Orificium internum uteri, alternatively known as the internal orifice of the uterus, is a defined anatomical term used in gynecology and reproductive medicine. It refers to the opening of the uterine cavity into the cervical canal, which is the passageway that connects the uterus with the vagina.
Located within the cervix, the orificium internum uteri serves as the lower entrance to the uterus and marks the boundary between the uterine cavity and the cervical canal. This narrow channel is lined with specialized cells known as the cervical epithelium, which secrete mucus and undergo changes during different stages of the menstrual cycle and pregnancy.
The orificium internum uteri plays a crucial role in various reproductive processes. For instance, during menstruation, the cervix constricts, partially closing the orifice to prevent blood from flowing back into the uterus. Conversely, during ovulation, the orifice relaxes and loosens to allow the passage of sperm through the cervical canal and into the uterus, enabling fertilization.
This anatomical structure is of particular interest and importance in obstetrics and gynecology, as it can affect fertility, contraception, and the progress of labor. Abnormalities or disorders in the orificium internum uteri, such as stenosis (narrowing) or incompetence (inability to stay closed during pregnancy), may require medical intervention or treatment.
