Cervix

Cervix uteri

ReproductiveOrgansPelvis

View in 3D

Shown on the female body.

What it is

Narrow, firm lower third of the uterus; its lower part projects into the top of the vagina and carries the small external os.

Function

Keeps the uterus closed with a mucus plug whose consistency changes through the cycle, then softens and dilates to about 10 cm in labour.

Size

About 2.5–3 cm long and 2.5 cm across.

Clinical note

The transformation zone at the external os is where HPV-related cervical cancer starts, which is why it is sampled in screening (Pap/HPV test).