Anatomy of the female reproductive system
The female reproductive system is divided into two parts:
Internal genital organs:
- The uterus
- Fallopian tubes
External genital organs: Labia minor, Labia major, clitoris and vaginal opening
The uterus is a muscular organ that is similar in shape and size to the inverted pear fruit and is located in the pelvis
The length of the uterus is 7-8 cm, and its width and thickness is 4-5 cm at the point of contact with the fallopian tubes
The uterus consists of two parts connected in an area called the isthmus:
- The body of the uterus: the upper part and connected to the fallopian tubes
- Cervix: It is the lower part and connected to the vagina.
The body of the uterus
The length of the body of the uterus is about 5 cm, and the uterus weighs about 50 grams in the adult lady who has not given birth before, and about 70 grams in the adult lady who has already given birth before.
The body of the uterus bends approximately 45 degrees forward in most women, but in about 1 percent of women, this curvature can be backward (called Retro-verted uterus) or there may be no curvature.
The Cervix of the uterus
The length of the cervix is about 2.5 to 3 cm, which is the distance between the highest point in the cervix which is called the internal os “the inner opening of the cervix” and the bottom point in the cervix which is called the external os “the external opening of the cervix”, which is the opening in the top of the cervix.
The cervix is connected with the vagina by entering a part of the cervix at the top of the vagina.
The outer opening of the cervix is circular in the woman who has not given birth before (Fig. 1) and turns into a spindle shaped in the woman who has already given birth (Fig. 2).
The internal and external openings of the cervix widen very little at the time of the menstrual cycle to allow the menstrual flow to exit, otherwise, both opening are closed.
Layers of the uterine wall
The wall of the uterus consists of three layers, namely:
- Outer layer: the peritoneum surrounding the uterus
- Middle layer (The Myometrium): It is the muscular layer of the uterus. This layer consists of two layers of muscle fibers, a thin outer layer of longitudinal fibers, and a thick inner layer of interlocking fibers which is the strongest.
- Inner layer (The
Endometrium): It is a thin layer of mucous spongy tissue and this layer
contains endometrial glands. Endometriosis consists of two layers:
- The basic layer: the layer adjacent to the muscle layer, it is a fixed layer that does not shed during the breakdown of menstruation, from which the functional surface layer arises with changes in the menstrual cycle.
- Functional layer: It is the renewable and lining layer of the uterine cavity and arises from the base layer under the influence of estrogen and progesterone during the ovarian cycle, and it is the layer that shed when the breakdown of menstrual blood.
- Round ligaments: connect the body of the uterus to the labia major
- Infundibulopelvic ligaments: connected to the ligaments of the ovaries and connect the body of the uterus to the pelvic wall on both sides
- Broad ligaments: composed of 2 layer of the peritoneum and connect the body of the uterus from both sides to the side wall of the pelvis
- Cardinal ligaments: the cervical ligaments that connect the sides of the cervix to the ischial spines
- Uterosacral ligaments: the posterior ligaments that connect the uterus to the anterior surface of the sacrum
Organs surrounding the uterus:
The urinary bladder is located to the front of the uterus, and the colon is located on the back of the uterus and the intestine come around the uterus
Each woman has two tubes called the fallopian tubes, also called salpinges (singular: salpinx) a muscular canal that connects the top of the uterine cavity and the ovaries on each side, and each measures about 7 – 14 cm in length
The fallopian tube is named after its Italian discoverer, Gabriel Fallopio.
The fallopian tube is divided into three parts:
- The isthmus the part related to the uterus
- The ampulla: the middle third
- The infundibulum: the third part near the fimbriae
- The fimbriae: which ends from the ovary with the cilia that capture the egg
The inner diameter of the fallopian tube is about 1 mm at the point of contact with the uterus and 3 mm at the end of the canal from the ovarian side.
The fallopian tube consists of four layers (from outside to inside):
- The outer layer is called the serosa, which is the peritoneum surrounding the tube.
- The second layer: the sub serous layer and consists of fibers and blood vessels
- The Muscular layer: It consists of two layers of muscles, an outer layer of longitudinal muscles and an inner layer of circular muscles
- The layer before the mucosa
- The Mucosa layer: the inner layer surrounding the cavity of the tube and lined with cilia that move towards the uterus to help the egg and the embryo after fertilization to move to the uterine cavity
The fallopian tube is connected to the ligament of the ovary that connects the ovary to the pelvic wall
Function of the fallopian tube: The fallopian tubes work to capture the egg from the ovary after the process of ovulation to transfer to the cavity of the uterus, and fertilization occurs through the sperm in the middle part of the fallopian tube to move the embryo into the uterine cavity.
The ovary is a basic female genital organ with a length of 2.5 to 5 cm and a width of 1.5 to 3 cm and a thickness of 0.5 to 1.5 cm for each woman ovary and each ovary weighs 4-8 grams
The ovary is connected to the pelvic wall by the ligament of the ovary and the uterus through the same ligament
The ovary consists of two layers, an outer layer (cortex), which contains the main epithelial cells that grow into some eggs, and the inner layer consists of connective tissue and some thin muscle fibers
The ovary works monthly to complete the growth of eggs until the process of ovulation and keep the corpus luteum in case of pregnancy until the end of the ninth week of pregnancy, in addition to the production of female hormones during this period
This term is generally called the external genital area, and consists of the following:
Each female has two labia major and is of a length of 6-8 cm, while the width of about 2-4 cm. These two labia are the outer borders of the vulva, and are connected to the round ligaments connected to the fundus of the uterus. They are made up of a layer of fatty tissue coated with muscle fibers covered with skin containing sweat glands and hair follicles
Each female has two labia minor made of leather folds; each is 5 cm in length and a thickness of about 0.5-1 cm, while the width varies according to age and the number of births, ranging from 3-6 cm, and both are connected to each other from the top at the clitoris.
It is the highest part of the vulva and is located behind the labia major at the point of contact of the labia minor to each other, and consists of cavernous tissue capable of erection when filled with blood in times of sexual arousal.
A duct-shaped muscular tube with an average length of about 9 cm, which connects from the inside with the cervix and from the outside with the labia minor
It consists of an outer muscle layer and an internal mucous layer
Function: It is the place where sexual intercourse occurs and receives semen in the area around the cervix, and also part of the course of the fetus in normal delivery.
It is the area behind the labia minor and contains the opening of the urethra from the front (about 2 cm below the clitoris) and then the opening of the vagina, which is closed by the hymen.
On both sides of the hymen at 5 and 3 o’clock there are openings for two gland ducts in the size of a pea called “Bartholin’s glands” which are responsible for the release of a lubricant fluid at the time of sexual arousal to facilitate sexual intercourse.
The area between the vulva and anus is called the perineum, an area that is surgically incised in normal delivery as needed to facilitate the baby’s exit.
It is a membrane covering the opening of the vagina, can be thin or thick, and has a small opening to allows the exit of menstrual blood monthly, and has many forms, including circular and longitudinal and crescentric and perforated and imperforate “non-perforated.”
The rupture of the membrane (defloration) usually occurs after the first sexual intercourse, but in some cases this membrane is of rubber tissue, which allows the occurrence of sexual intercourse and does not rupture except after normal delivery or through surgical intervention.
After the rupture of the hymen, it turns into small parts on the sides of the opening of the vagina.
The function of the pelvis is to carry the body weight and distribute it to the lower limbs. It is considered the birth canal in women and the keeping of the viscera such as the bladder, rectum and internal genitals.
The pelvis consists of:
- Hip bones: iliac bones (from above), ischium (from behind) and pubic bone(from front)
- Sacral vertebrae: five vertebrae which are fused together
- Coccygeal vertebrae: 4 vertebrae, the upper part of which is connected with the sacral vertebrae by a cartilage (this joint is important in normal birth as it allows to increase the area of the pelvic outlet)
The position of the pelvis in the body while standing is tilted so that the plane of the pelvic inlet makes with the horizontal plane an angle of 60 degrees.
There are different forms of the pelvis but the most common are: (1)gynecoid pelvis, (2) android pelvis, (3) anthropoid pelvis (pelvis-like monkey pelvis) and (4) The platypelloid pelvis (the broad pelvis)
The differences between the male and female pelvis:
- A woman’s bones are lighter and a place of muscles attachment is less pronounced than in men.
- The women’s pelvis is wider and shorter than the male pelvis
- The pelvic entrance is round or oval in women and heart shaped in men.
- The large and small sciatic foramen is wider and deeper in women than in men.
- The direction of the iliac spine and the iliac hump inside is less in women than in men.
- The pubic angle is 90 degrees in women and lower in men.