cervical canal, the canal within the uterine cervix, which protrudes into the vagina. The uterine end of the canal is closed at the internal os and, in the nullipara, at the distal end by the external os. The canal is a passageway through which the menstrual flow escapes and, vastly dilated and effaced by labor, through which the infant must pass to be delivered vaginally. Various diagnostic and therapeutic procedures require dilation of the muscular cervix surrounding the canal, including endometrial biopsy, suction and surgical curettage, and radium implantation. Pelvic inflammatory disease is the result of the entry of pathogenic bacteria into the uterus through the cervical canal. Sperm must travel upward through the canal to reach the uterus and fallopian tubes.
