| Cervical canal | |
|---|---|
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| Details | |
| Synonym | Canal of the cervix, endocervical canal, cervical canal of uterus, cavity of cervix |
| Identifiers | |
| Latin | canalis cervicis uteri |
| TA98 | A09.1.03.018 |
| TA2 | 3515 |
| FMA | 86485 |
| Anatomical terminology | |
The cervical canal is the spindle-shaped, flattened canal of the cervix which connects the vagina to the main cavity of the uterus in most mammals.
The cervical canal communicates with the uterine cavity via the internal orifice of the uterus (or internal os) and with the vagina via the external orifice of the uterus (ostium of uterus or external os). The internal orifice of the uterus is an interior narrowing of the uterine cavity. It corresponds to a slight constriction known as the isthmus that can be seen on the surface of the uterus about midway between the apex and base. The external orifice of the uterus is a small, depressed, somewhat circular opening on the rounded extremity of the cervix, opening to the vagina. Through this aperture, the cervical cavity communicates with that of the vagina.
The external orifice is bounded by two lips, an anterior and a posterior. The anterior is shorter and thicker, though it projects lower than the posterior because of the slope of the cervix. Normally, both lips are in contact with the posterior vaginal wall. Prior to pregnancy, the external orifice has a rounded shape when viewed through the vaginal canal (as through a speculum). Following childbirth, the orifice takes on an appearance more like a transverse slit or is "H-shaped".
The wall of the canal presents an anterior and a posterior longitudinal ridge, from each of which proceed a number of small oblique columns, the palmate folds, giving the appearance of branches from the stem of a tree; to this arrangement the name arbor vitae uteri is applied.
The folds on the two walls are not exactly opposed, but fit between one another so as to close the cervical canal.
The cervical canal is generally lined by "endocervical mucosa" which consists of a single layer of mucinous columnar epithelium. However, after menopause, the functional squamocolumnar junction moves into the cervical canal, and hence the distal part of the cervical canal may be lined by stratified squamous epithelium (conforming to a "type 3 transformation zone"). [2]
The endocervical mucosa is a site from which adenocarcinoma can arise. Endocervical adenocarcinoma, like cervical cancer (squamous cell carcinoma), often arises in the milieu of human papillomavirus infection. [3]
As most endometrial cancers are adenocarcinomas, differentiation of endocervical adenocarcinoma and endometrial adenocarcinomas is required, as the treatment differs. Immunohistochemical staining is often helpful in this regard, endocervical adenocarcinomas are typically CEA and p16 positive and estrogen receptor, progesterone receptor and vimentin negative.
The cervix or cervix uteri is a dynamic fibromuscular organ of the female reproductive system that connects the vagina with the uterine cavity. The human cervix has been documented anatomically since at least the time of Hippocrates, over 2,000 years ago[citation needed]. The cervix is approximately 4 cm long with a diameter of approximately 3 cm and tends to be described as a cylindrical shape, although the front and back walls of the cervix are contiguous. The size of the cervix changes throughout a women's life cycle. For example, during their fertile years of the reproductive cycle, females tend to have a larger cervix vis á vis postmenopausal females; likewise, females who have produced offspring have a larger sized cervix than females who have not produced offspring.
The endometrium is the inner epithelial layer, along with its mucous membrane, of the mammalian uterus. It has a basal layer and a functional layer: the basal layer contains stem cells which regenerate the functional layer. The functional layer thickens and then is shed during menstruation in humans and some other mammals, including other apes, Old World monkeys, some species of bat, the elephant shrew and the Cairo spiny mouse. In most other mammals, the endometrium is reabsorbed in the estrous cycle. During pregnancy, the glands and blood vessels in the endometrium further increase in size and number. Vascular spaces fuse and become interconnected, forming the placenta, which supplies oxygen and nutrition to the embryo and fetus. The speculated presence of an endometrial microbiota has been argued against.
The uterus or womb is the organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic and fetal development of one or more embryos until birth. The uterus is a hormone-responsive sex organ that contains glands in its lining that secrete uterine milk for embryonic nourishment.
In mammals and other animals, the vagina is the elastic, muscular reproductive organ of the female genital tract. In humans, it extends from the vestibule to the cervix. The outer vaginal opening is normally partly covered by a thin layer of mucosal tissue called the hymen. At the deep end, the cervix bulges into the vagina. The vagina allows for copulation and birth. It also channels menstrual flow, which occurs in humans and closely related primates as part of the menstrual cycle.
Endometrial cancer is a cancer that arises from the endometrium. It is the result of the abnormal growth of cells that have the ability to invade or spread to other parts of the body. The first sign is most often vaginal bleeding not associated with a menstrual period. Other symptoms include pain with urination, pain during sexual intercourse, or pelvic pain. Endometrial cancer occurs most commonly after menopause.
Antepartum bleeding, also known as antepartum haemorrhage (APH) or prepartum hemorrhage, is genital bleeding during pregnancy after the 28th week of pregnancy up to delivery.
An endometrial polyp or uterine polyp is a mass in the inner lining of the uterus. They may have a large flat base (sessile) or be attached to the uterus by an elongated pedicle (pedunculated). Pedunculated polyps are more common than sessile ones. They range in size from a few millimeters to several centimeters. If pedunculated, they can protrude through the cervix into the vagina. Small blood vessels may be present, particularly in large polyps.
A bicornuate uterus or bicornate uterus, is a type of müllerian anomaly in the human uterus, where there is a deep indentation at the fundus (top) of the uterus.
A nabothian cyst is a mucus-filled cyst on the surface of the cervix. They are most often caused when stratified squamous epithelium of the ectocervix grows over the simple columnar epithelium of the endocervix. This tissue growth can block the cervical crypts, trapping cervical mucus inside the crypts.
Cervical ectropion is a condition in which the cells from the 'inside' of the cervical canal, known as glandular cells, are present on the 'outside' of the vaginal portion of the cervix. The cells on the 'outside' of the cervix are typically squamous epithelial cells. Where the two cells meet is called the transformation zone, also known as the stratified squamous epithelium. Cervical ectropion can be grossly indistinguishable from early cervical cancer and must be evaluated by a physician to determine risks and prognosis. It may be found incidentally when a vaginal examination is done. The area may look red because the glandular cells are red. While many women are born with cervical ectropion, it can be caused by a number of reasons, such as:
Vaginal cancer is an extraordinarily rare form of cancer that develops in the tissue of the vagina. Primary vaginal cancer originates from the vaginal tissue – most frequently squamous cell carcinoma, but primary vaginal adenocarcinoma, sarcoma, and melanoma have also been reported – while secondary vaginal cancer involves the metastasis of a cancer that originated in a different part of the body. Secondary vaginal cancer is more common. Signs of vaginal cancer may include abnormal vaginal bleeding, dysuria, tenesmus, or pelvic pain, though as many as 20% of women diagnosed with vaginal cancer are asymptomatic at the time of diagnosis. Vaginal cancer occurs more frequently in women over age 50, and the mean age of diagnosis of vaginal cancer is 60 years. It often can be cured if found and treated in early stages. Surgery alone or surgery combined with pelvic radiation is typically used to treat vaginal cancer.
Hematometra is a medical condition involving collection or retention of blood in the uterus. It is most commonly caused by an imperforate hymen or a transverse vaginal septum.
A vaginal disease is a pathological condition that affects part or all of the vagina.
A cervical mucus plug (operculum) is a plug that fills and seals the cervical canal during pregnancy. It is formed by a small amount of cervical mucus that condenses to form a cervical mucus plug during pregnancy.
Neuroendocrine carcinoma of the cervix is best defined separately:Neuroendocrine: Of, relating to, or involving the interaction between the nervous system and the hormones of the endocrine glands.Carcinoma: An invasive malignant tumor derived from epithelial tissue that tends to metastasize to other areas of the body.
Cervical cancer staging is the assessment of cervical cancer to determine the extent of the spread of cancer beyond the cervix. This is important for determining how serious the cancer is and to create the best treatment plan.
Hysterosalpingography (HSG), also known as uterosalpingography, is a radiologic procedure to investigate the shape of the uterine cavity and the shape and patency of the fallopian tubes. It is a special x-ray procedure using dye to look at the womb (uterus) and fallopian tubes. In this procedure, a radio-opaque material is injected into the cervical canal, and radiographs are taken. A normal result shows the filling of the uterine cavity and the bilateral filling of the fallopian tube with the injection material. To demonstrate tubal patency, spillage of the material into the peritoneal cavity needs to be observed. Hysterosalpingography has vital role in treatment of infertility, especially in the case of fallopian tube blockage.
Müllerian duct anomalies are those structural anomalies caused by errors in Müllerian duct development during embryonic morphogenesis. Factors that precipitate include genetics, and maternal exposure to teratogens.
Microglandular hyperplasia (MGH) of the cervix is an epithelial benign abnormality (lesion) associated with gland proliferation. It can terminate in mature squamous metaplasia, and it is suspected reserve cells are involved in this process, perhaps in the form of reserve cell hyperplasia with glandular differentiation.
The vaginal epithelium is the inner lining of the vagina consisting of multiple layers of (squamous) cells. The basal membrane provides the support for the first layer of the epithelium-the basal layer. The intermediate layers lie upon the basal layer, and the superficial layer is the outermost layer of the epithelium. Anatomists have described the epithelium as consisting of as many as 40 distinct layers of cells. The mucus found on the epithelium is secreted by the cervix and uterus. The rugae of the epithelium create an involuted surface and result in a large surface area that covers 360 cm2. This large surface area allows the trans-epithelial absorption of some medications via the vaginal route.
This article incorporates text in the public domain from page 1260 of the 20th edition of Gray's Anatomy (1918)
