The cervix is located at the bottom of the uterus and protects it from bacterial infiltration. It is the location of a critical epithelial transition. The lining of the upper cervix (endocervix) is a simple columnar epithelium that contains mucous-secreting cells. The lower cervix, on the other hand, is lined by a stratified squamous epithelium. The external os is the transition point between these two epithelia. It is worth noting that the underlying layers of the cervix are primarily made up of collagenous and elastic connective tissue rather than smooth muscle fibers.