Chapter 2 – The Cervix

Summary of chapter

The cervix is the lower part of the uterus. In a non-pregnant woman it is typically 2.5cm long and forms a narrow canal, which separates the upper genital tract from the lower genital tract. The proximal end of this canal communicates with the uterus via the internal os, and the distal end opens into the vagina at the external os. The external os may appear as a tight circular aperture in nulliparous women, and more of a transverse slit following childbirth.(1)

The cervix can be divided into 2 parts: (see Figure 2.1)

The Endocervix – the inner part of the cervical canal, lined with columnar epithelium. The Ectocervix – the more distal part of the cervix that protrudes into the vagina and is covered by non-keratinised stratified squamous epithelium.

Between these two parts is the squamocolumnar junction or transformation zone, where there is progression of epithelial cells undergoing metaplastic change. It is in this zone where squamous cell carcinoma of the cervix tends to arise.(2)

Figure 2.1 The Ectocervix and Endocervix

Reproduced by permission of Jo’s Cervical Cancer Trust. The Cervix [Internet]. Updated 2016 Oct 20. Available from: ... Buy now