The female reproductive system includes external and internal genitalia.
The female internal genitalia consist of the vagina, uterus and cervix, fallopian tubes, and ovaries.
The female external genitalia are called the vulva. It consists of the mons pubis, labia majora and minora, hymen, clitoris, vestibule, urethra, Skene glands, Bartholin’s glands, and vestibular bulbs.
The labia majora cover the labia minora.
The clitoris is erectile tissue located within the glans clitoris, a fold formed by the joining of the two labia minora anteriorly. It has a rich nerve supply and is innervated by the dorsal nerve of the clitoris, a branch of the pudendal nerve.
The urethra opens just anterior to the vaginal opening, in the vestibule.
Skene’s glands (also called lesser vestibular glands or paraurethral glands) are located along the anterior wall of the vagina and open on either side of the urethral opening (urethral meatus). They produce female ejaculate and are analogous to the male prostate gland.
The vagina is a fibromuscular canal that leads to the cervix at its superior end. It lies anterior to the rectum and posterior to the bladder, and it is positioned at a 90 degree angle to the uterus.
It has four walls (anterior, posterior, and two lateral walls) and a superiorly located vaginal fornix that connects to the cervix.
Typically, the vaginal walls are collapsed, appearing like the letter H in cross section.
The vaginal wall has:
The mucosa shows numerous transverse folds called rugae, which allow the vagina to expand during childbirth.
The lower one-third of the vagina is fused with the perineal body. The pelvic diaphragm, sphincter urethrae and transverse peroneus muscles, and the perineal membrane support the vagina.
In the adult female, the vagina contains commensal Lactobacilli that help maintain vaginal pH below 4.5 (acidic) by producing lactic acid. This acidic environment has important antimicrobial properties.
Cervical glands, Bartholin’s glands, and Skene’s glands help lubricate the vagina.
Under the effect of estrogen (such as at the onset of puberty), epithelial cells accumulate glycogen, and there is proliferation of cells in the basal and parabasal layers.
Blood supply is via the vaginal artery, a branch of the anterior division of the internal iliac artery.
Sensory innervation of the lower part is by the pudendal nerve, and the upper part is by the autonomic nervous system via the pelvic plexus.
Lymphatic drainage is as follows:
The uterus is a muscular organ that sits in the pelvis. It is 2x3" in the non pregnant stage.
It can be divided into:
The uterus sits in the pelvis in an anteverted and anteflexed position.
The bladder lies anterior to the uterus, and the rectum lies posterior to it.
The cervix is a 3-5 cms long, cylindrical structure lying between the internal os and external os. Its cavity is called the endocervical canal.
The epithelium lining the endocervical canal is called the endocervix, and it is simple columnar. It contains many mucus producing glands.
The part of the cervix that projects into the vagina is lined by the ectocervix. In the prepubertal stage, it is lined by non-keratinized stratified squamous epithelium.
At puberty, the simple columnar epithelium of the endocervix migrates into the ectocervix. With exposure to the acidic vaginal milieu, the columnar epithelium undergoes squamous metaplasia in an area called the transformation zone. This zone is clinically important because it is the site of squamous cell cancers of the cervix.
Histologically, the uterus has three layers:
The endometrium is lined by simple columnar epithelium, which invaginates into the underlying stroma to form endometrial glands.
The endometrium has:
The myometrium is a thick smooth muscle layer, while the perimetrium is the outer connective tissue layer. Muscle fibres in the myometrium run horizontally, vertically, and diagonally.
The uterus is supplied by the uterine arteries, which are branches of the anterior division of the internal iliac arteries. The uterine artery lies in the cardinal ligament and divides into ascending and descending branches.
Within the myometrium, the uterine artery gives arcuate, radial, spiral, and basal artery branches.
The spiral artery supplies the endometrium, decidua, and placenta. Estrogen causes an increase in the size and number of the spiral arteries.
The uterus is supported in the pelvis by several ligaments.
The broad ligament is a fold of peritoneum that extends laterally from the uterus to the lateral pelvic walls. It has three parts:
The mesovarium extends to the hilum of the ovaries. The mesosalpinx is related to the fallopian (uterine) tubes. The mesometrium is related to the uterus.
The broad ligament contains the round ligament, the fallopian tube, blood vessels, lymphatics, and nerve fibres.
The superior margin of the broad ligament is called the round ligament. It is about 10-12 cm long. One end attaches to the cornu of the uterus (upper and lateral area, one on each side). From there it travels through the deep inguinal ring and inguinal canal, and ends at the labia majora and mons pubis.
Sampson’s artery is a branch of the uterine artery that runs with the round ligament. It must be ligated during hysterectomy.
The cardinal ligament forms the inferior border of the broad ligament and attaches to the lateral sides of the cervix.
The pubocervical ligament runs from the posterior surface of the symphysis pubis to the cervix.
The rectouterine (uterosacral) ligaments stretch from the cervix to the sacrum.
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