Lecture number 1. Anatomy and physiology of the female genital organs

1. Anatomy of the female genital organs

The genital organs of a woman are usually divided into external and internal. The external genitalia are the pubis, the labia majora and minora, the clitoris, the vestibule of the vagina, and the hymen. The internal organs include the vagina, uterus, fallopian tubes, and ovaries.

external genitalia

Pubis is an area rich in subcutaneous fat, covered with hair in adulthood, triangular in shape, with the base facing upwards.

Large labia formed by two folds of skin containing fatty tissue, sebaceous and sweat glands. They are connected to each other by the anterior and posterior commissures, and separated by the genital gap. In the thickness of the lower third of the labia majora are large glands of the vestibule - the Bartholin glands, the alkaline secret of which moisturizes the entrance to the vagina and dilutes the seminal fluid. The excretory ducts of these glands open in the groove between the labia minora and the hymen.

Small labia are a mucous membrane in the form of two folds. They are located medially from the labia majora. Normally, the inner surfaces of the large and small labia are in contact, the genital gap is closed.

Clitoris is an organ similar to the male penis, located in the anterior corner of the genital fissure, consists of two cavernous bodies, richly supplied with blood vessels and nerve plexuses.

Vaginal vestibule - the space bounded by the labia minora. It opens the external opening of the urethra, the excretory ducts of the large glands of the vestibule, the entrance to the vagina.

Hymen is a thin connective tissue septum separating the external and internal genital organs. It has a hole, depending on its shape and location of the hymen, it can be semilunar, annular, serrated, lobed. The hymen is torn during the first sexual intercourse, the remains of it are called hymenal papillae, and after additional breaks in childbirth - myrtle papillae.

internal sex organs

Vagina It is a muscular-fibrous tube 8-10 cm long. It is located in the pelvic cavity, adjoining the urethra and bladder in front, and the rectum in the back. The walls of the vagina are in contact with each other and in the upper section, around the vaginal part of the cervix form dome-shaped recesses - the anterior, posterior, right and left lateral vaults of the vagina. The deepest of them is the posterior fornix. It accumulates the contents of the vagina. The walls of the vagina consist of a mucous membrane, a muscular layer and surrounding tissue. The mucous membrane of the vagina is covered with stratified squamous epithelium, has a pink color and numerous transverse folds, which ensure its extensibility during childbirth. There are no glands in the vaginal mucosa, but it is always in a hydrated state due to the perspiration of fluid from the blood, lymphatic vessels and the attachment of secretocervical, uterine glands, sloughing epithelial cells, microorganisms and leukocytes. In a healthy woman, these secretions are mucous in nature, milky in color, characteristic odor and acidic. In accordance with the nature of the microflora, it is customary to distinguish four degrees of purity of the vaginal contents. At the first degree of purity, only vaginal sticks and individual epithelial cells are found in the acidic vaginal contents. At the second degree of purity, the vaginal sticks become smaller, individual cocci appear, single leukocytes, the reaction remains acidic. Both degrees of purity are considered normal. The third degree of purity is characterized by an alkaline reaction, the predominance of leukocytes, cocci and other types of bacteria. At the fourth degree of purity, vaginal sticks are absent, a variety of microbial pathogenic flora (cocci, E. coli, Trichomonas, etc.), a large number of leukocytes are found in the contents.

Uterus - hollow smooth muscle pear-shaped organ, flattened in the anteroposterior direction. In the uterus, the body, isthmus and neck are distinguished. The upper convex part of the body is called the fundus of the uterus. The uterine cavity has the shape of a triangle, in the upper corners of which the openings of the fallopian tubes open. At the bottom, the uterine cavity, narrowing, passes into the isthmus and ends with an internal pharynx.

Cervix - This is a narrow cylindrical shape of the lower part of the uterus. It distinguishes between the vaginal part, protruding into the vagina below the arches, and the supravaginal upper part, located above the arches. Inside the cervix passes a narrow cervical (cervical) canal 1-1,5 cm long, the upper section of which ends with an internal pharynx, and the lower one ends with an external one. The cervical canal contains a mucous plug that prevents the penetration of microorganisms from the vagina into the uterus. The length of the uterus in an adult woman is on average 7-9 cm, the thickness of the walls is 1-2 cm. The weight of the non-pregnant uterus is 50-100 g. The walls of the uterus consist of three layers. The inner layer is a mucous membrane (endometrium) with many glands, covered with ciliated epithelium. In the mucous membrane, two layers are distinguished: the layer adjacent to the muscular membrane (basal), and the surface layer - the functional one, which undergoes cyclic changes. Most of the uterine wall is the middle layer - the muscular (myometrium). The muscular coat is formed by smooth muscle fibers that make up the outer and inner longitudinal and middle circular layers. The outer - serous (perimetry) layer is the peritoneum covering the uterus. The uterus is located in the cavity of the small pelvis between the bladder and the rectum at the same distance from the walls of the pelvis. The body of the uterus is tilted anteriorly, towards the symphysis (anteversion of the uterus), has an obtuse angle with respect to the neck (anteflexia of the uterus), open anteriorly. The cervix is ​​facing backwards, the external os is adjacent to the posterior fornix of the vagina.

The fallopian tubes start from the corners of the uterus, go to the sides to the side walls of the pelvis. They are 10-12 cm long and 0,5 cm thick.

The walls of the tubes consist of three layers: the inner - mucous, covered with a single-layer ciliated epithelium, the cilia of which flicker towards the uterus, the middle - muscular and the outer - serous. In the tube, the interstitial part is distinguished, passing through the thickness of the uterine wall, the isthmic - the most narrowed middle part and the ampullar - the expanded part of the tube, ending with a funnel. The edges of the funnel look like fringes - fimbriae.

Ovaries are paired almond-shaped glands, 3,5-4, 1-1,5 cm in size, weighing 6-8 g. They are located on both sides of the uterus, behind the wide ligaments, attaching to their back sheets. The ovary is covered with a layer of epithelium, under which the albuginea is located, the cortical substance is located deeper, in which there are numerous primary follicles in different stages of development, corpus luteum. Inside the ovary is a medulla consisting of connective tissue with numerous vessels and nerves. During puberty in the ovaries, the process of maturation and release into the abdominal cavity of mature eggs capable of fertilization monthly rhythmically occurs. This process is aimed at the implementation of the reproductive function. The endocrine function of the ovaries is manifested in the production of sex hormones, under the influence of which during puberty the development of secondary sexual characteristics and genital organs occurs. These hormones are involved in the cyclical processes that prepare a woman's body for pregnancy.

Ligamentous apparatus of the genital organs and fiber of the small pelvis

The suspensory apparatus of the uterus consists of ligaments, which include paired round, wide, funnel-pelvic and proper ligaments of the ovaries. Round ligaments extend from the corners of the uterus, anterior to the fallopian tubes, go through the inguinal canal, attach at the pubic symphysis, pulling the bottom of the uterus forward (anteversion). Broad ligaments depart in the form of double sheets of peritoneum from the ribs of the uterus to the side walls of the pelvis. In the upper sections of these ligaments, the fallopian tubes pass, and the ovaries are attached to the posterior sheets. Funnel-pelvic ligaments, being a continuation of the broad ligaments, go from the funnel of the tube to the pelvic wall. Own ligaments of the ovaries go from the bottom of the uterus backwards and below the discharge of the fallopian tubes are attached to the ovaries. The fixing apparatus includes sacro-uterine, main, utero-vesical and vesico-pubic ligaments. The sacro-uterine ligaments extend from the posterior surface of the uterus in the area of ​​​​the transition of the body to the neck, cover the rectum on both sides and are attached to the anterior surface of the sacrum. These ligaments pull the cervix backwards. The main ligaments go from the lower part of the uterus to the side walls of the pelvis, the uterovesical - from the lower part of the uterus anteriorly, to the bladder and further to the symphysis, like the vesicopubic. The space from the lateral sections of the uterus to the walls of the pelvis is occupied by the periuterine parametric fiber (parametrium), in which the vessels and nerves pass.

Milk glands

They are modified sweat glands. During puberty, the mammary gland has a cluster-shaped structure and consists of many vesicles - alveoli, forming large lobules. The number of lobules is 15-20, each of which has its own excretory duct, which independently opens on the surface of the nipple. Each milk duct, before reaching the surface of the nipple, forms an expansion in the form of a sac - the milk sinus. Interlobular spaces are filled with layers of fibrous connective and adipose tissue. The lobules of the mammary glands contain cells that produce a secret - milk. On the surface of the gland is the nipple, covered with delicate, wrinkled skin and having a conical or cylindrical shape. The function of the mammary glands is the production of milk.

2. Physiology of the female reproductive system

The female reproductive system has four specific functions: menstrual, reproductive, reproductive, and secretory.

Menstrual cycle.

menstrual cycle Rhythmically repeated complex changes in the reproductive system and throughout the body of a woman are called, preparing her for pregnancy. The duration of one menstrual cycle is counted from the first day of the last menstruation to the first day of the next menstruation. On average, it is 28 days, less often 21-22 or 30-35 days. The duration of menstruation is normally 3-5 days, blood loss is 50-150 ml. Menstrual blood is dark in color and does not clot. Changes during the menstrual cycle are most pronounced in the organs of the reproductive system, especially in the ovaries (ovarian cycle) and the lining of the uterus (uterine cycle). An important role in the regulation of the menstrual cycle belongs to the hypothalamic-pituitary system. Under the influence of releasing factors of the hypothalamus in the anterior pituitary gland, gonadotropic hormones are produced that stimulate the function of the gonads: follicle-stimulating (FSH), luteinizing (LH) and luteotropic (LTH). FSH promotes the maturation of follicles in the ovaries and the production of follicular (estrogen) hormone. LH stimulates the development of the corpus luteum, and LTH - the production of the corpus luteum hormone (progesterone) and the secretion of the mammary glands. In the first half of the menstrual cycle, the production of FSH predominates, in the second half - LH and LTH. Under the influence of these hormones, cyclic changes occur in the ovaries.

Ovarian cycle.

This cycle consists of 3 phases:

1) development of the follicle - follicular phase;

2) rupture of a mature follicle - the phase of ovulation;

3) development of the corpus luteum - luteal (progesterone) phase.

In the follicular phase of the ovarian cycle, the growth and maturation of the follicle occurs, which corresponds to the first half of the menstrual cycle. There are changes in all components of the follicle: an increase, maturation and division of the egg, rounding and reproduction of the cells of the follicular epithelium, which turns into a granular membrane of the follicle, differentiation of the connective tissue membrane into the outer and inner. In the thickness of the granular membrane, follicular fluid accumulates, which pushes the cells of the follicular epithelium on one side to the egg, on the other - to the wall of the follicle. The follicular epithelium that surrounds the egg is called radiant crown. As the follicle matures, it produces estrogen hormones that have a complex effect on the genitals and the entire body of a woman. During puberty, they cause the growth and development of the genital organs, the appearance of secondary sexual characteristics, during puberty - an increase in the tone and excitability of the uterus, the proliferation of cells of the uterine mucosa. Promote the development and function of the mammary glands, awaken the sexual feeling.

ovulation called the process of rupture of a mature follicle and the release of a mature egg from its cavity, covered on the outside with a shiny membrane and surrounded by cells of the radiant crown. The egg enters the abdominal cavity and further into the fallopian tube, in the ampullary section of which fertilization occurs. If fertilization does not occur, then after 12-24 hours the egg begins to break down. Ovulation occurs in the middle of the menstrual cycle. Therefore, this time is the most favorable for conception.

The phase of development of the corpus luteum (luteal) occupies the second half of the menstrual cycle. In place of the ruptured follicle after ovulation, a corpus luteum is formed that produces progesterone. Under its influence, secretory transformations of the endometrium occur, which are necessary for implantation and development of the fetal egg. Progesterone reduces the excitability and contractility of the uterus, thereby contributing to the preservation of pregnancy, stimulates the development of the parenchyma of the mammary glands and prepares them for the secretion of milk. In the absence of fertilization, at the end of the luteal phase, the corpus luteum regresses, progesterone production stops, and a new follicle begins to mature in the ovary. If fertilization has occurred and pregnancy has occurred, then the corpus luteum continues to grow and function during the first months of pregnancy and is called corpus luteum of pregnancy.

uterine cycle.

This cycle is reduced to changes in the uterine mucosa and has the same duration as the ovarian one. It distinguishes two phases - proliferation and secretion, followed by rejection of the functional layer of the endometrium. The first phase of the uterine cycle begins after the rejection (desquamation) of the endometrium during menstruation ends. In the stage of proliferation, epithelialization of the wound surface of the uterine mucosa occurs due to the epithelium of the glands of the basal layer. The functional layer of the mucous membrane of the uterus thickens sharply, the endometrial glands acquire a sinuous shape, their lumen expands. The proliferation phase of the endometrium coincides with the follicular phase of the ovarian cycle. The secretion phase occupies the second half of the menstrual cycle, coinciding with the development phase of the corpus luteum. Under the influence of the corpus luteum hormone progesterone, the functional layer of the uterine mucosa is even more loosened, thickened and clearly divided into two zones: spongy (spongy), bordering on the basal layer, and more superficial, compact. Glycogen, phosphorus, calcium and other substances are deposited in the mucous membrane, favorable conditions are created for the development of the embryo if fertilization has occurred. In the absence of pregnancy at the end of the menstrual cycle, the corpus luteum in the ovary dies, the level of sex hormones decreases sharply, and the functional layer of the endometrium, which has reached the secretion phase, is rejected and menstruation occurs.

3. Anatomy of the female pelvis

The structure of the pelvis women is very important in obstetrics, since the pelvis serves as the birth canal through which the fetus is born. The pelvis consists of four bones: two pelvic bones, the sacrum and the coccyx.

Pelvic (innominate) bone It consists of three fused bones: the ilium, pubic and ischium. The bones of the pelvis are connected by means of a paired, almost immobile sacroiliac joint, an inactive semi-joint - the symphysis and a movable sacrococcygeal joint. The joints of the pelvis are reinforced with strong ligaments and have cartilaginous layers. The ilium consists of a body and a wing, expanded upwards and ending in a crest. In front, the crest has two protrusions - the anteroupper and anteroinferior awns, behind there are posterior superior and posterior inferior awns. The ischium consists of a body and two branches. The upper branch goes from the body down and ends with the ischial tuberosity. The lower branch is directed anteriorly and upward. On the back surface of it there is a protrusion - the ischial spine. The pubic bone has a body, upper and lower branches. On the upper edge of the upper branch of the pubic bone there is a sharp crest, which ends in front with a pubic tubercle.

Sacrum consists of five fused vertebrae. On the anterior surface of the base of the sacrum, a protrusion is the sacral promontory (promontorium). The apex of the sacrum is movably connected to coccyxconsisting of four to five undeveloped fused vertebrae. There are two sections of the pelvis: the large and small pelvis, between them there is a boundary, or nameless line. The large pelvis is available for external examination and measurement, unlike the small pelvis. The size of the small pelvis is judged by the size of the large pelvis. In the small pelvis, an entrance, a cavity and an exit are distinguished. In the pelvic cavity there are narrow and wide parts. Accordingly, four planes of the small pelvis are conditionally distinguished. The plane of entry into the small pelvis is the boundary between the large and small pelvis. At the entrance to the pelvis, the largest size is the transverse. In the cavity of the small pelvis, the plane of the wide part of the cavity of the small pelvis is conditionally distinguished, in which the direct and transverse dimensions are equal, and the plane of the narrow part of the cavity of the small pelvis, where the direct dimensions are somewhat larger than the transverse ones. In the plane of the exit of the small pelvis and the plane of the narrow part of the small pelvis, the direct size prevails over the transverse. In obstetric terms, the following dimensions of the small pelvis are important: true conjugate, diagonal conjugate and direct size of the pelvic outlet. The true, or obstetric, conjugate is the direct size of the entrance to the small pelvis. This is the distance from the cape of the sacrum to the most prominent point on the inner surface of the pubic symphysis. Normally, it is 11 cm. The diagonal conjugate is determined during a vaginal examination. This is the distance between the sacral cape and the lower edge of the symphysis. Normally, it is 12,5-13 cm. The direct size of the exit of the small pelvis goes from the top of the coccyx to the lower edge of the symphysis and is 9,5 cm. During childbirth, when the fetus passes through the small pelvis, this size increases by 1,5-2 cm due to the deviation of the tip of the coccyx posteriorly. The soft tissues of the pelvis cover the bone pelvis from the outer and inner surfaces and are represented by ligaments that strengthen the joints of the pelvis, as well as muscles. Important in obstetrics are the muscles located in the outlet of the pelvis. They close the bottom of the bone canal of the small pelvis and form the pelvic floor.

Obstetric (anterior) perineum called that part of the pelvic floor, which is located between the anus and the posterior commissure of the labia. The part of the pelvic floor between the anus and the coccyx is called back crotch. The pelvic floor muscles, together with the fascia, form three layers. These three layers can stretch and form a wide tube - a continuation of the bony birth canal, which plays a big role in the expulsion of the fetus during childbirth. The most powerful is the upper (inner) layer of the pelvic floor muscles, which consists of a paired muscle that lifts the anus, and is called the pelvic diaphragm. The middle layer of muscles is represented by the urogenital diaphragm, the lower (outer) - by several superficial muscles converging in the tendon center of the perineum: bulbous-spongy, ischiocavernosus, superficial transverse perineal muscle and external sphincter of the rectum. The pelvic floor performs the most important functions, being a support for the internal and other organs of the abdominal cavity. Failure of the pelvic floor muscles leads to prolapse and prolapse of the genitals, bladder, rectum.

Author: Ilyin A.A.

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