What is the extension of the vaginal lumen around the intravaginal part of the uterine cervix?

Fornix

The cervix is the inferior end of the uterus that projects into the vagina. This means that the vagina comes up and wraps around the cervix, creating the vaginal fornix. There are multiple fornices at the top of the vagina: anterior, posterior, and lateral. The cervical canal is the passageway through the cervix to the vagina. The uterine lumen is the hollow center of the uterus. The rectouterine and uterovesicular pouches are two peritoneal folds found in the pelvic cavity. The rectouterine pouch is a peritoneal fold extending across the floor of the pelvic cavity from the sacrum (beside the rectum) to the uterus. The uterovesicular pouch is a peritoneal fold extending from the uterus to the bladder.