Uterus

This article is about female reproductive anatomy. For the nightclub in Shibuya, Tokyo, see Womb (nightclub).

Uterus
Female internal reproductive anatomy
1. Round ligament 2. Uterus 3. Uterine cavity 4. Intestinal surface of Uterus 5. Versical surface(toward bladder) 6. Fundus of uterus 7. Body of uterus 8. Palmate folds of cervical canal 9. Cervical canal 10. Posterior lip 11. Cervical os (external) 12. Isthmus of uterus 13. Supravaginal portion of cervix 14. Vaginal portion of cervix 15. Anterior lip 16. Cervix
Gray\'s	subject #268 1258
Artery	ovarian artery, uterine artery, helicine branches of uterine artery
Lymph	body and cervix to internal iliac lymph nodes, fundus to superficial inguinal lymph nodes
Precursor	Müllerian duct
MeSH	Uterus

The uterus (from the Latin for womb) is the major female reproductive organ of most mammals, including humans. One end, the cervix, opens into the vagina; the other is connected on both sides to the fallopian tubes. The term uterus is commonly used within the medical and related professions, whilst womb is in more common usage. The plural of uterus is uteri.

Contents 1 Function 2 Forms in mammals 3 Anatomy 3.1 Regions 3.2 Layers 3.3 Support 3.3.1 Major ligaments 3.4 Position 4 Development 5 Pathology 6 Additional images 7 References 8 See also 9 External links

Function

The main function of the uterus is to accept a fertilized ovum which becomes implanted into the endometrium, and derives nourishment from blood vessels which develop exclusively for this purpose. The fertilized ovum becomes an embryo, develops into a fetus and gestates until childbirth. Due to anatomical barriers such as the pelvis, the uterus is pushed partially into the abdomen due to its expansion during pregnancy. Even in pregnancy the mass of a human uterus amounts to only about a kilogram (2.2 pounds).

Forms in mammals

In mammals, the four main forms in which it is found are:

Bipartite  

Found in ruminants (cattle, goats, sheep, camels, llamas, giraffes, bison, buffalo, deer, etc.).

Bicornuate 

Found in pigs, cats, and dogs.

Simplex  

Found in humans, other primates and horses.

Duplex  

Found in rodents (such as mice, rats and guinea pigs), marsupials and lagomorpha (rabbits and hares).

Anatomy

The uterus is located inside the pelvis immediately dorsal (and usually somewhat rostral) to the urinary bladder and ventral to the rectum. Outside of pregnancy, its size in humans is several centimeters in diameter. The uterus is a pear shaped muslcular organ which can be divided anatomically into four segments: The fundus, corpus, cervix and the internal os.

Regions

From outside to inside, the path to the uterus is as follows:

• Vulva
• Vagina
• Cervix uteri - "neck of uterus"
  • External orifice of the uterus
  • Canal of the cervix
  • Internal orifice of the uterus
• corpus uteri - "Body of uterus"
  • Cavity of the body of the uterus
  • Fundus (uterus)

Layers

The layers, from innermost to outermost, are as follows:

Endometrium 

The lining of the uterine cavity is called the "endometrium." In most mammals, including humans, the endometrium builds a lining periodically which, if no pregnancy occurs, is shed or reabsorbed. Shedding of the endometrial lining in humans is responsible for menstrual bleeding (known colloquially as a woman\'s "period") throughout the fertile years of a female and for some time beyond. In other mammals there may be cycles set as widely apart as six months or as frequently as a few days.

Myometrium 

The uterus mostly consists of smooth muscle, known as "myometrium." The innermost layer of myometrium is known as the junctional zone, which becomes thickened in adenomyosis.

Perimetrium 

The loose surrounding tissue is called the "perimetrium."

Peritoneum 

The uterus is surrounded by "peritoneum."

Support

The uterus is primarily supported by the pelvic diaphragm and the urogenital diaphragm. Secondarily, it is supported by ligaments and the peritoneum (broad ligament of uterus) The Pelvis University College Cork

Major ligaments

It is held in place by several peritoneal ligaments, of which the following are the most important (there are two of each):

Name	From	To
uterosacral ligament	the posterior cervix	the sacrum of pelvis
cardinal ligaments	the side of the cervix	the ischial spines
pubocervical ligament

Other named ligaments near the uterus, i.e. the broad ligament, the round ligament, the suspensory ligament of the ovary, the infundibulopelvic ligament, have no role in the support of the uterus.

Position

Under normal circumstances the uterus is both "anteflexed" and "anteverted." The meaning of these terms are described below:

Distinction	More common	Less common
Position tipped	"anteverted": tipped forward	"retroverted": tipped backwards
Position of fundus	"anteflexed": the fundus is pointing forward relative to the cervix	"retroflexed": the fundus is pointing backwards

Development

The bilateral Müllerian ducts form during early fetal life. In males, MIF secreted from the testes leads to their regression. In females these ducts give rise to the Fallopian tubes and the uterus. In humans the lower segments of the two ducts fuse to form a single uterus, however, in cases of uterine malformations this development may be disturbed. The different uterine forms in various mammals are due to various degrees of fusion of the two Müllerian ducts.

Pathology

Some pathological states include:

• Prolapse of the uterus
• Carcinoma of the cervix – malignant neoplasm
• Carcinoma of the uterus – malignant neoplasm
• Ectopic pregnancy
• Fibroids – benign neoplasms
• Adenomyosis – ectopic growth of endometrial tissue within the myometrium
• Pyometra – infection of the uterus, most commonly seen in dogs
• Uterine malformation
• Uterine Didelphys – split or doubled vagina/uterus
• Retroverted uterus
• Rokitansky syndrome
• Myoma

Additional images

Scheme female reproductive system-en.svg Schematic frontal view of female anatomy	Illu cervix.jpg Uterus and uterine tubes.	Illu icd o codes.jpg	Anatomical model of a human pregnancy
Gray34.png Sectional plan of the gravid uterus in the third and fourth month.	Gray38.png Fetus in utero, between fifth and sixth months.	Gray589.png Vessels of the uterus and its appendages, rear view.	Gray1161.png Uterus and right broad ligament, seen from behind.
Gray1165.png Female pelvis and its contents, seen from above and in front.	Gray1166.png Sagittal section of the lower part of a female trunk, right segment.	Gray1167.svg Posterior half of uterus and upper part of vagina.	Gray1170.png The arteries of the internal organs of generation of the female, seen from behind.
Gray1230.png Median sagittal section of female pelvis.

References

See also

• Myometrium
• Egg (ovum)
• Ovary
• Menopause
• Vulva
• Vagina
• Penis
• Uterine glands

External links

Look up Uterus in
Wiktionary, the free dictionary.

• Gray\'s s268
• Illustration at wku.edu
• SUNY Labs 43:01-0102 - "The Female Pelvis: Organs in the Female Pelvis in situ"

v • d • e Female reproductive system
Follicles/Folliculogenesis	corpus (hemorrhagicum, luteum, albicans) • Theca folliculi (externa, interna) • Follicular antrum (Follicular fluid) • Corona radiata • Zona pellucida • Membrana granulosa (Granulosa cells)
Ovaries/Oogenesis	Germinal epithelium • Tunica albuginea • cortex (Cumulus oophorus, Stroma) • Medulla
Fallopian tubes	Isthmus • Ampulla • Infundibulum • Fimbria
Ligaments	Broad (components: Mesovarium, Mesosalpinx, Mesometrium contents: Round of uterus, Proper of ovary) • Suspensory of ovary • Cardinal
Uterus	cervix/neck (External orifice - Canal of the cervix, Internal orifice) • corpus/body (Cavity of the body, Fundus) • layers (Endometrium, Myometrium, Perimetrium) • Uterine horns
Vulva/mons pubis	Labium: commissures (Anterior • Posterior) • Frenulum labiorum pudendi • Labia majora • Cleft of venus • Labia minora • Vulval vestibule • interlabial sulci Clitoris: Vestibular bulbs • Clitoral crura • Corpus cavernosa • Clitoral glans (Frenulum, Hood) Vagina: vestibular glands/ducts (Bartholin\'s glands/Bartholin\'s ducts, Skene\'s glands/Skene\'s ducts) • Fossa of vestibule of vagina • Vaginal fornix • Hymen • Orifice
Vestiges	Wolffian (Gartner\'s duct, Epoophoron, Paroöphoron) • Canal of Nuck
Other	G-spot • Urethral sponge

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