The cervix (from the Latin cervix uteri, meaning "neck of the womb") is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall. The cervix is made of cartilage covered by smooth, moist tissue, and it is about 1 inch across. Approximately half its length is visible with appropriate medical equipment; the remainder lies above the vagina beyond view. The cervix has an opening to allow sperm and menstrual fluid to move through. The cervix produces cervical mucus, % 90 water, which changes in consistency during the menstrual cycle to prevent or promote pregnancy.