Anatomy of the uterus: location, structure and function
Uterine diseases occupy one of the leading positions among all female pathologies. Their prevalence leads not only to a decrease in the fertility of a woman, but also to a violation of the quality of life, as well as to significant economic costs associated with the costs of diagnosis, treatment and forced absence of work.
The prevalence of uterine pathology is determined by the connection with other organs and systems and features of the structure of the entire reproductive area.
Structure and dimensions
Uterus is an unpaired female genital organ, predominantly composed of multidirectional smooth muscular fibers, externally covered with a modified peritoneum (perimetry), and from the inside lined with a mucous membrane (endometrium).
The adult womb of the nulliparous woman has a pear-shaped form and is flattened in the anterior-posterior direction. Anatomically, three parts are distinguished in the uterus:
- The bottom - the upper portion, located above the line of the entrance of the fallopian tubes into the uterine cavity.
- The body has a triangular shape. The wide part of the body is directed upwards, towards the abdominal cavity.
- The cervix is a direct continuation of the uterus body. In the neck distinguish two departments:
- Vaginal department (exocervix)lined with multilayer flat keratinized epithelium.
- Supravaginal area (endocervix, cervical canal, cervical canal), consisting mostly of smooth muscle fibers, circling the cervix, with inclusions of collagen and elastin fibers. Endocervix lined with single-layered cylindrical epithelium.
So a healthy womb should look like in a non-pregnant woman. At the onset of pregnancy, the shape of the uterus begins to change. In late pregnancy, the uterus looks like a globular muscle formation with thin walls. In some cases, palpation and ultrasound of the uterus in early pregnancy reveal a slight asymmetry. This is a variant of the norm and does not entail any consequences.
During pregnancy, the size of the uterus also changes. By the end of the second month of pregnancy, the size of the uterus is doubled, and by the end of the third month - four times.
Schematically, the woman's uterus can be depicted in the form of a triangle, the corners of which are the openings of the fallopian tubes and cervix.
The shape of the cervix is different in women giving birth and nulliparous. The cervical canal in the nulliparous is reminiscent of the spindle (i.e., narrowed at the ends and widened in the middle), and the uterine cervix (border between the cervical canal and vagina) has a round or oval appearance. In women giving birth, the cervical canal has a uniform width all along, and the shed is a transverse cleft with torn, healing edges.
The sizes of a uterus can differ depending on the period of a life of the woman and quantity of the transferred pregnancies and sorts. According to ultrasound, three sizes of the body and cervix are determined.
|Category of women||Dimensions of the body of the uterus, mm||Dimensions of the cervix, mm|
|"The Virgin Uterus"||37 - 49||26 - 38||40 - 50||25 - 35||23 - 30||25 - 35|
|After single delivery||45 - 58||35 - 45||46 - 56||28 - 39||25 - 32||28 - 37|
|After second and subsequent delivery||50 - 65||40 - 50||50 - 60||30 - 44||26 - 36||30 - 40|
|Early postmenopause (up to 5 years)||33 - 45||27 - 35||31 - 41||25 - 34||20 - 30||23 - 33|
|Late postmenopause (more than 5 years)||28 - 38||20 - 31||27 - 37||20 - 30||16 - 26||20 - 29|
Where is the uterus
The location of the uterus is a small pelvis, where its front wall is adjacent to the bladder, and the posterior surface is in contact with the rectum.
The uterus has a certain degree of mobility, and its position depends on the level of fluid in the bladder. If it is emptied, the bottom of the uterus is directed towards the abdomen, and the anterior surface - forward and slightly down. In this case, the uterus forms an acute angle with the cervix, which is open anteriorly. This condition is called anteversion. As the bladder is filled, the uterus begins to tilt backward, forming a corner with the neck, close to the unfolded one. A similar position of the uterus is called retroversion.
Functions of the uterus
The only function of the uterus is participation in pregnancy and childbirth. Due to its predominantly muscular structure, the uterus during gestation can increase its area severalfold. And due to the intensive coordinated reduction of the musculature during labor, the uterus plays a decisive role in expelling the fetus.
Anatomy of the uterus
The wall of the uterus has a three-layer structure:
- The internal mucosal membrane is the endometrium.Lining the uterus from the inside, the endometrium has no folds, is lined with a ciliary epithelium and is rich in glands. Epithelium also has a good blood supply, which explains its sensitivity to trauma and inflammatory processes. In the photo and video taken during hysteroscopy, the uterus from the inside is a smooth smooth space of different colors - from pink to grayish, depending on the phase of the female cycle and age women.
- The average muscular membrane is myometrium.This layer consists of smooth muscle cells intertwined in all directions. Since the muscle cells are smooth, a woman is not able to regulate uterine contractions. The consistency of the contraction of various parts of the myometrium at different periods of the cycle and during labor is subject to the autonomic nervous system.
- The outer layer is the perimeter, which is the peritoneum. This serous membrane covers the entire anterior wall of the body, and on the border with the neck it curves and passes to the bladder. Here, a vesicoureteral space is formed. The cervix in front is not covered by the peritoneum and is delimited from the bladder by a layer of fatty tissue. In addition to the entire back surface of the body, the peritoneum covers a small portion of the posterior vaginal vault. After that, the envelope flexes and spreads to the rectum, forming a rectum-uterine pocket. In this space, liquid can accumulate in ascites. This can include purulent inflammation, endometriosis, or malignant tumors. Through the back wall of the vagina, access is made to this space during the diagnostic procedure - culdoscopy.
Intended use of ligaments
The uterus is an organ for which a clear relatively constant position is of fundamental importance. This is achieved through the ligament of the uterus.
The ligamentous apparatus of the uterus performs three main functions:
- Suspension - attachment of the organ to the bones of the pelvis for the purpose of fixing the uterus in a stable position.
- Fixing is the retention of the uterus in the physiological position during the gestation of the fetus due to stretchable ligaments.
- Supporting - the formation of support for internal organs.
Characteristics of the suspension device
The hanging function of the uterus is due to four pairs of ligaments:
- Round uterine ligaments, containing in their composition smooth myocytes and connective tissue fibers. In appearance they resemble strands of 100 - 120 mm in length, extending from the corners of the uterus to the inguinal canal. Due to this direction, the round ligaments tilt the uterine fundus anteriorly.
- Wide uterine ligaments, which are derived from the peritoneum. They look like a "sail" stretched from the lateral surfaces of the uterus to the walls of the pelvis. In the upper part of these ligaments lie the tubes, and on the back surface are the ovaries. The space between the two between the two leaves is filled with cellulose, in which the neurovascular bundles are located.
- Suspension of ovary ligament, which are part of the wide uterine ligaments. They originate from the tubes of the uterus and are fixed to the walls of the pelvis.
- Own ovarian ligaments, which fix the ovary to the lateral surface of the uterus.
The structure and location of fixation ligaments
The fixing ligaments of the uterus are:
- Cardinal (transverse) uterine ligaments, which are powerful bundles and nerves rich in nerves, consisting of smooth muscles and fibers of connective tissue. These ligaments are modified by reinforced wide ligaments, for which the transverse ligaments serve as a support.
- Uterine-vesicle (cervical-bladder) ligaments are muscular-connective tissue fibers originating from the cervix and enveloping the bladder. Due to this direction, the ligaments prevent the uterus from moving in the posterior direction.
- The uterosacral ligaments are represented by smooth muscle and connective tissue fibers starting from the posterior wall of the uterus that surround the rectum and attach to the sacrum. These fibers do not allow the cervix to move in the pubic direction.
Supporting apparatus: muscles and fasciae
The supporting apparatus of the uterus is represented by the perineum - the muscular-fascial plate. The perineum includes the genitourinary and pelvic diaphragms, consisting of two layers of muscles, as well as the perineal fascia.
Structure of the ovaries
Ovaries are paired glandular organs located in the female body on both sides of the uterus and connected with it by the fallopian tubes.
In shape, the ovaries resemble the flattened anterior egg. The weight of this organ is approximately 7-10 g, length - 25 - 45 mm, and width - about 20 - 30 mm. The color of a healthy ovary can be from pinkish-blue to blue-lilac.
On the outside, the ovary is covered with coelomic (germinal) epithelium. Underneath it there is a fibrous white membrane, which forms the framework of the ovary. Deeper is the functional-active substance of the organ - parenchyma. It consists of two layers. Outside, there is a cortical layer in which the follicles are located. The inner layer - granular (brain substance) contains an egg.
In addition to the maturation of eggs, the ovaries perform a hormonal function, synthesizing estrogens (estradiol, estriol), gestagens (progesterone) and testosterone.
The fallopian tubes
The uterine (fallopian) tube is a pair of hollow muscular organs that connect the uterus cavity with the ovary.
Fallopian tubes have a length of 100 to 120 mm. The diameter of the pipe is different throughout its length and varies from 2 - 5 to 8 - 10 mm.
In the fallopian tube, the uterine part communicating with the uterine cavity is separated, as well as the isthmus, ampulla and funnel.
The funnel contains fimbriae. The longest of them - ovarian - approaches the tubal end of the ovary. This fimbria sends the egg into the tube.
The wall of the fallopian tube is represented mostly by smooth myocytes, located in two levels. The cells of the layer located more superficially are arranged longitudinally. Myocytes of the deep layer cover the wall of the fallopian tube in a circle.
Due to this structure, the walls of the fallopian tubes have the ability to contract (peristalsis). This is necessary to move the egg into the uterine cavity.
But under the influence of some unfavorable factors, the fertilized female germ cell is not evacuated into the uterus, but attached to the wall of the tube. Ectopic (tubal, ectopic) pregnancy develops. The increase in the size of the embryo causes the rupture of the wall of the fallopian tube. This leads to the development of massive internal bleeding.
Structure of the circulatory system
Uterus with appendages are organs that have a rich blood network. In this regard, the pathology of the female reproductive system is often accompanied by heavy bleeding, which poses a danger to the life of the patient.
The main arteries are:
- Uterine artery, which is a branch of the internal iliac artery. This vessel supplies the blood not only to the uterus itself, but also gives branches, blood supply to the tube, a wide uterine ligament, part of the vagina and the ovary. In the wall of the uterus, the artery forms an abundant network, connected with the uterine artery of the opposite side.
- The ovarian artery to the left departs from the aorta. The right ovarian artery is often a branch of the renal artery. This vessel blood supply mainly the ovaries, but also takes part in the feeding of the uterus due to anastomoses with the uterine artery.
The vagina receives blood from three sources:
- The branches of the uterine arteries feed a portion of the vagina adjacent to the cervix;
- Lower cystic and middle rectal arteries blood supply the central part;
- Medium rectal and internal pudend arteries deliver blood to the lower parts of the vagina.
From the upper parts of the uterus, tubes and ovaries on the right venous outflow is carried to the inferior vena cava, and to the left - to the left renal vein. Blood from the lower parts of the uterus, cervix and vagina flow into the internal iliac vein.
Outflow of lymph from internal genital organs
The main collectors for the body of the uterus, tubes and ovaries are lumbar lymph nodes. The iliac and sacral lymph nodes divert lymph from the cervix and the lower body of the uterus. A small part of the lymph from the uterus can be collected into the inguinal lymph nodes.
Further, all the lymph from the internal reproductive organs enters the lumbar lumbar spines and lactic tank, from where it passes through the thoracic duct into the internal jugular and left subclavian veins.
Innervation of the uterus and other reproductive organs of a woman
Sensitive innervation of the external genitalia and perineal skin provides a sham (genital) nerve, which is a branch of the sacral plexus. The same nerve gives the motor branches to the muscles that form the perineum.
Internal reproductive organs have only vegetative innervation. This means that the movements of the uterus do not submit to strong-willed efforts, but are carried out under the influence of neuro-vegetative changes. The body of the uterus has mostly sympathetic innervation, and the cervix is predominantly parasympathetic.
The peculiarity of the vegetative innervation of the internal genital organs is what happens through the plexus. The uterus receives innervation from the utero-vaginal plexus, the ovary - the ovarian, and the fallopian tubes - ovarian and utero-vaginal.
Functional changes during the monthly cycle
The monthly (menstrual) cycle is a complex of periodic changes in the endocrine system, ovaries and endometrium, aimed at conception. The duration of the cycle may be different and ranges from 3 to 5 weeks (or 28 ± 7 days).
Functional changes in the body of a woman occur in three stages.
|Cycle phase||Changes in the ovaries||Changes in the endometrium|
Lasts from 7 to 22 days
|The follicular phase||Menstrual phase|
|In the pituitary gland under the action of gonadoliberin, synthesis and release into the blood of FSG1 and LG2 begins. Under the influence of FSH in the ovaries several follicles mature, one of which becomes the dominant one. This follicle begins to synthesize in large volumes estradiol, which, in turn, causes an increase in the synthesis of gonadotropins. The concentration of gonadobiliary increases in proportion to the growth of the dominant follicle until a sharp release of LH from the adenohypophysis occurs.||If the egg was not fertilized, epithelial detachment occurs. This is manifested by menstrual bleeding.|
Duration - about 3 days
|The dominant follicle continues to grow and release estradiol. The follicle, which has reached a degree of maturity and ready for ovulation, is called a Graafian vesicle (GP). Emission of LH is the final stage of development of GP. There is a release of dissolving enzymes, which destroy the wall of the follicle. Mature, ready for fertilization, the egg leaves the cavity of the GP.|
Lasts for 13 - 14 days
|Luteal phase||Secretory phase|
|After the rupture, GP walls collapse, and a new endocrine organ, the yellow body (VT), is formed. ZHT releases estradiol, progesterone and androgens.
If the egg was fertilized and successfully attached to the wall of the uterus, VT secretes progesterone until the placenta is formed and begins to release estrogen and progesterone.
If pregnancy does not occur, VT is destroyed, which causes a decrease in the level of progesterone and estrogen.
|Estrogen and progesterone cause maturation of endometrial glands. These glands begin to actively secrete, preparing the endometrium for attachment (implantation) of a fertilized egg.
If pregnancy does not occur, in the absence of the effect of estrogen and progesterone of the yellow body, the endometrium begins to swell and necrotize. Eventually, his rejection occurs, and the cycle is restarted.
FSH - Follicle-stimulating hormone.
LH - Luteinizing hormone.
Pathologies and abnormalities
As a result of various adverse effects, the structure of the uterus or its position in the pelvic cavity may be disrupted.
Among the anomalies of the structure of the uterus in women, the following forms are distinguished:
- Doubling the organ. In this case, there is always a doubling of the vagina. Most often one of the queens is better developed than the other. In both cases, a normal monthly cycle occurs, and in each of them, the development of pregnancy is possible.
- Double-horned uterus. With this anomaly in the bottom area, there is a division of the organ into two horns connecting in the neck region. Clinically, this deviation is manifested in the violation of the menstrual cycle, miscarriages and infertility. One of the horns of the uterus may be underdeveloped (in this case it looks like a cord or a cavity formation that communicates with the uterus).
- Saddle (arch) uterus. It is an option of the two-horned uterus, in which the division of the bottom is expressed minimally. Most often this anomaly is asymptomatic and is an accidental finding.
- Intrauterine partition. This is a malformation of the organ, in which the uterus is divided into two cavities, which either completely isolated from each other (full septum), or communicate with each other in the neck area (incomplete partition). Clinically, the septum of the uterus is manifested by habitual miscarriages, less often - the inability to become pregnant.
The most common forms of abnormal uterine position are the following:
- Omission of the uterus. In this case, the vaginal part of the cervix does not stand outside the border of the genital gaps. Otherwise, they speak of a prolapse of the uterus.
- Elevation of the uterus. In this case, the bottom of the uterus is located above the upper plane of the pelvis. The lifting of the organ can be due to the adhesive process, the accumulation of menstrual blood with atresia of the hymen, with tumors of the rectum.
- Rotation of the uterus.With this anomaly, the cervix and uterine body turn in one direction. Unlike turning, when the uterus is twisted, the neck remains in place, and the turn is performed only by the body.
- Displacement of the entire uterus. This anomaly can manifest itself in various forms: forward bias (anteposition), backward (retroposition), left or right (sinistrostosition or dextroposition).
Pathological neoplasms are the first variety of diseases of the uterus.
Myoma of the uterus. This is a benign tumor that originates from the muscle layer. There are several types of myomatous nodes:
- Submucous. They are most often found in women of childbearing age;
- Intramural nodes are deep in myometrium;
- Superserous nodes are located outside the uterus, adjacent to the perimetry.
The main symptoms of uterine fibroids are profuse menstruation, miscarriages, infertility.
Fibroids of the uterus. If the uterine myoma contains mainly myocytes in its structure, fibroids are benign tumors consisting of cells of connective tissue. Allocate the same forms of fibroids as in the classification of fibroids. Separately, fibroids of the uterus are isolated - a tumor containing muscle cells in its composition, but with the obligatory inclusion of fibrous tissue. Clinical manifestations of fibroids are identical with those of uterine myomas.
Endometrial polyps- benign proliferation of vessels covered with epithelium. There are several types of polyps:
- fibrous - pale, round or oval, dense, smooth formations on the stem, up to 15 mm in size;
- glandular-cystic - large (up to 60 mm), oblong, smooth, pale pink, gray-pink or yellowish in color;
- adenomatous - dull gray color formation up to 15 mm.
Polyps can be asymptomatic or cause bleeding, pain and infertility.
Fall of the genital organ
Prolaps (prolapse) of the organs of the female reproductive system- this movement of the vagina, cervix or body of the uterus beyond the sexual slit.
There are three degrees of prolapse of genital organs:
- I degree (not a true prolapse): the cervix descends, but it does not go beyond the entrance to the vagina;
- II degree: incomplete prolapse - movement of the cervix beyond the border of the genital gaps, but the uterus is in the cavity of the small pelvis;
- III degree: complete prolapse - the entire uterus falls out.
The main cause of prolapse of the uterus is dysfunction of the ligamentous apparatus. This can be caused by connective tissue dysplasia, inflammatory and adhesive processes in the small pelvis, violation of the innervation and blood supply of the genital organs.
At the first stage, complaints can be absent. Sometimes women notice a feeling of heaviness in the perineum, discomfort when walking, pain in the lower back and sacrum.
The most characteristic symptom of the second and third stages is the formation that has fallen out of the sexual gap.
On examination, the fallen parts of the cervix and uterus body have a bluish tinge. The cause of this is a violation of blood circulation in the fallen parts of the body.
Conservative management of the prolapse of the organs of the female reproductive sphere is impossible! The only way to treat this pathology is surgical intervention.
The operation is aimed at returning organs to a physiological location, restoring and strengthening supporting structures of the uterus and treating concomitant pathologies.
"Rabies of the uterus"
This term hides two diseases, which are related to the field of pathological psychology rather than gynecology.
Nymphomania ("disease of forest nymphs")- Female hypersexuality, excessive attraction to a man. This disorder is manifested by constant sexual dissatisfaction, the desire for a constant change of sexual partners.
Hysteria ("monkey of all diseases")Is a disorder characterized by a pathological need to attract attention. Despite the fact that this condition is also found in men, it most clearly occurs in women. Hysteria can manifest itself in almost any known symptom - uncontrolled laughter and / or crying, convulsive attacks, fainting, blindness, deafness, dumbness, loss of sensitivity. To distinguish hysteria from a true disorder is not difficult. It is enough to remember that hysteria is manifested only in the presence of people, whose attention the patient is trying to achieve.
Both nymphomania and hysteria require treatment from a psychiatrist and a psychotherapist. But sometimes these disorders reach such severity that they require differential diagnosis with diseases of the nervous system (epilepsy, damage to the frontal lobes of the brain, stroke).
The dense womb is not an independent disease, but a symptom accompanying the development of many pathological conditions. Compaction of the uterus means focal or total thickening of the uterine wall, revealed by gynecological examination. The most common causes of dense uterus development are the myomatous nodes and foci of adenomyosis.
Adenomyosis (internal endometriosis) is a benign disease, which is based on the germination of the endometrium in the muscular layer of the uterus. The main symptoms that allow suspected adenomyosis, are violations of the menstrual cycle, intense blunt pain in the lower abdomen, pain with sexual contact, highlighting the "chocolate" color in middle of the cycle.
If during the examination the gynecologist revealed uterine compaction, an ultrasound should be performed to determine the cause.
Uterus removal and postoperative period
Indications for removal (amputation, extirpation) of the uterus (hysterectomy) are myomatous nodes of large size, malignant tumors of the uterus, widespread adenomyosis, abundant uterine bleeding, pronounced inflammatory process endometrium.
With a favorable outcome, it is possible to preserve the ovaries and cervix of the uterus. This gives the woman the opportunity to lead a normal sexual life and avoid the use of hormone replacement therapy. In addition, eggs stored in the ovaries can be used for surrogate motherhood.
In the postoperative period of hysterectomy, pain and spotting always occur.
Painful feelings bother the woman for about a week and are pulling. If the pain intensifies and becomes sharp, cramping, this indicates the development of complications.
Bloody discharge occurs due to the existence of a wound surface. By the end of the second week they gradually stop.
Long-term effects are associated with a violation of the location of the organs in the small pelvis. The bladder is shifted backwards, which can be manifested by various disorders of urination. The intestine is displaced downwards, which in the end can cause the prolapse of hemorrhoids.
If regional lymph nodes were removed along with the uterus, lymph drainage from the lower extremities is broken, which leads to the development of lymphostasis. This is manifested by swelling, severity, pain, and eating disorders of tissues.
The organs of the female reproductive system are very complicated. Knowledge of the anatomical structure of the reproductive system is necessary for understanding the nature of pathological processes and diagnosis of diseases of internal genital organs.