| 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 | |
Thecervical canal is the spindle-shaped, flattenedcanal of thecervix which connects thevagina to the main cavity of theuterus in most mammals.
The cervical canal communicates with theuterine cavity via theinternal orifice of the uterus (orinternal os) and with thevagina via theexternal orifice of the uterus (ostium of uterus orexternal os). The internal orifice of the uterus is an interior narrowing of the uterine cavity. It corresponds to a slight constriction known as theisthmus that can be seen on the surface of theuterus 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 thecervix, 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 aspeculum). Followingchildbirth, 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, thepalmate folds, giving the appearance of branches from the stem of a tree; to this arrangement the namearbor 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.
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The cervical canal is generally lined by "endocervical mucosa" which consists of a single layer of mucinous columnar epithelium. However, after menopause, the functionalsquamocolumnar 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 whichadenocarcinoma can arise. Endocervical adenocarcinoma, like cervical cancer (squamous cell carcinoma), often arises in themilieu ofhuman papillomavirus infection.[3]
As mostendometrial 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 typicallyCEA andp16 positive andestrogen receptor,progesterone receptor andvimentin negative.
This article incorporates text in thepublic domain frompage 1260 of the 20th edition ofGray's Anatomy(1918)
