Session 2B: Female External Genitalia And Pelvic Organs

Question 1

What is the vulva?

Answer 1

This is the collective term for all parts of the female external genitalia. There are many named parts of the vulva, which are summarized in the following table.

Question 2

What are the parts of the vulva?

Answer 2

Mons pubis
• Mound of fatty tissue located in front of the pubic symphysis causing an elevation of the hair-bearing skin.
Labia majora
• Prominent hair-bearing folds of skin that meet at the mons pubis anteriorly.
Labia minora
• Smaller, hairless folds of skin located medial to the labia majora.
• Fuse together anteriorly to form the hood of the clitoris.
• Form the boundaries of the vestibule.
Clitoris
• Pea-sized, highly sensitive tissue comprised of the erectile corpora cavernosa and corpus spongiosum.
• Becomes engorged during sexual arousal.
Vestibule
• Area between the labia minora.
• Contains the vaginal opening, urinary meatus and vestibular glands.
Vaginal opening
• Entrance to the vagina. Also known as the vaginal introitus.
Hymen
• Thin membrane that partially covers the vaginal opening.
• Often ruptures during the first episode of sexual intercourse and historically its presence was taken as proof of virginity. However, it can rupture spontaneously, during exercise, by using tampons or menstrual cups, or it may simply be absent altogether.
Urinary meatus
• Opening of the urethra.
• Located posterior to the clitoris, but anterior to the vaginal opening.
Vestibular glands
• Greater vestibular glands - also known as Bartholin’s glands - they are located just posterior to the vaginal opening and secrete a lubricant into the vagina during sexual arousal.
• Lesser vestibular glands - also known as Skene’s glands - they lie near the urethral opening. The function of the fluid they secrete is debated but it may lubricate the vaginal opening or urethra, or have an antimicrobial effect.

Question 3

What forms the clitoris?

Answer 3

The clitoris is formed of two corpora cavernosa and the glans clitoris. As in males, the corpora cavernosa are symmetrical and run along the left and right ischial rami to converge in the midline. The ‘crura of the clitoris’ refers to the parts of the corpora cavernosa that are attached to the ischial rami. The body of the clitoris is formed by the distal parts of the corpora cavernosa.

Question 4

Where does the corpus spongiosum lie in females?

Answer 4

In females, the corpus spongiosum lies in the midline on the perineal membrane, but it is split into two parts that flank the vaginal opening. These parts of the corpus spongiosum in females are named the bulbs of the vestibule (or the bulb of the clitoris). The anterior parts of the bulbs form the glans clitoris in the midline.

Question 5

What is the ischiocavernosus like in females?

Answer 5

As in males, the corpora cavernosa are covered by the ischiocavernosus muscles, and the corpus spongiosum is covered by the bulbospongiosus muscle. Ischiocavernosus forces blood from the crura to the body of the clitoris. Bulbospongiosus forces blood into the glans clitoris. It helps to maintain clitoral erection and constricts around the vaginal orifice which can help expression of fluid from the greater vestibular glands.

Question 6

What is the blood supply to the clitoris?

Answer 6

The blood supply to the clitoris is via the internal pudendal arteries (from the internal iliac arteries) – branches include the deep arteries of the clitoris and the arteries of the bulb of the vestibule. The erectile tissues of the clitoris are innervated by parasympathetic nerves. Ischiocavernosus and bulbospongiosus are innervated by the pudendal nerve (S2-S4).

Question 7

What is the innervation of the vulva?

Answer 7

The vulva is innervated via four nerves: the ilioinguinal nerve, the genital branch of the genitofemoral nerve, the pudendal nerve and the posterior cutaneous nerve of the thigh.

Question 8

What does the female pelvis contain?

Answer 8

The female pelvis contains the ovaries, uterus, uterine tubes, cervix, part of the vagina, the bladder and rectum.

Question 9

What is the structure of the ovary?

Answer 9

Ovary - The ovaries are almond-shaped organs about 4cm long and 2cm wide. They are attached to the posterior aspect of the broad ligament by a short mesentery; the mesovarium. The position of the ovary is not fixed, but it frequently lies in the ovarian fossa, formed by the angle between the internal and external iliac arteries. The ureter and the obturator nerve and vessels are close relations of the ovarian fossa.

Question 10

What is the structure of the uterus?

Answer 10

Uterus - The pear-shaped uterus is a hollow muscular organ about 8cm long. It communicates laterally with the uterine tubes and inferiorly with the vagina. The uterus has a fundus (above the uterine tubes), a body and a cervix. The body of the uterus is typically angled anteriorly (ante-flexed) and rests on the superior surface of the bladder. The junction between the body and cervix may be tilted anteriorly (anteverted) or posteriorly (retro-verted). The uterus is covered in a fold of peritoneum which adheres to itself at the sides of the uterus to form the broad ligament. The space behind the uterus but anterior to the rectum is called the rectouterine pouch (pouch of Douglas) and is lined with peritoneum. It is the deepest point in the peritoneal cavity, so it is a common site for the accumulation of intraperitoneal fluid or pus.

Question 11

What is the structure of the uterine tubes?

Answer 11

Uterine tubes (Fallopian tubes) - These paired tubes carry ova from the ovary towards the uterine cavity. They are about 10cm long and run in the upper border of the broad ligament. Near the uterus, the tubes have a narrow isthmus. Laterally, the uterine tubes have a dilated ampulla, leading into a funnel-shaped infundibulum. The free edge of the infundibulum is broken up into finger-like projections, the fimbriae, which are draped over the ovary.

Question 12

What is the structure of the cervix?

Answer 12

Cervix - The cervix has a narrow lumen, the cervical canal, which communicates with the uterine cavity via the internal os and with the vagina via the external os. The lower part of the cervix lies inside the vagina creating a recess, the vaginal fornices, around the cervix. The position of the cervix is stabilised by the tone of the levator ani muscle and ligaments which run from the lateral wall of the cervix to the lateral pelvic wall at the base of the broad ligament.

Question 13

What is the structure of the vagina?

Answer 13

Vagina - The vagina is the excretory duct of the uterus. It is approximately 10cm long. It is bordered superiorly by the cervix and terminates below at the introitus by opening into the vestibule (space) between the labia minora. The vagina passes through the pelvic floor; the upper two thirds of the vagina lie in the pelvic cavity and the lower one third in the perineum. The vagina is closely related to the bladder anteriorly and the urethra is often embedded in the anterior wall of the lower third of the vagina.

Question 14

What is the blood supply of the female pelvic organs?

Answer 14

All these structures receive arterial blood via branches of the internal iliac artery, except the ovary which is supplied by the ovarian artery. The ovarian artery is a direct branch of the abdominal aorta and also contributes to the blood supply of the uterine tubes.

Question 15

What is endometriosis?

Answer 15

Endometriosis is a condition in which endometrial tissue, which lines the inside of the uterus, is found outside the uterus. Most commonly these endometrial deposits affect the ovaries, uterine tubes, uterine ligaments and rectouterine pouch. Rarely, endometrial tissue is found outside the pelvis, even in distant sites such as the thorax. The cause is not fully understood but it can lead to painful periods, heavy bleeding during periods, chronic pelvic pain, and pain during intercourse. Endometriosis can make it difficult to conceive. It is formally diagnosed by taking biopsies during surgical exploration of the pelvis (diagnostic laparoscopy).

Question 16

What are fibroids?

Answer 16

These are benign growths of the uterus which may be asymptomatic or cause varied symptoms, including painful and heavy periods. They vary in size and may grow very large. They may grow into the lumen of the uterus and make it difficult to conceive.

Question 17

What causes gynaecological cancers?

Answer 17

Cancer can affect the ovaries, uterus, cervix, vagina, and vulva. Symptoms may include pelvic pain, abnormal vaginal discharge, abnormal vaginal bleeding (bleeding between periods, after intercourse or after the menopause), urinary disturbance, abdominal swelling, and more non-specific symptoms of malignancy such as fatigue and weight loss.

Ovarian cancer is often diagnosed late as symptoms tend to be non-specific, including abdominal bloating, pelvic pain, loss of appetite and weight loss. Uterine cancer typically presents with abnormal vaginal bleeding, for example, bleeding between periods, heavier periods than usual or bleeding after the menopause.

Cervical cancer also typically presents with abnormal vaginal bleeding, including bleeding between periods, after the menopause or after intercourse. Most cases of cervical cancer are caused by infection with specific types of human papillomavirus (HPV). In the UK, females aged 25-64 are regularly invited for a cervical screening (cervical smear test) as part of the cervical cancer screening programme. This involves taking a sample of cells from the cervix to see if these specific types of human papillomavirus (HPV) are present. Children in the UK are offered the HPV vaccine to prevent against these viruses and the chances of developing cervical cancer.

Question 18

What is a hysterectomy?

Answer 18

A hysterectomy is the surgical removal of the uterus. There are several types of hysterectomies, each with its own surgical approach and purpose. The most common type of hysterectomy, a total hysterectomy, involves the removal of the entire uterus, including the cervix and uterine tubes. A hysterectomy may be recommended for a variety of reasons, including uterine fibroids, endometriosis, uterine prolapse, and endometrial hyperplasia.

Question 19

What is an ectopic pregnancy?

Answer 19

Fertilisation usually occurs in one of the uterine tubes and the zygote is swept down the tube by ciliated cells, towards the body of the uterus where it implants as a blastocyst in the endometrium. An ectopic pregnancy occurs when the blastocyst implants outside the body of the uterus. The uterine tube is the most common place for an ectopic pregnancy to implant. The uterine tube cannot stretch to accommodate a growing embryo and so may rupture as the pregnancy progresses in the weeks after conception. This can cause significant pain and internal bleeding and may be life-threatening. A tubal pregnancy cannot progress, and surgery is often required to remove the pregnancy from the uterine tube.

Question 20

What is sterilisation?

Answer 20

Female sterilisation involves interrupting the uterine tubes so that the sperm and egg cannot meet. It is usually performed laparoscopically and is achieved either by using devices to clamp the tubes shut or by removing a small segment of tube.

Question 21

What is FGM?

Answer 21

This takes many forms, and may include removal of the clitoris, removal of the labia minora, and/or narrowing the entrance to the vagina. FGM can cause serious problems including chronic pain, infections, painful intercourse, complications in labour, emotional trauma, and mental health problems. In the UK, it is illegal to perform FGM or to take a girl to another country for FGM to be performed.
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