising from the internal iliac artery the uterine artery descends downwards and medially to enter into the base of the broad ligament. There it crosses over the ureter. Near the cervix it divides into two parts. The smaller cervicovaginal branch supplies the lower part of the cervix and the upper part of the vagina. The bigger branch turns upwards and runs upwards as a convoluted vessel along the lateral margin of the uterus. While running upwards it gives numerous branches that enters into the substance of the uterus. At the upper end the ovarian branch anastomose with ovarian artery. Another branch supply the tube and the third one supply the fundus of the uterus.

The uterus is held in position by some thick bands of fibrous tissue called ligaments. These fibrous tissues are continuous with connective tissue of the pelvis. Extending from the lateral border of the uterus are broad ligaments, round ligament and cardinal ligaments or Mackenrodt's ligament.

On either side of the uterus there are two ovaries. Ovaries are suspended from the broad ligament by mesovarium and are attached to the posterolateral aspects of the uterus with ovarian ligaments. Normally, the ovaries are situated at ovarian fossa'a depression on the lateral pelvic wall. The size of the ovary varies considerably. During reproductive period the length is 2.5–5 cm, breadth is 1.5–3 cm and thickness is 0.5–1.5 cm.

After ovulation it forms corpus luteum. Later on the follicle becomes fibrous and whitish in color. This is called tunica albuginea. The medulla is composed of loose connective tissue. Medulla contains blood vessels and few smooth muscle fibers.

The uterus and the fallopian tubes develop from the Müllerian ducts. Müllerian ducts appear at the upper part of the urogenital ridge by 5th week of intrauterine life. From the upper part of the Müllerian ducts develop the fallopian tubes. The lower parts of the tubes of both sides fuse in the midline and later on the intervening walls disappear to form the uterus and vagina below.

The ovaries develop from the genital ridge, an area in the urogenital ridge medial to the area wherefrom the Müllerian ducts originate. Germ cells migrate to this area from an area in the coelomic epithelium. The germ cells appear there by about 3rd week of intrauterine life and migrate to the genital ridge by fifth week. The development of ovum continues till term.

In female, breasts are secondary sex organ. During puberty size of the breast increases due to effects of hormones. It is composed of glands and fatty tissues.

Pelvis is richly supplied with blood vessels. These vessels not only supplies the genital organs but also supply the lower urinary tract, gastrointestinal tract, pelvic floor and perineum. The major vessels supplying the pelvis are –internal iliac artery and ovarian artery.

There is extensive collateral connections between different vessels supplying the pelvis.

The abdominal aorta bifurcates at the level of fifth lumber vertebra, into two common iliac arteries. Running downwards and outwards the common iliac artery bifurcate into external and internal iliac arteries. The external iliac artery runs downwards and outwards and passing below the inguinal ligament becomes femoral artery. Its main branches are inferior epigastric and deep circumflex arteries.

The uterine artery arises from the internal iliac artery directly or with the superior vesical artery. Running inwards at the base of the broad ligament crosses the ureter anteriorly and reaches the uterus at the level of the internal os. At this level it divides into two, one descending branch to supply the cervix and vagina. The main branch runs upwards along the lateral border of the uterus. It is tortuous and gives off branches to supply the uterus at all levels and at last anastomose with the ovarian artery. The branches from the main artery divides into anterior and posterior arcuate arteries which run circumferencially in the myometrium and anastomose with those from the opposite side.

The arcuate arteries give off radial arteries which end as basal arteries and supply the endometrium. Arcuate and radial arteries are also coiled.

The vaginal artery usually arises directly from the internal iliac artery and running forwards and inwards in the lower part of the broad ligament reaches the lateral fornix of vagina. In the vaginal fornix it anastomoses with branches of cervical artery. It supplies the upper vagina. The lower vagina is supplied by the middle and inferior rectal arteries and by branches of the internal pudendal artery.

The internal pudendal artery is the terminal branch of the internal iliac artery. It passes out of the pelvis through the greater sciatic notch. It gives branches to supply the labia, vagina, vestibule, perineum and perineal muscles. It ends as the dorsal artery to clitoris.

The ovarian artery is a branch of abdominal aorta. It runs retroperitonealy downwards and laterally. At the level of the brim of the pelvis it crosses the ureter and then enters the infundibulopelvic ligament. It divides into two branches. The main one reaches the ovary through the mesovarian. The other branch or the main trunk itself runs towards the cornu of the uterus and anastomose with the uterine artery. In the mesosalpinx vessels supply the round ligament and the fallopian tube from the vascular arch formed by the anastomosis of the ovarian and uterine arteries.

The veins accompany the arteries having the same name and drain into the internal iliac vein. Right ovarian vein drains into the inferior venacava and the left ovarian vein drains into the left renal vein. There are few venous plexuses in the pelvis. The important one is the pampiniform plexus situated in the upper part of broad ligament and drains the ovary and the uterus. The other venous plexuses are around the vagina, urethrovesical junction and the anorectal junction and all of them drain into internal iliac vein.

Lymphatics of vulva pass towards the mons pubis to enter into the medial group of superficial inguinal lymph nodes, then to the deep inguinal group. From deep inguinal group of glands lymphatics drain into the external iliac lymph nodes. Gland of Cloquet is situated beneath the inner end of the inguinal ligament. Lymphatics from clitoris directly drains into this gland when present. Lymphatics from the deeper tissues drain into the internal iliac nodes.

Lymphatics from lower vagina accompany the lymphatics of vulva and drain into the inguinal and femoral nodes. From upper part lymphatics accompany those from cervix.

Lymphatics from cervix drain into the obturator, external and internal iliac and sacral nodes. From cervix these lymphatics pass through the uterosacral ligaments to these glands. External and internal iliac nodes ultimately drain into the para-aortic lymph glands.

Upper part of the body of the uterus including the fundus are drained by lymphatics accompanying the ovarian vessels. Some lymphatics pass through the round ligament to the superficial inguinal nodes. The lower part has same lymphatic connection as in cervix.

The pudendal nerve is the main somatic supply of the pelvic organs. It has both motor and sensory fibers derived from the S2, S3 and S4 roots of the sacral plexus.

The motor fibers supply the voluntary muscles, vaginal sphincter, compressor urethrae, levator ani and external anal sphincter. The sensory fibers supply the skin of vulva, clitoris, external urethral meatus, lower vagina and perineum.

Autonomic nervous system regulates the activities of all the internal reproductive organs including upper vagina, urinary system, rectum and colon. These nerves carry both motor and sensory fibers. Nerves to and from the genital organs pass through some plexuses.

Sympathetic motor nerves arise from the T5 and T6 segments and sensory nerves arise from the T10 to L1 segments. These nerve go downwards from the coeliac plexus to the presacral plexus or the superior hypogastric plexus, situated over the bifurcation of the aorta and sacral promontory. Therefrom two hypogastric nerves run downwards and outwards, one on each side to join the inferior hypogastric plexus or the pelvic plexus. The pelvic plexus extends forwards beneath the uterosacral and broad ligaments.

Pelvic plexus also receives motor and sensory fibers from S2, S3 and S4 nerve roots, probably carrying sensation from lower uterus and cervix. Pelvic plexus supply sympathetic and parasympathetic nerves to all the pelvic organs except the fallopian tubes and ovaries. To the uterus and cervix these nerves pass through the paracervical ganglia. Body of the uterus and the cervix are relatively insensitive to cutting, burning, etc. Resection of all uterine nerves does not affect myometrial contraction even in labor.

Pelvic floor is formed by muscles and their fascial coats. The main constituents are pelvic peritoneum, endopelvic fascia, areolar tissue, levator ani muscle, and urogetital diaphragm. The most important of these are endopelvic fascia and levator ani muscle and their fascial coverings.

Levator ani is a wide sheet of muscle covering the whole of the pelvic floor. Anteriorly it is attached to the back of the pubic bone and posteriorly to the sacrum, coccyx and the anococcygeal raphe on each side. Laterally it is attached to the fascia covering the obturator internus and to the ischial spine. The muscle of each side sweeps downwards and inwards and meet in the midline forming a diaphragm. Three structures, i.e. the urethra anteriorly, vagina in the middle and the rectum posteriorly pass through the muscle. The fascial sheet of the muscle fuses with the fascia covering the vagina and rectum. Levator ani muscle is formed by the following parts.

This is the main part of the muscle. It stretches from the pubis to the coccyx, some part of it also inserts in the perineal body.

This sheet of muscle stretches from the fascia of obturator internus (white line) to the sacrum, coccyx and anococcygeal raphe. Some part is attached to the perineal body.

This part arises from the ischial spine and gets inserted in the sacrum and coccyx.

Levator ani is a voluntary muscle. It is supplied by fibers from S3 and S4 roots.

The triangular ligament or urogenital diaphragm lies below the levator muscle. It is consisted of two layers of fascia, attached anteriorly to the pubic rami. Laterally they are attached to the ischiopubic rami and posteriorly fuse with the central part of perineum. Between the fascial layers lie the compressor urethrae and deep transverse perineal muscles, branches of pudendal nerve 14and pudendal vessels. The triangular ligament is pierced by the dorsal vein of clitoris, by the urethra and by the vagina. The deep tranverse perineal muscle arises from the ischial rami and is inserted into the wall of the vagina and partly to the perineal body.

The perineal body lies between the lower part of vagina and the anal canal. It is pyramidal in shape and the apex lies at the lower end of rectovaginal septum. Here is insertion of anterior fibers of levator ani muscle, transverse perineal muscle, sphincter vaginae and external sphincter ani muscle. Below the perineal muscles and the perineal body comes the superficial fascia and skin.