The uterus is an organ in the lower belly (abdomen) or pelvis. It is part of the female reproductive system. It's where a baby grows. It's sometimes called the womb. Show The uterus is hollow and pear-shaped. It is about the size of a fist. It's in your lower belly (pelvic area). Your uterus is connected to the fallopian tubes. These tubes help carry eggs from the ovaries into the uterus. The lower part of the uterus connects to the vagina and is called the cervix. The wider, upper part of the uterus is called the corpus or fundus. The uterus has 3 layers:
In people who still have their periods, 1 ovary releases an egg into a fallopian tube each month. During this time, the endometrium becomes thicker to prepare for a fertilized egg. The egg enters the uterus. If it isn’t fertilized, it leaves the uterus through the vagina, and the endometrial lining is shed during a menstrual period. If the egg joins with a sperm cell (from a male), this fertilized egg attaches to the endometrium. The thick wall of the uterus protects the growing baby during pregnancy. During labor, the cervix opens (dilates). The muscles of the myometrium help push the baby out through the vagina. The balance of the female hormones estrogen and progesterone control this process. Most of these hormones are made by the ovaries. The ovaries are on either side of the womb. They make eggs and the hormone oestrogen. The fallopian tubes connect the ovaries to the womb. The lower part of the womb connects to the top of the vagina. This is called the cervix or the neck of the womb. Cancers that start in the cervix behave differently and are treated differently from womb cancer. Uterus. Also called the womb, the uterus is a hollow, pear-shaped organ located in a woman's lower abdomen, between the bladder and the rectum. Ovaries. Two female reproductive organs located in the pelvis. Fallopian tubes. Carry eggs from the ovaries to the uterus. Cervix. The lower, narrow part of the uterus (womb) located between the bladder and the rectum. It forms a canal that opens into the vagina, which leads to the outside of the body. Vagina. The passageway through which fluid passes out of the body during menstrual periods. It is also called the "birth canal." The vagina connects the cervix (the opening of the womb, or uterus) and the vulva (the external genitalia). The uterus is a hollow, pear-shaped organ that is responsible for a variety of functions, such as gestation (pregnancy), menstruation, and labor and delivery. On a coronal cut section, its cavity has an inverted triangle shape. Sometimes the development in utero may be incomplete; this is called a Mullerian anomaly and can lead to many variants, ranging from a uterine septum to uterine didelphys (double uterus). Anatomically, the uterus is located in the female pelvis immediately posterior to the bladder and anterior to the rectum. The female uterus subdivides into four main anatomic segments (from superior to inferior): the fundus; a broad curved area in which Fallopian tubes connect to the uterus, the corpus (body); the main part of a uterus, and it starts directly below the level of fallopian tubes and continues downward, isthmus; a lower neck region of the uterus, and cervix; which extends downwards from the isthmus and opens in the vagina.[1][2][3] Several ligaments support the uterus, including the utero-ovarian ligament, round ligament, broad ligament, cardinal ligament, and uterosacral ligaments. It is further supported (inferiorly) by the pelvic diaphragm, urogenital diaphragm, and perineal body. The uterus may naturally lie in different positions, such as anteverted/retroverted, anteflexed/retroflexed, or midline, and it may be rotated (especially during pregnancy). The uterus most commonly lies in an anteflexed and anteverted position in 50% of women. When the uterus is in a retroverted/retroflexed or "tipped" position, it may cause pelvic pain, dyspareunia, minor incontinence, fertility difficulty, and difficulty inserting tampons. In pregnancy, this may lead to uterine incarceration. Structure and FunctionThe uterus functions by nurturing the fertilized ovum, which passes through the fallopian tube. The ovum then implants into the endometrium, where it receives nourishment from blood vessels, which are exclusively developed for this purpose. As the embryo grows and matures, the uterus expands to accommodate the developing fetus. During normal labor, the uterus contracts as the cervix dilates, and this results in the delivery of the infant. EmbryologyThe early development of the uterus is quite complex. At about eight weeks of gestation, primordia for both female and male internal genitalia paramesonephric (Mullerian) and mesonephric (Wolffian) ducts appear. The sexual differentiation process involves a series of steps that occur due to growth factors, hormonal signals, and inherited genetic influences. The paramesonephric ducts of both sides extend caudally until they reach the urogenital sinus, where they project into its posterior wall to become the Mullerian tubercle. The Mullerian duct has three parts.
The first two portions of Mullerian ducts make the fallopian tube. The third part canalizes after fusion with its counterpart to form the uterus, cervix, and upper 1/5th of the vagina. In the female embryo, because of the absence of a Y chromosome and lack of testosterone from any testicular tissue, the typical sequence of developmental events results in canalization and fusion of the paramesonephric (Mullerian) ducts in the middle of the pelvis, which gives rise to the female pelvic organs. At this time, the mesonephric (Wolffian) ducts regress. Any abnormality that occurs during this phase of development may result in a variety of paramesonephric anomalies. Blood Supply and LymphaticsThe uterus receives blood from the uterine and ovarian arteries, which arise from the anterior branch of the internal iliac artery. The uterine arteries are the main blood vessels that supply blood to the uterus. As the blood supply enters the myometrium, it branches into the arcuate arteries, which branch into the radial arteries. As they enter the level of the endometrium, they branch into the basal and spiral arteries.[3] Uterine arteries supply the different parts of the uterus and play an essential role in maintaining blood supply during menstrual cycles and in pregnancy. The fundal area of the uterus chiefly drains into para-aortic lymph nodes along with the ovarian and fallopian tube lymphatic drainage. Some of it also drains into superficial inguinal lymph nodes along the round ligament. The lower portions of the uterus drain along uterine blood vessels into external and internal iliac lymph nodes. NervesThe internal pelvic organs receive nerve supply from the autonomic nervous system, sympathetic and parasympathetic nervous system. Autonomic T11 and T12 innervate the uterus, and it derives its sympathetic nerve supply from the hypogastric plexus, and the parasympathetic supply is from S2 to S4. The uterus and cervix are insensitive to cutting and burning. So the cervix can be cauterized without anesthesia during therapeutic procedures. However, the uterus and cervix are sensitive to stretch (distension), and dilation of the cervix causes pain during normal vaginal delivery.[4] MusclesThe uterus is located between the urinary bladder anteriorly and the rectum posteriorly. The average dimensions of the uterus in an adult female are 8 cm long, 5 cm across, and 4 cm thick. The uterine cavity has an average volume of 80 mL to 200 mL. The uterus subdivides into three segments, namely: the body, the cervix, and the fundus. The uterus has three tissue layers which include the following:
Physiologic VariantsThe long axis of the cervix is rarely in line with the long axis of the body of the uterus. Commonly, the long axis of the body of the uterus is tilted forward over the long axis of the cervix, which is called anteflexion of the uterus. A backward tilt at this level is called retroflection. In 80 percent of women, the long axis of the uterus lies at the right angle to the long axis of the vagina with a forward tilt. It is called anteversion retroversion, which is present in 20 percent of women and is a backward tilt of the uterus over the vagina.[5] The anatomical position within the pelvis may vary. The normal position is an anteverted uterus, where the uterus tips forward, whereas a retroverted uterus is angled slightly posteriorly. The uterine position is also sometimes described relative to the location of the fundus; that is, an anteflexed uterus, which is normal and where the fundus tilts forward. On the other hand, a retroflexed uterus tilts posteriorly. The uterus may also vary in size and shape depending on the reproductive phase of the female and its response to the female sex hormones.
Also, a nulliparous uterus is usually smaller than a multiparous uterus. Furthermore, as the female reaches menopause, the uterus starts to atrophy chiefly due to a lack of hormonal stimulation and loss of menstruation.[6][7] Surgical ConsiderationsUterine anomalies of clinical significance include:
Clinical SignificanceThe uterus is affected by a variety of gynecologic disorders, including prolapse, fibroids, polyps, infections, cancer, malformations, and adhesions. Hysterectomy is the second most common surgical procedure performed on women in the United States (cesarean section is the most common). The following are the most common uterine pathologies.
Uterine cancer is the most common gynecologic cancer in developed countries and is associated with excess estrogen. Exogenous sources of estrogen include tamoxifen use or unopposed estrogen replacement therapy. Tamoxifen increases endometrial cancer risk due to its ability to stimulate the estrogen receptors found in the endometrium. Endogenous sources of estrogen include polycystic ovary syndrome, obesity, and estrogen-secreting tumors such as granulosa cell tumors. The majority of women with endometrial cancer will present with abnormal vaginal bleeding or postmenopausal vaginal bleeding. Less commonly, they may present with abdominal pain, change in bowel habits, weight loss, and bloat. FigureThe Uterus, Posterior half of uterus and upper part of vagina, Uterine Tube, Cavity of body, Uterine wall, Internal Orifice, Vagaina. Contributed by Gray's Anatomy Plates References1.Chaudhry SR, Chaudhry K. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): Jul 25, 2022. Anatomy, Abdomen and Pelvis, Uterus Round Ligament. [PubMed: 29763145] 2.Craig ME, Sudanagunta S, Billow M. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): Jul 25, 2022. Anatomy, Abdomen and Pelvis, Broad Ligaments. [PubMed: 29763118] 3.Chaudhry R, Chaudhry K. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): Sep 5, 2022. Anatomy, Abdomen and Pelvis, Uterine Arteries. [PubMed: 29489202] 4.Tong XK, Huo RJ. The anatomical basis and prevention of neurogenic voiding dysfunction following radical hysterectomy. Surg Radiol Anat. 1991;13(2):145-8. [PubMed: 1925917] 5.Fidan U, Keskin U, Ulubay M, Öztürk M, Bodur S. Value of vaginal cervical position in estimating uterine anatomy. Clin Anat. 2017 Apr;30(3):404-408. [PubMed: 28192868] 6.Alimi Y, Iwanaga J, Loukas M, Tubbs RS. The Clinical Anatomy of Endometriosis: A Review. Cureus. 2018 Sep 25;10(9):e3361. [PMC free article: PMC6257623] [PubMed: 30510871] 7.Al-Qattan MM, Al-Qattan AM. Fibromodulin: Structure, Physiological Functions, and an Emphasis on its Potential Clinical Applications in Various Diseases. J Coll Physicians Surg Pak. 2018 Oct;28(10):783-790. [PubMed: 30266125] 8.Kinkel K, Ascher SM, Reinhold C. Benign Disease of the Uterus. In: Hodler J, Kubik-Huch RA, von Schulthess GK, editors. Diseases of the Abdomen and Pelvis 2018-2021: Diagnostic Imaging - IDKD Book [Internet]. Springer; Cham (CH): Mar 21, 2018. pp. 21–33. [PubMed: 31314373] 9.Rosa P, Pidhorecky I. A Case of Intravenous Leiomyomatosis with Involvement of a Renal Vein. Ann Vasc Surg. 2018 Nov;53:271.e11-271.e13. [PubMed: 30092420] 10.Paul PG, Gulati G, Shintre H, Mannur S, Paul G, Mehta S. Extrauterine adenomyoma: a review of the literature. Eur J Obstet Gynecol Reprod Biol. 2018 Sep;228:130-136. [PubMed: 29940416] 11.Pääkkö E, Niinimäki M. Diagnostics of endometriosis by using magnetic resonance imaging. Duodecim. 2017;133(1):61-7. [PubMed: 29200236] Where is uterus located left or right?In humans the uterus is located within the pelvic region immediately behind and almost overlying the bladder, and in front of the sigmoid colon. The human uterus is pear-shaped and about 7.6 cm (3.0 in) long, 4.5 cm (1.8 in) broad (side to side), and 3.0 cm (1.2 in) thick. A typical adult uterus weighs about 60 grams.
Where do I press to feel my uterus?Walk your fingers up the side of her abdomen (Figure 10.1) until you feel the top of her abdomen under the skin. It will feel like a hard ball. You can feel the top by curving your fingers gently into the abdomen. Figure 10.1 With the woman lying on her back, begin by finding the top of the uterus with your fingers.
Where is uterus located early pregnancy?Uterus. The uterus, or womb, is a hollow, pear-shaped organ ln a woman's lower stomach between the bladder and the rectum. It sheds its lining each month during menstruation. A fertilized egg (ovum) becomes implanted in the uterus, and the fetus develops.
Where does your uterus sit when not pregnant?Your Body Before Pregnancy
In its normal position, your uterus is above and behind the bladder, with the cervix protruding into the vagina.
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